This disclosure relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in one example described below, more particularly provides for mitigating swab and surge piston effects in wellbores.
Swab and surge effects can be caused when a tubular string (such as a drill string, casing string or completion string) is displaced in a wellbore. Such swab and surge effects can produce undesired pressure variations in the wellbore, possibly leading to fluid loss from the wellbore, influxes into the wellbore from a surrounding formation, fracturing of a formation, breakdown of a casing shoe, or other undesired consequences.
Therefore, it will be appreciated that improvements are continually needed in the art of mitigating swab and surge effects in wellbores.
In the
A non-return valve 26 may be provided to allow flow of a drilling fluid 28 in only one direction through the drill string toward the drill bit 16. The drilling fluid 28 returns to surface via an annulus 30 formed radially between the string 12 and the wellbore 14.
Although the
With the drill bit 16 in contact with a bottom 34 of the wellbore 14, only relatively slow displacement of the string 12 downward (as viewed in
Such displacement of the string 12 can be the result of heave motion on a floating rig (not shown), tripping into or out of the wellbore 14, and other displacements of the string. In the
Specifically, if the string 12 displaces downward (as viewed in
It is desired, in the
The well tools 38, 40 could be any type of well tools, for example, the drill bit 16, drill collars 18, MWD tool 20, drilling motor 22, steering tool 24, non-return valve 26, or any type of drilling, completion or cementing tool. The scope of this disclosure is not limited to use of any particular number, type or combination of well tools.
In the
Each of the tools 46 includes a flow control device 50 (e.g., a valve or choke) which opens and closes to respectively permit and prevent fluid communication between the flow passage 48 and the annulus 30 on an exterior of the string 12. Actuation of the device 50 is controlled by a processor 52, with memory 54 and a power supply 56 (such as batteries, a downhole generator, electrical conductors or fiber optics).
One or more sensors 58 detects one or more parameters indicative of movement of the string 12 relative to the wellbore 14. For example, pressure sensors 58 of the tools 46 can detect pressure in the annulus sections 30a,b and, thus, a pressure differential between the annulus sections which is due to movement of the string 12. Of course, a single pressure differential sensor could be used instead of separate sensors to detect pressures in separate sections of the wellbore 14.
An accelerometer can directly measure acceleration of the string 12, and an integrator can be used to determine velocity of the string from the measured acceleration (velocity equals acceleration integrated over time). A gyroscope or rotation sensor may be used to measure rotational speed and/or acceleration (for example, to determine whether the string 12 is rotating). Thus, the scope of this disclosure is not limited to use of any particular type of sensor(s) used to measure a parameter indicative of the movement of the string 12 in the wellbore 14.
When the sensors 58, or either of them, detect substantial movement of the string 12 sufficient to produce an undesired pressure increase and/or decrease in the wellbore 14, the flow control devices 50 can open, thereby providing fluid communication between the annulus sections 30a,b via the flow passage 48, and reducing or eliminating a pressure differential between the annulus sections. Opening of the flow control devices 50 can be synchronized by use of telemetry devices 60 (such as, devices capable of short hop acoustic or electromagnetic telemetry, or other types of wired or wireless telemetry).
In this manner, the opening and closing of the flow control devices 50 can be substantially simultaneous. If desired, actuation of a first flow control device 50 could be delayed, in order to allow for wireless transmission time and decoding to actuate a second flow control device 50, so that the flow control devices are actuated substantially simultaneously. If wired communication is used, simultaneous actuation may be achieved without the delay. Use of the telemetry devices 60 can also allow the number of sensors 58 to be reduced (e.g., a single accelerometer could be used to control actuation of multiple flow control devices 50).
In other examples, the flow control devices 50 may not be actuated synchronously. Thus, the scope of this disclosure is not limited to synchronous (or substantially synchronous) actuation of the flow control devices 50.
Note that it is not necessary for the sensors 58 to be contained in either or both of the tools 46. For example, if the MWD tool 20 includes an accelerometer and/or pressure sensor, those sensor(s) may be used in place of the sensors 58. The tools 46 may communicate with the MWD tool 20 via wired or wireless telemetry (e.g., short hop acoustic or electromagnetic telemetry).
Since MWD tools generally include a variety of sensors, those sensors can possibly be of use in controlling actuation of the pressure balancing tools 46 in other ways. For example, the MWD tool 20 can include a weight-on-bit and/or torque sensor 58 which measures compression and/or torque in the string 12.
