CA1217652A - Drilling fluid gas testing system and method - Google Patents
Drilling fluid gas testing system and methodInfo
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- CA1217652A CA1217652A CA000467222A CA467222A CA1217652A CA 1217652 A CA1217652 A CA 1217652A CA 000467222 A CA000467222 A CA 000467222A CA 467222 A CA467222 A CA 467222A CA 1217652 A CA1217652 A CA 1217652A
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Abstract
DRILLING FLUID GAS TESTING SYSTEM AND METHOD
Abstract of the Disclosure An apparatus and an associated method are provided for substantially continuously measuring and monitoring the relative concentration of combustible gases contained within the drilling mud that returns to the earth surface of an earth borehole while it is being drilled by a drilling rig employing liquid drilling fluid or mud to transport the cuttings, The apparatus includes a means to continuously extract a gas sample from the returning drilling mud flow and supply the sample to a measuring device where the relative concentration of combustible gas is measured and an electrical output signal produced. The electrical output signal is used to derive an electrical data signal repre-sentative of the relative concentration of combustible gases in the gas sample. A numerical representation of the electrical data signal is displayed for interpretation by the drilling rig operator. In the method of this invention.
the gas sample is taken from a flow of drilling mud at the earth surface and passed through the measuring device that includes a catalytic sensor to produce an electrical output signal. The sensor output signal is used to derive an electrical data signal that is processed to derive a numerical display indicative of the relative combustible gas concentration in the drilling mud.
Abstract of the Disclosure An apparatus and an associated method are provided for substantially continuously measuring and monitoring the relative concentration of combustible gases contained within the drilling mud that returns to the earth surface of an earth borehole while it is being drilled by a drilling rig employing liquid drilling fluid or mud to transport the cuttings, The apparatus includes a means to continuously extract a gas sample from the returning drilling mud flow and supply the sample to a measuring device where the relative concentration of combustible gas is measured and an electrical output signal produced. The electrical output signal is used to derive an electrical data signal repre-sentative of the relative concentration of combustible gases in the gas sample. A numerical representation of the electrical data signal is displayed for interpretation by the drilling rig operator. In the method of this invention.
the gas sample is taken from a flow of drilling mud at the earth surface and passed through the measuring device that includes a catalytic sensor to produce an electrical output signal. The sensor output signal is used to derive an electrical data signal that is processed to derive a numerical display indicative of the relative combustible gas concentration in the drilling mud.
Description
DRILLING FLUID GAS TESTING SYSTEM AND METHOD
Background of the Invention _ _ _ _ This invention is related to the automated testing of earth Barlow drilling fluid fox the content of combs-- 5 title gas that is returning to the earth surface during the drilling operation.
In the prior art such testing for combustible gas concentrations in returning drilling fluids has been done by physically removing a sample of the returning drilling mud in a small container and placing the container in an instrument that operates to extract gaseous material from the sample and analyze it for the presence of one or more combustible gases. In this testing, the sample must be taken by an individual and inserted into the testing apparatus then aster the testing is complete the sample removed and the equipment cleaned and prepared for testing a subsequent mud sample. Use of this equipment and prove-dune is cun~ersome in that a technician must physically remove the sample and perform -the testing procedures.
While this might be quite acceptable for an occasional test the mud's condition it is tedious, awkward and extremely expensive for a continuous operation that would follow a continuous twenty four hour per day drilling operation.
One object of this invention is to provide an I apparatus and an ass wilted method that overcome the aforementioned disadvantage of the prior art equipment and procedures Still, another object of this invention is to provide a system for measuring the relative concentration of combustible gases in the returning drilling mud from an earth Barlow drilling operation wherein the apparatus can be operated on a substantially continuous basis and provide a numerical indication of the relative gas concentration to the drilling rig operator and also provide the same information for recording or transmittal to a remote location for reporting.
Specifically, the invention relates to a system for measuring the relative gas concentration in drilling mud returning to the earth surface from an earth Barlow while being drilled, comprising: a means to continuously extract a gas sample from a return mud flow of a drilling rig; means receiving the was sample in a gas sample flow stream to measure the relative concentration of combustible gases in the gas sample including a catalytic sensor with a differential electrical signal output; means to sample the electrical signal output and derive an electrical data signal representative of the relative combustible gas content of the gas sample; means connected to the means to sample to display a numerical representation of the electrical data signal for interpretation by a drilling rig operator or the like.
In its method aspect the invention relates to a method of measuring the relative combustible gas concentration of gas carried in drilling mud returning to the earth surface from an earth Barlow while it is being drilled, comprising the steps of: taking a gas sample from a flow of drilling mud at the earth surface, passing the gas sample through a means to measure having a catalytic sensor measuring the relative combustible gas concentration of the gas sample and producing a sensor electrical output signal representative of the relative combustible gas concentration in the gas sample; sampling the sensor electrical output signal to derive an electrical data signal representative of the relative combustible gas concentration of the gas sample and processing the electrical data signal to derive and display a numerical value representative of the relative combustible gas concentration in the drilling mud.
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Various other advantages and features of this invention will become apparent to those skilled in the art from the following discussion taken in conjunction with the accompanying drawing, in which:
Description of the Drawing The sole drawing is a pictorial diagram illustrating in schematic form the system of this invention and including a drilling mud flow solid separator with a gas collecting device connected to the gas sampling and testing apparatus, and connected to a numerical display, a recorder and a device for transmission to a remote location The following is a discussion and description of preferred specific embodiments of the system, apparatus and method of this invention, such being made with reference to the drawing whereupon the same reference numerals are used to indicate the same or similar parts and/or structure. It is to be understood that this discussion and description is not to unduly limit the scope of the invention.
Detailed Description The gas testing system of this invention is shown in the pictorial diagram of Fig. 1 and it includes several general components that function together to form the complete system.
The gas sample extractor lo collects a sample of gas from the drilling mud of an earth Barlow drilling rig and communicates the sample into a gas handling conduit system, indicated generally at 12, where it is cooled, heated and tested for combustible gas content that exhaust -into the atmosphere. An electronic circuit, indicated generality 14, is connected to several elements of the gas handling conduit system to control their operation and receive data therefrom with the output of the electronic circuit being to a display devices, indicated - pa -oh I
generally at 16. The display devices include an output for the drilling rig operator to watch, a recording device, and if required the capability ox presenting the information for transmission to a remote monitoring and/or recording 5 location.
In extracting the gas sample from the drilling mud this is done at the earth surface at a location relatively close to the point at which the drilling mud exits the annular return flow passage of the Barlow and before the 10 mud is returned to the Barlow. In a typical drilling rig a mud flow conduit 18 deposits drilling mud into a solids separator device, indicated generally at 20, which is known in the trade as a "shale Shaker The solids separator 20 includes a tank 22 that has a vibrating screen 24 mounted 15 therein. Mud flow from conduit 18 is onto the top of screen 24 whereupon it flows across the screen in a relatively thin layer as indicated at 26. This flow moves from the screen 24 forming a curtain 28 of drilling mud between the end of screen 24 and the residual quantity of mud 30 residing in the bottom portion of tank 22. Mud flow curtain 28 forms substantially an inclined wall of mud flowing between the end of screen 26 and the residual mud level 30~ Sample extractor 10 includes a generally conically shaped hood 32 resembling a funnel with the enlarged portion downward and I the smaller portion extentind upward and joining a support conduit 34. The upper end portion of support conduit 34 is connected by a gas sample transfer conduit 36 connecting it with gas sample handling conduit system 12. The position of hood 32 is preferably generally positioned as illustrated with the inlet or most enlarged portion thereof positioned above shale shaker screen 24 with support conduit 34 extend in upward therefrom. The inlet of hood 32 is placed with its inlet below the normal mud flow level over screen 24 so the mud will contact the exterior of hood 32 and flow around it while roving over the screen. This somewhat contains yes as it leaves -the mud and provides a substantially undiluted gas sample flow for testing and analysis.
