CA1292886C - Method and apparatus for monitoring the density of a liquid - Google Patents
Method and apparatus for monitoring the density of a liquidInfo
- Publication number
- CA1292886C CA1292886C CA000539109A CA539109A CA1292886C CA 1292886 C CA1292886 C CA 1292886C CA 000539109 A CA000539109 A CA 000539109A CA 539109 A CA539109 A CA 539109A CA 1292886 C CA1292886 C CA 1292886C
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- container
- liquid
- pressurized fluid
- bed
- sample
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Abstract
ABSTRACT OF THE INVENTION
Disclosed is a method and apparatus for measuring the density of a liquid, such as a drilling mud, by continuously flowing a sample of the liquid through a container having a fixed predetermined volume. The container is supported by at least one bed of pressurized fluid. The pressure of the fluid is varied in response to fluctuations in the weight of the liquid sample in the container. A pressure transmitter monitors the pressure level in the bed and produces a signal indicative of the density of the liquid sample.
Disclosed is a method and apparatus for measuring the density of a liquid, such as a drilling mud, by continuously flowing a sample of the liquid through a container having a fixed predetermined volume. The container is supported by at least one bed of pressurized fluid. The pressure of the fluid is varied in response to fluctuations in the weight of the liquid sample in the container. A pressure transmitter monitors the pressure level in the bed and produces a signal indicative of the density of the liquid sample.
Description
r . . .
` ~ Z ~ Z ~ 86 METHOD AND APPARATUS FOR MONITORING
$HE DENSITY OF A LIQUID
Field of the Invention ~ he present invention relates generally to methods and apparatus for monitoring the density of liquids, and more particularly, to methods and S apparatus for monitoring the density of well drilling li quids.
ac~ground of the Invention It is frequently useful to monitor the density of a liquid used in industrial proce~ses. For instance, during drilling operations of a well bore, drilling mud is circulated through the drill pipe and the annulus of the well bore. The drilling mud serve~
several purposes in the drilllng process, including lubrication and cooling of the drill bit and the removal of cuttings resulting from the penetration of the subsurface formation~ Additionally, the weight of the drilling mud in the well bore exerts hydro~tatic pressure on the subsurface formations that acts to contain the subsurface pressure encountered during drilling operations. These subsurface pre~sures may be extremely high, such as 8,000-10,000 p~i, or the equivalent of two ~2) pound~ per square inch per foot of depth. If the hydrostatic pressure of the drilling lZ~2886 mud at the depth at which the sub~urface pre~ure i8 encountered i8 not equal to or greater than the sub~urface pres~ure, tbe reservoir fluld will emerge from the subsurface formation and travel to the surface through the well bore. This is known as a blow out and creates extremely dangerous conditions as the pressurized format~on fluid generally containing gas rapidly expands a~ it approaches the surface and atmospheric pressure. However, if the drilling mud hydrostatic pressure i8 too high, the subsurface formations may be fractured resulting in extensive loss of the relatively expensive drilling mud into the formation~ surrounding the well bore. Thus, the density of the drilling mud must be monitored and adjusted if necessary, to malntain it within a desired range during drilling operations. Another constraint on the denslty of the drilling mud is that an increase in the density tends to reduce the penetration of the drill bit.
Drilling mud is a liquid composition, u~ually utilizing oil or water a3 a base to which various sub~tances are added depending on the propertles desired in the drilling operatlons, the subsurface and environmental conditions, a8 well as other factors as are known in the art. Typically, the additives include solid particulates or clay~ to promote the formatlon of a filter cake on the wall~ of the well bore and to assist in suspending the cuttings until the drilllng mud containing the cuttlngs re~ches the surface, and weighting materials such a~ barites, to control the density of the drilling mud. After circulation through the well bore, the drilling mud is filtered to remove the cuttings carried from the bottom of the well bore and then stored in a mud pit for sub3equent use.
Under conventional drilling techniques, a small sample of the drilling mud i5 perlodlcally ~ 2 ~ ~
obtained as lt i8 deposited in the mud pit. The density of the sample i~ measured and a determinatlon made whether or not to ad~u~t the density of the drilling mud being u~ed in the well bore. Existing apparatus u~ed to measure the density of the drilling - mud sample i~ called a mud balance and consists of a container having a known volume on one end and a scale and weight on the other end. The apparatus ti.e. mud container, scale and weight) is then placed on a knife edge fulcrum. ~he container is then filled to its capacity with the sample of interest. The weight i8 moved along the scale until balanced. Indicia on the ~cale at the location of the weight indicate the den~ity of the mud sample. That is, the observed welght of the sample may be used to derive a measure of density by dividing the weight by the known volume of the container. The same scale can be calibrated in any set of units desired.
However, this and other conventional denRity monitoring procedures exhibit certain limitations. For instance, the monitoring of the drilling mud density is performed on an intermittent basis, and must be manually performed. This manual operation takes approximately 10-15 minutcs. When conditions are encountered that cause rap~d change~ in ~he mud density, the density may drastically change in a matter of minutes or seconds. Frequently, it is not economical or practical to weigh samples of the drilllng mud on an ongoing basls, since a skilled technician or engineer is required to perform the test.
Les~ frequent samples introduce a time lag into the monitoring process that is undesirable. Further, manual weighing of a drilling mud sample on a mud balance is relatively inaccurate and requires visual interpretation, thereby introducing the possibillty of human error. Finally, weighing of the drilling mud ~29Z886 sample must be performed on 9 ~ te and cannot conveniently be conducted remotely. None of the existing methods or apparatus for monitoring dr$11ing mud den~ity adequately solve the problems outlined above.
