Bottom hole assembly, downhole water channeling correction system and method for correcting water channeling

Abstract

The present application relates to the field of drilling technology, and provides a bottom hole assembly, a downhole water detection and drainage borehole straightening system and a deviation correction method thereof, the bottom hole assembly comprising a drill pipe, a drill bit and a centralizer assembly; the centralizer assembly comprising a centralizer main body, a first wear-resistant component and a second wear-resistant component, the outer surface of the centralizer main body being provided with a plurality of ridges in the axial direction, the ridges being uniformly distributed along the circumferential direction of the centralizer main body, the top edges of the ridges jointly defining a virtual circumscribed circle; the first and second wear-resistant components being respectively arranged at the two ends of the centralizer main body, the first wear-resistant component being connected with the drill bit; the second wear-resistant component being connected with the drill pipe; the diameters of the first and second wear-resistant components are both greater than or equal to the diameter of the circumscribed circle, and the diameters of the first and second wear-resistant components are both smaller than the diameter of the drill bit. The present application improves the wear resistance of the centralizer assembly, ensures the stability and reliability of the bottom hole assembly, improves the borehole deviation correction effect and optimizes the well trajectory control capability.

Description

Technical Field

[0001] This invention relates to the field of drilling technology, and in particular to a bottom drill string assembly, a downhole water exploration and drainage borehole deviation correction system, and a deviation correction method thereof. Background Technology

[0002] In many fields such as mineral exploration, tunnel engineering, geological disaster monitoring, and oil and gas drilling, the borehole inclination (apex angle) and azimuth angle, i.e., the borehole attitude, play a crucial role in ensuring project quality, assessing resource reserves, predicting geological risks, and optimizing construction plans.

[0003] In related technologies, during the construction of downhole water exploration and drainage boreholes, long-distance drilling is easily affected by factors such as uneven formation hardness, changes in rock dip angle, and the oscillation of the bottom drill string assembly, which can lead to borehole deviation and affect the water exploration and drainage effect.

[0004] The bottom drill string assembly oscillates because the stabilizer is prone to wear, which increases the gap between it and the borehole wall and reduces the correction effect. Summary of the Invention

[0005] This invention provides a bottom drill string assembly, a downhole water exploration and drainage borehole deviation correction system and its correction method, which solves at least one of the above-mentioned technical defects in the prior art, effectively improves the wear resistance of the centralizer assembly, thereby ensuring the stability and reliability of the bottom drill string assembly, improving the borehole deviation correction effect, and optimizing the wellbore trajectory control capability.

[0006] A first aspect of the present invention provides a bottom drill assembly, comprising: Drill pipe and drill bit; A stabilizer assembly, located between the drill pipe and the drill bit, comprises: The main body of the stabilizer has several protruding ridges arranged axially on its outer surface. The protruding ridges are evenly distributed along the circumference of the main body of the stabilizer, and the outer edge of the top of each protruding ridge together defines a virtual circumcircle. The main body of the stabilizer has a first end and a second end arranged opposite to each other. The first wear-resistant component is located at the first end of the centralizer body and is connected to the drill bit. The second wear-resistant component is located at the second end of the stabilizer body and is connected to the drill pipe; The diameters of the first wear-resistant component and the second wear-resistant component are both greater than or equal to the diameter of the circumscribed circle, and the diameters of the first wear-resistant component and the second wear-resistant component are both smaller than the diameter of the drill bit.

[0007] According to the bottom drill assembly provided by the present invention, a plurality of first wear-resistant composite sheets are fixedly embedded on the surface of the first wear-resistant component, and at least three first wear-resistant composite sheets form a group, each group is arranged at intervals along the axial direction of the first wear-resistant component, and the first wear-resistant composite sheets in each group are evenly distributed in the circumferential direction of the first wear-resistant component. And / or, The surface of the second wear-resistant component is fixedly embedded with a plurality of second wear-resistant composite sheets, and at least three second wear-resistant composite sheets form a group. Each group is arranged at intervals along the axial direction of the second wear-resistant component, and the second wear-resistant composite sheets in each group are evenly distributed in the circumferential direction of the second wear-resistant component.

[0008] According to the bottom drill assembly provided by the present invention, on the first wear-resistant component, the density of the first wear-resistant composite sheet decreases from the position close to the drill bit to the position far away from the drill bit.

[0009] According to the bottom drill assembly provided by the present invention, in a group consisting of at least three first wear-resistant composite plates, the circumferential angle between two adjacent first wear-resistant composite plates is 120°. And / or, In a group consisting of at least three second wear-resistant composite sheets, the circumferential angle between two adjacent second wear-resistant composite sheets is 120°.

[0010] According to the bottom drill assembly provided by the present invention, the first wear-resistant composite sheet and the second wear-resistant composite sheet are both made of tungsten carbide, diamond composite sheet or cubic boron nitride.

[0011] According to the bottom drill assembly provided by the present invention, the difference between the diameter of the first wear-resistant component and the diameter of the circumscribed circle ranges from 0.3 mm to 0.5 mm. And / or, the difference between the diameter of the second wear-resistant component and the diameter of the circumscribed circle is in the range of 0.3 mm to 0.5 mm.

[0012] According to the bottom drill assembly provided by the present invention, the surface of the first wear-resistant component is provided with a plurality of first slag discharge grooves along the axial direction, and the plurality of first slag discharge grooves are evenly distributed in the circumferential direction of the first wear-resistant component. And / or, The surface of the second wear-resistant component is provided with a plurality of second slag discharge grooves along the axial direction, and the plurality of second slag discharge grooves are evenly distributed in the circumferential direction of the second wear-resistant component.