The gas handling conduit system 12 receives the to gas sample flow in transfer conduit 36. The gas sample flow is moved by a main yes sample pump 38. Movement of the gas sample flow is detected by a pressure switch 40 connected in fluid communication with a conduit from the output of pump 38. A flow indicating a light emitting diode functioning as an indicating lamp is connected with pressure switch 40 and positive an negative voltage sources from a power supply (not shown) to signal an operator that gas flow is present in this system.
When a gas sample is extracted it may contain a certain quantity of liquid or liquefiable elements that are preferably removed prior to testing and in order to prevent damage to the apparatus. For this purpose a condenser having a cooling coil 44 is connected to the output of pump 38. Cooling coil 44 is exposed to a flow of preferably cooler than ambient air. The output of cooling coil 44 is connected to the input of a coalescing filter 46 where condensation of extraneous liquid material can occur and this material can be removed from the jilter periodically as desired. Coalescing filter 46 is provided with a gas sample exhaust and with a gas sample outlet. A gas sample exhaust is used to exhaust to the atmosphere a portion of the extracted gas sample that will not be used in the actual sampling or testing process. The typical flow of gas through pump 38 is substantially in excess of that needed in the measuring or testing portion of this system In order to insure a flow of recently extracted sample gas for the measuring and testing procedures the quantity of sample extracted is in excess of that actually needed for the test and the unused quantity of gas is discarded through unused sample exhaust 48.
The gas outlet from coalescing filter 46 is connected to a heating coil 50 where the gas sample flow is heated so any remaining moisture or liquid materials therein will remain in gaseous suspension until the measuring and testing procedure is completed end the analyzed gas sample is exhausted to the atmosphere. The output of heating coil 50 is connected to a gas sample flow dilution circuit used for dilution of the gas sample with air when the gas sample . .
I
contains high concentrations of combustible materials The gas sample flow dilution circuit has an air dilution inlet valve 52 in a loop with a metering valve to admit air and mix it with the gas sample in a predetermined ratio This dilution valve 52 is a two position valve with its inlet connected to the outlet of heating coil 50 and the valve's outlet connected to dilution valve outlet conduit 54. A
valve bypass look includes a valve bypass loop conduit 56 connected in fluid communication with both the inlet and the outlet conduits to dilution valve 52 with a metering or control valve 58 mounted therein. A dilution air inlet Z0 is provided to admit air into the gas sample handling conduit system. Dilution air inlet 60 is connected to a flow indicator 62 that it in turn connected to a second inlet ox dilution valve 52.
With dilution valve 52 positioned as shown gas sample flow is through conduit 54 with a very small portion of the gas sample flow through conduit 56. With dilution valve 52 shifted to the other position gas sample flow through conduit 54 is blocked and the gas sample flow is directed through conduit 56 and metering valve 58. Air is admitted through dilution air inlet 60 and dilution valve 52 into conduit 54 so the concentration of the gas sample downstream of the junction of conduit 54 and conduit loop 56 is diluted with air. Metering valve 58 is used to adjust the dilution mixture of the gas sample The outlet from the dilution circuit is through conduit 54 joining one inlet of a purge valve 64.
Purge valve 64 is a two position valve used for a purging cycle in conjunction with initializing the combs-title gas concentration measuring device. The second inlet of purge valve 64 is connected to an air inlet 66. With purge valve 64 positioned us shown gas sample flow is through the valve prom one inlet to the outlet and into the housing of the was simple testing device 70. When purge valve 64 is actuated to be displaced to its second position the previous gas sample flow through the valve is blocked and air inlet 66 is introduced into the gas sample flow stream exclusively. Purge value 64 is use for an '7~;5~
initializing procedure to be described in the following.
The gas sample tester or combustible gas concern-traction measuring device includes a chamber containing two sets of beads made of a catalytic material and mounted with heating elements 72 and 74. The heating elements are resistive type heating elements that are closely associated with the catalytic beads and joined in a series or end to end fashion. The heating elements warm the catalytic beads so their temperature is elevated sufficiently that a gala-lyric reaction will be formed with combustible gases contained within the gas sample flow. When the gas sample has a quantity of combustible material a catalytic reaction will be formed and the beads will generate additional heat whereupon the resistive heating elements will measurably change in resistance. This measurable change is used in an electrical bridge type circuit to derive a relative indication of combustible gas content in the gas sample flow. Electrical conductor 76 joins one end of bead hefting element 74, and electrical conductor 80 joins the junction of the bead heating elements 72 and 74.
Sample pump 82 is connected to the outlet of the sample tester housing and used to pull the gas sample through the preceding conduit portions of the system from coalescing filter 46. The outlet of sample pump 82 is connected to the inlet of a flow indicator 84 with the output of flow indicator 84 bring exhausted to the atoms phone. Flow indicator 84 is an operational indicator to provide a technician an indication of the flow of gaseous material through sample pump 82. The exhaust from flow indicator 84 can be simply discharged to the atmosphere or to any suitable apparatus for discarding such samples.
Electronic circuits 14 are shown contained within a dashed line box. Generally, the electronic circuit includes a whetstone bridge to operate with the heating elements in sample tester 70, associated instrumentation amplifiers, an zeroing or initializing and referencing circuit, and a scaling and output circuit with the outputs to devices or visual display, recording and transmission to I a remote location "I
I
Sample tester 70 has both of its heating element-resistor elements I and 74 connected to the electronic circuit by wires 76, 78 and 80 as illustrated. Wires 76 and 78 are connected in series with a balance bridge resistor 90. Positive voltage is applied to one side of the bridge as illustrated from a power supply. Balance bridge resistor 90 is a variable resistor with the wiper 92 connect-d as one input to an instrumentation amplifier 94. Two elements of the bridge circuit are formed by the lo catalytic bead heating elements 72 and 74 and these are connected to bridge balance resistor 90 so that portions of the resistor on either side of wiper 92 form the other pair of bridge resistive elements. The center connection of the catalytic bead heating elements is joined by wire 80 with a second input of instrumentation amplifier 94.
Instrumentation amplifier 94 is a differential amplifier with two inputs and a Nolan voltage input. Initially balance resistor 90 is adjusted for a zero output from amplifier 94 for a condition with sample tester 70 exposed to air that does not contain combustible gasps. When combustible gases pass through sample tester 70 the resistance of catalytic bead heaving elements 72 and 74 changes due to the catalytic heating effect. This change in resistance will result in a different -total resistance across both of the heating elements and at its center junction. This change results in a different voltage across bridge balance resistor 90 and at its wiper. The bridle resistor wiper voltage and the heating element center voltage are supplied as voltage signals are supplied as inputs to instrumentation amplifier 94. I've output of this amplifier 94 is the voltage signal indicative of the change in resistance in the heating elements due to the catalytic reaction and that is in turn indicative of the relative portion of combustible gases in the gas sample passing through sample tester 70.
The electrical output from instrumentation amply-lien 94 is connected to the input of a track and hold amplifier 96. The output from track and hold amplifier 96 is supplied to the input of a range switching divider I I I
circuit 98 that supplies output data signals to a panel display ~etex 100 and to a recorder 102 for use by drilling rip operating personnel. The output from track and hold amplifier 96 is also supplied to a remote recorder and transmitter 104 used for relaying this data to a remote location.