Summary of the Invention This invention provldes a method and apparatus to measure the den~ity of a liquid on a continuou~
basis, such as drilling mud returning from circulation in a well bore. The physical principal utilized is that a force ~F) is proportional to pressure (P) and area ~A), where F equals the orce in pounds and P
equal~ pressure in PSI and A equals area in square inches. A continuous sample of the drilling mud is flowed through a conta$ner having a fixed predetermined volume. The container and the sample o the liquid is ~upported on at least one bed of pressurized fluid.
The pressure of the fluid is varied by fluctuatlons in the weight of the container and liquid sample, 80 a~ to equalize the forces acting across the seal of the valve. A pressure transmitter is connected to the chamber and generates a continuous electrical ~ignal indicative of the instantaneous pressure in the bed of pressurized fluid required to support the container and liguid sample. The electrical signal from the pressure transmitter is converted to a measure of the density of the drilling mud by electronically dividing it by a constant signal representative of the volume of the container cavity. Preferably, the valve is a spherical vaive and acts to automatically maintain the container in an upright position, and is designed to have negligible pressure drop across the seal of the valve.
Therefore, it is a principal feature and advantage of this inventlon to provide an improved method and apparatus for continuou~l~ monitoring the " 1'29~86 ' density of a liquid.
It i8 another feature and advantage of this invention to provide an improved method and apparatus for instantaneou~ly and automatically monitoring the density o~ a liquid.
It i 8 another eature and advantage of thi 8 invention to provide an improved method and appara us for monitoring the den~ity of a llquid in which the density of the liquid made may be remotely monitored.
Brief DescriPtion of the Drawin~s So that the manner in which the above recited features and advantages of the inventlon, as well as others which will become apparent to tho~e skilled in the art, are obtained and can be understood in detail, a more particular description of the invention briefly summar~zed above may be had by reference to the embodiments thereof whlch are illustrated in the accompanying drawings, which drawings form a part of the ~peciflcation and in which like numerals depict like parts in the several views. It is noted, however, that the appended drawings lllustrate only a preferred embodiment of the invention and are therefore not to be consldered limitlng of its scope, for the invention may admit to other equally effective embodiments.
Figure 1 is a schematla representation of a density measuring device according to thls invention.
Figure 2 i8 a front view, partially in cross section, of a density measuring device according to this invention.
Figure 3 is a side v~ew, partially in cross section, of the density measuring device of Figure 2.
Figure 4 is a cross sectional view along view 4-4 of the density measuring device of Figure 3.
F$gure 5 is a magnified view of the ball valve of Figure 3.
Detalled De~cri~tion of the Invention Referring now to Figure 1, the reference numeral 10 generally ~ndicates the apparatus of thi~
invention, including generally rectangular housing or enclosure 12. The housing is po~itioned over mud p~t 14 containing a quantity of drllling mud 16. Drilling mud intake pipe 1~ i3 connected at one end tnot shown) to the circulatlon ~ystem tnot shown) for the drilling mud and is adapted to continuslly convey to the hou~ing a sample before the drilling mud is returned to the mud pit. Drilllng mud outlet 20 extends downwardly from the bottom of the housing and i8 positioned to return the sample stream of drilling mud to the mud pit after exiting from the housing. Pressurized fluid conduit 22 is connected at one end ~not shown) to a source of pressurized fluid tnot shown). Although air may be utilized as the fluid, any suitable fluid may be utilized within conduit 22 if desired. The other end of the fluid conduit extends into the interior of the housing, as will be explained hereinafter. Wire or cable 24 extends outwardly of the housing and is remotely connected to meter 26 for providing a display indicative of the density of the drilling mud ~ample.
Turning now to Figures 2-4, the hou~ing is shown in greater detail mounted on rigid external framework 28 tnot a part of the apparatus) which consists of interconnected beams and trusses and is provided to support the hous~ng over the mud pit tnot shown). Housing 12 includes top, bottom, front and bac~ walls and defines left and right sides, 12a and 12b, respectively, a~ seen in Figure 2. Container 30 iq provided within the housing to receive a continuous sample of the drilling mud. The container consists of a cylindrical body with an open upper end communicating with cavity 31 therewithin having a fixed and predetermined volume. Drilling mud is continuously ~2928~36 introduced into tbe cavity of the container through drill~ng mud intake pipe 18, which does not contact container 30 at any place. Preferably, orifice 32 of the drilling mud inta~e pipe i8 located at a point below the upper rim of the container and the incoming drilling mud is pres~urized sufficiently to maintain the entire volume of the cavity completely filled with the dr$11ing mud at all tlmes. If necessary! a pump (not shown) may be interposed into the drilling mud intake pipe upstream of the housing.
The drilling mud i8 most conveniently induced to overflow the upper end of the container and 8pill downwardly therefrom. Referring now again to Figure 1, it will be seen that the drilllng mud spilling from the container will fall through drilling mud outlet 20 and be returned to the mud pit on a continuous basis. As previously explained, drilling mud usually contains various additives. If the drilling mpd is allowed to run down the sides of the container, these additive~
will have a tendency to be deposited on the container and to accumulate thereon, adding to the weight of the container and thereby introducing errors into the density measurement of the drilling mud. To prevent this accumulation, splash guard 34 is mounted on the upper rim of the container and flares outwardly and downwardly therefrom. The splash guard acts to direct the drilling mud spilling over from the container away therefrom and into the drilling mud outlet. The container and splash guard are mounted on support 36 which extends upwardly within the apparatus housing.
The container support is connected to valve 38, as will be explained in greater detail hereinafter.
Even with the splash guard, it may be deQirable to periodically clean or inspect the container or other portions of the apparatus. To accomplish this in the illustrated embodiment, the `
.
lZ~B6 entire lower portion of the hous~ng i~ con~tructed as a unitary structure h~nged at 37 ~shown in Figure 3) along the bac~ side thereof and secured by latch 39 on the front side, which may be a magnetic latch.
