Patent Grant
6986282
1. Field of the Invention
This invention relates generally to the determination of various downhole parameters in a subsurface formation penetrated by a wellbore. More particularly, this invention relates to the determination downhole parameters, such as annular, formation and/or pore pressure, during a drilling operation.
2. Description of the Related Art
Present day oil well operation and production involves continuous monitoring of various subsurface formation parameters. One aspect of standard formation evaluation is concerned with the parameters of reservoir pressure and the permeability of the reservoir rock formation. Continuous monitoring of parameters such as reservoir pressure and permeability indicate the formation pressure change over a period of time, and is essential to predict the production capacity and lifetime of a subsurface formation.
Present day operations typically obtain these parameters through wireline logging via a “formation tester” tool. This type of measurement requires a supplemental “trip” downhole. In other words, the drill string must be removed from the wellbore so that a formation tester may be run into the wellbore to acquire the formation data and, after retrieving the formation tester, running the drill string back into the wellbore for further drilling. Thus, it is typical for formation parameters, including pressure, to be monitored with wireline formation testing tools, such as those tools described in U.S. Pat. Nos.: 3,934,468; 4,860,581; 4,893,505; 4,936,139; and 5,622,223. Each of these patents is limited in that the formation testing tools described therein are only capable of acquiring formation data as long as the wireline tools are disposed in the wellbore and in physical contact with the formation zone of interest. Since “tripping the well” to use such formation testers consumes significant amounts of expensive rig time, it is typically done under circumstances where the formation data is absolutely needed, when tripping of the drill string is done for a drill bit change or for other reasons.
The availability of reservoir formation data on a “real time” basis during well drilling activities is a valuable asset. Real time formation pressure obtained while drilling will allow a drilling engineer or driller to make decisions concerning changes in drilling mud weight and composition, as well as penetration parameters, at a much earlier time to thus promote the safety aspects of drilling. The availability of real time reservoir formation data is also desirable to enable precision control of drill bit weight in relation to formation pressure changes and changes in permeability so that the drilling operation can be carried out at its maximum efficiency.
Techniques have been developed to acquire formation data from a subsurface zone of interest while the downhole drilling tool is present within the wellbore, and without having to trip the well to run formation testers downhole to identify these parameters. Examples of techniques involving measurement of various downhole parameters during drilling are set forth in U.K. Patent Application GB 2,333,308 assigned to Baker Hughes Incorporated, U.S. Pat. No. 6,026,915 assigned to Halliburton Energy Services, Inc. and U.S. Pat. Nos. 6,230,557 and 6,164,126 assigned to the assignee of the present invention.
Despite the advances in obtaining downhole formation parameters, there remains a need to further develop reliable techniques which permit data collection during the drilling process. Benefits may also be achieved by utilizing the wellbore environment and the existing operation of the drilling tool to facilitate measurements. It is desirable that such techniques be provided that are automatic and/or without the need of signals from the surface to activate operation. It is further desirable that such techniques provide one or more of the following, among others, simplified operation, minimal impact on the drilling operation, fast operation, minimal test volume, external testing of a variety of downhole parameters, elimination of test flow line, multiple test devices about the tool for multiple opportunities for test results, reduction or elimination the use of motors, pumps and/or valves, low power consumption, reduction in moving parts, compact design, durability for even high impact operations, rapid response. Added benefit would be achieved where such a device could be used in combination with a pre-test piston to provide pressure readings, pretest functions as well as other downhole data.
The invention relates generally to an apparatus for collecting downhole data during a drilling operation via a downhole drilling tool positioned in a wellbore. The wellbore has an annular pressure therein. The wellbore penetrates a subterranean formation having a pore pressure therein. The downhole tool is adapted to pass a drilling mud flowing therethrough such that an internal pressure is created therein. The internal pressure and annular pressure generate a differential pressure therebetween.
In at least one aspect, the apparatus includes a drill collar, a piston and a sensor. The drill collar is operatively connectable to a drill string of the drilling tool, and has a passage therein for passing the drilling mud therethrough. The drill collar has an opening therein extending into a pressure chamber. The pressure chamber is in fluid communication with the passage and/or the wellbore. The piston is slidably positioned in the pressure chamber and has a rod extending therefrom into the opening. The piston is movable to a closed position in response to an increase in differential pressure and to an open position in response to a decrease in differential pressure such that in the closed position the rod fills the opening and in the open position at least a portion of the rod is drawn into the chamber such that a cavity is formed in the opening for receiving downhole fluid. The sensor is positioned in the rod for collecting data from the downhole fluid in the cavity.
