GB2261308A - Data transmission - Google Patents
Data transmission Download PDFInfo
- Publication number
- GB2261308A GB2261308A GB9210934A GB9210934A GB2261308A GB 2261308 A GB2261308 A GB 2261308A GB 9210934 A GB9210934 A GB 9210934A GB 9210934 A GB9210934 A GB 9210934A GB 2261308 A GB2261308 A GB 2261308A
- Authority
- GB
- United Kingdom
- Prior art keywords
- acoustic
- data
- data transmission
- drill bit
- borehole
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000005540 biological transmission Effects 0.000 title claims description 19
- 239000011435 rock Substances 0.000 claims abstract description 16
- 239000012530 fluid Substances 0.000 claims abstract description 12
- 230000002457 bidirectional effect Effects 0.000 claims description 3
- 239000000523 sample Substances 0.000 claims 1
- 238000005553 drilling Methods 0.000 description 14
- 238000000034 method Methods 0.000 description 12
- 230000015572 biosynthetic process Effects 0.000 description 4
- 239000012636 effector Substances 0.000 description 4
- 238000005755 formation reaction Methods 0.000 description 4
- 230000005260 alpha ray Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000013144 data compression Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000013598 vector Substances 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B44/00—Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems; Systems specially adapted for monitoring a plurality of drilling variables or conditions
- E21B44/005—Below-ground automatic control systems
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
- E21B47/12—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
- E21B47/14—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling using acoustic waves
- E21B47/18—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling using acoustic waves through the well fluid, e.g. mud pressure pulse telemetry
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
- E21B47/26—Storing data down-hole, e.g. in a memory or on a record carrier
Landscapes
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Geology (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geophysics (AREA)
- Remote Sensing (AREA)
- Acoustics & Sound (AREA)
- Geophysics And Detection Of Objects (AREA)
- Arrangements For Transmission Of Measured Signals (AREA)
Abstract
Data is transmitted from a rotating drill bit (3) to a non-rotating main section (2) of the drill string through an acoustic data link passing through the fluid within the borehole (1) and the rock around the borehole (1). The bit (3) and sensors (9a, 9b) are rotated by a mud motor 4 and data is transmitted to the receiving section (2). The data is then relayed to the surface or stored and recovered later. <IMAGE>
Description
Data Transmission
This invention relates to data transmission within a borehole.
When a borehole is being drilled it can be very useful to transmit information from the end of the drill string to the surface. One situation where this is necessary is in deviated drilling where the drill is producing a non-vertical borehole. In deviated drilling position and orientation sensors are positioned near to the drill bit in order to allow the precise location of the drill bit and orientation of the borehole to be measured.
Another situation is measuring while drilling (M.W.D.) where peterological, geological and geotechnical information about the rock formations around the borehole are gathered while drilling, typical sensors used are for example alpha ray and neutron detectors, acoustical sensors and resistivity and dielectric constant measuring systems. An objective of M.W.D. is to carry out formation evaluation while drilling (F.E.W.D.) where information about the rock formations around the borehole is gathered and analysed in order to produce a real time prediction of the rock structure being drilled into. This prediction can then be used to provide a warning that over-pressure regions are about to be drilled into.
This is desirable because drilling into an over-pressure region can result in loss of the borehole and in extreme cases damage to above ground instillations unless a large enough mass of fluid, generally known as mud, has been placed in the borehole to make the pressure in the borehole equal to or greater than the pressure in the over-pressure region.
Furthermore after a borehole has been drilled, for example to produce oil, it is often necessary to carry out operations within it. These operations include inspection of the borehole walls, the formation and removal of plugs and treating the borehole wall to increase fluid flow rates among others. One method of doing this is to pass a narrow bore continuous tube with a sensor or end effector at its end down the borehole. In order to monitor and control this sensor/effector data must be passed up the borehole and instructions must be passed down.
One known method of obtaining information from sensors down boreholes is to record the data at the sensor, and periodically extract the entire drill string from the borehole to allow the recorded data to be read out at the surface for analysis. The main disadvantage of this procedure is the time taken by extracting and replacing the drill string and the resulting reduction in the speed of drilling.
Another method of obtaining information from sensors down boreholes is to transmit the information from the sensor to a receiver on the surface.
One known technique for doing this is to transmit the information as a binary code of pressure pulses in the mud filling the borehole using a mud pulser. The disadvantage of this technique is the very low data transmission rate, typically about 1 bit per second. As a result only a very small amount of information can be transmitted to the surface for analysis in real time.
Another known technique, used only with a continuous drill tube, is to pass a coaxial or multi-core cable down the centre of the drill tube.
