Abrasive jet flow-based production and injection increasing system and method for radial horizontal well

Abstract

The invention belongs to the field of oil and gas field development, and relates to a radial horizontal well yield and injection increasing system and method based on abrasive jet. The system comprises a forging, milling and reaming unit and a radial drilling unit, the forging, milling and chambering unit comprises a rotary faucet and a forging, milling and chambering tool string; the radial drilling unit comprises a radial drilling tool string; the forging, milling and chambering tool string is used for performing hydraulic forging, milling and chambering treatment on the casing section and the near wellbore zone reservoir to form a reservoir cavity; the radial drilling tool string is used for implementing radial horizontal drilling in a reservoir. According to the method, a casing, a well cementation cement sheath and a reservoir are subjected to erosion crushing through abrasive jet, and the casing forging and milling process and the reservoir chambering process are integrated into one pipe column operation to be completed; then, abrasive jet is conveyed through a continuous oil pipe, radial horizontal rock breaking drilling is carried out on the reservoir, and multi-layer and multi-direction radial horizontal holes are formed; the system and the method are suitable for shaft transformation operation under the conditions of low porosity, low permeability and hard reservoirs.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas field development and relates to a radial horizontal well production enhancement and injection enhancement system and method based on abrasive jet. Background Technology

[0002] In the field of oil and gas field development, traditional vertical wells and conventional completion methods are insufficient to effectively expand the drainage area during the development of low-porosity and low-permeability reservoirs, thin-layer oil and gas reservoirs, tight sandstone, coalbed methane, and unconventional energy sources. The high proportion of flow resistance near the wellbore in the total pressure drop restricts the improvement of oil and gas production and injection capacity. Therefore, how to improve near-wellbore seepage conditions and enhance the connectivity between the wellbore and the reservoir without large-scale fracturing has become a pressing technical problem in oil and gas development. To address these issues, radial horizontal well technology has gradually been applied. This technology utilizes downhole steering devices and hydraulic rock-breaking drill bits to drill multiple horizontal holes radially around the wellbore to penetrate the near-wellbore contamination zone, reduce the flow pressure drop, and achieve increased production or injection. Compared to conventional horizontal wells, existing radial horizontal well technology has advantages such as shorter well construction cycles and relatively simpler surface equipment. However, it still has several shortcomings, mainly reflected in the following aspects.

[0003] (1) In the casing forging and milling and reservoir reaming stage, existing technologies mostly adopt mechanical forging and milling, which involves many construction steps and dispersed processes. It usually requires multiple stages or trips to complete. Mechanical forging and milling has high requirements for tool strength, downhole stability and construction window. In deep wells or old wells, it is easy to encounter risks such as stuck drill and block falling. At the same time, the reaming capacity is significantly restricted by the formation properties and has a narrow range of applications.

[0004] (2) In the process of rock breaking drilling of radial horizontal wells, existing technologies mostly use water jet as rock breaking medium. This method can be applied in medium and low strength formations, but in hard formations or high strength rock formations, the rock breaking capacity is insufficient, the drilling speed is low, the quality of well forming is unstable, and it is difficult to meet the actual engineering needs, thus limiting the promotion and application of radial horizontal well technology in complex reservoirs.

[0005] (3) In existing radial horizontal well technology, multiple short pipes are often welded together as drill pipes for drilling. Their length is limited by the height of the derrick and the surface working conditions, making it difficult to extend the horizontal drilling footage further. At the same time, the multi-section welded structure has problems with sealing reliability and fatigue life under high pressure conditions, which is not conducive to long-distance drilling operations.

[0006] In summary, existing radial horizontal well and related jet drilling technologies still have significant shortcomings in terms of integrated construction, rock breaking capacity, applicable formation range, drilling footage control, and operational efficiency, and cannot fully meet the engineering application needs under complex reservoir and old well renovation conditions. Summary of the Invention

[0007] The purpose of this invention is to address the aforementioned deficiencies in existing technologies by providing a radial horizontal well production enhancement and injection enhancement system and method based on abrasive jets. This system utilizes the powerful erosive and destructive effect of abrasive jets to perform hydraulic milling and reaming treatment on the casing section and near-wellbore reservoir. The two key processes of casing milling and reservoir reaming are integrated into a single tubing string operation, reducing the complexity, long operation cycle, and accumulated downhole risks associated with staged construction and multiple tubing string trips. Simultaneously, during the radial horizontal well drilling phase, an "abrasive jet + coiled tubing" approach is used to break the rock in the target reservoir. Multi-level and multi-directional drilling is achieved through downhole tool strings. With the coordination of surface fluid supply, proppant addition, and flowback processes, multiple radial horizontal wells are formed, thereby improving near-wellbore connectivity and meeting the engineering requirements for production enhancement or injection enhancement operations. By integrating key processes and making the process continuous, this invention reduces the number of tubing string trips and the frequency of process switching, improving single-well construction efficiency and operational stability. At the same time, abrasive jets have stronger rock-breaking and cutting capabilities than water jets, which can significantly improve the adaptability to reservoir media such as hard formations, dense sandstone and high-strength cemented bodies, and reduce the impact of formation strength changes on drilling efficiency and borehole formation quality. This makes radial horizontal borehole construction easier to achieve controllable and repeatable engineering results, and has a wide range of applications.