In the initialization or zeroing of this apparatus a zeroing logic circuit 106 is used to control the system's functions temporarily. Zeroing logic circuit 106 contains a timer that periodically causes the system to go through the initialization procedure. Typically this time period is selected to be between one and two hours. First, when the initializing procedure begins track and hold amplifier 96 is enabled into its hold position by a pulse or other signal supplied through line 108. A storage capacitor lug connected to track and hold amplifier 96 is used to store the present output signal of the amplifier and to maintain this output signal through the duration of the initialize-lion procedure. Typically time for the initializing pro-seedier will be in the range of about two to three minutes Next solenoid driver 112 is enabled through line 114 and it in turn actuates the solenoid of purge valve 64 through line 116. When the solenoid is actuated the purge valve 64 shifts to the position other than that shown whereupon the gas sample flow is blocked and air is admitted to the fluid circuit through purge valve air inlet 66. This air flows through the chamber of sample tester 70 and exposes the catalytic elements to air that does not contain a significant quantity of combustible gases.
This purging air flow continues through gas sample tester 70 for a short period of time to purge the chamber of con~ustihle gases. Aster this time has elapsed zeroing logic 106 will examine the output ox instrwnentation of amplifier 94 as compared with a zero voltage. This was done by a zero voltage Capote amplifier ~18 that has one input connected to the output ox instrumentation difference amplifier 94 and the other input connected to ground.
Zeroing logic 106 operates in a digital mode and has a counter that counts upward from zero. us the counting 7~ii S
proceeds the digital count output signal is directed to a digital to analog converter 120 and from there via a connecting line 122 as an analog voltage to a nutting or offset input of instrumentation amplifier 94. As the nutting voltage arriving at instrumentation amplifier 94 increases the output voltage of this amplifier will decrease accordingly. us the output of amplifier 94 decreases it is compared with a zero voltage by zero voltage comparator amplifier 11~. As the counting progresses a point will be reached when the output of zero voltage comparator amplifier 118 is substantially zero or slightly there above. At this point the counting will stop and the nutting voltage will be held at that determined level.
When counting steps the electrical output of same pie tester 70 has been initialized or zeroed. Next, sole nod ill will be again actuated to cause the solenoid of purge valve 64 to actuate the valve and again position it as illustrated thereby again returning the gas sample flow through sample tester 70~ after this occurs track and hold amplifier 96 will be switched from the holding mode to a tracking mode and the output of instrumentation amplifier 94 again passes through amplifier 96 and be supplied to output portions of the circuit.
The gas testing system of this invention provides an indication of the relative quantity of combustible gas in the gas sample over a very broad range of concentrations.
Because the system provides a relative indication of concentrations the output data from the instrument is in terms of units ranging prom zero to ten thousand By way ox reference a reading of 200 units is approximately equivalent to a test gas sample containing one percent methane. This results in a correlation of unit readings that is approximately equivalent to unit readings that would be requited if the tests were done using the prior art manual procedure of taking a Bud simple and extracting the gay to arrive at the gas concentration information.
Because of the extremely wide range of gas concentrations that can be detected by this apparatus and the relative accuracy of the sampling device it is necessary to dilute issue the gas sample for higher concentrations of combustibles.
Along with dilution of the gas sample, it is necessary to adjust the output range of the display devices in order to accurately report the relative combustible gas concentra-lions. In order to accomplish Tess task a range and dilution logic circuit 130 is provided. Generally, range and dilution logic circuit 130 senses the output of track and hold amplifier 96 and depending upon its value and preceding sequence it functions to appropriately adjust the range of outputs to the display devices 16.
The output of track and hold amplifier 94 is connected to the input of a low threshold comparator amplifier 134 and the input of a high threshold comparator amplifier 136. The other inputs to these threshold comparator amplifiers are provided from a voltage diviner network where a referenced voltage V rev is divided above ground by a first resistor 140, a second resistor 142 and a third resistor 144 providing a low threshold reference voltage and a high threshold reference voltage on opposite sides of resistor 142. The outputs of comparator amplifiers 134 and 136 are connected to separate inputs of range and dilution logic circuit 130. One output from logic circuit 130 is to range switching dividing 98. Another output of logic circuit 130 is to a solenoid driver 146 that is in turn connected to actuate the solenoid of air dilution valve 52 through a connecting line 148.
Dilution logic circuit 130 has a low range mode of operation and a high range mode of operation. In the low range mode of operation the output signal from low threshold comparator amplifier 134 is used in range and dilution logic circuit 130. This circuit junctions (by simple logic operations or steps, not shown) to activate range switching divider 98 to pass the output signal from track and hold amplifier 96 directly to panel meter 100 end recorder 102 in a low range scale rode. While this is occurring a feedback signal from the low threshold comparator 134 is presented through line 150 to zeroing logic circuit 106 so the logic circuit will be provided with data indicating the point of operation in the low range mode. For operation in Jo I
the low range initializing as described above will occur at the predetermined intervals However, preferably for operation in the low range mode above a predetermined value of units the initializing will not occur repetitively.
When the relative concentrations of combustible gases rises sufficiently to cross over from the low range mode Jo the high range mode dilution of the air sample begins. The transition for changing between the low range mode of operation and the high range mode can be selected at approximately 900 units. When this condition occurs range and dilution logic 130 is activated by a changed output voltage of high threshold comparator amplifier 136.
When this occurs several things happen. First, solenoid driver 146 is signaled to actuate the solenoid of air dilution valve 52. This action shifts the valve to the position other than that shown whereupon air enters the gas sample circuit through air inlet 60 and dilution air flow indicator 62. The gas sample then passes through metering valve 58 and mixes with the air to provide an air diluted gas sample. my way of example the dilution ratio could be conveniently selected at ten parts of air to one part of gas sample thus requiring shifting of the scale range of the instrument by a ten to one ratio. In accordance with this choice metering valve 58 must be set to the predetermined 10 to l ratio flow in accordance with the movement of air through inlet 60. The second occurrence in dilution logic circuit 130 is that range switching divider circuit 98 is switched from the low range of operation to a high range of operation in order that panel meter 100 and recorder 102 will properly display the correct units of measure corresponding to the appropriate relative gas concentrations present in the extracted gas sample.
The device for remote recording and transmitting of the data signal is provide with one input directly from track and hold amplifier 96 and another input from range and dilution logic circuit 130 in order to record the signal data and the range data separately. It is to be noted that if desired the data supplied to remote recorder and transmitter 104 could be the same as that supplied to panel I
meter 100 and recorder 102.
As long as the system is operating in the high concentration range mode zeroing or initializing of the system will not occur. This is preferable in order to provide the drilling rig operators with a continuous flow of data or safety reasons owing to the relative high gas concentrations involved and thy potential dangerous situp-lions that might be encountered. When gas concentrations began to decrease and fall below that normally reported in the high range mode of operation, approximately 900 units, the input voltage to the threshold comparator amplifiers will drop to a point below that which changes the output of high threshold comparator ~nplifier 136. In this signal condition range and dilution logic 130 continues operation in the high concentration mode until the gas concentration drops significantly to about 800 units. Continued operation in the high concentration mode is done to prevent unneces-spry switching between the modes of operation for conditions when the gas concentration oscillates about the 900 unit level or progresses to a higher level. Once the combustible gas concentration drops below 800 units range and dilution logic 130 will again recognize the input from low threshold comparator amplifier 134. At this point in the operation when the output of low threshold comparator amplifier 134 is again recognized range and logic circuit 130 will respond accordingly signaling range switching divider 98 and remote recorder and transmitter 104 indicating a change to the low range scale. Range switching divider 98 will accordingly adjust its output to panel meter 100 and recorder 102 to the 1:1 scale used in the low range mode In the above described gas sampling system the devise can be incorporated with a drilling recording data handling and transmission system to provide a complimentary element of information for the drilling rig operators. In the use and operation of the gas tester system of this invention it is seen that it provides a substantially continuous display of critical data concerning the presence of combustible gases in the drilling mud for reference and use by the drilling rig operators. The apparatus can ..