There are three main disadvantages associated with this technique, the first is that the environment at the bottom of the borehole can be very different from that at the top, temperatures up to 2000C and pressures of 15,000 pSi can be encountered at the bottom of a borehole. This can cause considerable problems as the electrical properties of the cable change as the environment around it changes resulting in a wire having different characteristics along its length. This can result in unacceptable electrical attenuation in signals passing along the cable. Secondly, in addition to the changes in conditions along the borehole's length conditions within the tube are extremely hostile, apart from the pressures and temperatures naturally present within the borehole it is often necessary to pump fluid under high pressure down the pipe to power end effectors such as drills.This produces an unacceptably high rate of cable failures, and withdrawing the pipe and replacing the cable is both time consuming and costly. The third problem is that the lengths of the cable and tube must of course be matched precisely and the length of the tube must be matched to the depth in the borehole at which the work or examination is to be done and as a result a very large number of tubes and cables must be held as stock at great expense, which is clearly undesirable.
In order to overcome these disadvantages it has been proposed to employ an acoustic data transmission system sending information along the borehole in the form of acoustic travelling waves in the drill pipe. The drill pipe could be a continuous tube or a conventional drill stem formed by sections held together by threaded joints.
At present sensors which transmit information to the surface are placed some 20 metres or more from the actual drill bit because the sensor must be behind the joint between the rotating drill bit and the non rotating part of the drill string. This is because all of the known information transmission techniques suffer from the problem that they are unable to transmit information to the surface across this joint.Mud pulsers cannot be used because the rotating drill bit is rotated by a turbine driven by the drilling fluid, so there is no differential fluid pressure available to operate a mud pulser, electrical cables cannot be used because the extreme conditions at the end of the borehole rapidly destroy rotating electrical connectors and known acoustic systems cannot be used because the rotating and static portions of the drill string are separated by a gap which prevents successful propagation of acoustic waves along the drill string.
It is desirable to be able to place sensors in the rotating drill bit portion of the drill string. Direction and inclination while drilling (D.I.W.D.), especially near to the horizontal for enhanced oil recovery (E.O.R.) demands high precision in the positioning of the drill bit relative to the surrounding rock strata. In order for drill directional steering vectors to be applied it is necessary to have sensors close to the drill bit and to transmit this data in real time back up the drill string. In deviated drilling this will allow the position and orientation of the end of the borehole to be more accurately measured. In M.W.D. and F.E.W.D. it will allow the use of sensors to actually look ahead of the drill bit directly at the rock strata being drilled into, at present it is only possible to look at the rock strata around the drill and try to deduce from this the structure of the rock strata being drilled into.
This invention was intended to produce a data transmission system at least partially overcoming this problem.
This invention provides a data transmission system for transmitting data within a borehole between first and second parts of a drill string capable of relative rotation comprising first and second acoustic transducers associated with the first and second parts respectively and able to transmit data between them as acoustic waves through the fluid and rock surrounding the drill string.
This allows information to be transmitted acoustically between the rotating drill bit and non-rotating part of the drill string along the continuous acoustic path formed by the fluid within the borehole and rock around the borehole.
Although the terms rotating and non-rotating have been used systems of this type could of course be used between any two relatively rotating portions of the drill string.
Referring to Figure 1 the lower end of a drill assembly is shown within a borehole 1. The drill assembly comprises a non-rotating main section 2 and a rotating drill bit section 3 separated by a mud motor section 4. Drilling fluid, generally referred to as mud, is pumped under high pressure down the inside of the main section 2 of the drill assembly and passes through the mud motor 4 to drive the drill bit 3. The mud motor 4 is a fluid turbine driven by the mud. Behind the mud motor 4 is a directional sub section 5 which can alter the orientation of the drill bit 3 and mud motor 4 relative to the main section 2 of the drill in order to control the direction in which the borehole 1 is drilled.
The drill bit section 3 rotates relative to the main section 2 and as a result there is inevitably a discontinuity between the two sections of the drill assembly. This discontinuity is represented by a gap 6 between the drill bit section 3 and the mud motor 4. The two sections of the drill assembly are of course held together by a bearing as is well known in the art, and the actual position and profile of the discontinuity will depend on the structure of the bearing, but this precise position and profile is not relevant to the invention and need not be described in detail.
The directional sub-section 5 comprises a joint allowing movement of the drill bit 3 and the mud motor 4 about two orthogonal axes relative to the main section 2 and actuators and sensors to control and measure the relative orientation of the two sections about these axes. This joint will also involve a discontinuity between the two parts of the drill assembly, this discontinuity is represented by a gap 7 between the mud motor 4 and the directional sub-section 5.