[0008] The radial horizontal well production enhancement and injection enhancement system based on abrasive jets described in this invention includes a forging and milling reaming unit and a radial drilling unit.

[0009] The forging and milling reaming unit includes a rotary swivel and a forging and milling reaming tool string connected to the rotary swivel. The rotary swivel enables the forging and milling reaming tool string to continuously and stably deliver high-pressure abrasive slurry to the wellbore even in the "rotation + lifting" state, avoiding the restriction or interruption of the slurry supply path under rotation conditions, thereby improving the continuity, stability and operation efficiency of the forging and milling reaming process.

[0010] The radial drilling unit includes a coiling machine, and the coiled tubing of the coiling machine is connected in series with the radial drilling tool.

[0011] The radial drilling tool string includes a radial drilling tubing; a reversible anchor is fitted outside the radial drilling tubing; a cavity is provided inside the radial drilling tubing, and a metal drill pipe is provided inside the cavity, with the lower end of the metal drill pipe fixedly connected to the drill bit and the upper end connected to the continuous tubing; the lower end of the radial drilling tubing is connected to a downhole steering device.

[0012] The metal drill pipe is welded to the coiled tubing or connected via a conversion coupling, allowing the coiled tubing to serve as both the run-in and supply path. It forms an integrated drilling execution unit with the metal drill pipe and drill bit. The radial drilling execution end possesses higher structural rigidity and controllability, facilitating the formation of a stable radial horizontal wellbore at the target formation and adapting to abrasive jet rock-breaking conditions. The drill bit incorporates a commonly used swirl modulation structure to modulate the fluid into a rotating jet. Furthermore, this invention utilizes coiled tubing as a long-distance run-in and supply path, structurally avoiding the length limitations imposed by the derrick caused by welding multiple short tubing sections. Since the coiled tubing is a continuous, integral tubing string, the number of joints / welds under high-pressure conditions is significantly reduced, thereby improving sealing reliability and fatigue life, and facilitating longer horizontal drilling operations.

[0013] A reversible anchor is fitted onto the outside of the radial drilling tubing and connected to it via API tubing threads. It is lowered into the well along with the radial drilling tubing. The central channel of the reversible anchor is coaxially connected to the inner cavity of the radial drilling tubing, allowing the metal drill pipe and its end drill bit to pass through. During operation, the reversible anchor expands and anchors itself to the inner wall of the casing, providing positioning and support for the entire radial drilling tool string. This invention, through the reversible anchor and the radial drilling tubing forming a positionable tool string reference, enables repeated positioning and multi-branch construction at different layers or orientations within the same wellbore, improving the efficiency and consistency of multi-radial hole construction. In this invention, the downhole steering device is connected to the radial drilling tubing via threads.

[0014] The downhole steering device includes a housing connected to the radial drilling tubing. An annular space is formed between the upper part of the housing and the metal drill pipe. A through-hole is provided in the middle, penetrating both sides of the housing. A guide shoe is located at the bottom, connected to the housing. A piston, sealed to the housing, is housed within the annular space. A spring is fitted around the piston, and a cavity is provided inside the piston for the metal drill pipe and drill bit to pass through. A steering short-joint assembly is located within the through-hole. The bottom end of the piston is connected to the steering short-joint assembly. The steering short-joint assembly includes several steering short joints.

[0015] With the above structure, during subsequent construction, the piston moves downward under the hydrostatic pressure of the annulus between the coiled tubing and the radial drilling tubing, pushing the steering sub-assembly to form a steering track, allowing the metal drill pipe and drill bit to complete the axial-to-radial steering within it. This invention employs a downhole self-driven steering structure of "annulus hydrostatic pressure driving the piston—multi-stage steering sub-assemblies unfolding into a track," which simplifies the downhole steering power chain and improves the stability and reliability of the downhole steering process.

[0016] The forging and milling reaming tool string includes a drill rod and a forging and milling reamer connected to its lower end.

[0017] The forging and milling reamer includes a forging and milling reamer body, an internal cavity communicating with the drill rod, a carbide protective sleeve on the outer circumference and a forging and milling reamer nozzle communicating with the cavity, and the forging and milling reamer nozzle being connected to the forging and milling reamer body through a nozzle sleeve; wherein the forging and milling reamer nozzle includes an internal flow channel and an elongated nozzle outlet.

[0018] During the forging and milling reaming process, high-speed sand-containing two-phase flow and the backflow of metal and rock cuttings can cause significant erosion to critical parts of the reamer. By installing a carbide protective sleeve on the outer circumference of the forging and milling reamer, and in conjunction with a nozzle sleeve to structurally protect the nozzle mounting area, the erosion resistance of critical parts can be improved, tool life can be extended, and operational reliability can be enhanced. Simultaneously, the elongated nozzle outlet creates a striped erosion zone on the target surface, which, combined with the forging and milling reaming operation method of rotating the tool string and slowly lifting it, helps to improve effective coverage and reaming efficiency per unit time, promotes the formation of a continuous reaming profile, and thus more efficiently forms reservoir cavities in the reservoir to meet the needs of subsequent radial drilling.