Further, support 36 includes a lower portion secured to the container and splash guard and hlnged at 41 along its front side and secured by latch 43, which may be a magnetic latch. When cleaning or in~pection of the container i~ desired, the lower portion of the housing is released and rotated in a counter clockwise direction ~as seen in Figure 3), exposing the container. The lower portion of the support is released and rotated in a clockwise direction, bringing the container outside of the housing and providing ready access. Reversal of the above procedure places the container in position to resume monitoring operation~.
Pressurized fluid conduit 22 enter~ the housing through its back wall and extends to preqsure regulator 40 mounted on the interior of the housing.
The pressure regulator reduces the pressure of the fluid in the apparatus downstream of the pressure regulator to a level convenient for the purposes hereinafter described. Although not shown, the pressure regulator may include a pressure guage to aid in ad~uQting the output of the pre3sure regulator to desired levels. Conduit 22 extends from the outlet of the pressure regulator to pressure transmitter 42 mounted on internal framework 44 mounted on the housing. The pressure transmitter is sensltive to the pressure of the flu$d in the conduit downstream of the pressure regulator and generate~ a contlnuou~
electrical signal indicat~ve of the pre~sure. The electrical signal from the pressure transmitter is conveyed externally of the housing by wire 24 to meter 26, where the calibrated pressure reading of the r~
lZ(~Z~6 pre~8Ure tranBmitter i8 electronically converted to a signal, di~played by the meter, which i5 a mea~urement o~ the liquid denslty, as will be explained hereinafter. Pre~sure reservoir 46 is mounted on an upper portion of the container support over the valve.
Conduit 48 extend~ from the pres~ure tran~mitter to the pressure reservoir to convey the pres~urized fluid to the pre~ure reservoir.
F~gure ~ ~how~ in detall the constructlon of valve 38. Bracket S0 i8 mounted on internal framework 44 of the housing. Valve member 52 i8 mounted on the bracket, such a8 by ~olt 54 or any other conventional means. In the preferred embodiment of the invention, the valve member is spherical, as shown in Figure 5.
Upper valve portlon 56 1B mounted on the under slde of pressure reservoir 46. The upper valve portion includes conduit 58 communicating with the pressure reservoir and terminatlng in conical valve seat 60.
The valve seat includes 0-ring seal 62 mounted ln annu-lar groove 64 of the valve seat. The valve member ispartlally located wlthin the valve sQat ad~acent the seal and i8 loosely restralned therewlthln by retaining plate 66 mounted on the upper valve portlon by bolts 68 snd secured by spacers 70 carrled about each of the bolts 68. The retalning plate lncludes concentric openlng 72 of le~ser dlameter than the dlameter of the valve member. The spacers 70 enable limited vertical movement of the upper valve portlon, bolts, spacers, and retalning plate wlth respect to the valve member in directlons 74 ~downward) and 76 ~upward). The upper valve portion is inherently urged downwardly in direc-tion 74 into seallng engagement wlth th~ valve member by the comblned weight of the contalner~ container support, pressure reservoir, pressure transmitter, and the weight of the drilling mud sample carried by the container.
It is one of the advantages of the spherical valve ~ 86 member that it inherently acts w~th the conical valve ~eat to center the support and the container and maintain the container in an upright and level pos~tion over the drilling mud outlet. The contalner is thus maintained in an upright and level posltion and the ample of drilllng mud prevented from overflowing the container at a greater rate than the drilling mud i8 in~ected into the cavity.
In operation, a continuous ~tream of the drilling mud iB in~ected into the cavity through the orif$ce of the drilling mud input plpe at a regulated flow rate, completely filling thè cavity at all times.
The contents of the container at any qiven tlme constitut2s a representative and timely sample of the drilllng mud emerging from the well bore. The rate of flow through the input pipe is ad~usted, 80 that the pace of sampling may be any selected pace. For instance, should the chamber of the container have a capacity of 1 gallon and the desired pace of the sampling be one minute intervals, then the flow rate into the container would be ad~usted to a rate of 1 gallon per minute. The drilling mud is in~ected withln the cavity o~ the container at 3ufficient pressure 80 that the sample stream continuously flows upward through the cavity and overflows the container onto the splash guard, through the drilling mud outlet and into the mud pit. At the same time, pressurized fluid is introduced into pressure reservoir 46 through conduits 22 and 48, pressure regulator 40 and presure transmltter 42. The pressurized ~luid is lntroduced into the upper valve portion of the spherical valve through conduit 58 and acts against the surface of the valve member above the 0-ring seal to liEt the container and the contalner ~upport upwards ln direction 76, llm~ted by contact between the lower part of the valve member and the retaining piate. If the lZ9Z~86 combined weight of the container, support, and the sample of drilling mud contained in the cavity i.8 less than or equal to the force of the pressurized fluid acting on the valve, then the valve will remain closed.
However, if the force of the pres~urized fluid on the valve member exceeds the welght of the conta~ner, support, and the sample of drilling mud contained in the cavity, then the valve will be opened and the flu~d will be vented from the reservolr through the valve.
This venting will continue until the pressure in the pres~ure reservoir i8 reduced to a point that the force exerted on the valve $8 sufficient to maintain the valve slightly open with a relat~vely small constant rate of fluid being vented, thereby creating a stable pressure ln the pressure reservoir. Thus, the pressure of the fluid in the pressure reservoir will rapidly assume the equilibrium level determined by the combined weight of the container, support, and the sample of drilling mud contained in the cavity. Of course, the pre~surized fluid as controlled by the pressure regulator, must be supplied to the pressure reservoir at a level high enough to open the valve for all anticipated drilling mud denslties.
Since the weight of the aontainer, pressure reservoir, pressure transmlttQr and the ~upport is flxed and predetermined, any fluctuation in the force urging the valve towards A closed position, as measured by the lnstantaneou~ equlllbrlum pressure wlthin the pressure reservoir, must be due to changes in the weight of the drilling mud sample in the cavity of the container. Because the volume of the cavity is also fixed and predetermined, the welght of the sample varies as the density of the drilling mud varies. The electrical signal of the pressure transmltter is indicative of the weight of the drilling mud sample.