The drill bit 3 includes a collar and an instrument package 8 and a processor and acoustic transducer unit 9 are contained within the collar.
The instrument package 8 comprises an acoustic transmitter and receiver 8A and a position sensing system 8B including an accelerometer, a magnetometer and an inclinometer to produce positional information. The processor and acoustic transducer unit 9 contains a first processor 9A and a first acoustic transducer 9B.
The acoustic transmitter and receiver 8A transmits acoustic energy into the rock strata ahead of the drill bit 3 and then receives the acoustic energy reflected back by this rock strata and produces a digital output signal corresponding to this reflected acoustic energy. The position sensing system 8B generates digital output signals giving the position and orientation of the drill bit 3.
The output signals from the acoustic transmitter and receiver 8A and the position sensing system 8B are supplied to the first processor 9A which processes the output signals from the position sensing system 8B to obtain the position and orientation of the drill bit 3. The first processor 9A then places this position and orientation data and the output signals from the acoustic transmitter and receiver 8A into a suitable format for transmission, this will involve the use of data-compression techniques and the addition of error correction codes. Such techniques and codes are well known and need not be described in detail here.
The first processor 9A then supplies this formatted data to the first acoustic transducer 9B. The first acoustic transducer 9B generates an acoustic signal encoded with the data supplied by the first processor 9A. This acoustic signal is radiated into the drilling mud within the borehole 1 and the surrounding rock and is received by a second acoustic transducer 10 in the main section 2.
The second acoustic transducer 10 converts the acoustic signal back into a digital electrical signal and supplies it to a second processor 11.
The main section 2 also includes a number of M.W.D.
sensors, an alpha ray detector, a neutron detector, resistivity sensor and a dielectric constant sensor, shown collectively as sensors 12. The digital data from the sensors 12 is supplied to the second processor 11.
The second processor 11 is also supplied with data from a rotation sensor giving the speed of rotation of the drill bit 3 relative to the main portion 2, a pressure sensor giving the differential pressure of the mud across the mud motor 4 and the position sensor giving the orientation of the drill bit 3 relative to the main portion 2. For clarity these sensors are not shown individually but are represented by the sensors 12.
The second processor 11 compares the position and orientation data from the first processor 9A with the desired position and orientation of the drill bit which has been programmed into it and instructs the directional sub-section 5 to alter the relative orientations of the drill bit 3 and main section 2 in order to get the position and orientation of the drill bit 3 to their desired values.
The second processor 11 carries out a data fusion function combining the data from all of the sensors 12 and the second acoustic transducer 10, it then compresses the data, adds error correction codes and passes the resulting data to a third acoustic transducer 13.
The third acoustic transducer 13 generates an acoustic signal comprising longitudinal compression waves in the metal of the drill assembly walls encoded with the data supplied by the second processor 11 and transmits it along the drill assembly to the top of the borehole 1 where it is detected and used. A data transmission system of this type suitable for passing acoustic data up a drill string to the surface is shown in co-pending UK Patent Application No.
9120420.
The rate at which data is generated by the various sensors in the drill assembly may be greater than the rate at which the third acoustic transducer 13 can transmit it to the surface If this is the case the second processor 11 must be programmed to send only the most time-critical data, probably the data from the instrument package 8, to the surface and to record the rest of the data on a local recording device.
Alternatively or additionally a recording device could be provided in the rotating drill bit section 3 and the first processor 9A could be programmed to send only the most time critical data from the instrument package 8 to the first acoustic transducer 9B and to record the rest on the recording device.
The third acoustic transducer 13 could be replaced by some other known system for transmitting data along a drill string, such as a mud pulser or wire link.
In some circumstances it may be desirable to pass instructions down the drill string from the surface, in this case a forth transducer will be needed adjacent the third transducer 13, the forth transducer will convert acoustic longitudinal compression waves sent from the surface in the walls of the drill assembly into electrical signals for supply to the second processor 11.
It may be desirable to pass instructions from the second processor 11 to the first processor 9A, these instructions could be generated by the second processor 11 or be sent from the surface and only passed on by the first processor 11. In this case a fifth sending transducer will be required in the main section 2 and a sixth receiving transducer will be required in the drill bit section 3.
Alternatively the first and second transducers 9B and 10 respectively could be arranged to be capable of both generating and receiving acoustic signals to provide a bidirectional acoustic data link.