[0019] The steering knuckle assembly includes five steering knuckles. The bottom end of the piston is rigidly connected to the upper end of the first steering knuckle of the assembly. Adjacent steering knuckles in the middle are hinged together by follower hinges. The fourth and fifth steering knuckles are hinged together by fixed hinges, which are hinged to the housing of the downhole steering device. There is an included angle between adjacent steering knuckles. When the steering knuckle assembly is in extreme bending state, its side can abut and form a positioning. Multiple guide wheel sets are provided in all steering knuckles.

[0020] The guide wheel assembly includes a wheel axle, with both ends installed in corresponding shaft holes of the steering sub. Rollers are fitted on the wheel axle, and retaining springs are installed in the grooves at the ends of the wheel axles. The guide wheel assembly is used to clamp, guide, and reduce friction of the metal drill pipe, which can significantly reduce frictional resistance and the risk of uneven wear during steering and propulsion, and improve the continuity of drilling propulsion and the stability of the wellbore trajectory.

[0021] The radial horizontal well production enhancement and injection system based on abrasive jet according to the present invention further includes a fluid circulation unit; the fluid circulation unit includes a water tank, a sand box, a sand mixing truck, and a fracturing truck; the water tank and the sand box are respectively connected to the sand mixing truck through atmospheric pressure pipelines, and the sand mixing truck is connected to the fracturing truck through atmospheric pressure pipelines; the water tank is connected to the annulus through a return pipeline; the fracturing truck is connected to a rotary tap through a high-pressure abrasive slurry delivery pipe.

[0022] The water tank is connected to the radial drilling unit through a high-pressure clean water delivery pipe, which is equipped with a high-pressure clean water pump.

[0023] The fluid circulation unit can provide high-pressure clean water or high-pressure abrasive slurry depending on the specific working conditions. Metal shavings and rock fragments generated during construction can also be returned to the fluid circulation unit, settled, and then recycled.

[0024] In addition, the present invention can be equipped with wellhead tees or crosses, as well as coiled tubing injection heads, coiled tubing sealing boxes and other devices at the wellhead, depending on the specific working conditions, which is more conducive to the construction.

[0025] Using the aforementioned radial horizontal well production enhancement and injection enhancement system based on abrasive jets, this invention also proposes a radial horizontal well production enhancement and injection enhancement method based on abrasive jets, comprising the following steps:

[0026] (S1) The fluid circulation unit delivers high-pressure abrasive slurry to the forging and milling reaming tool string through a rotating faucet, forming an abrasive jet. This jet performs abrasive jet hydraulic forging and milling and reaming impact on the casing, cementing sheath and reservoir. During this process, the forging and milling reaming tool string rotates and slowly rises, gradually forming reservoir cavities in the reservoir.

[0027] (S2) Lower the radial drilling tool string to the reservoir cavity and anchor it to the inner wall of the casing, with the drill bit remaining inside the piston.

[0028] (S3) Inject high-pressure clean water into the annulus between the coiled tubing and the radial drilling tubing, as well as into the coiled tubing, so that the piston in the downhole steering device pushes the steering short section to form a steering track and guides the metal drill pipe to complete the steering from the vertical direction to the horizontal direction.

[0029] (S4) After the drill bit has completely passed through the steering sub, the high-pressure abrasive slurry is transported into the radial drilling tool string to form a rotating abrasive jet, which performs radial horizontal rock breaking drilling on the reservoir to form at least one radial reservoir horizontal wellbore.

[0030] (S5) After completing a radial reservoir horizontal wellbore, by releasing the anchoring state of the reversible anchor, adjust the drilling layer or drilling azimuth of the radial drilling tool string, and repeat steps (S1)-(S4) to form multiple radial reservoir horizontal wellbores in the same wellbore.

[0031] During the above process, the abrasive and the resulting metal and rock chips can be returned through the annulus and guided to the water tank through the return pipe. After sedimentation, the water in the water tank is recycled.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] (1) To realize the integrated operation of casing forging and milling and reservoir borehole enlargement, and improve the integration of construction.

[0034] By using abrasive jets to perform hydraulic milling and reaming on the casing section and near-wellbore reservoir, and adopting a "rotation + lifting" operation method, the two key processes are integrated into a single tubing string operation. This reduces the complexity of procedures, long operation cycles, and accumulation of downhole risks caused by staged construction and multiple tubing string trips in existing technologies, which is conducive to improving overall construction efficiency and operational safety.

[0035] (2) Avoid the high dependence of mechanical forging and milling on downhole working conditions and tool strength, and reduce construction risks.

[0036] Compared to existing casing processing methods that primarily rely on mechanical forging and milling, this invention employs abrasive jets for hydraulic forging and milling and hole enlargement. This reduces mechanical contact and the high load transfer process, decreasing the dependence on downhole stability, the working window, and tool strength. It also helps to reduce the risks of stuck drill bits and block falling off in deep and old wells.

[0037] (3) Significantly enhances the rock-breaking ability of radial horizontal pores in hard formations and complex reservoirs.

[0038] This invention uses abrasive jets as the rock-breaking medium during the radial horizontal well drilling stage. Compared with water jets, it has stronger erosion and cutting capabilities, and can effectively adapt to reservoir conditions such as hard formations, dense sandstone, and high-strength cemented bodies. It reduces the impact of formation strength changes on drilling efficiency and well formation quality, and expands the applicable formation range of radial horizontal well technology.

