Patent Grant
11933174
Porous rock formations contain hydrocarbon reservoirs below the surface of the earth, which contain hydrocarbon fluids. These hydrocarbon fluids are then extracted by production wells that are drilled into the hydrocarbon reservoirs. Production wells may be drilled vertically from the surface, deviated from vertical, or vertical to horizontal in order to access the subsurface hydrocarbon reservoirs effectively and efficiently.
A typical practice in well construction involves casing the wellbore with tubulars and cementing the tubulars in place. This isolates the well from the surrounding formations that may be prone to collapse or have undesirable hazards present, such as shallow gas. Generally, each section of the well is drilled by a mill bit that is attached to a drill string that extends from a drilling rig at surface to the bottom of the wellbore. The drill string and the mill bit are pulled out of the wellbore upon completion of drilling a section of wellbore, and a section of casing is deployed and cemented into place, creating isolation from the newly drilled formation.
Often in well construction it is necessary to alter an existing wellbore trajectory, a practice referred to as “side-tracking”. Instances when side-tracking is typically utilized include, but are not limited to, failure of an existing wellbore, a need to avoid subsurface hazards (faults, shallow gas, etc.), planned multilateral wellbore wells, missed geological targets, and reuse of an existing wellbore that has depleted reservoir production. A longitudinal tubular body with an inclined plane, or “whipstock”, is a device that is regularly installed to facilitate the altering of a wellbore trajectory. When deployed into the wellbore, the whipstock serves as a deflection surface or ramp to alter the trajectory of the mill bit and, thus, the wellbore.
In general, in one aspect, embodiments disclosed herein relate to a system that includes a milling assembly with a mill bit and a drill string that mill a new wellbore section. The system further includes a whipstock assembly that is formed by a reamer shoe that reams an obstruction in a wellbore, a whipstock that deflects the milling assembly away from the wellbore, and a bypass valve mechanism that guides a fluid to circulate through the reamer shoe. Within the system, the milling assembly is fluidly connected to the whipstock assembly.
In general, in one aspect, embodiments disclosed herein relate to a method that includes running a whipstock assembly that is fluidly connected to a milling assembly into a wellbore to a desired depth. A fluid is controlled and guided by a bypass valve mechanism of the whipstock assembly to circulate through the whipstock assembly. The method further includes reaming an obstruction in the wellbore with a reamer shoe of a whipstock assembly. A whipstock of the whipstock assembly is then used to deflect the milling assembly away from the wellbore, and the milling assembly mills a new wellbore section away from the wellbore.
Specific embodiments of the disclosed technology will now be described in detail with reference to the accompanying figures. Like elements in the various figures are denoted by like reference numerals for consistency. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not necessarily drawn to scale, and some of these elements may be arbitrarily enlarged and positioned to improve drawing legibility.
Specific embodiments of the disclosure will now be described in detail with reference to the accompanying figures. In the following detailed description of embodiments of the disclosure, numerous specific details are set forth in order to provide a more thorough understanding of the disclosure. However, it will be apparent to one of ordinary skill in the art that the disclosure may be practiced without these specific details. In other instances, well known features have not been described in detail to avoid unnecessarily complicating the description.
Throughout the application, ordinal numbers (e.g., first, second, third, etc.) may be used as an adjective for an element (i.e., any noun in the application). The use of ordinal numbers is not intended to imply or create any particular ordering of the elements nor to limit any element to being only a single element unless expressly disclosed, such as using the terms “before”, “after”, “single”, and other such terminology. Rather, the use of ordinal numbers is to distinguish between the elements. By way of an example, a first element is distinct from a second element, and the first element may encompass more than one element and succeed (or precede) the second element in an ordering of elements.
In addition, throughout the application, the terms “upper” and “lower” may be used to describe the position of an element in a well. In this respect, the term “upper” denotes an element disposed closer to the surface of the Earth than a corresponding “lower” element when in a downhole position, while the term “lower” conversely describes an element disposed further away from the surface of the well than a corresponding “upper” element. Likewise, the term “axial” refers to an orientation substantially parallel to the well, while the term “radial” refers to an orientation orthogonal to the well.