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operate substantially unattended and provide data on a continuous basis which is a significant improvement over prior art devices requiring technicians to sample the drilling mud and provide tune data. Awls is apparent from the applicant described method and apparatus a quite effective improvement has been provided for monitoring the relative combustible gas concentration in returning drilling mud.
As will become apparent from the foregoing description of the applicant's Drilling Fluid Gas Tester System and Method, a relatively complete system is provided to continuously monitor combustible gases in drilling mud returning to the earth surface during well drilling. The system is operable in a substantially continuous manner to provide relative combustible as content data to drilling rig operators without requiring a technician to physically sample the drilling mud and test it for combustible gas concentrations.
Although specific preferred embodiments of this invention have been described in detail in the preceding description, this description is not intended to limit the invention to the particular form or embodiments disclosed herein since they are to be recognized as illustrative rather than restrictive and it would be obvious to those skilled in the art that the invention is not so limited.
Thus, the invention is declared to Cover all changes and modifications of the specific example of the invention herein disclosed for purposes of illustration which does not constitute departures from the spirit and scope of the invention.
Background of the Invention _ _ _ _ This invention is related to the automated testing of earth Barlow drilling fluid fox the content of combs-- 5 title gas that is returning to the earth surface during the drilling operation.
In the prior art such testing for combustible gas concentrations in returning drilling fluids has been done by physically removing a sample of the returning drilling mud in a small container and placing the container in an instrument that operates to extract gaseous material from the sample and analyze it for the presence of one or more combustible gases. In this testing, the sample must be taken by an individual and inserted into the testing apparatus then aster the testing is complete the sample removed and the equipment cleaned and prepared for testing a subsequent mud sample. Use of this equipment and prove-dune is cun~ersome in that a technician must physically remove the sample and perform -the testing procedures.
While this might be quite acceptable for an occasional test the mud's condition it is tedious, awkward and extremely expensive for a continuous operation that would follow a continuous twenty four hour per day drilling operation.
One object of this invention is to provide an I apparatus and an ass wilted method that overcome the aforementioned disadvantage of the prior art equipment and procedures Still, another object of this invention is to provide a system for measuring the relative concentration of combustible gases in the returning drilling mud from an earth Barlow drilling operation wherein the apparatus can be operated on a substantially continuous basis and provide a numerical indication of the relative gas concentration to the drilling rig operator and also provide the same information for recording or transmittal to a remote location for reporting.
Specifically, the invention relates to a system for measuring the relative gas concentration in drilling mud returning to the earth surface from an earth Barlow while being drilled, comprising: a means to continuously extract a gas sample from a return mud flow of a drilling rig; means receiving the was sample in a gas sample flow stream to measure the relative concentration of combustible gases in the gas sample including a catalytic sensor with a differential electrical signal output; means to sample the electrical signal output and derive an electrical data signal representative of the relative combustible gas content of the gas sample; means connected to the means to sample to display a numerical representation of the electrical data signal for interpretation by a drilling rig operator or the like.
In its method aspect the invention relates to a method of measuring the relative combustible gas concentration of gas carried in drilling mud returning to the earth surface from an earth Barlow while it is being drilled, comprising the steps of: taking a gas sample from a flow of drilling mud at the earth surface, passing the gas sample through a means to measure having a catalytic sensor measuring the relative combustible gas concentration of the gas sample and producing a sensor electrical output signal representative of the relative combustible gas concentration in the gas sample; sampling the sensor electrical output signal to derive an electrical data signal representative of the relative combustible gas concentration of the gas sample and processing the electrical data signal to derive and display a numerical value representative of the relative combustible gas concentration in the drilling mud.
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Various other advantages and features of this invention will become apparent to those skilled in the art from the following discussion taken in conjunction with the accompanying drawing, in which:
Description of the Drawing The sole drawing is a pictorial diagram illustrating in schematic form the system of this invention and including a drilling mud flow solid separator with a gas collecting device connected to the gas sampling and testing apparatus, and connected to a numerical display, a recorder and a device for transmission to a remote location The following is a discussion and description of preferred specific embodiments of the system, apparatus and method of this invention, such being made with reference to the drawing whereupon the same reference numerals are used to indicate the same or similar parts and/or structure. It is to be understood that this discussion and description is not to unduly limit the scope of the invention.
Detailed Description The gas testing system of this invention is shown in the pictorial diagram of Fig. 1 and it includes several general components that function together to form the complete system.
The gas sample extractor lo collects a sample of gas from the drilling mud of an earth Barlow drilling rig and communicates the sample into a gas handling conduit system, indicated generally at 12, where it is cooled, heated and tested for combustible gas content that exhaust -into the atmosphere. An electronic circuit, indicated generality 14, is connected to several elements of the gas handling conduit system to control their operation and receive data therefrom with the output of the electronic circuit being to a display devices, indicated - pa -oh I
generally at 16. The display devices include an output for the drilling rig operator to watch, a recording device, and if required the capability ox presenting the information for transmission to a remote monitoring and/or recording 5 location.
In extracting the gas sample from the drilling mud this is done at the earth surface at a location relatively close to the point at which the drilling mud exits the annular return flow passage of the Barlow and before the 10 mud is returned to the Barlow. In a typical drilling rig a mud flow conduit 18 deposits drilling mud into a solids separator device, indicated generally at 20, which is known in the trade as a "shale Shaker The solids separator 20 includes a tank 22 that has a vibrating screen 24 mounted 15 therein. Mud flow from conduit 18 is onto the top of screen 24 whereupon it flows across the screen in a relatively thin layer as indicated at 26. This flow moves from the screen 24 forming a curtain 28 of drilling mud between the end of screen 24 and the residual quantity of mud 30 residing in the bottom portion of tank 22. Mud flow curtain 28 forms substantially an inclined wall of mud flowing between the end of screen 26 and the residual mud level 30~ Sample extractor 10 includes a generally conically shaped hood 32 resembling a funnel with the enlarged portion downward and I the smaller portion extentind upward and joining a support conduit 34. The upper end portion of support conduit 34 is connected by a gas sample transfer conduit 36 connecting it with gas sample handling conduit system 12. The position of hood 32 is preferably generally positioned as illustrated with the inlet or most enlarged portion thereof positioned above shale shaker screen 24 with support conduit 34 extend in upward therefrom. The inlet of hood 32 is placed with its inlet below the normal mud flow level over screen 24 so the mud will contact the exterior of hood 32 and flow around it while roving over the screen. This somewhat contains yes as it leaves -the mud and provides a substantially undiluted gas sample flow for testing and analysis.
The gas handling conduit system 12 receives the to gas sample flow in transfer conduit 36. The gas sample flow is moved by a main yes sample pump 38. Movement of the gas sample flow is detected by a pressure switch 40 connected in fluid communication with a conduit from the output of pump 38. A flow indicating a light emitting diode functioning as an indicating lamp is connected with pressure switch 40 and positive an negative voltage sources from a power supply (not shown) to signal an operator that gas flow is present in this system.