[0039] (4) Combine coiled tubing to achieve continuous and controllable radial drilling process.

[0040] By adopting the drilling method of "abrasive jet + coiled tubing", the problem of limited drill pipe length due to welding multiple short pipes can be avoided, which is conducive to extending the radial horizontal borehole footage. At the same time, the coiled tubing method reduces the number of connection links, which helps to improve the continuity and stability of the drilling process.

[0041] (5) Stability and reliability of downhole turning process.

[0042] The piston is driven by annular hydrostatic pressure to deploy the steering track, eliminating the need for other clamping and propulsion power systems and corresponding control mechanisms. This simplifies the downhole steering power chain and improves the stability and reliability of the downhole steering process. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the assembly method of the forging, milling, and reaming equipment of the present invention;

[0044] Figure 2 This is a schematic diagram of the forging, milling, and reaming tool string of the present invention;

[0045] Figure 3 This is a schematic diagram of the forging and milling reamer structure of the present invention;

[0046] Figure 4 This is a schematic diagram of the forging and milling nozzle structure of the present invention;

[0047] Figure 5 This is a schematic diagram of the forging and milling process for the starting section of the hole enlargement in this invention.

[0048] Figure 6 This is a schematic diagram of the process of the forging, milling, and hole-expanding embodiment of the present invention;

[0049] Figure 7 This is a schematic diagram of the reservoir after the forging, milling, and hole enlargement are completed according to the present invention;

[0050] Figure 8 This is a schematic diagram of the radial drilling equipment assembly method of the present invention;

[0051] Figure 9 This is a schematic diagram of the radial drilling tool string of the present invention;

[0052] Figure 10 This is a front view of the downhole steering mechanism structure of the present invention;

[0053] Figure 11 This is a left view of the downhole steering mechanism structure of the present invention;

[0054] Figure 12 This is a schematic diagram of the guide wheel assembly structure in the downhole steering gear of the present invention;

[0055] Figure 13 This is a schematic diagram of the structure of the downhole steering device of the present invention after forming a steering track;

[0056] Figure 14 This is a schematic diagram of the radial drilling starting section process of the present invention;

[0057] Figure 15 This is a schematic diagram of the radial drilling and jetting process of the present invention;

[0058] Figure 16 This is a schematic diagram of the radial drilling jet rock breaking process of the present invention;

[0059] Figure 17 This is a schematic diagram of the jet rock breaking process after radial drilling and azimuth change according to the present invention.

[0060] In the diagram: 1 is the drilling rig, 2 is the forging and milling reamer tool string, 3 is the water tank, 4 is the sand box, 5 is the sand mixing truck, 6 is the fracturing truck, 7 is the rotary swivel, 8 is the wellhead tee, 9 is the formation, 10 is the casing, 11 is the cementing sheath, 12 is the reservoir, 13 is the high-pressure clean water pump, 14 is the coiled tubing injection head, 15 is the coiled tubing sealing box, 16 is the wellhead cross, 17 is the coiled tubing, 18 is the tubing coiler, and 19 is the radial drilling tool string.

[0061] A is the atmospheric pressure pipeline, B is the reflux pipeline, C is the high-pressure abrasive slurry delivery pipe, D is the high-pressure clean water delivery pipe, S is the abrasive direct jet, K is the reservoir cavity, M is the rotating abrasive jet, and T is the reservoir horizontal wellbore.

[0062] 2-1 is the drill rod, 2-2 is the forging and milling reamer, 2-2-1 is the forging and milling reamer body, 2-2-2 is the carbide protective sleeve, 2-2-3 is the forging and milling reamer nozzle, 2-2-4 is the nozzle sleeve, 2-2-3-1 is the nozzle inner flow channel, and 2-2-3-2 is the elongated nozzle outlet;

[0063] 19-1 is the downhole steering device, 19-2 is the drill bit, 19-3 is the metal drill pipe, 19-4 is the reversible anchor, and 19-5 is the radial drilling tubing.

[0064] 19-1-1 is the housing, 19-1-2 is the piston, 19-1-3 is the spring, 19-1-4 is the first steering joint, 19-1-5 is the second steering joint, 19-1-6 is the third steering joint, 19-1-7 is the fourth steering joint, 19-1-8 is the fifth steering joint, 19-1-9 is the guide shoe, 19-1-10 is the guide wheel assembly, 19-1-11 is the fixed hinge, 19-1-12 is the follower hinge, 19-1-13 is the seal, and 19-1-14 is the through hole;

[0065] 19-1-10-1 is a snap ring, 19-1-10-2 is a wheel axle, and 19-1-10-3 is a roller. Detailed Implementation

[0066] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0067] Example 1

[0068] Reference Figure 1-4 as well as Figure 8 A radial horizontal well production enhancement and injection system based on abrasive jets includes a forging and milling reaming unit and a radial drilling unit.

[0069] The forging and milling reaming unit includes a rotary tap 7 and a forging and milling reaming tool string 2 connected to the rotary tap.

[0070] The forging and milling reaming tool string 2 includes a drill rod 2-1 and a forging and milling reamer 2-2 connected to its lower end, which are connected by an API standard thread.