[0013] A second aspect of the present invention provides a downhole water exploration and drainage borehole deviation correction system, comprising the bottom drill string assembly described in any of the preceding claims, and further comprising: Ground control system; The top drive system, connected to the ground control system, is used to adjust the speed and torque; An automatic drilling system, connected to the ground control system, is used to adjust the drilling pressure; A mud pump, connected to the ground control system, is used to regulate the flow rate; The bottom drill string assembly is connected to the top drive system, the automatic drilling system and the mud pump respectively. The bottom drill string assembly is equipped with a drilling rig and a high-frequency impact device. The drilling rig and the high-frequency impact device are connected to the ground control system.

[0014] A third aspect of the present invention provides a method for correcting the deviation of a downhole water exploration and drainage borehole, which is controlled based on the aforementioned downhole water exploration and drainage borehole deviation correction system, and includes the following steps: Real-time acquisition of borehole inclination and azimuth angles; When the inclination angle is determined to be greater than or equal to the preset threshold, the drilling pressure and rotation speed are adjusted, and the inclination angle and azimuth angle of the borehole are continuously monitored within the target test section; When the deviation of the inclination angle shows an increasing trend after a certain number of consecutive preset cycles, automatic correction is triggered: the flow rate of the mud pump is controlled to change the hydraulic load of the drill string, inducing the drill bit to cut laterally; the high-frequency short-stroke impact device is activated simultaneously to enhance the active correction capability of the centralizer on the borehole wall.

[0015] According to the downhole water exploration and drainage borehole correction method provided by the present invention, the step of adjusting the drilling pressure and rotation speed when the inclination angle is greater than or equal to a preset threshold includes: Reduce drilling pressure to 5-10 kN and increase rotation speed to 400-500 rpm to use centrifugal force of the stabilizer to suppress the upward tendency; Alternatively, increase the drilling pressure to 20-25kN, reduce the rotation speed to 200-300rpm, and strengthen the lateral support force of the stabilizer.

[0016] The bottom drill string assembly provided by this invention, through an innovative structure of the centralizer component, cleverly solves the problem of easy wear and failure at the end of traditional centralizers by combining protruding ridges with wear-resistant components. The protruding ridges achieve efficient centralization and reduce friction, while high-hardness wear-resistant components provide focused protection for key vulnerable areas, and size control (smaller than the drill bit diameter) ensures downhole safety. This effectively improves the wear resistance of the centralizer component, thereby ensuring the stability and reliability of the bottom drill string assembly, enhancing borehole deviation correction, optimizing wellbore trajectory control, and ultimately reducing drilling risks, increasing drilling efficiency, and saving overall costs.

[0017] Specifically, firstly, a raised ridge is provided along the axial direction on the outer surface of the centralizer body. The centralizer body contacts the well wall through the raised ridge. Compared with a bare tube or full-hole centralizer, the contact area between the centralizer body and the well wall is reduced, which can effectively limit the lateral movement and sway of the drill pipe in the wellbore and force the drill pipe to tend to be centered along the wellbore axis.

[0018] Secondly, the connection area between the centralizer body and the drill bit / drill pipe is subject to relative movement, vibration, vortexing, and drilling fluid erosion, making it the most severely worn part. Wear in these areas of traditional centralizers leads to loose connections, reduced strength, and even failure. However, this invention addresses this by providing a first wear-resistant component and a second wear-resistant component at each end of the centralizer body. These wear-resistant components act as "sacrificial layers," preferentially bearing wear and protecting the structural integrity of the centralizer body. By concentrating wear on replaceable or highly wear-resistant components, it effectively protects the more valuable and structurally complex centralizer body and its connecting threads, preventing overall scrapping due to end wear.

[0019] Furthermore, the diameters of both the first and second wear-resistant components are greater than or equal to the diameter of their circumscribed circles. This design results in a relatively slow wear rate of the convex edges, and each wear-resistant component maintains the effective outer diameter of the centralizer body. This ensures that the centralizer provides a stable and reliable centralizing effect throughout its entire service life, maintaining the centralizing function for an extended period and contributing to the preservation of the mechanical properties of the bottom drill string assembly (such as its ability to increase, decrease, and stabilize inclination). Additionally, the diameters of both the first and second wear-resistant components are smaller than the drill bit diameter. This design ensures that the centralizer assembly (including the wear-resistant components) can smoothly pass through the wellbore drilled by the drill bit under any circumstances, maintaining the designed wellbore diameter. If its diameter were equal to or larger than the drill bit diameter, it would be highly susceptible to stuck pipe during drilling operations, particularly at points of reduced diameter, sections with high dogleg, or areas of wellbore collapse.

[0020] The downhole water exploration and drainage borehole deviation correction system provided by the present invention, because it includes the above-mentioned bottom drill string assembly, has all the advantages of the above-mentioned bottom drill string assembly.

[0021] The downhole water exploration and drainage borehole deviation correction method provided by this invention can adjust the drill bit attitude in real time and improve the accuracy of borehole trajectory control. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1This is an exploded view of the bottom drill assembly provided in an embodiment of the present invention.

[0024] Figure 2 This is a cross-sectional schematic diagram of the centralizer body in the bottom drill assembly provided in an embodiment of the present invention.