In another aspect, the apparatus includes a drill collar, a probe, a piston and a sensor. The drill collar is operatively connectable to a drill string of the drilling tool. The drill collar has a passage therein for passing the drilling mud therethrough. The drill collar has a collar opening therein extending into a pressure chamber. The pressure chamber is in fluid communication with the passage and/or the wellbore. The probe is slidably positioned in the pressure chamber. The probe movable between a retracted position in the pressure chamber and an extended position extending from the drill collar into the collar opening. The probe is positionable adjacent the sidewall of the wellbore for sealing engagement therewith. The probe has a probe opening therethrough extending into a probe chamber therein. The piston is slidably positioned in a probe chamber in the probe and has a rod extending therefrom into the probe opening. The piston is movable to a closed position in response to an increase in differential pressure and to an open position in response to a decrease in differential pressure such that in the closed position the rod fills the opening and in the open position at least a portion of the rod is drawn into the chamber such that a cavity is formed in the probe opening for receiving downhole fluid. The sensor is positioned in the rod for collecting data from the downhole fluid in the cavity.
The apparatus may be provided with a hydraulic control circuit to manipulate the internal and/or annular pressure for activation of the piston and/or probe. The hydraulics may also be used to affect the timing of tests performed by the piston and/or probe.
The sensor may be provided with circuitry arranged to facilitate collection and/or communication of data. The circuitry may be of an overlapping communication coil, back-to-back-coil and/or other arrangements.
Finally, in another aspect, the invention relates to a method of collecting downhole data during a drilling operation via a downhole drilling tool positioned in a wellbore. The wellbore has an annular pressure therein. The wellbore penetrating a subterranean formation having a pore pressure therein. A differential pressure being generated between the internal pressure and the annular pressure. The method comprises providing a downhole drilling tool with a drill collar having a passage therethrough, positioning the downhole drilling tool into a wellbore, selectively changing the differential pressure such that the piston is moved between the open and closed position, and sensing data from the downhole fluid in the cavity. The drill collar having an opening therein extending into a chamber and a piston slidably positioned in the chamber and having a rod extending therefrom into the opening. The piston is movable between a closed and an open position. Measurements may be taken continuously or at desired intervals.
Other aspects of the invention will be clear from the description provided herein.
Drill string 12 is suspended within wellbore 11 and includes drill bit 15 at its lower end. Drill string 12 is rotated by rotary table 16, energized by means not shown, which engages kelly 17 at the upper end of the drill string. Drill string 12 is suspended from hook 18, attached to a traveling block (also not shown), through kelly 17 and rotary swivel 19 which permits rotation of the drill string relative to the hook.
Drilling fluid or mud 26 is stored in pit 27 formed at the well site. Pump 29 delivers drilling fluid 26 to the interior of drill string 12 via a port in swivel 19, inducing the drilling fluid to flow downwardly through drill string 12 as indicated by directional arrow 9. The drilling fluid exits drill string 12 via, ports in drill bit 15, and then circulates upwardly through the region between the outside of the drillstring and the wall of the wellbore, called the annulus, as indicated by direction arrows 32. In this manner, the drilling fluid lubricates drill bit 15 and carries formation cuttings up to the surface as it is returned to pit 27 for recirculation.
The drilling mud performs various functions to facilitate the drilling process, such as lubricating the drill bit 15 and transporting cuttings generated by the drill bit during drilling. The cuttings and/or other solids mix within the drilling fluid to create a “mudcake” 160 that also performs various functions, such as coating the borehole wall.
The dense drilling fluid 26 conveyed by a pump 29 is used to maintain the drilling mud in the wellbore at a pressure (annular pressure PA) higher than the pressure of fluid in the surrounding formation F (pore pressure PP) to prevent formation fluid from passing from surrounding formations into the borehole. In other words, the annular pressure (PA) is maintained at a higher pressure than the pore pressure (PP) so that the wellbore is “overbalanced”(PA>PP) and does not cause a blowout. The annular pressure (PA) usually is also maintained below a given level to prevent the formation surrounding the wellbore from cracking, and to prevent drilling fluid from entering the surrounding formation. Thus, downhole pressures are typically maintained within a given range.
Drillstring 12 further includes a bottom hole assembly, generally referred to as 100, near the drill bit 15 (in other words, within several drill collar lengths from the drill bit). The bottom hole assembly includes capabilities for measuring, processing, and storing information, as well as communicating with the surface. Bottom hole assembly 100 thus includes, among other things, measuring and local communications apparatus 200 for determining and communicating the resistivity of formation F surrounding wellbore 11. Communications apparatus 200, including transmitting antenna 205 and receiving antenna 207, is described in detail in U.S. Pat. No. 5,339,037, commonly assigned to the assignee of the present application, the entire contents of which are incorporated herein by reference.