[0071] The forging milling reamer 2-2 includes a forging milling reamer body 2-2-1. The forging milling reamer body 2-2-1 has a cavity inside that communicates with the drill rod 2-1. A carbide protective sleeve 2-2-2 is provided on the outer circle and a forging milling reamer nozzle 2-2-3 communicating with the cavity is provided. The forging milling reamer nozzle 2-2-3 is connected to the forging milling reamer body 2-2-1 through a nozzle sleeve 2-2-4. The forging milling reamer nozzle 2-2-3 includes an inner flow channel 2-2-3-1 and an elongated nozzle outlet 2-2-3-2.

[0072] Specifically, the outer conical surface of the forging and milling reaming nozzle 2-2-3 is tightly fitted with the inner conical surface of the nozzle sleeve 2-2-4, and then screwed onto the forging and milling reaming device body 2-2-1 via threads on the nozzle sleeve 2-2-4. When the high-pressure abrasive slurry is delivered to the forging and milling reaming nozzle 2-2-3, it is first accelerated by the inner flow channel 2-2-3-1 of the nozzle, and then modulated to form a direct abrasive jet S through the elongated nozzle outlet 2-2-3-2, increasing the operational efficiency of casing forging and milling and reservoir reaming.

[0073] The radial drilling unit includes a coiler 18, and the coiled tubing 17 of the coiler 18 is connected to the radial drilling tool string 19.

[0074] The radial drilling tool string 19 includes a radial drilling tubing 19-5; a reversible anchor 19-4 is sleeved on the outside of the radial drilling tubing 19-5; the radial drilling tubing 19-5 has a cavity inside, and a metal drill pipe 19-3 is installed in the cavity. The lower end of the metal drill pipe 19-3 is fixedly connected to the drill bit 19-2, and the upper end is connected to the continuous tubing 17; the lower end of the radial drilling tubing 19-5 is threadedly connected to a downhole steer 19-1.

[0075] The metal drill pipe 19-3 is welded to the coiled tubing 17 or connected via a conversion coupling. The reversible anchor 19-4 is fitted onto the outside of the radial drilling tubing 19-5 and connected to it via API tubing threads.

[0076] The drill bit 19-2 has an internal swirl modulation structure for modulating the fluid to form a rotating jet.

[0077] The downhole steering device 19-1 includes a housing 19-1-1 connected to the radial drilling tubing 19-5. An annular space is formed between the upper part of the housing 19-1-1 and the metal drill pipe 19-3. A through hole 19-1-14 is provided in the middle, penetrating both sides of the housing 19-1-1. The lower part is a guide shoe 19-1-9 connected to the housing 19-1-1. A piston 19-1-2 is provided in the annular space and is sealed to the housing 19-1-1. A spring 19-1-3 is sleeved on the outside of the piston 19-1-2. A cavity is provided inside the piston 19-1-2 for the metal drill pipe 19-3 and the drill bit 19-2 to pass through. A steering short joint assembly is provided in the through hole 19-1-14. The bottom end of the piston 19-1-2 is connected to the steering short joint assembly.

[0078] In this embodiment, the steering short-knuckle assembly includes steering short-knuckle 19-1-4, steering short-knuckle 19-1-5, steering short-knuckle 19-1-6, steering short-knuckle 19-1-7, and steering short-knuckle 19-1-8; piston 19-1-2 is installed inside housing 19-1-1, with a seal 19-1-13 between them, and the bottom end of piston 19-1-2 is connected to the upper end of steering short-knuckle 19-1-4. Rigid connections are used; steering stubs 1-4, 2-5, 3-6, and 4-7 are hinged to each other via follower hinges 19-1-12; steering stub 4-7 and steering stub 5-8 are hinged to each other via fixed hinges 19-1-11, which are also hinged to the housing 19-1-1. Adjacent steering stubs are at an included angle, allowing their sides to abut and provide positioning when the steering stub assembly is in its extreme bending state; the cross-section of the steering stubs can be trapezoidal or parallelogram-shaped. Multiple guide wheel assemblies 19-1-10 are installed within each steering stub.

[0079] The guide wheel assembly 19-1-10 includes a wheel axle 19-1-10-2, both ends of which are installed in the corresponding shaft holes of the steering short joint. A roller 19-1-10-3 is sleeved on the wheel axle 19-1-10-2, and a retaining ring 19-1-10-1 is assembled in the retaining groove at the end of the wheel axle 19-1-10-2.

[0080] The radial horizontal well production enhancement and injection system based on abrasive jet also includes a fluid circulation unit; the fluid circulation unit includes a water tank 3, a sand box 4, a sand mixing truck 5, and a fracturing truck 6; the water tank 3 and the sand box 4 are respectively connected to the sand mixing truck 5 through an atmospheric pressure pipeline A, and the sand mixing truck 5 is connected to the fracturing truck 6 through an atmospheric pressure pipeline A; the water tank 3 is connected to the annulus through a return pipeline B; the fracturing truck 6 is connected to a rotary tap 7 through a high-pressure abrasive slurry delivery pipe C.

[0081] Water tank 3 is connected to the radial drilling unit via high-pressure clean water delivery pipe D, and high-pressure clean water pump 13 is installed on high-pressure clean water delivery pipe D. Wellhead is equipped with wellhead tee 8 or wellhead cross 16, as well as coiled tubing injection head 14 and coiled tubing sealing box 15.