[0025] Figure 3 This is a cross-sectional schematic diagram of the first wear-resistant component in the bottom drill assembly provided in an embodiment of the present invention.

[0026] Figure 4 This is a cross-sectional schematic diagram of the second wear-resistant component in the bottom drill assembly provided in an embodiment of the present invention.

[0027] Figure 5 This is a system block diagram of the downhole water exploration and drainage borehole deviation correction system provided in an embodiment of the present invention.

[0028] Figure 6 This is one of the flowcharts illustrating the well drilling deviation correction method for water exploration and drainage provided in this embodiment of the invention.

[0029] Figure 7 This is the second schematic diagram of the downhole water exploration and drainage borehole deviation correction method provided in the embodiments of the present invention.

[0030] Figure label: 10. Drill pipe; 20. Drill bit; 30. Centralizer assembly; 31. Centralizer body; 311. First end; 312. Second end; 32. Protruding ridge; 33. First wear-resistant component; 331. First slag discharge trough; 34. Second wear-resistant component; 341. Second slag discharge trough; 35. First wear-resistant composite sheet; 36. Second wear-resistant composite sheet; C. Circumcircle. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0032] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0033] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0034] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0035] Figure 1 This is an exploded view of the bottom drill assembly provided in an embodiment of the present invention. Figure 2 This is a cross-sectional schematic diagram of the centralizer body in the bottom drill assembly provided in an embodiment of the present invention.

[0036] See Figure 1 and Figure 2 This invention provides a bottom drill assembly (BHA) including a drill pipe 10, a drill bit 20, and a centralizer assembly 30. The drill pipe 10 mainly provides power transmission and mud passage, while the drill bit 20 is mainly responsible for breaking rocks.

[0037] The centralizer assembly 30 is located between the drill pipe 10 and the drill bit 20, and is mainly used to stabilize the wellbore trajectory and protect the drill string. The centralizer assembly 30 includes a centralizer body 31, a first wear-resistant component 33, and a second wear-resistant component 34.

[0038] The centralizer body 31 is a cylindrical or near-cylindrical tubular structure, usually made of high-strength alloy steel. The interior of the centralizer body 31 has through holes to ensure the smooth flow of drilling fluid (mud).

[0039] The outer surface of the centralizer body 31 is machined with several (usually 3-6) raised ribs (i.e., raised ribs 32) along the axial direction (parallel to the axis of the drill pipe 10). The raised ribs 32 are evenly distributed along the circumference of the centralizer body 31. For example, 3 raised ribs 32 are distributed at 120 degrees, and 4 raised ribs 32 are distributed at 90 degrees. It is common to have 3 or 4 ribs. More ribs (such as 6 ribs) may be used in soft formations or large wellbores to increase stability. In hard formations or small-gap wellbores, the number of ribs may be reduced (such as 3 ribs) to reduce torque and resistance.

[0040] The cross-sectional shape of the ridge 32 can be rectangular, trapezoidal, arc-shaped (such as a "blade"), or a combination thereof. A trapezoidal or arc-shaped top helps reduce the risk of stuck drill bits and improves mud flow. The ridge 32 can be fully axial (straight ridge) or designed as a low-angle helix. Helical ridges provide some rotational stability and help smooth vibrations, but straight ridges are more common in applications emphasizing rigidity and stability.

[0041] The surface of the protruding ridge 32 can be overlaid with hard alloy (such as tungsten carbide particles), inlaid with hard alloy blocks, or made entirely of wear-resistant alloy steel to resist wear. The top outer edge of each protruding ridge 32 collectively defines a virtual circumcircle C, that is, the highest point (top outer edge) of all the protruding ridges 32 collectively defines a virtual circumcircle C, and the diameter of the circumcircle C represents the "nominal stable diameter" of the centralizer body 31 in the wellbore.

[0042] The stabilizer body 31 has a first end 311 (near the drill bit end) and a second end 312 (near the drill rod end) disposed opposite to each other; a first wear-resistant component 33 is disposed at the first end 311 of the stabilizer body 31 and is directly connected to the drill bit 20 (usually a joint or gauge section of the drill bit 20) by thread or other reliable means. The outer diameter of the first wear-resistant component 33 is designed to be greater than or equal to the diameter of the circumscribed circle C defined by the top of the protrusion 32 of the stabilizer body 31, but strictly smaller than the diameter of the connected drill bit 20.

[0043] The second wear-resistant component 34 is located at the second end 312 of the centralizer body 31 and is directly connected to the upper drill rod 10 (or other BHA components, such as the weighted drill rod 10, the shock absorber, etc.) by thread or other reliable means. The outer diameter of the second wear-resistant component 34 is designed to be greater than or equal to the diameter of the circumscribed circle C defined by the top of the protrusion 32 of the centralizer body 31, but strictly smaller than the diameter of the drill bit 20 to which it is connected.

[0044] The first wear-resistant component 33 and the second wear-resistant component 34 are designed as detachable collars or bushings, and are installed at the end of the centralizer body 31 by threads, locking pins, or interference fits. When wear is severe, only the wear-resistant bushing needs to be replaced, without replacing the entire centralizer body 31, which is more economical. In this embodiment of the invention, each wear-resistant component is internally machined with standard API or special threads for connection with the drill bit 20 and drill rod 10, and the connection points must have sufficient strength.