The flow control devices 50 can be maintained closed when the weight-on-bit or torque sensor 58 measures compression or torque in the string 12 indicative of a bit-on-bottom condition or drilling ahead (in which case movement of the string 12 relative to the wellbore 14 should be insufficient to produce harmful pressure variations). In this manner, for example, accelerations measured by the sensor 58 during drilling (which accelerations may be quite large, but of relatively short duration, so that they do not cause excessive pressure variations in the wellbore 14) will not cause the flow control devices 50 to open.
The processor 52 may be programmed to maintain the flow control devices 50 closed if compression and/or torque in the string 12 is above a predetermined threshold. The processor 52 may be programmed to only open the flow control devices 50 if acceleration, velocity or other displacement of the string 12 is above a predetermined value or duration threshold. However, the scope of this disclosure is not limited to any particular manner of controlling actuation of the flow control devices 50.
Although the pressure balancing tools 46 are depicted in
Although the pressure balancing tools 46 are depicted in
A separate flow passage 62 extends longitudinally in the well tools 38, 40 for providing fluid communication between the annulus sections 30a,b. A single flow control device 50 in the upper pressure balancing tool 46 is used to control flow through the passage 62, in order to reduce or eliminate any pressure differentials between the annulus sections 30a,b.
The lower pressure balancing tool 46 does not include a flow control device, processor or memory in this example. Only the sensors 58, power supply 56 and telemetry device 60 are included in the lower tool 46. However, various configurations of the upper and lower tools 46 may be used, in keeping with the scope of this disclosure.
When the sensors 58 (or only one sensor, or any combination of sensors) detects that sufficient movement of the string 12 is occurring to cause undesired pressure increases and/or decreases in the wellbore 14, the flow control device 50 can be opened to prevent or relieve any pressure differential across the well tools 38, 40 by allowing flow between sections of the wellbore on opposite sides of the well tools 38, 40.
Note that, in the
In the
In other examples, the flow passage 62 could connect to another flow passage section in another well tool (similar to the arrangement depicted in
Nozzles 64 which provide for fluid communication between the flow passage 48 and the lower end of the drill bit 16 may be used for reducing or eliminating pressure increases and/or decreases in the bottom of the wellbore 34 below the drill bit. The nozzles 64 may be configured so that a total flow area through the nozzles can be varied during drilling. An example is described in U.S. Publication No. 2003/0010532.
In addition, using the flow passage 48 (which can extend through one or more additional well tools, as in the
Referring additionally now to
During conveyance of the casing or liner string into the wellbore 14, pressure below the string 12 can increase due, for example, to enlarged outer dimensions D of well tools 66, 68 connected in the string. Pressure in the annulus section 30b above the well tools 66, 68 may decrease when the string 12 is conveyed into the wellbore 14, due to a flow restriction in the annulus 30 caused by the enlarged outer dimensions D.
The well tools 66, 68 are depicted in
The upper flow control device 50 provides selective fluid communication between the flow passage 48 and the upper annulus section 30b. The lower flow control device 50 provides selective fluid communication between the flow passage 48 and the wellbore 14 below the string 12, and across a check valve or float valve 70 in the well tool 68.
The flow control devices 50 may be connected to one or more processors 52, sensors 58, power supplies 56 and telemetry devices 60, as described for the other examples above, so that the flow control devices will open when desired to reduce or eliminate pressure differentials across the well tools 66, 68. Although the
Referring additionally now to
In step 74, acceleration is sensed by the acceleration sensor 58. In step 76, pressure is sensed by the pressure sensor 58. If the output of either of these sensors 58 indicates that displacement of the string 12 is causing, or will cause, undesired pressure increases and/or decreases in the wellbore 14, the flow control device 50 is opened in step 78. This prevents, relieves or at least reduces pressure differentials across well tools in the string 12.
If a rotation sensor (e.g., a gyroscope in the MWD tool 20) indicates that rotation of the string 12 is less than a predetermined level, and accelerometer and/or pressure sensors indicate an undesired pressure condition is occurring or will be produced, the flow control device 50 can be opened. Weight on bit and/or torque sensors (for example, in the MWD tool 20) could be used to ensure that the string 12 is not being used to drill the wellbore 14 when the flow control device 50 is opened.