Since the volume of the cavity i~ known, the slgnal `` lZ92886 from the pressure transmitter may be electronically divided by a fixed electrlcal signal representative of ths cavity volume, in a manner known in the art, to achieve a measurement of the drilllng mud density, which is displayed on the meter, which may be remotely located with respect to the remainder of the apparatus.
Alternatively, the density measurement may be recorded for future use~ in lieu of or in addition to display on the meter.
~hus, the apparatus and method of the pre~ent invention enables the density of the drilling mud returning from the well bore to be monitored on a continuous basis and is instantly responsive to fluctuations ln that den~ity, indicative of downhole conditions. Further, monitoring operations may be conducted automatically and controlled remotely, and provides a more accurate ~nd consi~tent measurement than conventional systems.
Although the invention has been disclosed above, with regard to particular and preferred embodiments, these are advanced for illustrative purpoQes only, and are not intended to limit the scope of this invention. For instance, although the invention has been de~cribed as having u single bed of pressurized 1uid above the container and from which the container i~ su~pended, the invention may employ more than one bed of pressurized 1uid or the bed or beds may be located below or to the side of the container. Further, although the spherical valve i8 utilized as having self centering features in order to maintain the container in an upright and level position, other types of valves may be used and separate means employed to maintain the container in an upright and level position. Finally, the invention is not l$mited to monltoring of drilling mud density, but may be applied to various other liquids. These varia-tlons remain within the invention as claimed ~elow.
` ~ Z ~ Z ~ 86 METHOD AND APPARATUS FOR MONITORING
$HE DENSITY OF A LIQUID
Field of the Invention ~ he present invention relates generally to methods and apparatus for monitoring the density of liquids, and more particularly, to methods and S apparatus for monitoring the density of well drilling li quids.
ac~ground of the Invention It is frequently useful to monitor the density of a liquid used in industrial proce~ses. For instance, during drilling operations of a well bore, drilling mud is circulated through the drill pipe and the annulus of the well bore. The drilling mud serve~
several purposes in the drilllng process, including lubrication and cooling of the drill bit and the removal of cuttings resulting from the penetration of the subsurface formation~ Additionally, the weight of the drilling mud in the well bore exerts hydro~tatic pressure on the subsurface formations that acts to contain the subsurface pressure encountered during drilling operations. These subsurface pre~sures may be extremely high, such as 8,000-10,000 p~i, or the equivalent of two ~2) pound~ per square inch per foot of depth. If the hydrostatic pressure of the drilling lZ~2886 mud at the depth at which the sub~urface pre~ure i8 encountered i8 not equal to or greater than the sub~urface pres~ure, tbe reservoir fluld will emerge from the subsurface formation and travel to the surface through the well bore. This is known as a blow out and creates extremely dangerous conditions as the pressurized format~on fluid generally containing gas rapidly expands a~ it approaches the surface and atmospheric pressure. However, if the drilling mud hydrostatic pressure i8 too high, the subsurface formations may be fractured resulting in extensive loss of the relatively expensive drilling mud into the formation~ surrounding the well bore. Thus, the density of the drilling mud must be monitored and adjusted if necessary, to malntain it within a desired range during drilling operations. Another constraint on the denslty of the drilling mud is that an increase in the density tends to reduce the penetration of the drill bit.
Drilling mud is a liquid composition, u~ually utilizing oil or water a3 a base to which various sub~tances are added depending on the propertles desired in the drilling operatlons, the subsurface and environmental conditions, a8 well as other factors as are known in the art. Typically, the additives include solid particulates or clay~ to promote the formatlon of a filter cake on the wall~ of the well bore and to assist in suspending the cuttings until the drilllng mud containing the cuttlngs re~ches the surface, and weighting materials such a~ barites, to control the density of the drilling mud. After circulation through the well bore, the drilling mud is filtered to remove the cuttings carried from the bottom of the well bore and then stored in a mud pit for sub3equent use.
Under conventional drilling techniques, a small sample of the drilling mud i5 perlodlcally ~ 2 ~ ~
obtained as lt i8 deposited in the mud pit. The density of the sample i~ measured and a determinatlon made whether or not to ad~u~t the density of the drilling mud being u~ed in the well bore. Existing apparatus u~ed to measure the density of the drilling - mud sample i~ called a mud balance and consists of a container having a known volume on one end and a scale and weight on the other end. The apparatus ti.e. mud container, scale and weight) is then placed on a knife edge fulcrum. ~he container is then filled to its capacity with the sample of interest. The weight i8 moved along the scale until balanced. Indicia on the ~cale at the location of the weight indicate the den~ity of the mud sample. That is, the observed welght of the sample may be used to derive a measure of density by dividing the weight by the known volume of the container. The same scale can be calibrated in any set of units desired.
However, this and other conventional denRity monitoring procedures exhibit certain limitations. For instance, the monitoring of the drilling mud density is performed on an intermittent basis, and must be manually performed. This manual operation takes approximately 10-15 minutcs. When conditions are encountered that cause rap~d change~ in ~he mud density, the density may drastically change in a matter of minutes or seconds. Frequently, it is not economical or practical to weigh samples of the drilllng mud on an ongoing basls, since a skilled technician or engineer is required to perform the test.
Les~ frequent samples introduce a time lag into the monitoring process that is undesirable. Further, manual weighing of a drilling mud sample on a mud balance is relatively inaccurate and requires visual interpretation, thereby introducing the possibillty of human error. Finally, weighing of the drilling mud ~29Z886 sample must be performed on 9 ~ te and cannot conveniently be conducted remotely. None of the existing methods or apparatus for monitoring dr$11ing mud den~ity adequately solve the problems outlined above.