[0045] It is understood that the bottom drill string assembly provided in this embodiment of the invention, through the innovative structure of the centralizer assembly 30, combines the convex ridge 32 with wear-resistant components, cleverly solving the pain point of easy wear and failure at the end of traditional centralizers. The convex ridge 32 achieves efficient centralization and reduces friction, while high-hardness wear-resistant components provide focused protection for key vulnerable areas, and size control (less than 20mm in diameter of the drill bit) ensures downhole safety. This effectively improves the wear resistance of the centralizer assembly, thereby ensuring the stability and reliability of the bottom drill string assembly, enhancing borehole deviation correction, optimizing wellbore trajectory control, and ultimately reducing drilling risks, increasing drilling efficiency, and saving overall costs.

[0046] Specifically, firstly, a convex rib 32 is provided along the axial direction on the outer surface of the centralizer body 31. The centralizer body 31 contacts the well wall through the convex rib 32. Compared with a bare tube or full-bore centralizer, the contact area between the centralizer body 31 and the well wall is reduced, which can effectively limit the lateral movement and sway of the drill pipe 10 in the wellbore and force the drill pipe 10 to tend to be centered along the wellbore axis.

[0047] Secondly, the connection area between the centralizer body 31 and the drill bit 20 and drill pipe 10 is subject to relative movement, vibration, eddy current, and drilling fluid erosion, making it the most severely worn part. Wear in these areas of a traditional centralizer can lead to loose connections, reduced strength, or even failure. However, this invention addresses this by providing a first wear-resistant component 33 and a second wear-resistant component 34 at both ends of the centralizer body 31. These wear-resistant components act as "sacrificial layers," preferentially bearing wear and protecting the structural integrity of the centralizer body 31. By concentrating wear on replaceable or highly wear-resistant components, the invention effectively protects the more valuable and structurally complex centralizer body 31 and its connecting threads, preventing overall scrapping due to end wear and reducing replacement frequency.

[0048] Furthermore, the diameters of the first wear-resistant component 33 and the second wear-resistant component 34 are both greater than or equal to the diameter of the circumscribed circle C. This design results in a relatively slow wear rate of the convex ridge 32, and each wear-resistant component maintains the effective outer diameter of the centralizer body 31. This ensures that the centralizer provides a stable and reliable centralizing effect throughout its entire service life, maintaining the centralizing function for an extended period and contributing to the preservation of the mechanical properties of the bottom drill string assembly (such as its ability to increase, decrease, and stabilize inclination). Additionally, the diameters of the first wear-resistant component 33 and the second wear-resistant component 34 are both smaller than the diameter of the drill bit 20. This design ensures that the centralizer assembly 30 (including the wear-resistant components) can smoothly pass through the wellbore drilled by the drill bit 20 under any circumstances, maintaining the designed wellbore diameter. If its diameter were equal to or greater than the diameter of the drill bit 20, it would be highly susceptible to stuck pipe during drilling or tripping operations, particularly at points of reduced diameter, sections with high dogleg, or areas of wellbore collapse.

[0049] Figure 3 This is a cross-sectional schematic diagram of the first wear-resistant component in the bottom drill assembly provided in an embodiment of the present invention. Figure 4 This is a cross-sectional schematic diagram of the second wear-resistant component in the bottom drill assembly provided in an embodiment of the present invention.

[0050] Continue reading Figure 1 And see also Figure 3 and Figure 4 In some embodiments of the present invention, a plurality of first wear-resistant composite sheets 35 are fixedly embedded on the surface of the first wear-resistant component 33. The first wear-resistant composite sheets 35 may be ultra-hard wear-resistant composite sheets, including tungsten carbide, diamond composite sheets (PDC), or cubic boron nitride composite sheets (PCBN). Their structure typically involves sintering an extremely thin (0.5mm-2mm) but extremely hard and wear-resistant polycrystalline diamond (PCD) or polycrystalline cubic boron nitride (PCBN) layer onto a cemented carbide (tungsten carbide) substrate.

[0051] Diamond composite (PDC) sheets are suitable for abrasive formations (sandstone, conglomerate, etc.) and most soft to medium-hard formations. They offer optimal abrasion resistance and a low coefficient of friction. Cubic boron nitride composite (PCBN) sheets are slightly less hard than PDC sheets, but offer better thermal stability and impact resistance, making them suitable for hard formations, highly abrasive formations, or high-temperature well sections.

[0052] The first wear-resistant composite sheet 35 is mostly circular in shape, but it can also be elliptical, rectangular, or irregular in shape to suit specific positions. The first wear-resistant composite sheet 35 covers 10-20% of the surface area of ​​the first wear-resistant component 33. The diameter of the first wear-resistant composite sheet 35 is preferably slightly larger than the designed embedding depth, which is 2-3 mm, forming a small protrusion (0.5 mm-2 mm).

[0053] At least three first wear-resistant composite sheets 35 form a group, that is, each group contains at least three wear-resistant composite sheets. The first wear-resistant composite sheets 35 in each group are arranged at intervals along the axial direction of the first wear-resistant component 33, and the first wear-resistant composite sheets 35 in each group are evenly distributed in the circumferential direction. That is, the wear-resistant composite sheets in the same group are evenly distributed in the circumferential direction of the wear-resistant component. For example, each group has 3 sheets, and each sheet is spaced 120 degrees apart; or each group has 4 sheets, and each sheet is spaced 90 degrees apart; or each group has 6 sheets, and each sheet is spaced 60 degrees apart, to ensure that each group can form symmetrical and stable support points on the circumference.

[0054] Three wear-resistant composite plates form a stable triangular support, while four or six plates provide more uniform support and wear resistance, but increase cost and processing complexity. The specific choice depends on the formation abrasiveness, wellbore size, and expected life.