As is commonly known in the art, whipstock assemblies are run downhole by a drill string in a cased wellbore. However, in some cases, the well contains an obstruction in the form of a cement plug, debris, the bottom of the wellbore, or another obstruction, which are often met prior to the whipstock assembly reaching its predetermined setting depth. In such instances, in order for the whipstock to reach the desired depth, the whipstock must be removed from the wellbore and one or more costly and time consuming clean out trips are made by a bottom hole assembly (BHA) to clear out the obstructions.
Accordingly, embodiments disclosed herein describe a whipstock assembly, temporarily connected to a milling assembly, disposed at a downhole end of a wellbore at a wellsite. The new whipstock assembly system is able to ream through any obstruction while retaining the whipstock so that one or more dedicated clean out reaming trips may be avoided, thereby saving time and costs. In general, the whipstock assembly is formed from two portions: a lower portion and an upper portion. The lower portion includes a bypass valve mechanism, a turbine, and a reamer shoe. The bypass valve mechanism controls and guides a fluid pumped into the whipstock assembly from a surface of the wellbore by a variable control pressure nozzle. The bypass valve mechanism is attached at its lower end to the turbine. The bypass valve mechanism includes a plurality of valve openings at its lower end that are fluidly connected to the turbine. In addition, the bypass valve mechanism further includes a gate that is lowered by a pressure drop within the bypass valve mechanism. With the gate in an open position, the fluid passes from the bypass valve mechanism into the turbine through the plurality of valve openings, rotationally actuating the turbine by applying force upon a blade of the turbine.
The turbine is attached to the reamer shoe by a turbine output shaft. The turbine output shaft rotates with the turbine, and in turn, forces the reamer shoe to also rotate. The reamer shoe includes a plurality of flow ports and a convex shaped nose formed of bonded polycrystalline diamond (PDC), tungsten carbide, or steel. The flow ports allow the fluid to exit the system and enter the wellbore. Because the reamer shoe is situated on an obstruction at the bottom end of the wellbore, as it rotates, the reamer shoe reams the obstruction until a desired setting depth is met. Once the desired setting depth is reached, the variable control pressure nozzle reduces the pressure of the fluid. The variable control pressure nozzle is capable of adjusting the pressure of the fluid according to a size of the whipstock, a flow rate, and a fluid density.
The upper portion of the whipstock assembly includes a whipstock, an anchor connection, a whipstock anchor, a whipstock packer, and a piston. When a pressure measurement of the fluid falls below a specified requirement, the gate closes the plurality of valve openings of the bypass valve mechanism, thereby creating a pressure reaction on the piston. The piston is connected to the whipstock anchor and the whipstock packer, and when the pressure reaction applies force to the piston, the piston causes the whipstock packer to set and the whipstock packer to expand. The whipstock anchor sets by digging into the casing of the wellbore, and the whipstock packer expands in the wellbore until it reaches the casing, forming a seal within the wellbore.
In one or more embodiments, the milling assembly of the system is used to ream a new wellbore section. Prior to detaching from the whipstock assembly, the milling assembly is connected to the whipstock by a shear bolt. Upon reaching the desired setting depth and subsequent to setting the whipstock, a downward force is applied by the drill string, the shear bolt shears, detaching the milling assembly from the whipstock assembly.
In one or more embodiments, the milling assembly includes a drill string, a coupling, a stabilizer, and a mill bit, whereby each of which aid in milling a new wellbore section. The drill string of the milling assembly is a conduit, formed of several steel pipes, joined together by a coupling. The stabilizer is disposed on the drill string above the mill bit and is designed to minimize torque and drag on the drill string while milling. The stabilizer includes multiple spiral ribs constructed of high-strength alloy steel. The mill bit is commonly formed of tungsten carbide, steel, or PDC, and is designed to mill through the formation or elements within the wellbore, such as the casing or whipstock.