Summary of the Invention This invention provldes a method and apparatus to measure the den~ity of a liquid on a continuou~
basis, such as drilling mud returning from circulation in a well bore. The physical principal utilized is that a force ~F) is proportional to pressure (P) and area ~A), where F equals the orce in pounds and P
equal~ pressure in PSI and A equals area in square inches. A continuous sample of the drilling mud is flowed through a conta$ner having a fixed predetermined volume. The container and the sample o the liquid is ~upported on at least one bed of pressurized fluid.
The pressure of the fluid is varied by fluctuatlons in the weight of the container and liquid sample, 80 a~ to equalize the forces acting across the seal of the valve. A pressure transmitter is connected to the chamber and generates a continuous electrical ~ignal indicative of the instantaneous pressure in the bed of pressurized fluid required to support the container and liguid sample. The electrical signal from the pressure transmitter is converted to a measure of the density of the drilling mud by electronically dividing it by a constant signal representative of the volume of the container cavity. Preferably, the valve is a spherical vaive and acts to automatically maintain the container in an upright position, and is designed to have negligible pressure drop across the seal of the valve.
Therefore, it is a principal feature and advantage of this inventlon to provide an improved method and apparatus for continuou~l~ monitoring the " 1'29~86 ' density of a liquid.
It i8 another feature and advantage of this invention to provide an improved method and apparatus for instantaneou~ly and automatically monitoring the density o~ a liquid.
It i 8 another eature and advantage of thi 8 invention to provide an improved method and appara us for monitoring the den~ity of a llquid in which the density of the liquid made may be remotely monitored.
Brief DescriPtion of the Drawin~s So that the manner in which the above recited features and advantages of the inventlon, as well as others which will become apparent to tho~e skilled in the art, are obtained and can be understood in detail, a more particular description of the invention briefly summar~zed above may be had by reference to the embodiments thereof whlch are illustrated in the accompanying drawings, which drawings form a part of the ~peciflcation and in which like numerals depict like parts in the several views. It is noted, however, that the appended drawings lllustrate only a preferred embodiment of the invention and are therefore not to be consldered limitlng of its scope, for the invention may admit to other equally effective embodiments.
Figure 1 is a schematla representation of a density measuring device according to thls invention.
Figure 2 i8 a front view, partially in cross section, of a density measuring device according to this invention.
Figure 3 is a side v~ew, partially in cross section, of the density measuring device of Figure 2.
Figure 4 is a cross sectional view along view 4-4 of the density measuring device of Figure 3.
F$gure 5 is a magnified view of the ball valve of Figure 3.
Detalled De~cri~tion of the Invention Referring now to Figure 1, the reference numeral 10 generally ~ndicates the apparatus of thi~
invention, including generally rectangular housing or enclosure 12. The housing is po~itioned over mud p~t 14 containing a quantity of drllling mud 16. Drilling mud intake pipe 1~ i3 connected at one end tnot shown) to the circulatlon ~ystem tnot shown) for the drilling mud and is adapted to continuslly convey to the hou~ing a sample before the drilling mud is returned to the mud pit. Drilllng mud outlet 20 extends downwardly from the bottom of the housing and i8 positioned to return the sample stream of drilling mud to the mud pit after exiting from the housing. Pressurized fluid conduit 22 is connected at one end ~not shown) to a source of pressurized fluid tnot shown). Although air may be utilized as the fluid, any suitable fluid may be utilized within conduit 22 if desired. The other end of the fluid conduit extends into the interior of the housing, as will be explained hereinafter. Wire or cable 24 extends outwardly of the housing and is remotely connected to meter 26 for providing a display indicative of the density of the drilling mud ~ample.
Turning now to Figures 2-4, the hou~ing is shown in greater detail mounted on rigid external framework 28 tnot a part of the apparatus) which consists of interconnected beams and trusses and is provided to support the hous~ng over the mud pit tnot shown). Housing 12 includes top, bottom, front and bac~ walls and defines left and right sides, 12a and 12b, respectively, a~ seen in Figure 2. Container 30 iq provided within the housing to receive a continuous sample of the drilling mud. The container consists of a cylindrical body with an open upper end communicating with cavity 31 therewithin having a fixed and predetermined volume. Drilling mud is continuously ~2928~36 introduced into tbe cavity of the container through drill~ng mud intake pipe 18, which does not contact container 30 at any place. Preferably, orifice 32 of the drilling mud inta~e pipe i8 located at a point below the upper rim of the container and the incoming drilling mud is pres~urized sufficiently to maintain the entire volume of the cavity completely filled with the dr$11ing mud at all tlmes. If necessary! a pump (not shown) may be interposed into the drilling mud intake pipe upstream of the housing.
The drilling mud i8 most conveniently induced to overflow the upper end of the container and 8pill downwardly therefrom. Referring now again to Figure 1, it will be seen that the drilllng mud spilling from the container will fall through drilling mud outlet 20 and be returned to the mud pit on a continuous basis. As previously explained, drilling mud usually contains various additives. If the drilling mpd is allowed to run down the sides of the container, these additive~
will have a tendency to be deposited on the container and to accumulate thereon, adding to the weight of the container and thereby introducing errors into the density measurement of the drilling mud. To prevent this accumulation, splash guard 34 is mounted on the upper rim of the container and flares outwardly and downwardly therefrom. The splash guard acts to direct the drilling mud spilling over from the container away therefrom and into the drilling mud outlet. The container and splash guard are mounted on support 36 which extends upwardly within the apparatus housing.
The container support is connected to valve 38, as will be explained in greater detail hereinafter.
Even with the splash guard, it may be deQirable to periodically clean or inspect the container or other portions of the apparatus. To accomplish this in the illustrated embodiment, the `
.
lZ~B6 entire lower portion of the hous~ng i~ con~tructed as a unitary structure h~nged at 37 ~shown in Figure 3) along the bac~ side thereof and secured by latch 39 on the front side, which may be a magnetic latch.