Assembly 100 further includes drill collar 130 for performing various other measurement functions, and surface/local communications subassembly 150. Subassembly 150 includes antenna 250 used for local communication with apparatus 200, and a known type of acoustic communication system that communicates with a similar system (not shown) at the earth's surface via signals carried in the drilling fluid or mud. Thus, the surface communication system in subassembly 150 includes an acoustic transmitter which generates an acoustic signal in the drilling fluid that is representative of measured downhole parameters.
One suitable type of acoustic transmitter employs a device known as a “mud siren” which includes a slotted stator and a slotted rotor that rotates and repeatedly interrupts the flow of drilling fluid to establish a desired acoustical wave signal in the drilling fluid. The driving electronics in subassembly 150 may include a suitable modulator, such as a phase shift keying (PSK) modulator, which conventionally produces driving signals for application to the mud transmitter. These driving signals can be used to apply appropriate modulation to the mud siren.
The generated acoustical wave is received at the surface by transducers represented by reference numeral 31. The transducers, for example, piezoelectric transducers, convert the received acoustical signals to electronic signals. The output of transducers 31 is coupled to uphole receiving subsystem 90, which demodulates the transmitted signals. The output of receiving subsystem 90 is then couple to processor 85 and recorder 45.
Uphole transmitting system 95 is also provided, and is operative to control interruption of the operation of pump 29 in a manner that is detectable by transducers 99 in subassembly 150. In this manner, there is two-way communication between subassembly 150 and the uphole equipment as described in greater detail in U.S. Pat. No. 5,235,285.
Drill string 12 is further equipped in the embodiment of
The stabilizer collar 300a has a tubular mandrel 302 adapted for axial connection in a downhole tool, such as the drill string 12 of FIG. 1. Thus, mandrel 302 may be equipped with pin and box ends 304, 306 for conventional make-up within the drill string. As shown in
Stabilizer collar 300 further includes stabilizer element or sleeve 308 positioned about tubular mandrel 302 between ends 304 and 306. Thrust bearings 312 are provided to reduce the frictional forces and bear the axial loads developed at the axial interface between sleeve 308 and mandrel ends 304, 306. Rotary seals 348 and radial bearings 346 are also provided at the radial interface between mandrel 302 and sleeve 308.
The stabilizer collar 300a of
For illustration purposes a cross-sectional view of two embodiments of a pressure assembly 210a and 210b are depicted. Pressure assembly 210a is positioned within stabilizer blade 314a for performing various measurements. Pressure assembly 210a may be used to monitor annular pressure in the borehole and/or pressures of the surrounding formation when positioned in engagement with the wellbore wall. As shown in
As best seen in
The piston is preferably provided with a sensor 360, such as a pressure gauge, capable of taking downhole measurements. The sensor is preferably exposed to fluids adjacent the first portion 370 of piston 350. The sensor may be enabled to monitor and/or selectively take readings, such as pressure measurements during the downhole operations.
Spring 365 is positioned about the first portion 370 in a pocket 381 formed in chamber 355 between the second portion 375 of the piston and the walls of the chamber. As shown in
During drilling operation, mud flowing through the downhole tool creates an internal pressure PI The internal pressure and borehole pressure PA create a differential pressure. When fluid is flowing in passage 215, the differential pressure increases and pressure is applied to the chamber 355. A choke 240 (
Fluid in pocket 381 may freely pass between the borehole and the pocket via conduit 390. The first portion 375 of the piston compresses the spring 365. Second portion 370 moves towards opening 385 and fills the passage 380. Thus, while drilling fluid passes through the passage 215, internal pressure generated therefrom applies a force to the piston 350 and moves it to the closed position. When the pressure assembly is in non-engagement with the borehole wall and mudcake, the sensor may take downhole readings of the wellbore, such as the annular pressure PA of the wellbore.
As shown in
Retraction of the piston into the stabilizer blade creates a small cavity 395 (typically of about 1 cc to about 3 cc) extending from the opening 385 and into the passage 380. Pressure sensor 360 measures the pressure of the fluid in the cavity as the piston retracts into the tool. When in non-engagement with the wellbore wall, fluid from the borehole is permitted to fill the cavity 395. In this position, the sensor may take or continue to take borehole measurements. However, when the pressure assembly is in engagement with the borehole wall 110, retraction of the piston into the stabilizer blade will draw formation fluid into cavity 395 and provide formation data, such as pore or formation pressure. The flow of fluid into the cavity and the corresponding measurement may also be used to perform a pretest. Techniques for performing pretests are known by those of skill in the art and are described, for instance, in U.S. Pat. Nos. 4,860,581 and 4,936,139 issued to Zimmerman et al, both of which are assigned to the assignee of the present invention.