That is, it is preferred that the flow control device 50 not be opened if the string 12 is being used to drill the wellbore 14. Various types of sensors (e.g., a gyroscope or other rotation sensor, a weight on bit sensor, a torque sensor), in combination with appropriate logic programming, may be used to determine whether drilling is currently being performed.
If a downhole electrical generator is included in the string 12 to generate electrical power in response to flow of the drilling fluid 28 through the string, an output of the generator may provide an indication of whether a drilling ahead operation is occurring. For example, if a revolutions per minute, voltage output or current output of the generator indicates that the fluid 28 is circulating through the string 12, this can be an indication that a drilling ahead operation is occurring (although, in some situations, fluid may be circulated through the string while not drilling ahead).
In steps 80 and 82, acceleration and pressure are again sensed by the sensors 58. If the outputs of the sensors 58 do not indicate that displacement of the string 12 is causing, or will cause, undesired pressure increases and/or decreases in the wellbore 14, the flow control device 50 is closed in step 84. This allows normal operations (e.g., drilling operations, stimulation or completion operations or cementing operations) to proceed without the flow control device 50 being open.
The flow control device 50 can be prevented from opening if the sensors 58 detect compression or torque in the string 12, or rotation of the string, as described above. This can be particularly advantageous if the flow control device 50, passage 48 and/or other components are located in the drill bit 16, so that these components are not plugged or otherwise damaged by drill cuttings.
Although
Note that, if a choke is used for the flow control device 50, then opening or closing the flow control device can include partially opening or partially closing the flow control device. Thus, fluid communication between wellbore sections may be increased or decreased via the flow control device 50, without such fluid communication through the flow control device being completely permitted or prevented.
It may now be fully appreciated that the above disclosure provides significant advancements to the art of mitigating swab and surge effects in wellbores. In examples described above, undesired pressure increases and decreases in the wellbore 14 can be mitigated by use of one or more flow control devices 50 that reduce or prevent pressure differentials across well tools caused by displacement of a well tool string 12 in the wellbore.
A method 72 of mitigating undesired pressure variations in a wellbore 14 due to movement of a well tool string 12 is provided to the art by the above disclosure. In one example, the method 72 can comprise: selectively decreasing and increasing fluid communication between sections (e.g., bottom section 36, annulus sections 30a,b) of a wellbore 14 on opposite sides of at least one well tool 16, 18, 20, 22, 24, 26, 38, 40, 66, 68 in the well tool string 12, the fluid communication being increased in response to detecting a threshold movement of the well tool string 12 relative to the wellbore 14.
The threshold movement may comprise a predetermined level of acceleration of the well tool string 12. The well tool string 12 can include at least one sensor 58 which senses acceleration of the well tool string 12.
The threshold movement may comprise sufficient movement of the well tool string 12 to cause a predetermined level of pressure differential across the well tool 16, 18, 20, 22, 24, 26, 38, 40, 66, 68. The well tool string 12 can include at least one sensor 58 which senses a pressure differential across the well tool 16, 18, 20, 22, 24, 26, 38, 40, 66, 68. The pressure differential may be in an annulus 30 external to the well tool string 12.
The fluid communication may be prevented in response to detecting compression and/or torque in the well tool string 12.
The step of providing the fluid communication can comprise opening at least one flow control device 50, thereby providing fluid communication between an internal flow passage 48, 62 of the well tool string 12 and each of the wellbore sections 36, 30a,b. The flow passage 48 may be configured for directing drilling fluid 28 to a drill bit 16. The flow passage 48 may extend through a drill bit 16.
A well tool string 12 is also provided to the art by the above disclosure. In one example, the string 12 can include at least one well tool 16, 18, 20, 22, 24, 26, 38, 40, 66, 68 connected in the well tool string 12, the well tool 16, 18, 20, 22, 24, 26, 38, 40, 66, 68 having an outer dimension D which is enlarged relative to at least one adjacent section 42, 44 of the well tool string 12, a flow passage 48, 62 extending between opposite ends of the well tool 16, 18, 20, 22, 24, 26, 38, 40, 66, 68, a sensor 58, and at least one flow control device 50 configured to selectively increase and decrease fluid communication between the opposite ends of the well tool 16, 18, 20, 22, 24, 26, 38, 40, 66, 68 via the flow passage 48, 62, in response to an output of the sensor 58 indicative of movement of the well tool string 12.