Further, support 36 includes a lower portion secured to the container and splash guard and hlnged at 41 along its front side and secured by latch 43, which may be a magnetic latch. When cleaning or in~pection of the container i~ desired, the lower portion of the housing is released and rotated in a counter clockwise direction ~as seen in Figure 3), exposing the container. The lower portion of the support is released and rotated in a clockwise direction, bringing the container outside of the housing and providing ready access. Reversal of the above procedure places the container in position to resume monitoring operation~.
Pressurized fluid conduit 22 enter~ the housing through its back wall and extends to preqsure regulator 40 mounted on the interior of the housing.
The pressure regulator reduces the pressure of the fluid in the apparatus downstream of the pressure regulator to a level convenient for the purposes hereinafter described. Although not shown, the pressure regulator may include a pressure guage to aid in ad~uQting the output of the pre3sure regulator to desired levels. Conduit 22 extends from the outlet of the pressure regulator to pressure transmitter 42 mounted on internal framework 44 mounted on the housing. The pressure transmitter is sensltive to the pressure of the flu$d in the conduit downstream of the pressure regulator and generate~ a contlnuou~
electrical signal indicat~ve of the pre~sure. The electrical signal from the pressure transmitter is conveyed externally of the housing by wire 24 to meter 26, where the calibrated pressure reading of the r~
lZ(~Z~6 pre~8Ure tranBmitter i8 electronically converted to a signal, di~played by the meter, which i5 a mea~urement o~ the liquid denslty, as will be explained hereinafter. Pre~sure reservoir 46 is mounted on an upper portion of the container support over the valve.
Conduit 48 extend~ from the pres~ure tran~mitter to the pressure reservoir to convey the pres~urized fluid to the pre~ure reservoir.
F~gure ~ ~how~ in detall the constructlon of valve 38. Bracket S0 i8 mounted on internal framework 44 of the housing. Valve member 52 i8 mounted on the bracket, such a8 by ~olt 54 or any other conventional means. In the preferred embodiment of the invention, the valve member is spherical, as shown in Figure 5.
Upper valve portlon 56 1B mounted on the under slde of pressure reservoir 46. The upper valve portion includes conduit 58 communicating with the pressure reservoir and terminatlng in conical valve seat 60.
The valve seat includes 0-ring seal 62 mounted ln annu-lar groove 64 of the valve seat. The valve member ispartlally located wlthin the valve sQat ad~acent the seal and i8 loosely restralned therewlthln by retaining plate 66 mounted on the upper valve portlon by bolts 68 snd secured by spacers 70 carrled about each of the bolts 68. The retalning plate lncludes concentric openlng 72 of le~ser dlameter than the dlameter of the valve member. The spacers 70 enable limited vertical movement of the upper valve portlon, bolts, spacers, and retalning plate wlth respect to the valve member in directlons 74 ~downward) and 76 ~upward). The upper valve portion is inherently urged downwardly in direc-tion 74 into seallng engagement wlth th~ valve member by the comblned weight of the contalner~ container support, pressure reservoir, pressure transmitter, and the weight of the drilling mud sample carried by the container.
It is one of the advantages of the spherical valve ~ 86 member that it inherently acts w~th the conical valve ~eat to center the support and the container and maintain the container in an upright and level pos~tion over the drilling mud outlet. The contalner is thus maintained in an upright and level posltion and the ample of drilllng mud prevented from overflowing the container at a greater rate than the drilling mud i8 in~ected into the cavity.
In operation, a continuous ~tream of the drilling mud iB in~ected into the cavity through the orif$ce of the drilling mud input plpe at a regulated flow rate, completely filling thè cavity at all times.
The contents of the container at any qiven tlme constitut2s a representative and timely sample of the drilllng mud emerging from the well bore. The rate of flow through the input pipe is ad~usted, 80 that the pace of sampling may be any selected pace. For instance, should the chamber of the container have a capacity of 1 gallon and the desired pace of the sampling be one minute intervals, then the flow rate into the container would be ad~usted to a rate of 1 gallon per minute. The drilling mud is in~ected withln the cavity o~ the container at 3ufficient pressure 80 that the sample stream continuously flows upward through the cavity and overflows the container onto the splash guard, through the drilling mud outlet and into the mud pit. At the same time, pressurized fluid is introduced into pressure reservoir 46 through conduits 22 and 48, pressure regulator 40 and presure transmltter 42. The pressurized ~luid is lntroduced into the upper valve portion of the spherical valve through conduit 58 and acts against the surface of the valve member above the 0-ring seal to liEt the container and the contalner ~upport upwards ln direction 76, llm~ted by contact between the lower part of the valve member and the retaining piate. If the lZ9Z~86 combined weight of the container, support, and the sample of drilling mud contained in the cavity i.8 less than or equal to the force of the pressurized fluid acting on the valve, then the valve will remain closed.
However, if the force of the pres~urized fluid on the valve member exceeds the welght of the conta~ner, support, and the sample of drilling mud contained in the cavity, then the valve will be opened and the flu~d will be vented from the reservolr through the valve.
This venting will continue until the pressure in the pres~ure reservoir i8 reduced to a point that the force exerted on the valve $8 sufficient to maintain the valve slightly open with a relat~vely small constant rate of fluid being vented, thereby creating a stable pressure ln the pressure reservoir. Thus, the pressure of the fluid in the pressure reservoir will rapidly assume the equilibrium level determined by the combined weight of the container, support, and the sample of drilling mud contained in the cavity. Of course, the pre~surized fluid as controlled by the pressure regulator, must be supplied to the pressure reservoir at a level high enough to open the valve for all anticipated drilling mud denslties.