[0055] Furthermore, the number of groups is determined based on the axial length of the wear-resistant component and the severity of wear. Typically, at least two groups are required, with critical areas potentially needing three or more. The spacing between groups needs to be balanced: close enough to provide continuous wear protection, and far enough to avoid stress concentration, allow for heat dissipation and chip removal through the slurry channels, and reduce machining difficulty and cost. Adjacent groups of composite sheets can be aligned circumferentially or staggered (e.g., at 60 or 45 degrees). Staggered arrangement provides a more uniform wear distribution and better surface coverage, reducing the risk of groove wear in unprotected areas.

[0056] Multiple second wear-resistant composite sheets 36 are fixedly embedded on the surface of the second wear-resistant component 34. The shape and arrangement of the second wear-resistant composite sheets 36 are the same as those of the first wear-resistant composite sheet 35, and are specifically arranged with reference to the arrangement of the first wear-resistant composite sheet 35. At least three second wear-resistant composite sheets 36 form a group, and each group of second wear-resistant composite sheets 36 is arranged at intervals along the axial direction of the second wear-resistant component 34, and each group of second wear-resistant composite sheets 36 is evenly distributed in the circumferential direction.

[0057] In other words, the array scheme of the wear-resistant composite sheet can be applied alone to the first wear-resistant component 33 (drill bit end), or alone to the second wear-resistant component 34 (drill rod end), or simultaneously to the first wear-resistant component 33 (drill bit end) and the second wear-resistant component 34 (drill rod end), mainly determined according to the specific working conditions and wear expectations (the drill bit end usually bears greater impact and drilling pressure, while the drill rod end bears rotational friction for a longer period of time).

[0058] During manufacturing, blind holes (embedded holes) matching the shape and size of the composite sheet can be machined onto the outer surface of the wear-resistant component (usually a steel or cemented carbide substrate). The depth of the holes is slightly less than the thickness of the composite sheet, allowing the protruding portion of the composite sheet to contact the well wall first, bearing the main frictional wear and maximizing the protection of the wear-resistant component. The composite sheet protruding from the wear-resistant component acts as sacrificial wear-resistant bumps. Wear mainly occurs at these bumps, while the wear-resistant component below them is protected. Even if the composite sheet wears down to the level of the wear-resistant component, its remaining portion and the wear-resistant component still provide some protection. The composite sheet is fixed in the embedded hole by an interference fit (cold pressing) or a more reliable high-temperature brazing process. High-strength silver-based or copper-based brazing filler metal is used to ensure a strong metallurgical bond between the composite sheet and the substrate, capable of withstanding high impact and shear forces.

[0059] This invention utilizes the "sacrificial bumps" of superhard materials to achieve lattice-like protection, maximizing wear resistance, while optimizing friction, heat dissipation, and mud flow through discrete contact. This effectively maintains the centering function and protects critical connections. By reducing tripping in and out of the hole, increasing drilling speed, and lowering accident risks, it brings significant economic benefits and safety improvements to drilling operations.

[0060] In some embodiments of the present invention, on the first wear-resistant component 33, the density of the first wear-resistant composite sheet 35 decreases from the position near the drill bit 20 to the position away from the drill bit 20, that is, the density near the drill bit end is ≥8 sheets / cm², and the density away from the drill bit end is ≤5 sheets / cm². Through the design of the axial density gradient, the wear gradient is matched, the wear resistance and the drilling pressure transmission efficiency are balanced, and the overall performance and service life are improved.

[0061] The area near the drill bit (high wear zone) is the most severely worn region in the entire centralizer assembly 30. This is because the intense vibrations and shock waves generated when the drill bit 20 breaks rock are first transmitted to the first wear-resistant component 33 near the drill bit, which is directly connected to it. The drilling pressure is transmitted through the drill pipe 10 and ultimately acts on the drill bit 20. The reaction force causes the connection between the drill bit 20 and the centralizer to bear enormous pressure, exacerbating the friction between this point and the wellbore. Conversely, further away from the drill bit (wear reduction zone), as the axial distance increases, vibration, impact, drilling pressure concentration effect, linear velocity, and the direct erosion intensity of the drilling fluid all significantly decrease, resulting in a corresponding reduction in wear.

[0062] By deploying more and denser wear-resistant composite plates in the high-density zone (near the drill bit), a robust "shield" is formed to provide the strongest defense against the harshest abrasion environments. This ensures that critical areas have the highest wear resistance reserve, effectively slowing down the wear rate and preventing premature failure. Fewer and sparser wear-resistant composite plates are deployed in the low-density zone (away from the drill bit). Because wear is relatively less in this area, excessive density would lead to wasted resources (expensive composite plate costs) and unnecessary increases in frictional resistance. A lower density is sufficient to meet the wear resistance requirements of this area.

[0063] In some embodiments of the present invention, in each group of first wear-resistant composite sheets 35, the circumferential angle between two adjacent first wear-resistant composite sheets 35 is 120°; or in each group of second wear-resistant composite sheets 36, the circumferential angle between two adjacent second wear-resistant composite sheets 36 is 120°. Alternatively, three wear-resistant composite sheets are provided on each wear-resistant component to form a stable triangular support.