The types and numbers of sensors used to produce the data transmitted and recorded can of course be varied. Also end effectors could be used in addition to or in place of the sensors and controlled by the first and second processors 9A and 11 in response to the data produced by the sensors and instructions sent from the surface or pre-programmed into the processors 9A and 11.
The desired position and orientation of the drill bit 3 can be programmed into the second processor 11 in advance or supplied to it from the surface during operation.
If the quantity of data to be transmitted from the processor in the collar section of the drill bit 3 to the main section 2 is not too great the data could be stored in the first processor 9A during drilling and drilling could be stopped periodically to allow this stored data to be transmitted. The resulting reduced noise level would make the acoustic data transfer simpler to carry out.
Claims (8)
1. A data transmission system for transmitting data within a borehole between first and second parts of a drill string capable of relative rotation comprising first and second acoustic transducers associated with the first and second parts respectively and able to transmit data between them as acoustic waves through the fluid and rock surrounding the drill string.
2. A system as claimed in claim 1 where the first part includes a rotating drill bit.
3. A data transmission system as claimed in claim 2 where the first part includes an acoustic transmitter and receiver arranged to accoustically probe the rock ahead of the drill bit.
4. A system as claimed in claim 2 where the first acoustic transducer transmits the acoustic waves and the second acoustic transducer receives the acoustic waves.
5. A system as claimed in claim 2 where the first and second parts are separated by a mud motor arranged to drive the drill bit.
6. A system as claimed in any preceding claim wherein the first and second acoustic transducers form a bidirectional data transmission path.
7. A data transmission system as claimed in any preceding claim where a third acoustic transmitter is also included to transmit signals received by the second acoustic transmitter to the surface.
8. A data transmission system substantially as shown in or as described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9210934A GB2261308B (en) | 1991-11-06 | 1992-05-22 | Data transmission |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB919123583A GB9123583D0 (en) | 1991-11-06 | 1991-11-06 | Data transmission |
| GB9210934A GB2261308B (en) | 1991-11-06 | 1992-05-22 | Data transmission |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9210934D0 GB9210934D0 (en) | 1992-07-08 |
| GB2261308A true GB2261308A (en) | 1993-05-12 |
| GB2261308B GB2261308B (en) | 1996-02-28 |
Family
ID=26299818
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9210934A Expired - Fee Related GB2261308B (en) | 1991-11-06 | 1992-05-22 | Data transmission |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2261308B (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0708872A1 (en) * | 1993-07-20 | 1996-05-01 | Baroid Technology, Inc. | Method and apparatus for controlling the head of a drilling or core-drilling device |
| EP0728915A2 (en) * | 1995-02-16 | 1996-08-28 | Baker Hughes Incorporated | Method and apparatus for monitoring and recording of operating conditions of a downhole drill bit during drilling operations |
| EP0975851A1 (en) * | 1997-04-21 | 2000-02-02 | Halliburton Energy Services, Inc. | Acoustic data link for downhole mwd system |
| US6230822B1 (en) | 1995-02-16 | 2001-05-15 | Baker Hughes Incorporated | Method and apparatus for monitoring and recording of the operating condition of a downhole drill bit during drilling operations |
| EP1143105A1 (en) * | 2000-04-04 | 2001-10-10 | Schlumberger Holdings Limited | Directional drilling system |
| GB2420826A (en) * | 2004-12-02 | 2006-06-07 | Avocet Hardware Ltd | Egress hinge with first and second releasable retainers |
| GB2427632A (en) * | 2005-05-12 | 2007-01-03 | Schlumberger Holdings | Transmitting MWD signals through a mud motor |
| GB2476653A (en) * | 2009-12-30 | 2011-07-06 | Wajid Rasheed | Tool and Method for Look-Ahead Formation Evaluation in advance of the drill-bit |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1097083A (en) * | 1964-06-10 | 1967-12-29 | Mobil Oil Corp | Logging-while-drilling system |
| US3932836A (en) * | 1974-01-14 | 1976-01-13 | Mobil Oil Corporation | DC/AC motor drive for a downhole acoustic transmitter in a logging-while-drilling system |
| US3949354A (en) * | 1974-05-15 | 1976-04-06 | Schlumberger Technology Corporation | Apparatus for transmitting well bore data |