Since the weight of the aontainer, pressure reservoir, pressure transmlttQr and the ~upport is flxed and predetermined, any fluctuation in the force urging the valve towards A closed position, as measured by the lnstantaneou~ equlllbrlum pressure wlthin the pressure reservoir, must be due to changes in the weight of the drilling mud sample in the cavity of the container. Because the volume of the cavity is also fixed and predetermined, the welght of the sample varies as the density of the drilling mud varies. The electrical signal of the pressure transmltter is indicative of the weight of the drilling mud sample.
Since the volume of the cavity i~ known, the slgnal `` lZ92886 from the pressure transmitter may be electronically divided by a fixed electrlcal signal representative of ths cavity volume, in a manner known in the art, to achieve a measurement of the drilllng mud density, which is displayed on the meter, which may be remotely located with respect to the remainder of the apparatus.
Alternatively, the density measurement may be recorded for future use~ in lieu of or in addition to display on the meter.
~hus, the apparatus and method of the pre~ent invention enables the density of the drilling mud returning from the well bore to be monitored on a continuous basis and is instantly responsive to fluctuations ln that den~ity, indicative of downhole conditions. Further, monitoring operations may be conducted automatically and controlled remotely, and provides a more accurate ~nd consi~tent measurement than conventional systems.
Although the invention has been disclosed above, with regard to particular and preferred embodiments, these are advanced for illustrative purpoQes only, and are not intended to limit the scope of this invention. For instance, although the invention has been de~cribed as having u single bed of pressurized 1uid above the container and from which the container i~ su~pended, the invention may employ more than one bed of pressurized 1uid or the bed or beds may be located below or to the side of the container. Further, although the spherical valve i8 utilized as having self centering features in order to maintain the container in an upright and level position, other types of valves may be used and separate means employed to maintain the container in an upright and level position. Finally, the invention is not l$mited to monltoring of drilling mud density, but may be applied to various other liquids. These varia-tlons remain within the invention as claimed ~elow.
Claims (21)
1. A method of continually monitoring the density of a liquid, comprising the steps of:
(a) continually obtaining samples of the liquid;
(b) flowing the samples into a container having a closed bottom and sides;
(c) overflowing the container so as to maintain a fixed predetermined volume of the liquid samples within the container;
(d) supporting the container and liquid samples on at least one bed of pressurized fluid; and (e) varying the pressure of the fluid as a function of the weight of the container and liquid to produce a signal representative of the density of the liquid.
(a) continually obtaining samples of the liquid;
(b) flowing the samples into a container having a closed bottom and sides;
(c) overflowing the container so as to maintain a fixed predetermined volume of the liquid samples within the container;
(d) supporting the container and liquid samples on at least one bed of pressurized fluid; and (e) varying the pressure of the fluid as a function of the weight of the container and liquid to produce a signal representative of the density of the liquid.
2. The method of claim 1 further comprising the step of deflecting the overflowing liquid samples from the container so as to prevent the accumulation of the liquid on the sides of the container.
3. The method of claim 1, in which the liquid samples are flowed into the container at a point below an upper end of the container, thereby causing a continuous change in the contents of the container.
4. The method of claim 1, in which the liquid is a drilling mud which has been returned from the well bore to a mud pit at the surface and in which the drilling mud is sampled prior to its return to the mud pit and further in which the overflow from the container is returned to the mud pit.
5. The method of claim 1, in which the bed of pressurized fluid is established above the container.
6. Apparatus for continuously monitoring the density of a liquid, comprising:
(a) a container having a closed bottom and sides;
(b) means for continuously obtaining samples of the liquid;
(c) means for flowing the samples of the liquid into said container;
(d) means for maintaining a fixed predetermined volume of the liquid samples in said container by overflowing the container;
(e) means for providing at least one bed of pressurized fluid;
(f) means for supporting said container and the liquid samples on said bed of pressurized fluid and means for varying the pressure of the fluid as a function of the weight of the container and the liquid to produce a signal representative of the density of the liquid.
(a) a container having a closed bottom and sides;
(b) means for continuously obtaining samples of the liquid;
(c) means for flowing the samples of the liquid into said container;
(d) means for maintaining a fixed predetermined volume of the liquid samples in said container by overflowing the container;
(e) means for providing at least one bed of pressurized fluid;
(f) means for supporting said container and the liquid samples on said bed of pressurized fluid and means for varying the pressure of the fluid as a function of the weight of the container and the liquid to produce a signal representative of the density of the liquid.
7. The apparatus of claim 6, in which said means for supporting said container on said bed of pressurized fluid includes:
(a) a housing;
(b) a structure having a spherical outer surface mounted in fixed relation to said housing; and (c) a support having an upper portion supported solely on said spherical structure and a lower portion for receiving said container, whereby said support may move about said spherical structure to maintain said container in a horizontal position relative to the earth's surface.
(a) a housing;
(b) a structure having a spherical outer surface mounted in fixed relation to said housing; and (c) a support having an upper portion supported solely on said spherical structure and a lower portion for receiving said container, whereby said support may move about said spherical structure to maintain said container in a horizontal position relative to the earth's surface.
8. The apparatus of claim 6, further including means formed at the top of said container for directing overflow of liquid from said container away from outer sides of the container to avoid buildup of any sediments in the liquid on the outer sides of said container.
9. Apparatus for continuously monitoring the density of a liquid, comprising:
(a) a housing including a source of pressurized fluid;
(b) a container having a closed bottom and sides and defining a fixed predetermined volume for receipt of the liquid;
(c) means for continuously flowing a sample of the liquid into said container, said continuous sample filling said volume within container and continuously overflowing said container;
(d) at least one bed of pressurized fluid mounted on said housing and connected to said source of pressurized fluid, said container being solely supported by said bed by varying the pressure level of said fluid responsive to the weight of said container and said sample of the liquid;
and (e) means for continuously measuring the value of fluid pressure in said bed necessary to support said container and liquid sample and generating a signal indicative of the density of the liquid.