[0082] Example 2

[0083] The radial horizontal well production enhancement and injection enhancement method based on abrasive jet includes casing milling and reservoir enlargement, as well as radial rock-breaking drilling process.

[0084] Reference Figure 1 , Figures 5-7 The specific steps for casing forging and milling and reservoir enlargement are as follows:

[0085] (S1) The fluid circulation unit delivers the high-pressure abrasive slurry to the milling and reaming tool string 2 via the rotating faucet 7, forming an abrasive jet S, which performs abrasive jet hydraulic milling and reaming impact on the casing 10, cementing sheath 11 and reservoir 12. During this process, the milling and reaming tool string 2 rotates and slowly lifts, gradually forming a reservoir cavity K in the reservoir 12.

[0086] Specifically, after the drill pipe 2-1 and the forging milling reamer 2-2 are connected by the API standard thread, they form a downhole forging milling reamer tool string 2, which is sent into the well by the drilling rig 1. A rotating swivel 7 is installed on the upper end of the drill pipe 2-1.

[0087] Water tank 3 and sand box 4 are connected to sand mixing truck 5 through atmospheric pressure pipeline A. After water and sand are evenly mixed in sand mixing truck 5, they enter fracturing truck 6 through another atmospheric pressure pipeline A. After being pressurized by fracturing truck 6, the high-pressure abrasive slurry is transported to rotary swivel 7 through high-pressure abrasive slurry delivery pipe C. Then, it is guided into forging milling reamer 2-2 through drill pipe 2-1. The forging milling reamer nozzle 2-2-3 inside forging milling reamer 2-2 modulates to form a direct abrasive jet S, which impacts casing 10, cementing sheath 11 and reservoir 12 at high speed.

[0088] The downhole milling and reaming tool string 2 is driven by the drilling rig 1 to rotate and slowly lift, gradually eroding in the reservoir 12 to form a reservoir cavity K, providing downhole space for subsequent radial drilling.

[0089] Metal chips, rock chips, and abrasives generated during forging and milling return through the annulus between the downhole forging and milling tool string 2 and the casing 10. After passing through the wellhead tee 8, they are guided to the water tank 3 by the return pipe B. After sedimentation, the water in the water tank 3 is recycled.

[0090] During forging, milling, and reaming, the high-pressure abrasive slurry discharge rate needs to be 800~1500L / min, and the pressure drop of the forging and milling reamer 2-2 needs to be 40~70MPa.

[0091] The diameter of the reservoir cavity K needs to be >650mm, and the height is about 3000mm.

[0092] Reference Figures 8-17 Radial rock-breaking drilling includes the following steps:

[0093] (S2) Lower the radial drilling tool string 19 to the reservoir cavity K and anchor it to the inner wall of the casing 10. The drill bit 19-2 stays in the piston 19-1-2.

[0094] The drill bit 19-2, metal drill pipe 19-3, and coiled tubing 17 are guided into the radial drilling tubing 19-5 through the coiled tubing injection head 14 and remain inside the piston 19-1-2, but must not enter the first steering sub 19-1-4; the radial drilling tool string 19 is lowered into the well through the radial drilling tubing 19-5 and lowered to the reservoir cavity K. The guide shoe 19-1-9 can guide it to be lowered smoothly. Then, by lifting and lowering, the reversible anchor 19-4 is stably anchored to the inner wall of the casing 10; at this time, the metal drill pipe 19-3 and the piston 19-1-2 are sealed by the seal 19-1-13; when the coiled tubing 17 is lowered into the well, the coiled tubing sealing box 15 seals the joint surface between the coiled tubing 17 and the wellhead four-way connector 16.

[0095] (S3) Without adding sand, high-pressure clean water is injected into the annulus between the coiled tubing 17 and the radial drilling tubing 19-5, as well as into the coiled tubing 17, so that the piston 19-1-2 in the downhole steering device 19-1 pushes the steering short section assembly to form a steering track and guides the metal drill pipe 19-3 to complete the steering from the vertical direction to the horizontal direction.

[0096] Specifically, the water tank 3 is connected to the high-pressure clean water pump 13. After the clean water is pressurized by the high-pressure clean water pump 13, it enters the annulus between the coiled tubing 17 and the radial drilling tubing 19-5 through the high-pressure clean water delivery pipe D. This applies hydrostatic pressure to the piston 19-1-2 in the downhole steering device 19-1, pushing the piston 19-1-2 downward and compressing the spring 19-1-3. Simultaneously, this pushes the first steering sub-joint 19-1-4, the second steering sub-joint 19-1-5, the third steering sub-joint 19-1-6, and the fourth steering sub-joint 19-1-4. Steering stub 19-1-7 and steering stub 5 19-1-8 form a steering track; among them, the follower hinge 19-1-12 between steering stub 1 19-1-4, steering stub 2 19-1-5, steering stub 3 19-1-6 and steering stub 4 19-1-7 follows the adjacent steering stubs, while the fixed hinge 19-1-11 between steering stub 4 19-1-7 and steering stub 5 19-1-8 rotates at a fixed point on the housing 19-1-1.