Once detached from the whipstock assembly, the milling assembly rotates and lowers deeper into the wellbore. As the milling assembly lowers, its trajectory is guided by the whipstock, and more specifically by a deflection surface of the whipstock. The deflection surface is utilized to deflect the milling assembly away from the wellbore to mill the new wellbore parallel to the deflection surface. Therefore, as the milling assembly mills in the direction set by the deflection surface, the milling assembly mills through the casing and into the formation until a desired location is reached. The desired location is determined prior to drilling.
A derrick structure 13 is used to suspend the drill string 7 in the wellbore 3. The top of the derrick structure 13 is mounted with a crown block 15. From the crown block 15, a traveling block 17 hangs down by means of a cable or drill line 19. One end of the drill line 19 is connected to a drawworks 21, which is a reeling device that adjusts the length of the drill line 19 so that the traveling block 17 is capable of moving up or down the derrick structure 13. The traveling block 17 includes a hook 23 that supports a top drive 25. The top drive 25 is coupled to the top of the drill string 7 and is operable to rotate the drill string 7. The drill string 7 is pumped with drilling fluid (commonly called mud) from a mud system 27. The mud flows into the drill string 7 through appropriate flow paths in the top drive 25. Details of the mud flow path have been omitted for simplicity but would be understood by a person skilled in the art.
During a drilling operation at the well site 1, in order to break rock, the drill string 7 is rotated relative to the wellbore 3 and weight is applied to the mill bit 11. In some cases, the mill bit 11 is rotated independently with a drilling motor. In other embodiments, the mill bit 11 is rotated using a combination of a drilling motor and the top drive 25 to rotate the drill string 7. Mud is pumped into the drill string 7 while the mill bit 11 cuts through the rock. The mud flows down the drill string 7 and exits through a nozzle in the mill bit 11 into the bottom of the wellbore 3. Once in the wellbore 3, the mud flows back up to a surface 31 in an annular space between the drill string 7 and the wellbore 3 carrying entrained cuttings to the surface 31. The mud with the cuttings is returned to the mud system 27 to be circulated back again into the drill string 7. Before pumping the mud again into the drill string 7, the cuttings are typically removed from the mud, and the mud is reconditioned as necessary.
Upon the retrieval of the drill string 7, the BHA 9, and the mill bit 11 from the wellbore 3, the drilling operations are complete. Alternatively, the production casing operations commence in some embodiments of wellbore 3 construction. In such instances, a casing 33 made up of one or more larger diameter tubulars that have a larger inner diameter than the drill string 7 but a smaller outer diameter than the wellbore 3 is lowered into the wellbore 3 on the drill string 7. The casing 33 is designed to isolate the internal diameter of the wellbore 3 from the adjacent formation 5. Once the casing 33 is positioned, it is set and cement is pumped down through the internal space of the casing 33, out of the bottom of a casing shoe 35, and into the annular space between the wellbore 3 and the outer diameter of the casing 33. This creates the desired isolation between the wellbore 3 and the formation 5 and secures the casing 33 in place. Afterwards, the drilling of the next section of the wellbore 3 begins.
A whipstock 37 is deployed when there is a need to alter the trajectory of the wellbore 3. In one or more embodiments a whipstock 37 includes a lower anchoring mechanism, an inclined deflection surface 39, and a releasable connection to a milling assembly 41 located at the top of the whipstock 37. The lower anchoring mechanism may be a hydraulic or mechanical anchor configured to be removable following a drilling operation, while the releasable connection may be a shear bolt 43 or an equivalent shearing connection. The whipstock 37 and the milling assembly 41 are deployed into the wellbore 3 as an assembly during whipstock operations. The anchoring mechanism is activated and attaches the whipstock 37 to the inside surface of the casing 33 once the setting depth is reached.
Afterwards, a downward force to the whipstock 37 is applied from the drill string 7, severing the releasable connection, thereby releasing the milling assembly 41 and the mill bit 11 from the whipstock 37. Alternatively, the whipstock 37 is anchored in the wellbore 3 without being attached to the milling assembly 41 if the whipstock 37 is deployed in the wellbore 3 by a separate running tool. In either configuration, once placed, the whipstock 37 is anchored in the wellbore 3 independent of the milling assembly 41 such that the milling assembly 41 moves freely within the wellbore 3. As the mill bit 11 begins drilling, the deflection surface 39 of the whipstock 37 is used as a guide to deflect the mill bit 11 away from the existing wellbore 3 to begin drilling a new wellbore 45 of a different trajectory.