| GB1491810A (en) * | 1975-02-24 | 1977-11-16 | Mobil Oil Corp | Method and apparatus for transmitting downhole information from a well |
| GB1592995A (en) * | 1976-09-29 | 1981-07-15 | Schlumberger Technology Corp | Motor control method and apparatus for measuring-while-drilling |
| EP0309030A1 (en) * | 1987-09-22 | 1989-03-29 | Anadrill International SA | Sinusoidal pressure pulse generator for measurement while drilling tool |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5168942A (en) * | 1991-10-21 | 1992-12-08 | Atlantic Richfield Company | Resistivity measurement system for drilling with casing |
| NO306522B1 (en) * | 1992-01-21 | 1999-11-15 | Anadrill Int Sa | Procedure for acoustic transmission of measurement signals when measuring during drilling |
-
1992
- 1992-05-22 GB GB9210934A patent/GB2261308B/en not_active Expired - Fee Related
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1097083A (en) * | 1964-06-10 | 1967-12-29 | Mobil Oil Corp | Logging-while-drilling system |
| US3932836A (en) * | 1974-01-14 | 1976-01-13 | Mobil Oil Corporation | DC/AC motor drive for a downhole acoustic transmitter in a logging-while-drilling system |
| US3949354A (en) * | 1974-05-15 | 1976-04-06 | Schlumberger Technology Corporation | Apparatus for transmitting well bore data |
| GB1491810A (en) * | 1975-02-24 | 1977-11-16 | Mobil Oil Corp | Method and apparatus for transmitting downhole information from a well |
| GB1592995A (en) * | 1976-09-29 | 1981-07-15 | Schlumberger Technology Corp | Motor control method and apparatus for measuring-while-drilling |
| EP0309030A1 (en) * | 1987-09-22 | 1989-03-29 | Anadrill International SA | Sinusoidal pressure pulse generator for measurement while drilling tool |
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0708872A4 (en) * | 1993-07-20 | 1997-11-26 | Baroid Technology Inc | Method and apparatus for controlling the head of a drilling or core-drilling device |
| EP0708872A1 (en) * | 1993-07-20 | 1996-05-01 | Baroid Technology, Inc. | Method and apparatus for controlling the head of a drilling or core-drilling device |
| US6419032B1 (en) * | 1995-02-16 | 2002-07-16 | Baker Hughes Incorporated | Method and apparatus for monitoring and recording of the operating condition of a downhole drill bit during drilling operations |
| EP0728915A3 (en) * | 1995-02-16 | 1997-08-27 | Baker Hughes Inc | Method and apparatus for monitoring and recording of operating conditions of a downhole drill bit during drilling operations |
| US5813480A (en) * | 1995-02-16 | 1998-09-29 | Baker Hughes Incorporated | Method and apparatus for monitoring and recording of operating conditions of a downhole drill bit during drilling operations |
| EP1632644A3 (en) * | 1995-02-16 | 2007-07-25 | Baker Hughes Incorporated | Method and apparatus for monitoring and recording of operating conditions of a downhole drill bit during drilling operations |
| US6230822B1 (en) | 1995-02-16 | 2001-05-15 | Baker Hughes Incorporated | Method and apparatus for monitoring and recording of the operating condition of a downhole drill bit during drilling operations |
| EP1632644A2 (en) * | 1995-02-16 | 2006-03-08 | Baker Hughes Incorporated | Method and apparatus for monitoring and recording of operating conditions of a downhole drill bit during drilling operations |
| EP0728915A2 (en) * | 1995-02-16 | 1996-08-28 | Baker Hughes Incorporated | Method and apparatus for monitoring and recording of operating conditions of a downhole drill bit during drilling operations |
| EP0975851A4 (en) * | 1997-04-21 | 2004-08-11 | Halliburton Energy Serv Inc | Acoustic data link for downhole mwd system |
| EP0975851A1 (en) * | 1997-04-21 | 2000-02-02 | Halliburton Energy Services, Inc. | Acoustic data link for downhole mwd system |
| EP1143105A1 (en) * | 2000-04-04 | 2001-10-10 | Schlumberger Holdings Limited | Directional drilling system |
| GB2420826A (en) * | 2004-12-02 | 2006-06-07 | Avocet Hardware Ltd | Egress hinge with first and second releasable retainers |
| GB2427632A (en) * | 2005-05-12 | 2007-01-03 | Schlumberger Holdings | Transmitting MWD signals through a mud motor |
| GB2427632B (en) * | 2005-05-12 | 2011-03-16 | Schlumberger Holdings | Apparatus and method for measuring while drilling |
| US8827006B2 (en) | 2005-05-12 | 2014-09-09 | Schlumberger Technology Corporation | Apparatus and method for measuring while drilling |
| GB2476653A (en) * | 2009-12-30 | 2011-07-06 | Wajid Rasheed | Tool and Method for Look-Ahead Formation Evaluation in advance of the drill-bit |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9210934D0 (en) | 1992-07-08 |
| GB2261308B (en) | 1996-02-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20110522 |