(a) a housing including a source of pressurized fluid;
(b) a container having a closed bottom and sides and defining a fixed predetermined volume for receipt of the liquid;
(c) means for continuously flowing a sample of the liquid into said container, said continuous sample filling said volume within container and continuously overflowing said container;
(d) at least one bed of pressurized fluid mounted on said housing and connected to said source of pressurized fluid, said container being solely supported by said bed by varying the pressure level of said fluid responsive to the weight of said container and said sample of the liquid;
and (e) means for continuously measuring the value of fluid pressure in said bed necessary to support said container and liquid sample and generating a signal indicative of the density of the liquid.
10. The apparatus of claim 9, wherein said bed of pressurized fluid includes a valve mounted on said housing urged to a closed position by the weight of said container and said sample of the liquid, said valve being connected to said source of pressurized fluid and urged to an open position by said pressurized fluid, so as to continuously vary the value of pressure of said fluid responsive to fluctuations in the weight of said container and said sample of liquid thereby equalizing the forces acting on said valve.
11. The apparatus of claim 10, wherein said valve is automatically self centering.
12. The apparatus of claim 10, wherein said valve is a spherical valve.
13. The apparatus of claim 10, wherein said container is suspended from said valve and including means for automatically and continuously maintaining said container in an upright and level position.
14. The apparatus of claim 9, wherein said measuring means comprises a pressure transmitter connected to said source of pressurized fluid and adapted to generate an electrical signal indicative of the density of the liquid.
15. The apparatus of claim 9, wherein said source of pressurized fluid is a pressure reservoir mounted on said housing.
16. Apparatus for continuously measuring the density of a drilling mud being returned to a mud pit after circulation through a well bore, comprising:
(a) a housing;
(b) a container having a closed bottom and sides and defining a fixed predetermined volume;
(c) means for continuously filling said container with a sample of the circulated drilling mud prior to its return to the mud pit and further in which the overflow from the container is returned to the mud pit, said means injecting said sample into said container at a point below an upper end of the container and in which a predetermined volume of the drilling mud is maintained in said container by overflowing the sides of the container;
(d) means formed at the top of said container for directing overflow of drilling mud away from the sides of the container to avoid buildup of sediments in the drilling mud on the sides of said container;
(e) means for establishing a bed of pressurized fluid, said means being mounted on said housing above said container and adapted for connection to a source of pressurized fluid, said container being supported from said means by varying the pressure of said fluid responsive to the weight of said container and said sample of the liquid;
and (f) a pressure transmitter connected to said means for establishing a bed of pressurized fluid for generating an electrical signal responsive to the pressure of the fluid in the bed indicative of the density of the liquid.
(a) a housing;
(b) a container having a closed bottom and sides and defining a fixed predetermined volume;
(c) means for continuously filling said container with a sample of the circulated drilling mud prior to its return to the mud pit and further in which the overflow from the container is returned to the mud pit, said means injecting said sample into said container at a point below an upper end of the container and in which a predetermined volume of the drilling mud is maintained in said container by overflowing the sides of the container;
(d) means formed at the top of said container for directing overflow of drilling mud away from the sides of the container to avoid buildup of sediments in the drilling mud on the sides of said container;
(e) means for establishing a bed of pressurized fluid, said means being mounted on said housing above said container and adapted for connection to a source of pressurized fluid, said container being supported from said means by varying the pressure of said fluid responsive to the weight of said container and said sample of the liquid;
and (f) a pressure transmitter connected to said means for establishing a bed of pressurized fluid for generating an electrical signal responsive to the pressure of the fluid in the bed indicative of the density of the liquid.
17. The apparatus of claim 16, wherein said bed includes a valve mounted on said housing urged to a closed position by the weight of said container and said sample of the liquid, said valve being connected to the source of pressurized fluid and urged to an open position by said pressurized fluid in said bed of pressurized fluid, 80 as to continuously vary the pressure of said fluid responsive to fluctuations in the weight of said container and said sample of liquid, thereby equalizing the forces acting on said valve.
18. The apparatus of claim 16, in which said means formed at the top of said container for directing overflow of liquid from said container away from its outer sides to avoid buildup of any sediments in the liquid on the outer sides of said container comprises an annular lip extending downwardly and outwardly from said container.
19. The apparatus of claim 8, wherein said means for directing the overflow of the liquid from said container is an annular lip depending outwardly and downwardly from said container.
20. The apparatus of claim 9, further comprising means formed at the top of said container for directing overflow of liquid from said container away from its outer sides to avoid build-up of any sediment in the liquid on the outer side of said container.
21. The apparatus of claim 20 wherein said means for directing the overflow of liquid from said container is an annular lip extending downwardly and outwardly from said container.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000539109A CA1292886C (en) | 1987-06-08 | 1987-06-08 | Method and apparatus for monitoring the density of a liquid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000539109A CA1292886C (en) | 1987-06-08 | 1987-06-08 | Method and apparatus for monitoring the density of a liquid |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1292886C true CA1292886C (en) | 1991-12-10 |
Family
ID=4135843
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000539109A Expired - Lifetime CA1292886C (en) | 1987-06-08 | 1987-06-08 | Method and apparatus for monitoring the density of a liquid |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1292886C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105823708A (en) * | 2015-01-08 | 2016-08-03 | 上海朝辉压力仪器有限公司 | Density transducer |
| CN108333078A (en) * | 2018-03-05 | 2018-07-27 | 济南鲁纺仪佳自控技术有限公司 | Fully-automatic on-line sampling formula slurry density measurement device |
-
1987
- 1987-06-08 CA CA000539109A patent/CA1292886C/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105823708A (en) * | 2015-01-08 | 2016-08-03 | 上海朝辉压力仪器有限公司 | Density transducer |
| CN108333078A (en) * | 2018-03-05 | 2018-07-27 | 济南鲁纺仪佳自控技术有限公司 | Fully-automatic on-line sampling formula slurry density measurement device |
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