The mill bit 11 is designed for milling through metal or steel and is a fixed-style bit. Generally, in the oil and gas industry, when there is a need to ‘sidetrack’ or change the trajectory of a wellbore 3, this type of mill bit 11 is utilized to mill a window in the casing 33. The mill bit 11 is typically formed from tungsten carbide; however, one of ordinary skill in the art would appreciate that the mill bit 11 may be formed from steel, a high strength alloy, or equivalent, and may further be coated with a PDC layer.
Further,
Upon exiting the bypass valve mechanism 59, the fluid enters the turbine 61 of the lower portion of the whipstock assembly 57. The turbine 61 is situated between the bypass valve mechanism 59 and the reamer shoe 63 and contains a helically shaped steel blade 69. Additionally, the turbine 61 may include helically shaped lobes or a plurality of blades rather than a helical blade 69. Regardless of the structure thereof, the blade 69 rotates under the force generated by the fluid passing over it. As the blade 69 rotates, it forces a turbine output shaft 71 of the turbine 61 to rotate as well. The turbine output shaft 71 is formed of steel and connects the turbine 61 and the reamer shoe 63, such that the reamer shoe 63 rotates with the turbine 61. Further, the bypass valve mechanism 59, the turbine 61, the turbine output shaft 71, and the reamer shoe 63 are sequentially aligned on a same vertical axis 72.
The reamer shoe 63 is disposed at the lower end of the lower portion of the whipstock assembly 57 and is made up of a PDC nose 73 and a plurality of flow ports 75. The nose 73 is convex shaped with ledge riding capabilities and is employed to ream through an obstruction 77 at the bottom end of the wellbore 3. The obstruction 77 may be created by sloughing of a wall of the wellbore 3 or as a result of the casing 33 pushing debris ahead of the bottom end of the casing 33 along the wellbore 3 until it forms a bridge. Further, the fluid from the turbine 61 enters the reamer shoe 63 through an opening situated at a top end of the reamer shoe 63 and exits the reamer shoe 63 into the wellbore 3 through the flow ports 75 of the reamer shoe 63.
The upper portion of the whipstock assembly 57 is composed of a whipstock 37, an anchor connection 49, a whipstock anchor 79, a whipstock packer 81, and a piston 83. The whipstock 37 is a long steel casing disposed downhole and designed to deflect a mill bit 11 from the wellbore 3 with a deflection surface 39. The deflection surface 39 is a tapered, concave shaped bar located towards an upper end of the whipstock 37 that is used to deflect the mill bit 11 to alter the trajectory of the mill bit 11. The anchor connection 49 is commonly a hinge system design that connects the whipstock 37 to the whipstock anchor 79. The whipstock anchor 79, typically formed of high-strength alloy steel, secures the whipstock assembly 57 in the wellbore 3 by digging into the casing 33 when set. The whipstock packer 81 is often formed of elastomeric materials and acts as a seal, preventing any fluid from passing through it. The piston 83 of the whipstock assembly 57, composed of steel, is designed to set the whipstock anchor 79 and whipstock packer 81 subsequent to a pressure reaction acting on the piston 83 created within the bypass valve mechanism 59.