[0064] In some embodiments of the present invention, the difference between the diameter of the first wear-resistant component 33 and the diameter of the circumscribed circle C ranges from 0.3 mm to 0.5 mm; or, the difference between the diameter of the second wear-resistant component 34 and the diameter of the circumscribed circle C ranges from 0.3 mm to 0.5 mm. Alternatively, the difference between the diameters of the first wear-resistant component 33 and the second wear-resistant component 34 and the diameter of the circumscribed circle C both range from 0.3 mm to 0.5 mm.

[0065] Continue reading Figure 3 and Figure 4 In some embodiments of the present invention, the surface of the first wear-resistant component 33 is provided with a plurality of first slag discharge grooves 331 along the axial direction. The cross-sectional shape of the first slag discharge grooves 331 is usually U-shaped, V-shaped or trapezoidal, with a smooth transition at the bottom to reduce stress concentration. U-shaped grooves can provide a larger volume and smooth mud channel; V-shaped grooves are beneficial for guiding rock cuttings and self-cleaning.

[0066] Multiple first slag discharge grooves 331 are evenly distributed in the circumferential direction of the first wear-resistant component 33. The number of first slag discharge grooves 331 is usually 3 to 6 (matching or multiple of the number of protrusions 32 of the centralizer body 31). For example, when 3 first slag discharge grooves 331 are arranged in a circumferential array, two adjacent first slag discharge grooves 331 are arranged at a 120° interval to ensure uniform slag discharge and force in the circumferential direction.

[0067] The first slag discharge trough 331 can be designed to be arranged between or staggered with the various groups of the first composite sheet to avoid cutting the composite sheet. The structure of the first slag discharge trough 331 increases the contact surface area between the first wear-resistant component 33 and the drilling fluid, providing a cooling and cleaning channel for the first composite sheet. The mud flowing at high speed through the first slag discharge trough 331 forces the trough wall to be flushed, efficiently removing frictional heat (from the friction between the first composite sheet or the first wear-resistant component 33 and the well wall), preventing the composite sheet from overheating and failing (especially protecting the high-temperature sensitive PDC composite sheet).

[0068] The surface of the second wear-resistant component 34 is provided with a plurality of second slag discharge grooves 341 along the axial direction, and the plurality of second slag discharge grooves 341 are evenly distributed in the circumferential direction of the second wear-resistant component 34. The shape and arrangement of the second slag discharge grooves 341 are the same as those of the first slag discharge groove 331 described above, and are specifically arranged with reference to the arrangement of the first slag discharge groove 331.

[0069] Essentially, the slag discharge trough can be applied individually to the first wear-resistant component 33 (drill bit end), individually to the second wear-resistant component 34 (drill rod end), or simultaneously to both components, depending on the specific working conditions. The width of the slag discharge trough can be set to 20-30mm to ensure timely discharge of rock powder and prevent accumulation that could affect the accuracy of deviation correction and drilling efficiency.

[0070] Figure 5 This is a system block diagram of the downhole water exploration and drainage borehole deviation correction system provided in an embodiment of the present invention.

[0071] See Figure 5 This invention also provides a downhole water exploration and drainage borehole deviation correction system, which includes a top drive system, an automatic drilling system, a surface control system, a mud pump, and a bottom drill string assembly of any one of the above. The bottom drill string assembly is connected to the top drive system, the automatic drilling system, and the mud pump, and is equipped with a drilling rig and a high-frequency impact device. The drilling rig and the high-frequency impact device are connected to the surface control system.

[0072] The MWD instrument is installed on the bottom hull assembly (BHA) and can be embedded inside the centralizer assembly or placed close to the drill bit. The MWD instrument is used to monitor the borehole inclination (θ) and azimuth (ψ) in real time, and feeds the monitored data back to the surface control system via mud pulses or electromagnetic waves.

[0073] The surface control system, acting as the core decision-making hub, receives data from the borehole survey instrument and sends control commands to other execution systems based on preset thresholds. Based on the preset borehole trajectory and real-time data, the surface control system calculates correction commands and sends them to the automatic drilling system (adjusting drill pressure), the top drive system (adjusting rotational speed and torque), the high-frequency impact device (adjusting frequency and stroke), and the mud pump (adjusting flow rate).

[0074] The top drive system, acting as the rotational power source, drives the drill pipe and drill bit to rotate, and is used to regulate speed and torque. The automatic feed system is linked to the top drive system, regulating drilling pressure by controlling the drill pipe feed. A high-frequency impact device, integrated into the near-bit stabilizer of the bottom drill string assembly, generates instantaneous lateral force to embed the centralizer assembly into the borehole wall, forming a fulcrum. The high-frequency impact device is used to regulate frequency and stroke. The mud pump provides the mud circulation power for the entire system; changes in its flow rate affect the hydraulic state of the bottom drill string assembly, and the mud pump is used to regulate the flow rate.

[0075] Furthermore, each execution system (automatic drilling system, top drive system, high-frequency impact device, and mud pump) feeds its status back to the surface control system. Based on the measurement data and preset algorithms, the surface control system generates control commands and sends them to each execution system. The mud pump then pumps mud through the drill pipe into the bottom assembly (BHA), forming a circulation.

[0076] Specifically, the flow of control commands for the downhole water exploration and drainage borehole deviation correction system is shown in the table below:

[0077] The data feedback flow direction of the downhole water exploration and drainage borehole deviation correction system is shown in the table below:

[0078] It is understood that the downhole water exploration and drainage borehole deviation correction system provided in this embodiment of the invention, because it includes the above-mentioned bottom drill string assembly, has all the advantages of the above-mentioned bottom drill string assembly.