When a gas sample is extracted it may contain a certain quantity of liquid or liquefiable elements that are preferably removed prior to testing and in order to prevent damage to the apparatus. For this purpose a condenser having a cooling coil 44 is connected to the output of pump 38. Cooling coil 44 is exposed to a flow of preferably cooler than ambient air. The output of cooling coil 44 is connected to the input of a coalescing filter 46 where condensation of extraneous liquid material can occur and this material can be removed from the jilter periodically as desired. Coalescing filter 46 is provided with a gas sample exhaust and with a gas sample outlet. A gas sample exhaust is used to exhaust to the atmosphere a portion of the extracted gas sample that will not be used in the actual sampling or testing process. The typical flow of gas through pump 38 is substantially in excess of that needed in the measuring or testing portion of this system In order to insure a flow of recently extracted sample gas for the measuring and testing procedures the quantity of sample extracted is in excess of that actually needed for the test and the unused quantity of gas is discarded through unused sample exhaust 48.
The gas outlet from coalescing filter 46 is connected to a heating coil 50 where the gas sample flow is heated so any remaining moisture or liquid materials therein will remain in gaseous suspension until the measuring and testing procedure is completed end the analyzed gas sample is exhausted to the atmosphere. The output of heating coil 50 is connected to a gas sample flow dilution circuit used for dilution of the gas sample with air when the gas sample . .
I
contains high concentrations of combustible materials The gas sample flow dilution circuit has an air dilution inlet valve 52 in a loop with a metering valve to admit air and mix it with the gas sample in a predetermined ratio This dilution valve 52 is a two position valve with its inlet connected to the outlet of heating coil 50 and the valve's outlet connected to dilution valve outlet conduit 54. A
valve bypass look includes a valve bypass loop conduit 56 connected in fluid communication with both the inlet and the outlet conduits to dilution valve 52 with a metering or control valve 58 mounted therein. A dilution air inlet Z0 is provided to admit air into the gas sample handling conduit system. Dilution air inlet 60 is connected to a flow indicator 62 that it in turn connected to a second inlet ox dilution valve 52.
With dilution valve 52 positioned as shown gas sample flow is through conduit 54 with a very small portion of the gas sample flow through conduit 56. With dilution valve 52 shifted to the other position gas sample flow through conduit 54 is blocked and the gas sample flow is directed through conduit 56 and metering valve 58. Air is admitted through dilution air inlet 60 and dilution valve 52 into conduit 54 so the concentration of the gas sample downstream of the junction of conduit 54 and conduit loop 56 is diluted with air. Metering valve 58 is used to adjust the dilution mixture of the gas sample The outlet from the dilution circuit is through conduit 54 joining one inlet of a purge valve 64.
Purge valve 64 is a two position valve used for a purging cycle in conjunction with initializing the combs-title gas concentration measuring device. The second inlet of purge valve 64 is connected to an air inlet 66. With purge valve 64 positioned us shown gas sample flow is through the valve prom one inlet to the outlet and into the housing of the was simple testing device 70. When purge valve 64 is actuated to be displaced to its second position the previous gas sample flow through the valve is blocked and air inlet 66 is introduced into the gas sample flow stream exclusively. Purge value 64 is use for an '7~;5~
initializing procedure to be described in the following.
The gas sample tester or combustible gas concern-traction measuring device includes a chamber containing two sets of beads made of a catalytic material and mounted with heating elements 72 and 74. The heating elements are resistive type heating elements that are closely associated with the catalytic beads and joined in a series or end to end fashion. The heating elements warm the catalytic beads so their temperature is elevated sufficiently that a gala-lyric reaction will be formed with combustible gases contained within the gas sample flow. When the gas sample has a quantity of combustible material a catalytic reaction will be formed and the beads will generate additional heat whereupon the resistive heating elements will measurably change in resistance. This measurable change is used in an electrical bridge type circuit to derive a relative indication of combustible gas content in the gas sample flow. Electrical conductor 76 joins one end of bead hefting element 74, and electrical conductor 80 joins the junction of the bead heating elements 72 and 74.
Sample pump 82 is connected to the outlet of the sample tester housing and used to pull the gas sample through the preceding conduit portions of the system from coalescing filter 46. The outlet of sample pump 82 is connected to the inlet of a flow indicator 84 with the output of flow indicator 84 bring exhausted to the atoms phone. Flow indicator 84 is an operational indicator to provide a technician an indication of the flow of gaseous material through sample pump 82. The exhaust from flow indicator 84 can be simply discharged to the atmosphere or to any suitable apparatus for discarding such samples.
Electronic circuits 14 are shown contained within a dashed line box. Generally, the electronic circuit includes a whetstone bridge to operate with the heating elements in sample tester 70, associated instrumentation amplifiers, an zeroing or initializing and referencing circuit, and a scaling and output circuit with the outputs to devices or visual display, recording and transmission to I a remote location "I
I
Sample tester 70 has both of its heating element-resistor elements I and 74 connected to the electronic circuit by wires 76, 78 and 80 as illustrated. Wires 76 and 78 are connected in series with a balance bridge resistor 90. Positive voltage is applied to one side of the bridge as illustrated from a power supply. Balance bridge resistor 90 is a variable resistor with the wiper 92 connect-d as one input to an instrumentation amplifier 94. Two elements of the bridge circuit are formed by the lo catalytic bead heating elements 72 and 74 and these are connected to bridge balance resistor 90 so that portions of the resistor on either side of wiper 92 form the other pair of bridge resistive elements. The center connection of the catalytic bead heating elements is joined by wire 80 with a second input of instrumentation amplifier 94.
Instrumentation amplifier 94 is a differential amplifier with two inputs and a Nolan voltage input. Initially balance resistor 90 is adjusted for a zero output from amplifier 94 for a condition with sample tester 70 exposed to air that does not contain combustible gasps. When combustible gases pass through sample tester 70 the resistance of catalytic bead heaving elements 72 and 74 changes due to the catalytic heating effect. This change in resistance will result in a different -total resistance across both of the heating elements and at its center junction. This change results in a different voltage across bridge balance resistor 90 and at its wiper. The bridle resistor wiper voltage and the heating element center voltage are supplied as voltage signals are supplied as inputs to instrumentation amplifier 94. I've output of this amplifier 94 is the voltage signal indicative of the change in resistance in the heating elements due to the catalytic reaction and that is in turn indicative of the relative portion of combustible gases in the gas sample passing through sample tester 70.
The electrical output from instrumentation amply-lien 94 is connected to the input of a track and hold amplifier 96. The output from track and hold amplifier 96 is supplied to the input of a range switching divider I I I
circuit 98 that supplies output data signals to a panel display ~etex 100 and to a recorder 102 for use by drilling rip operating personnel. The output from track and hold amplifier 96 is also supplied to a remote recorder and transmitter 104 used for relaying this data to a remote location.
In the initialization or zeroing of this apparatus a zeroing logic circuit 106 is used to control the system's functions temporarily. Zeroing logic circuit 106 contains a timer that periodically causes the system to go through the initialization procedure. Typically this time period is selected to be between one and two hours. First, when the initializing procedure begins track and hold amplifier 96 is enabled into its hold position by a pulse or other signal supplied through line 108. A storage capacitor lug connected to track and hold amplifier 96 is used to store the present output signal of the amplifier and to maintain this output signal through the duration of the initialize-lion procedure. Typically time for the initializing pro-seedier will be in the range of about two to three minutes Next solenoid driver 112 is enabled through line 114 and it in turn actuates the solenoid of purge valve 64 through line 116. When the solenoid is actuated the purge valve 64 shifts to the position other than that shown whereupon the gas sample flow is blocked and air is admitted to the fluid circuit through purge valve air inlet 66. This air flows through the chamber of sample tester 70 and exposes the catalytic elements to air that does not contain a significant quantity of combustible gases.