Once circulation of drilling fluid through the tool is re-initiated and sufficient differential pressure is present, the piston returns to the position of FIG. 3A. In this manner, the pressure assembly may be used to take multiple downhole measurements. When fluid is flowing through the downhole tool, the piston moves to the closed position of
The pressure assembly 210b includes an internal pressure assembly 405 mounted within a probe assembly 410. The probe assembly 410 includes a carriage 412, a packer 414, a spring 416 and a collar 417. The carriage 412 is positioned in a chamber 418 in stabilizer blade 314a and is slidably movable therein. Seals 420 may be provided to seal the probe in the chamber and facilitate movement therein. Packer 414, typically of an elastomer or rubber, is provided at an exterior end of the carriage 412 to facilitate sealing engagement with the borehole wall. Collar 417 is preferably threadably mounted within chamber 418 about an opening 415 in the stabilizer blade. The collar 417 encircles the carriage, and the carriage is slidably movable therein. Spring 416 encircles the carriage and is compressed in a pocket 419 between the collar 417 and a shoulder 422 of carriage 412. A pocket 421 is formed between shoulder 422, carriage 412 and the stabilizer blade 314a.
The carriage 412 has an internal chamber 355b therein. The internal pressure assembly 405 is positioned in the internal chamber 355b. Like pressure assembly 210a of
The hydraulic control circuit 400 used to operate the pressure assembly 210b includes a low pressure compensator 424, a high pressure compensator 426, and an accumulator 428. Hydraulic control circuit is preferably provided to allow selective activation or de-activation of the probe and/or pressure sensor assemblies. This additional control may be necessary in drilling, tripping or other situations where activation or de-activation of the pressure control assemblies is desired. The sensor(s) may be used to provide data to determine whether such a situation has occurred.
The compensators are preferably capable of accommodating volume changes caused by the pressure differences, temperature difference and/or movement of the downhole tool. The low pressure compensator 424 is operatively connected to chamber 418 in the stabilizer blade 314a via conduit 429. The low pressure compensator has a slidable piston 433 forming a first variable volume chamber 430 and a second variable volume chamber 432. The first chamber 430 is in fluid communication with the conduit 429, and a second chamber 432 in fluid communication with the borehole (and/or the annual pressure PA therein).
Accumulator 428 is operatively connected to conduit 429 via conduit 434. The accumulator stores oil at high pressure, and may be used to increase pressure in chamber 421. The accumulator has a spring-loaded piston 435 defining a first chamber 436 and a second chamber 438. The first chamber 436 is in fluid communication with conduit 434 and conduit 429. The second chamber 438 of the accumulator is connected via conduits 456, 440 and 442 to the high pressure compensator 426; via conduits 444 and 446 to the chamber 421; and via conduits 444, 460, 440 and 442 to pocket 419.
The high pressure compensator 426 has a slidable piston 453 defining a first variable volume chamber 450 and a second variable volume chamber 452. The first chamber 450 is in fluid communication with chamber 421 via conduits 442, 440 and 446; with the accumulator 428 via conduits 442, 440 and 456; and with pocket 419 via conduits 442, 440, and 448. A check valve 454 is positioned in conduit 456 to prevent fluid from flowing from second chamber 438 of accumulator 428 to conduit 440. The second chamber 452 of high pressure compensator 426 is in fluid communication with passage 215 of stabilizer collar 300a (
Various devices may be provided in the control circuit to monitor, manipulate and/or control the flow of fluid and/or the operation of the probe and/or pressure assemblies. Internal pressure sensor 490 may be provided to monitor the internal pressure in passage 425. Annular pressure sensor 495 may be provided to monitor the annular pressure of the wellbore. Both pressure may also be monitored simultaneously via a differential pressure sensor (not shown). A choke 458 (or leak orifice, electrical controller or other restrictor) is preferably provided in conduit 460 to slow the flow of fluid through conduit 460 (ie. between the second chamber 438 of accumulator 428 and the high pressure compensator 426). A choke 462 is preferably positioned in conduit 460 to restrict and/or delay the flow of fluid out of chamber 355b.