[0097] Water tank 3 and sand box 4 are connected to sand mixing truck 5 via atmospheric pressure pipeline A. Without adding sand, only the fracturing truck 6 pressurizes the clean water and delivers it to the coiling machine 18 via high-pressure abrasive slurry delivery pipe C. Then, it is delivered to the radial drilling tool string 19 via continuous tubing 17. Under the hydrostatic pressure, drill bit 19-2 drives metal drill pipe 19-3 to move forward along the turning track and gradually change from vertical to horizontal. During this process, metal drill pipe 19-3 is held by multiple guide wheel sets 19-1-10 to reduce friction and assist in guidance. When metal drill pipe 19-3 moves forward, it is pulled by coiling machine 18 through continuous tubing 17 to control its forward speed.

[0098] (S4) After the drill bit 19-2 has completely passed through the steering sub, the high-pressure abrasive slurry is transported into the radial drilling tool string 19 to form a rotating abrasive jet M, which performs radial horizontal rock breaking drilling on the reservoir 12 to form at least one radial reservoir horizontal wellbore T.

[0099] Specifically, after drill bit 19-2 has completely penetrated the No. 5 steering sub-unit 19-1-8, sand box 4 is opened and sand is added. Water and sand are evenly mixed in sand mixing truck 5 and then enter fracturing truck 6. After being pressurized by fracturing truck, the high-pressure abrasive slurry is still transported to coiling machine 18 through high-pressure abrasive slurry delivery pipe C, and then transported to the radial drilling tool string 19 through coiled tubing 17. Finally, drill bit 19-2 modulates it into a high-speed rotating abrasive jet M to erode reservoir 12. Breaking; Drill bit 19-2 and metal drill pipe 19-3 are driven by hydrostatic pressure to gradually extend horizontally, forming reservoir horizontal wellbore T in the reservoir; During this process, abrasive and rock cuttings are horizontally returned through the annulus between reservoir horizontal wellbore T and metal drill pipe 19-3 and enter the annulus between radial drilling tubing 19-5 and casing 10, and finally return to the wellhead four-way 16, and are guided to water pool 3 by return pipe B. After sedimentation, the water in water pool 3 is recycled.

[0100] (S5) After completing a radial reservoir horizontal well T, by releasing the anchoring state of the reversible anchor 19-4, the drilling layer or drilling azimuth of the radial drilling tool string 19 is adjusted, and steps (S1)-(S4) are repeated to form multiple radial reservoir horizontal wells T in the same wellbore.

[0101] Specifically, after the horizontal wellbore T in a reservoir is completed, the fracturing truck 6 is shut down. The piston 19-1-2 moves upward under the push of the spring 19-1-3, causing the No. 1 steering sub 19-1-4, No. 2 steering sub 19-1-5, No. 3 steering sub 19-1-6, No. 4 steering sub 19-1-7, and No. 5 steering sub 19-1-8 to re-enter the downhole steering device 19-1. At this time, the radial drilling tool string 19 is raised and lowered, and the reversible anchoring is released. The radial drilling tool string 19-4 is anchored and suspended inside the casing 10; the radial drilling tool string 19 is moved to the next radial drilling layer or the next azimuth, and the radial drilling tool string 19 is raised and lowered again. The reversible anchor 19-4 is then stably anchored and suspended on the inner wall of the casing 10. Following the above radial drilling process, the second reservoir horizontal well T is drilled. The above process is repeated until all reservoir horizontal wells T are drilled. The radial drilling tool string 19 is then pulled out, and the construction is completed.

[0102] During radial rock-breaking drilling, the abrasive volume ratio is 8%~12%, the fracturing truck displacement is 500~1000L / min, and the pressure drop of the rotating abrasive jet rock-breaking drill bit is 40~70MPa.

[0103] Any person skilled in the art can modify the above-described technical solutions or modify them into equivalent technical solutions. Therefore, any simple modifications or equivalent transformations made based on the technical solutions of this invention are within the scope of protection claimed by this invention.

Claims

1. A radial horizontal well production enhancement and injection enhancement system based on abrasive jet, characterized in that, Includes a forging and milling reaming unit and a radial drilling unit; The forging and milling reaming unit includes a rotary tap (7) and a forging and milling reaming tool string (2) connected to the rotary tap (7); The radial drilling unit includes a coiler (18), and the coiled tubing (17) of the coiler (18) is connected to the radial drilling tool string (19); The radial drilling tool string (19) includes a radial drilling tubing (19-5); a reversible anchor (19-4) is fitted outside the radial drilling tubing (19-5); the radial drilling tubing (19-5) has a cavity inside, and a metal drill pipe (19-3) is installed inside the cavity. The lower end of the metal drill pipe (19-3) is fixedly connected to the drill bit (19-2), and the upper end is connected to the continuous tubing (17); the lower end of the radial drilling tubing (19-5) is connected to the downhole steer (19-1). The downhole steering device (19-1) includes a housing (19-1-1) connected to the radial drilling tubing (19-5). An annular space is formed between the upper part of the housing (19-1-1) and the metal drill pipe (19-3). A through hole (19-1-14) is provided in the middle, penetrating both sides of the housing. The lower part is a guide shoe (19-1-9) connected to the housing (19-1-1). A piston (19-1-2) is provided in the annular space and is sealed to the housing (19-1-1). A spring (19-1-3) is sleeved on the outside of the piston (19-1-2). A cavity is provided inside the piston (19-1-2) for the metal drill pipe (19-3) and the drill bit (19-2) to pass through. A steering short joint assembly is provided in the through hole (19-1-14). The bottom end of the piston (19-1-2) is connected to the steering short joint assembly.