This purging air flow continues through gas sample tester 70 for a short period of time to purge the chamber of con~ustihle gases. Aster this time has elapsed zeroing logic 106 will examine the output ox instrwnentation of amplifier 94 as compared with a zero voltage. This was done by a zero voltage Capote amplifier ~18 that has one input connected to the output ox instrumentation difference amplifier 94 and the other input connected to ground.
Zeroing logic 106 operates in a digital mode and has a counter that counts upward from zero. us the counting 7~ii S
proceeds the digital count output signal is directed to a digital to analog converter 120 and from there via a connecting line 122 as an analog voltage to a nutting or offset input of instrumentation amplifier 94. As the nutting voltage arriving at instrumentation amplifier 94 increases the output voltage of this amplifier will decrease accordingly. us the output of amplifier 94 decreases it is compared with a zero voltage by zero voltage comparator amplifier 11~. As the counting progresses a point will be reached when the output of zero voltage comparator amplifier 118 is substantially zero or slightly there above. At this point the counting will stop and the nutting voltage will be held at that determined level.
When counting steps the electrical output of same pie tester 70 has been initialized or zeroed. Next, sole nod ill will be again actuated to cause the solenoid of purge valve 64 to actuate the valve and again position it as illustrated thereby again returning the gas sample flow through sample tester 70~ after this occurs track and hold amplifier 96 will be switched from the holding mode to a tracking mode and the output of instrumentation amplifier 94 again passes through amplifier 96 and be supplied to output portions of the circuit.
The gas testing system of this invention provides an indication of the relative quantity of combustible gas in the gas sample over a very broad range of concentrations.
Because the system provides a relative indication of concentrations the output data from the instrument is in terms of units ranging prom zero to ten thousand By way ox reference a reading of 200 units is approximately equivalent to a test gas sample containing one percent methane. This results in a correlation of unit readings that is approximately equivalent to unit readings that would be requited if the tests were done using the prior art manual procedure of taking a Bud simple and extracting the gay to arrive at the gas concentration information.
Because of the extremely wide range of gas concentrations that can be detected by this apparatus and the relative accuracy of the sampling device it is necessary to dilute issue the gas sample for higher concentrations of combustibles.
Along with dilution of the gas sample, it is necessary to adjust the output range of the display devices in order to accurately report the relative combustible gas concentra-lions. In order to accomplish Tess task a range and dilution logic circuit 130 is provided. Generally, range and dilution logic circuit 130 senses the output of track and hold amplifier 96 and depending upon its value and preceding sequence it functions to appropriately adjust the range of outputs to the display devices 16.
The output of track and hold amplifier 94 is connected to the input of a low threshold comparator amplifier 134 and the input of a high threshold comparator amplifier 136. The other inputs to these threshold comparator amplifiers are provided from a voltage diviner network where a referenced voltage V rev is divided above ground by a first resistor 140, a second resistor 142 and a third resistor 144 providing a low threshold reference voltage and a high threshold reference voltage on opposite sides of resistor 142. The outputs of comparator amplifiers 134 and 136 are connected to separate inputs of range and dilution logic circuit 130. One output from logic circuit 130 is to range switching dividing 98. Another output of logic circuit 130 is to a solenoid driver 146 that is in turn connected to actuate the solenoid of air dilution valve 52 through a connecting line 148.
Dilution logic circuit 130 has a low range mode of operation and a high range mode of operation. In the low range mode of operation the output signal from low threshold comparator amplifier 134 is used in range and dilution logic circuit 130. This circuit junctions (by simple logic operations or steps, not shown) to activate range switching divider 98 to pass the output signal from track and hold amplifier 96 directly to panel meter 100 end recorder 102 in a low range scale rode. While this is occurring a feedback signal from the low threshold comparator 134 is presented through line 150 to zeroing logic circuit 106 so the logic circuit will be provided with data indicating the point of operation in the low range mode. For operation in Jo I
the low range initializing as described above will occur at the predetermined intervals However, preferably for operation in the low range mode above a predetermined value of units the initializing will not occur repetitively.
When the relative concentrations of combustible gases rises sufficiently to cross over from the low range mode Jo the high range mode dilution of the air sample begins. The transition for changing between the low range mode of operation and the high range mode can be selected at approximately 900 units. When this condition occurs range and dilution logic 130 is activated by a changed output voltage of high threshold comparator amplifier 136.
When this occurs several things happen. First, solenoid driver 146 is signaled to actuate the solenoid of air dilution valve 52. This action shifts the valve to the position other than that shown whereupon air enters the gas sample circuit through air inlet 60 and dilution air flow indicator 62. The gas sample then passes through metering valve 58 and mixes with the air to provide an air diluted gas sample. my way of example the dilution ratio could be conveniently selected at ten parts of air to one part of gas sample thus requiring shifting of the scale range of the instrument by a ten to one ratio. In accordance with this choice metering valve 58 must be set to the predetermined 10 to l ratio flow in accordance with the movement of air through inlet 60. The second occurrence in dilution logic circuit 130 is that range switching divider circuit 98 is switched from the low range of operation to a high range of operation in order that panel meter 100 and recorder 102 will properly display the correct units of measure corresponding to the appropriate relative gas concentrations present in the extracted gas sample.
The device for remote recording and transmitting of the data signal is provide with one input directly from track and hold amplifier 96 and another input from range and dilution logic circuit 130 in order to record the signal data and the range data separately. It is to be noted that if desired the data supplied to remote recorder and transmitter 104 could be the same as that supplied to panel I
meter 100 and recorder 102.
As long as the system is operating in the high concentration range mode zeroing or initializing of the system will not occur. This is preferable in order to provide the drilling rig operators with a continuous flow of data or safety reasons owing to the relative high gas concentrations involved and thy potential dangerous situp-lions that might be encountered. When gas concentrations began to decrease and fall below that normally reported in the high range mode of operation, approximately 900 units, the input voltage to the threshold comparator amplifiers will drop to a point below that which changes the output of high threshold comparator ~nplifier 136. In this signal condition range and dilution logic 130 continues operation in the high concentration mode until the gas concentration drops significantly to about 800 units. Continued operation in the high concentration mode is done to prevent unneces-spry switching between the modes of operation for conditions when the gas concentration oscillates about the 900 unit level or progresses to a higher level. Once the combustible gas concentration drops below 800 units range and dilution logic 130 will again recognize the input from low threshold comparator amplifier 134. At this point in the operation when the output of low threshold comparator amplifier 134 is again recognized range and logic circuit 130 will respond accordingly signaling range switching divider 98 and remote recorder and transmitter 104 indicating a change to the low range scale. Range switching divider 98 will accordingly adjust its output to panel meter 100 and recorder 102 to the 1:1 scale used in the low range mode In the above described gas sampling system the devise can be incorporated with a drilling recording data handling and transmission system to provide a complimentary element of information for the drilling rig operators. In the use and operation of the gas tester system of this invention it is seen that it provides a substantially continuous display of critical data concerning the presence of combustible gases in the drilling mud for reference and use by the drilling rig operators. The apparatus can ..
"` .~.~1'7i~
operate substantially unattended and provide data on a continuous basis which is a significant improvement over prior art devices requiring technicians to sample the drilling mud and provide tune data. Awls is apparent from the applicant described method and apparatus a quite effective improvement has been provided for monitoring the relative combustible gas concentration in returning drilling mud.
As will become apparent from the foregoing description of the applicant's Drilling Fluid Gas Tester System and Method, a relatively complete system is provided to continuously monitor combustible gases in drilling mud returning to the earth surface during well drilling. The system is operable in a substantially continuous manner to provide relative combustible as content data to drilling rig operators without requiring a technician to physically sample the drilling mud and test it for combustible gas concentrations.