The bypass valve mechanism 59 is depicted with the gate 67 in the open position in
Actuation of the gate 67 is driven by fluid pressure acting on the combination of the pressure equalizing holes 82, the spring 84, the sensor 86, and the pad ring 80. As noted above, the gate 67 is initially in an open position, allowing fluid communication to the remainder of the milling assembly through the valve opening 65. However, once an obstruction is cleared and the milling operation is no longer necessary, the gate 67 is closed to prevent fluid waste. In such instances, an operator at the surface of the wellbore increases the fluid pressure in the drill string, thereby creating fluid backflow that enters the pressure equalizing holes 82. This backflow acts on the top of the pad ring 80, which compresses the spring 84. The compressed spring 84 passively transmits the backflow pressure to the gate 67 which causes the gate 67 to be actuated against and through the stop 85, at which point the spring 84 is no longer compressed. As shown in
Accordingly, the actuation of the gate 67 depends upon the size of the pressure equalizing holes 82, the size of the valve opening 65, the amount of resistance provided by the stop 85, the surface area of the pad ring 80, and the spring constant of the spring 84, each of which are determined according to the potential backflow pressure that can be developed to ensure proper actuation of the gate 67. By way of example, for a given fluid pressure and a known dimension of the valve opening 65, the size and structure of the pad ring 80, the stop 85, the pressure equalizing holes 82, and spring 84 may be adjusted such that the backpressure created by increasing the pressure of the fluid above the given fluid pressure is sufficient to actuate the gate 67.
Because the stop 85 is embodied as a series of gripping ledges, it is further envisioned that cyclic backpressure forces the gate 67 to actuate over only one ledge per backpressure cycle such that the full actuation of the gate 67 depends on the duration or number of cycles of pressure applied to the pad ring 80. Specifically, when the operator increases the flow rate of a mud pump, the resultant increase in fluid pressure creates the requisite backflow and the gate 67 is actuated through one of the ledges of the stop 85, thereby changing the size of the valve opening 65. This change in sizing causes a pressure buildup within the bypass valve mechanism 59 and reduces the amount of fluid entering the remainder of the whipstock assembly.
The change of fluid pressure in the bypass valve mechanism 59 is conveyed to an operator through the sensor 86. Upon receiving information that the gate 67 has moved through the first ledge of the stop 85, the operator continues the operation by raising the pressure again (to actuate the gate 67 through a subsequent ledge) or retaining the same pressure, in which case the gate 67 remains in position. Thus, the number of ledges of the stop 85 determines the number of pressure cycles required to actuate the gate 67. By way of nonlimiting example, and as shown in
While the above description is directed towards an operator monitoring the pressure drop in cycles to actuate the gate 67 through each individual ledge of the stop 85, it is contemplated that the operator may actuate the gate 67 through every ledge of the stop 85 without waiting to monitor a pressure change in the bypass valve mechanism 59. In this case, a prerequisite pressure is established that is greater than initial pressure and the pressure differential created by changing the size of the valve openings 65. During operation, when an operator wishes to actuate the gate 67 such that the gate 67 is actuated through every ledge of the stop 85 without adjustment, the operator adjusts the backpressure of the system to match the prerequisite pressure. As a result, the backpressure developed in the bypass valve mechanism 59 overcomes the initial pressure and the pressure differential(s) created by changing the size of the valve openings 65 to such a degree that the gate 67 is actuated through each ledge of the stop 85 without delay.
The inner and outer diameters of the turbine 61 are determined according to the size of the whipstock. By way of nonlimiting example only, for a 9⅝ inch diameter whipstock, the turbine 61 has a maximum outer diameter of 7 inches and minimum inner diameter of 5 inches. Similarly, by way of nonlimiting example, for a 7 inch diameter whipstock, the turbine 61 is has a maximum outer diameter of 3¾ inches and minimum inner diameter of 1¾ inches.
As shown in
After the completion of milling the new wellbore 45, the milling assembly 41 is lifted back towards the whipstock 37. The milling assembly 41 and whipstock assembly 57 reconnect via the electromagnet connection once the first electromagnetic connection piece 95 and second electromagnetic connection piece 97 come into contact, thereby permitting the two assemblies to be extracted from the well together. Alternatively, if the milling assembly 41 mills towards an unexpected hazard or an additional obstruction 77, the milling assembly 41 can be retracted to reattach to the whipstock 37. In this instance, the whipstock assembly 57 can ream further through the obstruction 77 in the wellbore 3 until it is believed the milling assembly 41 can mill into the formation 5 without meeting another hazard or obstruction 77. Further, in this alternative embodiment, the reamer shoe 63 is rotationally actuated by a battery powered reamer motor 99 that can be controlled from the surface 31.