[0079] Figure 6 This is one of the flowcharts illustrating the wellbore drilling deviation correction method for water exploration and drainage provided in this embodiment of the invention. Figure 7 This is the second flowchart illustrating the method for correcting the deviation of downhole water exploration and drainage boreholes provided in this embodiment of the invention.

[0080] See Figure 6 and Figure 7 This invention also provides a method for correcting the deviation of a downhole water exploration and drainage borehole, which is controlled based on the aforementioned downhole water exploration and drainage borehole deviation correction system, and includes the following steps: Step S100: Obtain the borehole inclination and azimuth angles in real time.

[0081] Initial parameter setting module: Based on the formation lithology (compressive strength σ_c of sandstone / shale) and fracture index K, the drilling pressure P = 10-25kN, rotation speed N = 200-400rpm, and mud flow rate Q = 80-150L / min are matched. Based on the formation lithology (e.g., sandstone, shale) and degree of fracture, the borehole dip angle (θ) and azimuth angle (ψ) are monitored in real time using a wireless measurement-while-drilling (MWD) instrument.

[0082] Step S200: When the inclination angle is greater than or equal to the preset threshold, adjust the drilling pressure and rotation speed, and continuously monitor the inclination angle and azimuth angle of the borehole within the target test section (e.g., 10m).

[0083] When the inclination angle (θ) exceeds a preset threshold (e.g., ±1.5° / 100m), adjust the drill pressure and rotation speed. Reduce the drill pressure through the automatic feed system to decrease lateral cutting forces. Increase the rotation speed of the top drive system to enhance the centrifugal stabilization effect.

[0084] In other words, when the inclination angle (θ) exceeds ±1.5° / 100m, the inclination is reduced by decreasing the drilling pressure by 5-10kN and increasing the rotation speed to 400-500rpm. The centrifugal force of the stabilizer is used to suppress the upward tendency, thus achieving inclination reduction and correction. Alternatively, the drilling pressure is increased to 20-25kN and the rotation speed is reduced to 200-300rpm to increase the inclination, strengthening the lateral support force of the stabilizer and achieving inclination increase and correction.

[0085] Specifically, the dip angle θ is monitored using a wireless survey while drilling instrument. When |Δθ|>1.5° / 100m: Deceleration mode: P is lowered to 5-10kN and N is increased to 400-500rpm, using centrifugal force to suppress upward tilting; Inclination mode: P is increased to 20-25kN and N is decreased to 200-300rpm, enhancing lateral support.

[0086] Step S300: When the deviation of the inclination angle shows an increasing trend after a preset number of consecutive steps, trigger automatic correction: control the mud pump flow rate to change the hydraulic load of the drill bit and induce lateral cutting of the drill bit; simultaneously start the high-frequency short-stroke impact device to enhance the active correction capability of the centralizer on the borehole wall.

[0087] Specifically, when deviations occur three times consecutively, the prediction model controls the mud pump flow rate (±20L / min) to change the hydraulic load on the drill string and induces the drill bit to cut laterally; simultaneously, the high-frequency short-stroke impact device (frequency 50-100Hz, stroke 2-3mm) is activated to enhance the centralizer's active correction capability on the borehole wall.

[0088] The path correction prediction model is based on historical inclinometer data (θ0, θ1, ..., θ). n A finite element-fuzzy PID composite control model is established based on the rock strata parameters (compressive strength σ_c, stratum thickness h, anisotropy coefficient α), outputting the optimal drilling pressure-rotation speed matching curve and impact frequency parameters, calculating the optimal correction path, and establishing a borehole trajectory prediction model.

[0089] The borehole inclination angle (θ) is monitored every 0.3m. When the inclination angle (θ) continues to deviate, the mud pump flow rate (+5L / min) is controlled to change the hydraulic load on the drill string and induce the drill bit to cut laterally. At the same time, the high-frequency short-stroke impact device (frequency +10Hz) is activated to enhance the active correction capability of the centralizer on the borehole wall.

[0090] This invention takes a water exploration and drainage borehole in a coal mine (designed depth 400m, target stratum sandstone) as an example: Wear-resistant components are formed on the main body of the centralizer using 30CrMnSiA alloy steel welding. The outer diameter of the wear-resistant components is 73.5mm (drilling design diameter is 75mm). Tungsten carbide composite sheets (80 mesh) are fixedly embedded on the wear-resistant components. Three sets of slag discharge grooves are opened on the side wall of each wear-resistant component.

[0091] The initial drilling pressure is set to 18 kN, the rotation speed to 300 rpm, and the flow rate to 120 L / min.

[0092] When the borehole inclinometer shows θ=1.8° (0.3° above the threshold), reduce the drilling pressure to 12kN and increase the rotation speed to 450rpm to trigger or activate the high-frequency impact device. Within 5 minutes, θ returns to 1.2°. After retesting with the borehole inclinometer, the average curvature of the entire hole is 0.5° / 100m, and the wear of the composite plate is ≤0.2mm, which meets the design requirements.

[0093] When three consecutive inclinometer readings show an increase in the θ deviation (2.1°→2.4°→2.7°), the inclinometer detects a deteriorating trend and transmits the data in real time to the ground control system. The ground control system then uses a predictive model to calculate the optimal parameters.

[0094] When drilling for water exploration frequently encounters fault zones, sudden changes in strata can easily lead to sudden deviations. This triggers an "emergency deviation correction mode"—when the instantaneous rate of change of θ > 3° / 10m, the drilling speed is automatically reduced to 40 rpm and the maximum drill pressure differential is applied.