Although specific preferred embodiments of this invention have been described in detail in the preceding description, this description is not intended to limit the invention to the particular form or embodiments disclosed herein since they are to be recognized as illustrative rather than restrictive and it would be obvious to those skilled in the art that the invention is not so limited.
Thus, the invention is declared to Cover all changes and modifications of the specific example of the invention herein disclosed for purposes of illustration which does not constitute departures from the spirit and scope of the invention.
Claims (16)
1. A system for measuring the relative gas concentration in drilling mud returning to the earth surface from an earth borehole while being drilled, comprising:
(a) a means to continuously extract a gas sample from a return mud flow of a drilling rig;
(b) means receiving said gas sample in a gas sample flow stream to measure the relative concentration of combustible gases in said gas sample including a catalytic sensor with a differential electrical signal output;
(c) means to sample said electrical signal output and derive an electrical data signal repre-sentative of the relative combustible gas content of said gas sample;
(d) means connected to said means to sample to display a numerical representation of said electrical data signal for interpretation by a drilling rig operator or the like.
(a) a means to continuously extract a gas sample from a return mud flow of a drilling rig;
(b) means receiving said gas sample in a gas sample flow stream to measure the relative concentration of combustible gases in said gas sample including a catalytic sensor with a differential electrical signal output;
(c) means to sample said electrical signal output and derive an electrical data signal repre-sentative of the relative combustible gas content of said gas sample;
(d) means connected to said means to sample to display a numerical representation of said electrical data signal for interpretation by a drilling rig operator or the like.
2. The system of claim 1, wherein:
said means to continuously extract a gas sample includes a means to dilute said gas sample with air in a predetermined ratio prior to entering said means to measure when said gas sample has a combustible gas content that is above a predetermined value.
said means to continuously extract a gas sample includes a means to dilute said gas sample with air in a predetermined ratio prior to entering said means to measure when said gas sample has a combustible gas content that is above a predetermined value.
3. The system of claim 2, wherein said means to dilute includes:
(a) a dilution fluid circuit having an inlet to receive said gas sample from said means to continuously extract a gas sample, a two position dilution valve connected to said inlet, an outlet in fluid communication with said means to measure and a source of air and a metering loop conduit connected between said inlet and said outlet and containing a variable flow control metering valve such that said dilution valve in a first position passes said gas sample in fluid communication to said means to measure and in a second position said gas sample will be in fluid communication with said means to measure through said variable flow control metering valve and air will be introduced into the gas flow from said source of air in order to dilute said gas sample passing into said means to measure by a predetermined amount adjust-able by said variable flow control metering valve; and (b) a dilution electronic circuit means connected to said dilution valve, said means to sample, and said means to display being operable to adjust the displayed numerical representation in proportion to the amount of air dilution of gas sample.
(a) a dilution fluid circuit having an inlet to receive said gas sample from said means to continuously extract a gas sample, a two position dilution valve connected to said inlet, an outlet in fluid communication with said means to measure and a source of air and a metering loop conduit connected between said inlet and said outlet and containing a variable flow control metering valve such that said dilution valve in a first position passes said gas sample in fluid communication to said means to measure and in a second position said gas sample will be in fluid communication with said means to measure through said variable flow control metering valve and air will be introduced into the gas flow from said source of air in order to dilute said gas sample passing into said means to measure by a predetermined amount adjust-able by said variable flow control metering valve; and (b) a dilution electronic circuit means connected to said dilution valve, said means to sample, and said means to display being operable to adjust the displayed numerical representation in proportion to the amount of air dilution of gas sample.
4. The system of claim 1, additionally including:
(a) a means to periodically initialize said means to measure the relative concentration of combustible gases including a display holding circuit means operable to hold said means to display at a constant numerical representa-tion;
(b) a purge valve connected in fluid communication with said gas sample flow stream upstream of said means to measure in order to temporarily close normal gas sample flow thereinto and admit a flow of substantially uncontaminated air thereinto for a predetermined period of time;
(c) an electrical initialization logic circuit connected to said means to sample, said purge valve and said means to display, and being operable to display a constant numerical value while initializing said means to measure, to open said purge valve for a predetermined period of time then close said purve valve and also to resume display of said electrical data signal.
(a) a means to periodically initialize said means to measure the relative concentration of combustible gases including a display holding circuit means operable to hold said means to display at a constant numerical representa-tion;
(b) a purge valve connected in fluid communication with said gas sample flow stream upstream of said means to measure in order to temporarily close normal gas sample flow thereinto and admit a flow of substantially uncontaminated air thereinto for a predetermined period of time;
(c) an electrical initialization logic circuit connected to said means to sample, said purge valve and said means to display, and being operable to display a constant numerical value while initializing said means to measure, to open said purge valve for a predetermined period of time then close said purve valve and also to resume display of said electrical data signal.
5. The system of claim 4, wherein said electrical initialization logic circuit includes means to display a constant numerical value for a predetermined time before said purge valve is opened to admit air and for a predeter-mined time after said purge valve is closed and said gas sample flow resumes through said means to measure.
6. The system of claim 4, wherein said means to continuously extract a gas sample has a gas sample collector mounted at the mud flow output of a solids separating device at a drilling rig and including a hollow conical hood mounted with said device and positioned above a separating screen to have mud flowing over a portion thereof with the inlet to said hood being below the surface of the liquid on said screen, and having a gas sample displacement pump connected by conduit to an outlet of said sample collecting hood with an outlet of said pump connected to said means to measure.
7. A system for measuring the relative gas concentration in drilling mud returning to the earth surface from an earth borehole while being drilled, comprising:
(a) a means to continuously extract a gas sample from a return mud flow of a drilling rig forming a gas sample flow stream;
(b) a means to filter said extracted gas sample removing excessive moisture and particulate materials therefrom and a means to hold residual moisture and entrained liquifiable materials in said extracted gas sample in gaseous suspension while passing through said system;
(c) means to dilute said gas sample with air in a predetermined ratio prior to entering said means to measure when said gas sample has a combustible gas content that is above a predetermined value;
(d) means receiving said gas sample in a gas sample flow stream to measure the relative concentration of combustible gases in said gas sample and to generate an electrical output signal;
(e) means to sample said electrical output signal and derive an electrical data signal repre-sentative of the relative combustible gas content of said gas sample;
(f) means operable with said means to measure and said means to sample to periodically initialize said means to measure in order to adjust the relative accuracty of measurements taken therewith; and (g) means connected to said means to sample to display a numerical representation of said electrical data signal for interpretation by a drilling rig operator or the like.
(a) a means to continuously extract a gas sample from a return mud flow of a drilling rig forming a gas sample flow stream;
(b) a means to filter said extracted gas sample removing excessive moisture and particulate materials therefrom and a means to hold residual moisture and entrained liquifiable materials in said extracted gas sample in gaseous suspension while passing through said system;
(c) means to dilute said gas sample with air in a predetermined ratio prior to entering said means to measure when said gas sample has a combustible gas content that is above a predetermined value;
(d) means receiving said gas sample in a gas sample flow stream to measure the relative concentration of combustible gases in said gas sample and to generate an electrical output signal;
(e) means to sample said electrical output signal and derive an electrical data signal repre-sentative of the relative combustible gas content of said gas sample;
(f) means operable with said means to measure and said means to sample to periodically initialize said means to measure in order to adjust the relative accuracty of measurements taken therewith; and (g) means connected to said means to sample to display a numerical representation of said electrical data signal for interpretation by a drilling rig operator or the like.