The well tool string 12 can comprise multiple flow control devices 50, actuation of the flow control devices 50 being synchronized, so that the flow control devices 50 open and close together. The actuation of the flow control devices 50 may be synchronized via telemetry.
Preferably, the flow control devices 50 provide indications of their positions/configurations (e.g., open or closed). Such indications may be transmitted to a remote location (such as, to a control system at the earth's surface). Based on these indications, additional control could be exercised over the various tools in the string 12.
Flow through the flow passage 48, 62 may be permitted in response to the sensor 58 output being indicative of a predetermined level of acceleration of the well tool string 12, and/or in response to the sensor 58 output being indicative of a predetermined level of pressure differential across the well tool 16, 18, 20, 22, 24, 26, 38, 40, 66, 68.
Flow through the passage 48, 62 may not be permitted in response to the sensor 58 output being indicative of a drilling ahead operation. For example, if the string 12 is rotating at greater than a predetermined level of revolutions per minute (e.g., as measured by a rotation sensor), if there is compression in the string (e.g., as measured by a weight on bit sensor), and/or if there is torque in the string (e.g., as measured by a torque sensor), then the flow control device(s) 50 may not be opened.
Another method 72 of mitigating undesired pressure differentials across at least one well tool 16, 18, 20, 22, 24, 26, 38, 40, 66, 68 in a well tool string 12 is also described above. In one example, the method 72 comprises sensing at least one parameter indicative of pressure differential across the well tool 16, 18, 20, 22, 24, 26, 38, 40, 66, 68; and opening at least one flow control device 50, thereby providing fluid communication between sections 36, 30a,b of a wellbore 14 on opposite sides of the well tool 16, 18, 20, 22, 24, 26, 38, 40, 66, 68, the opening being performed when the parameter exceeds a threshold level.
The parameter may comprise acceleration of the well tool string 12. The parameter may comprise pressure differential between the wellbore sections 36, 30a,b. Other measured parameters may include rotation, weight on bit 16 and torque in the string 12.
The opening step can include permitting flow through a flow passage 48, 62 extending through the well tool 16, 18, 20, 22, 24, 26, 38, 40, 66, 68.
The flow passage 48 may be configured for directing drilling fluid 28 to a drill bit 16. The flow passage 48, 62 may extend through the drill bit 16. The flow passage 48, 62 may extend longitudinally through the well tool string 12.
The opening step may comprise opening multiple flow control devices 50, thereby permitting fluid communication between the flow passage 48, 62 and the wellbore sections 36, 30a,b.
The method 72 can include synchronizing the opening and/or closing of the flow control devices 50 via telemetry. Such wired or wireless telemetry may be initiated from the surface, and/or from downhole control systems.
Although various examples have been described above, with each example having certain features, it should be understood that it is not necessary for a particular feature of one example to be used exclusively with that example. Instead, any of the features described above and/or depicted in the drawings can be combined with any of the examples, in addition to or in substitution for any of the other features of those examples. One example's features are not mutually exclusive to another example's features. Instead, the scope of this disclosure encompasses any combination of any of the features.
Although each example described above includes a certain combination of features, it should be understood that it is not necessary for all features of an example to be used. Instead, any of the features described above can be used, without any other particular feature or features also being used.
It should be understood that the various embodiments described herein may be utilized in various orientations, such as inclined, inverted, horizontal or vertical, and in various configurations, without departing from the principles of this disclosure. The embodiments are described merely as examples of useful applications of the principles of the disclosure, which is not limited to any specific details of these embodiments.
In the above description of the representative examples, directional terms (such as “above,” “below,” “upper,” and “lower”) are used for convenience in referring to the accompanying drawings. However, it should be clearly understood that the scope of this disclosure is not limited to any particular directions described herein.
The terms “including,” “includes,” “comprising,” “comprises,” and similar terms are used in a non-limiting sense in this specification. For example, if a system, method, apparatus or device is described as “including” a certain feature or element, the system, method, apparatus or device can include that feature or element, and can also include other features or elements. Similarly, the term “comprises” is considered to mean “comprises, but is not limited to.”
Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the disclosure, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to the specific embodiments, and such changes are contemplated by the principles of this disclosure. For example, structures disclosed as being separately formed can, in other examples, be integrally formed and vice versa. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the invention being limited solely by the appended claims and their equivalents.
Filing Document | Filing Date | Country | Kind |
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PCT/US2012/072102 | 12/28/2012 | WO | 00 |