In block 201, the whipstock assembly 57, connected to the milling assembly 41, is run into the wellbore 3. The two assemblies are connected to each other by the shear bolt 43 and are lowered in the wellbore 3 until the whipstock assembly 57 meets an obstruction 77. If no obstruction is met, the whipstock assembly is set at the desired depth.
In block 202, the fluid is pumped into the drill string 7 of the milling assembly 41 from the surface 31. The fluid is transported from the milling assembly 41 to the whipstock assembly 57. Specifically, the fluid transfer line 29 transports the fluid out of the milling assembly 41 and into the opening of the upper end of the whipstock 37. The fluid continues to flow downward through the whipstock 37 and into the bypass valve mechanism 59. The gate 67 of the bypass valve mechanism 59 is in the open position until the whipstock 37 is set, thereby facilitating the passage of fluid through the plurality of valve openings 65 of the bypass valve mechanism 59.
In block 203, the fluid flows from the bypass valve mechanism 59 into the turbine 61 by passing through the plurality of valve openings 65. This is facilitated by the gate 67 being in the open position. As the fluid flows through the turbine 61, the fluid applies force on the blade 69 of the turbine 61, thereby rotationally actuating the turbine 61, and thus, the turbine output shaft 71 and the reamer shoe 63. The power generated by the fluid flowing through the turbine 61 is enough to force the reamer shoe 63 to ream through the obstruction 77. While the reamer shoe 63 is reaming the obstruction 77, fluid exits the reamer shoe 63 through the plurality of flow ports 75 and enters the wellbore 3. From the wellbore 3, the fluid flows back up to the surface 31. In addition, the fluid lifts the debris 89 from the reamed obstruction 77 to the surface 31. The reamer shoe 63 continues to ream the obstruction 77 until the desired depth is reached.
In block 204, subsequent to the desired depth being reached by the reamer shoe 63, a variable control pressure nozzle reduces the pressure of the fluid. When the pressure measurement of the fluid falls below the specified requirement, the gate 67 of the bypass valve mechanism 59 closes the plurality of valve openings 65. This, in turn, creates a pressure reaction on the piston 83 of the whipstock assembly 57, thereby setting the whipstock anchor 79 and expanding the whipstock packer 81. As the whipstock anchor 79 sets, it digs into the casing 33 of the wellbore 3 until the whipstock assembly 57 is secured.
In block 205, subsequent to the whipstock assembly 57 setting in the wellbore 3, a downward force is applied onto the milling assembly 41 from the surface 31. The force is great enough to detach the milling assembly 41 from the whipstock assembly 57 by shearing the shear bolt 43 temporarily holding the two assemblies together. Once detached, the milling assembly 41 retracts upwards in the wellbore 3, away from the whipstock assembly 57, and begins to rotate the mill bit 11. Once the mill bit 11 begins to rotate, the milling assembly 41 is lowered back down to create a new wellbore 45.
In block 206, as the milling assembly 41 is lowered, the deflection surface 39 of the whipstock assembly alters the trajectory of the milling assembly 41, guiding it at an angle away from the wellbore 3. The mill bit 11 is designed to mill through the casing 33 and creates a new wellbore 45 section external to the wellbore 3.
Accordingly, the aforementioned embodiments as disclosed relate to devices and methods useful for both reaming an obstruction 77 in a wellbore and milling a new wellbore 45 under the control of a bypass valve mechanism 59.
The disclosed system for and methods of reaming an obstruction 77 in a wellbore and milling a new wellbore 45 under the control of a bypass valve mechanism 59 advantageously run the whipstock 37 safely to the desired depth without any additional cleanout trips. This benefit, in turn, advantageously reduces additional rig time and associated costs. Furthermore, the ability of the disclosed system and methods to ream any obstruction 77 while being deployed to a specified depth advantageously reduces the chances of the system getting stuck.
Although only a few embodiments of the invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims.
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| Number | Date | Country | |
|---|---|---|---|
| 20230272672 A1 | Aug 2023 | US |