2. The radial horizontal well production enhancement and injection enhancement system based on abrasive jet according to claim 1, characterized in that, The forging and milling reaming tool string (2) includes a drill rod (2-1) and a forging and milling reamer (2-2) connected to its lower end.

3. The radial horizontal well production enhancement and injection enhancement system based on abrasive jet according to claim 2, characterized in that, The forging milling reamer (2-2) includes a forging milling reamer body (2-2-1), the forging milling reamer body (2-2-1) has a cavity inside that communicates with the drill rod (2-1), a carbide protective sleeve (2-2-2) is provided on the outer circle and a forging milling reamer nozzle (2-2-3) communicating with the cavity is opened, the forging milling reamer nozzle (2-2-3) is connected to the forging milling reamer body (2-2-1) through a nozzle sleeve (2-2-4); wherein the forging milling reamer nozzle (2-2-3) includes an inner flow channel (2-2-3-1) and an elongated nozzle outlet (2-2-3-2).

4. The radial horizontal well production enhancement and injection enhancement system based on abrasive jet according to claim 1, characterized in that, The steering knuckle assembly includes five steering knuckles. The bottom end of the piston (19-1-2) is rigidly connected to the upper end of the first steering knuckle (19-1-4) of the steering knuckle assembly. The middle adjacent steering knuckles are hinged by a follower hinge (19-1-12). The fourth and fifth steering knuckles are hinged by a fixed hinge (19-1-11). The fixed hinge (19-1-11) is hinged to the housing (19-1-1). There is an included angle between adjacent steering knuckles. When the steering knuckle assembly is in the extreme bending state, its side can abut and form a positioning. Multiple guide wheel assemblies (19-1-10) are provided in all steering knuckles.

5. The radial horizontal well production enhancement and injection enhancement system based on abrasive jet according to claim 4, characterized in that, The guide wheel assembly (19-1-10) includes a wheel axle (19-1-10-2), both ends of which are installed in the corresponding shaft holes of the steering short knuckle. A roller (19-1-10-3) is sleeved on the wheel axle (19-1-10-2), and a retaining ring (19-1-10-1) is installed in the retaining groove at the end of the wheel axle (19-1-10-2).

6. The radial horizontal well production enhancement and injection enhancement system based on abrasive jet according to claim 1, characterized in that, It also includes a fluid circulation unit; the fluid circulation unit includes a water tank (3), a sand box (4), a sand mixing truck (5) and a fracturing truck (6); the water tank (3) and the sand box (4) are respectively connected to the sand mixing truck (5) through an atmospheric pressure pipeline (A), and the sand mixing truck (5) is connected to the fracturing truck (6) through an atmospheric pressure pipeline (A); the water tank (3) is connected to the annulus through a return pipeline (B); the fracturing truck (6) is connected to a rotating faucet (7) through a high-pressure abrasive slurry delivery pipe (C).

7. The radial horizontal well production enhancement and injection enhancement system based on abrasive jet according to claim 6, characterized in that, The water tank (3) is connected to the radial drilling unit through the high-pressure clean water delivery pipe (D), and the high-pressure clean water delivery pipe (D) is equipped with a high-pressure clean water pump (13).

8. A radial horizontal well production enhancement and injection enhancement method based on abrasive jet, characterized in that, The radial horizontal well production enhancement and injection enhancement system based on abrasive jet as described in claim 7 includes the following steps: (S1) The fluid circulation unit delivers high-pressure abrasive slurry to the milling and reaming tool string (2) via a rotating faucet (7) to form an abrasive jet (S), which performs abrasive jet hydraulic milling and reaming impact on the casing (10), cementing sheath (11) and reservoir (12). During this process, the milling and reaming tool string (2) rotates and slowly lifts, gradually forming a reservoir cavity (K) in the reservoir (12). (S2) Lower the radial drilling tool string (19) to the reservoir cavity (K) and anchor it to the inner wall of the casing (10), with the drill bit (19-2) remaining inside the piston (19-1-2); (S3) Inject high-pressure clean water into the annulus between the coiled tubing (17) and the radial drilling tubing (19-5) and into the coiled tubing (17), so that the piston (19-1-2) in the downhole steering device (19-1) pushes the steering sub-unit to form a steering track and guides the metal drill pipe (19-3) to complete the steering from the vertical direction to the horizontal direction; (S4) After the drill bit (19-2) has completely passed through the steering sub, the high-pressure abrasive slurry is transported to the interior of the radial drilling tool string (19) to form a rotating abrasive jet (M) to carry out radial horizontal rock breaking drilling on the reservoir (12) and form at least one radial reservoir horizontal wellbore (T).

9. The radial horizontal well production enhancement and injection enhancement method based on abrasive jet according to claim 8, characterized in that, It also includes the following steps: (S5) After completing a radial reservoir horizontal well (T), by releasing the anchoring state of the reversible anchor (19-4), the drilling layer or drilling azimuth of the radial drilling tool string (19) is adjusted, and steps (S1)-(S4) are repeated to form multiple radial reservoir horizontal wells (T) in the same wellbore.

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