8. The system of claim 7, additionally including:
(a) said means to periodically initialize additionally including a display holding circuit means operable to hold said means to display at a constant numerical representation;
(b) a purge valve connected in fluid communication with said gas sample flow stream upstream of said means to measure in order to temporarily close normal gas sample flow thereinto and admit a flow of substantially non combustible air thereinto for a predetermined period of time;
(c) an electrical initialization logic circuit connected to said means to sample, said purge valve and said means to display, and being operable to display a constant numerical value while initializing said means to measure, to open said purge valve for a predetermined period of time then close said purge valve and also to resume display of said electrical data signal; and (d) said means to measure including a catalytic reaction combustible material sensor having a plurality of heated catalytic elements mounted in operating relation with variable resistance elements operable to change resistance in relation to the quantity of combustible material in said gas sample.
(a) said means to periodically initialize additionally including a display holding circuit means operable to hold said means to display at a constant numerical representation;
(b) a purge valve connected in fluid communication with said gas sample flow stream upstream of said means to measure in order to temporarily close normal gas sample flow thereinto and admit a flow of substantially non combustible air thereinto for a predetermined period of time;
(c) an electrical initialization logic circuit connected to said means to sample, said purge valve and said means to display, and being operable to display a constant numerical value while initializing said means to measure, to open said purge valve for a predetermined period of time then close said purge valve and also to resume display of said electrical data signal; and (d) said means to measure including a catalytic reaction combustible material sensor having a plurality of heated catalytic elements mounted in operating relation with variable resistance elements operable to change resistance in relation to the quantity of combustible material in said gas sample.
9. The system of claim 8, wherein:
(a) said means to filter includes a condenser and a coalessing filter connected in series in said gas sample flow stream upstream of said means to measure; and (b) said means to hold includes heated evaporator operably connected in said gas sample flow stream between said condenser and said means to measure.
(a) said means to filter includes a condenser and a coalessing filter connected in series in said gas sample flow stream upstream of said means to measure; and (b) said means to hold includes heated evaporator operably connected in said gas sample flow stream between said condenser and said means to measure.
10. The system of claim 8, wherein said means to dilute include s:
(a) a dilution fluid circuit having an inlet to receive said gas sample from said evaporator, a two position dilution valve connected to said inlet, an outlet in fluid communication with said means to measure and a source of air and a metering loop conduit connected between said inlet and said outlet and con-taining a variable flow control metering valve such that said dilution valve in a first position passes said gas sample in fluid communication to said means to measure and in a second position said gas sample will be in fluid communication with said means to measure through said variable flow control metering valve and air will be introduced into the gas flow from said source of air in order to dilute said gas sample passing into said means to measure by a predetermined amount adjustable by said variable flow control metering valve; and (b) a dilution electronic circuit means connected to said dilution valve, said means to sample, and said means to display being operable to adjust the displayed numerical representation in proportion to the amount of air dilution of said gas sample.
(a) a dilution fluid circuit having an inlet to receive said gas sample from said evaporator, a two position dilution valve connected to said inlet, an outlet in fluid communication with said means to measure and a source of air and a metering loop conduit connected between said inlet and said outlet and con-taining a variable flow control metering valve such that said dilution valve in a first position passes said gas sample in fluid communication to said means to measure and in a second position said gas sample will be in fluid communication with said means to measure through said variable flow control metering valve and air will be introduced into the gas flow from said source of air in order to dilute said gas sample passing into said means to measure by a predetermined amount adjustable by said variable flow control metering valve; and (b) a dilution electronic circuit means connected to said dilution valve, said means to sample, and said means to display being operable to adjust the displayed numerical representation in proportion to the amount of air dilution of said gas sample.
11. The system of claim 7, wherein said means to continuously extract a gas sample has a gas sample collector mounted at the mud flow output of a drilling mud solids separating device at a drilling rig and including a hollow conical hood mounted with said device and position above a separating screen to have mud flowing over a lower portion thereof with the inlet to said hood being below the surface of the drilling mud on said screen, and having a gas sample displacement pump connected by conduit to an outlet of said sample collecting hood with an outlet of said pump connected to said means to measure.
12. A method of measuring the relative combustible gas concentraction of gas carried in drilling mud returning to the earth surface from an earth borehole while it is being drilled, comprising the steps of:
(a) taking a gas sample from a flow of drilling mud at the earth surface;
(b) passing said gas sample through a means to measure having a catalytic sensor measuring the relative combustible gas concentration of said gas sample and producing a sensor electrical output signal representative of the relative combustible gas concentration in said gas sample;
(c) sampling the sensor electrical output signal to derive an electrical data signal repre-sentative of the relative combustible gas concentration of said gas sample and (d) processing the electrical data signal to derive and display a numerical value repre-sentative of the relative combustible gas concentration in said drilling mud,
(a) taking a gas sample from a flow of drilling mud at the earth surface;
(b) passing said gas sample through a means to measure having a catalytic sensor measuring the relative combustible gas concentration of said gas sample and producing a sensor electrical output signal representative of the relative combustible gas concentration in said gas sample;
(c) sampling the sensor electrical output signal to derive an electrical data signal repre-sentative of the relative combustible gas concentration of said gas sample and (d) processing the electrical data signal to derive and display a numerical value repre-sentative of the relative combustible gas concentration in said drilling mud,
13. The method of claim 12 additionally including:
(a) repeating said sampling and said processing to revise the displayed data substantially continuously; and (b) periodically initializing the catalytic sensor of the means to measure to a zero value then continuing measuring of the gas sample.
(a) repeating said sampling and said processing to revise the displayed data substantially continuously; and (b) periodically initializing the catalytic sensor of the means to measure to a zero value then continuing measuring of the gas sample.
14. The method of claim 13, wherein said period-ically initializing includes the steps of:
(a) holding the display at a constant value at a last measured and displayed value;
(b) purging the means to measure with a substan-tially non combustible gas;
(c) deriving from said sensor output signal a signal representative of a substantially zero combustible gas condition indicative of a zero value data signal;
(d) reconnecting the means to measure with the gas sample flow and resuming said measuring and said sampling; and (e) resuming said processing of the electrical data signal.
(a) holding the display at a constant value at a last measured and displayed value;
(b) purging the means to measure with a substan-tially non combustible gas;
(c) deriving from said sensor output signal a signal representative of a substantially zero combustible gas condition indicative of a zero value data signal;
(d) reconnecting the means to measure with the gas sample flow and resuming said measuring and said sampling; and (e) resuming said processing of the electrical data signal.
15. The method of claim 14, wherein said taking a gas sample includes cooling said gas sample to substantially an ambiant temperature, then filtering said gas sample to remove particulate material, then heating the filtered gas sample to an above ambiant temperature in order to maintain impurities in the gas sample in a gaseous state throughout the passage of the gas sample through the measuring apparatus.
16. The method of claim 12, wherein:
(a) said passing soil gas sample additionally includes diluting the gas sample to a pre-determined gas sample to air ratio; and (b) said processing including deriving the numerical value from the data signal indica-tive of the relative concentraction of combustible gases in said diluted gas sample adjusted by said gas sample to air ratio.
(a) said passing soil gas sample additionally includes diluting the gas sample to a pre-determined gas sample to air ratio; and (b) said processing including deriving the numerical value from the data signal indica-tive of the relative concentraction of combustible gases in said diluted gas sample adjusted by said gas sample to air ratio.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US54909983A | 1983-11-07 | 1983-11-07 | |
| US549,099 | 1983-11-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1217652A true CA1217652A (en) | 1987-02-10 |
Family
ID=24191662
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000467222A Expired CA1217652A (en) | 1983-11-07 | 1984-11-07 | Drilling fluid gas testing system and method |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1217652A (en) |
-
1984
- 1984-11-07 CA CA000467222A patent/CA1217652A/en not_active Expired
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