An electrical on-off switch (not shown) may also be provided to activate the hydraulic control circuit 400. Once activated, no further signals are required to activate the system to perform tests. The system is capable of operating without activation. However, it is possible to add electronic controls and/or signals for communication with the system. One way to affect such activation is by incorporating an on/off switch into the hydraulic control system. An electrical on/off switch may be connected to the first chamber 430 of the low pressure compensator and/or the first chamber 450 of the high pressure compensator to send a signal to isolate the high pressure compensator from the system. In this case, the accumulator would not be charged and the differential pressure changes would no longer have an effect on the system.
In the position depicted in
As fluid in accumulator chamber 438 is expelled, the piston 435 moves and expands chamber 436. Fluid is drawn from chamber 430 of low pressure compensator 433 into chamber 436 via conduits 434 and 429. Fluid in chamber 430 is also permitted to flow via flowline 429 into chamber 418.
The internal pressure assembly 405 is also movable within the probe assembly 410 between an open, or testing, position as depicted in
Retraction of the piston into the collar creates a cavity 395 (typically of about 1 cc to about 3 cc) extending from an opening 385 and into the passage 380. Fluid from the formation is permitted to fill the cavity 395 when a seal is formed between the packer 414 and the formation. Pressure sensor 360 is preferably positioned adjacent the cavity to measure the pressure of the fluid in the cavity as the piston retracts into the tool. A pretest and/or other measurements may then be taken to determine various downhole properties of the surrounding formation.
The movement of the internal pressure assembly 405 and the probe assembly 410 may be manipulated such that movement occurs at the desired time. For example, the choke may be used to delay the flow of fluid and the corresponding retraction of the internal pressure assembly to allow sufficient time for a seal to form between the probe assembly and the borehole wall. Other variations to the circuitry may be envisioned to provide selective flow of fluid through the circuit and manipulate the operation of the pressure assembly.
Once the spring accumulator 428 has fully expanded, oil/pressure from chamber 438 bleeds off through conduits 444, 460, 440, and 442 into chamber 450. The pressure in conduit 446 continues to drop until it reaches the ambient hydrostatic pressure. The spring 416 retracts the probe assembly back into blade 314a and completes the cycle. Piston 350 is in its open, or testing position, and the process may be repeated.
Fluid also flows from chamber 450 into chamber 355b via conduits 442 and 448, pocket 419, and conduit 460. The flow of fluid into chamber 355b overcomes the force of the spring 365 and causes the piston to move toward opening 385. The spring 365 is compressed in pocket 381 between the second portion 375 and the walls of the chamber. Fluid is released from pocket 381 via conduit 465 to chamber 418 and back to chamber 430 via conduit 429. The first portion 375 of the piston is pressed against the spring 365, and the second portion, or rod, 370 fills the passage 380. The internal pressure assembly 405 is now charged to perform the next pressure measurement.
Referring now to
The tool electronics preferably provide power for and/or communication with the sensors. In
A magnetic field is B created between sensor coil 500 and transmission coil 505. The field enables a wireless coupling between the sensor coil and transmission coil. Power and data transfer is provided to the sensor through the wireless coupling. However, a wired coupling is used to create a link between the pressure assembly electronics and the electronics in the remainder of the tool as depicted by the curled arrow. The transmission coil preferably overlaps with the sensor coil, but is independent of the sensor position within chamber 355.
The back-to-back coil embodiment of
A magnetic field Ba is created between sensor coil 500a and transmission coil 505a through ceramic window 560. A field provides a wireless connection between the sensor coil and transmission coil. Power and data transfer is provided to the sensor through the wireless coupling. In this embodiment, a wireless coupling may also be used to create a link between the pressure assembly electronics and the electronics in the remainder of the tool.
This embodiment eliminates the need for wires for the sensor and the surrounding threaded cup. One or more non-metallic ceramic windows may be positioned between the sensor coil and the transmission coil to allow coupling therethrough. The mechanical assembly eliminates the need for feed-throughs for the coil wire. Instead the-metallic window(s) between the sensor and the host transmission coil are provided. The windows allow coupling between the two coils. While the depicted embodiments eliminate wired connections and/or feed-throughs, some embodiments may incorporate such items.
A battery 725 may be included to provide power to the controller and/or to the sensors. The battery delivers power to a power amplifier 730. The power signal is passed through the signal distribution and protection device to the pressure sensor(s) 360. The power signal can be used to provide power to the sensor(s).
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. For example, embodiments of the invention may be easily adapted and used to perform specific formation sampling or testing operations without departing from the spirit of the invention. Accordingly, the scope of the invention should be limited only by the attached claims.
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