[0095] The downhole water exploration and drainage borehole deviation correction method provided by this invention can adjust the drill string attitude in real time, improving the accuracy of borehole trajectory control. Dynamic parameter adjustment ensures that the borehole trajectory curvature is ≤0.8° / 100m, improving correction accuracy and significantly optimizing it compared to traditional methods (≥2° / 100m). Furthermore, it reduces the number of tripping operations caused by deviation correction, shortening single-hole construction time by 20-30% and improving construction efficiency.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A downhole water exploration and drainage borehole deviation correction system, characterized in that, include: The bottom drill string assembly includes: Drill pipe and drill bit; A stabilizer assembly, located between the drill pipe and the drill bit, comprises: The main body of the stabilizer has several protruding ridges arranged axially on its outer surface. The protruding ridges are evenly distributed along the circumference of the main body of the stabilizer, and the outer edge of the top of each protruding ridge together defines a virtual circumcircle. The main body of the stabilizer has a first end and a second end arranged opposite to each other. The first wear-resistant component is located at the first end of the centralizer body and is connected to the drill bit. The second wear-resistant component is located at the second end of the stabilizer body and is connected to the drill pipe; Wherein, the diameters of the first wear-resistant component and the second wear-resistant component are both greater than or equal to the diameter of the circumscribed circle, and the diameters of the first wear-resistant component and the second wear-resistant component are both smaller than the diameter of the drill bit; a plurality of first wear-resistant composite sheets are fixedly embedded on the surface of the first wear-resistant component, at least three of the first wear-resistant composite sheets form a group, each group is arranged at intervals along the axial direction of the first wear-resistant component, and the first wear-resistant composite sheets in each group are evenly distributed in the circumferential direction of the first wear-resistant component; and / or, a plurality of second wear-resistant composite sheets are fixedly embedded on the surface of the second wear-resistant component, at least three of the second wear-resistant composite sheets form a group, each group is arranged at intervals along the axial direction of the second wear-resistant component, and the second wear-resistant composite sheets in each group are evenly distributed in the circumferential direction of the second wear-resistant component; On the first wear-resistant component, the density of the first wear-resistant composite sheet decreases from the position closer to the drill bit to the position farther away from the drill bit; the surface of the first wear-resistant component is provided with a plurality of first slag discharge grooves along the axial direction, and the plurality of first slag discharge grooves are evenly distributed in the circumferential direction of the first wear-resistant component; and / or, the surface of the second wear-resistant component is provided with a plurality of second slag discharge grooves along the axial direction, and the plurality of second slag discharge grooves are evenly distributed in the circumferential direction of the second wear-resistant component; and includes: Ground control system; The top drive system, connected to the ground control system, is used to adjust the speed and torque; An automatic drilling system, connected to the ground control system, is used to adjust the drilling pressure; A mud pump, connected to the ground control system, is used to regulate the flow rate; The bottom drill string assembly is connected to the top drive system, the automatic drilling system and the mud pump respectively. The bottom drill string assembly is equipped with a drilling rig and a high-frequency short-stroke impact device. The drilling rig and the high-frequency short-stroke impact device are connected to the ground control system.

2. The downhole water exploration and drainage borehole deviation correction system according to claim 1, characterized in that, In a group consisting of at least three of the first wear-resistant composite sheets, the circumferential angle between two adjacent first wear-resistant composite sheets is 120°. And / or, In a group consisting of at least three second wear-resistant composite sheets, the circumferential angle between two adjacent second wear-resistant composite sheets is 120°.

3. The downhole water exploration and drainage borehole deviation correction system according to claim 1, characterized in that, Both the first wear-resistant composite sheet and the second wear-resistant composite sheet are made of tungsten carbide, diamond composite sheet or cubic boron nitride.

4. The downhole water exploration and drainage borehole deviation correction system according to claim 1, characterized in that, The difference between the diameter of the first wear-resistant component and the diameter of the circumscribed circle ranges from 0.3 mm to 0.5 mm. And / or, the difference between the diameter of the second wear-resistant component and the diameter of the circumscribed circle is in the range of 0.3 mm to 0.5 mm.

5. A method for correcting the deviation of a downhole water exploration and drainage borehole, controlled by the downhole water exploration and drainage borehole deviation correction system according to any one of claims 1 to 4, characterized in that, Includes the following steps: Real-time acquisition of borehole inclination and azimuth angles; When the inclination angle is determined to be greater than or equal to the preset threshold, the drilling pressure and rotation speed are adjusted, and the inclination angle and azimuth angle of the borehole are continuously monitored within the target test section; When the deviation of the inclination angle shows an increasing trend after a certain number of consecutive preset cycles, automatic correction is triggered: the flow rate of the mud pump is controlled to change the hydraulic load of the drill string, inducing the drill bit to cut laterally; the high-frequency short-stroke impact device is activated simultaneously to enhance the active correction capability of the centralizer on the borehole wall.

6. The method for correcting the deviation of downhole water exploration and drainage boreholes according to claim 5, characterized in that, When the determined inclination angle is greater than or equal to a preset threshold, adjusting the drilling pressure and rotation speed includes: Reduce drilling pressure to 5-10 kN and increase rotation speed to 400-500 rpm to use centrifugal force of the stabilizer to suppress the upward tendency; Alternatively, increase the drilling pressure to 20-25kN, reduce the rotation speed to 200-300rpm, and strengthen the lateral support force of the stabilizer.

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