A fixed-distance directional sliding device, fishbone stinger completion string and construction method

Abstract

The application provides a fixed-distance directional sliding device, a fishbone stinger completion string and a construction method, and belongs to the technical field of oil and gas exploitation. The fixed-distance directional sliding device comprises a center pipe, a plurality of sliding grooves parallel to the center axis are arranged on the outer wall of the center pipe, a sliding sleeve is arranged on the outer wall of the center pipe, a plurality of guide sliding pins are arranged on the sliding sleeve in the circumferential direction, and the guide sliding pins are arranged at the positions of the sliding grooves. The fishbone stinger completion string comprises a casing, a lower oil pipe, the fixed-distance directional sliding device and an upper oil pipe are sequentially arranged in the casing from bottom to top, and a perforating gun and a jet needle pipe are sequentially arranged in the lower oil pipe from bottom to top. The fixed-distance directional sliding device combines the perforating of the perforating bullet with the hydraulic jet drilling, realizes the drilling process of perforating first and then jetting, avoids the problem of cutting the casing wall, improves the opening efficiency, and makes the multi-branch fishbone stinger well technology applicable to the casing well.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas extraction technology, specifically relating to a fixed-distance directional sliding device, a fishbone completion string, and a construction method. Background Technology

[0002] Multi-branch fishbone drilling technology is a reservoir enhancement and stimulation technique. It utilizes small-diameter flexible tubing to achieve directional drilling within the casing or open hole, and then drills into the reservoir using high-pressure hydraulic rock breaking. This new drilling and completion technology aims to liberate the reservoir while ensuring safe drilling and reservoir protection. This technology can directionally drill multiple wellbores up to 10 meters in length in different directions within the oil-bearing layer, connecting the wellbore to the reservoir. By drilling in parallel, multiple branches are formed within the reservoir, increasing the drainage area and thus increasing crude oil production.

[0003] Chinese patent publication CN105443085A discloses an oil and gas extraction device and method that utilizes multi-branch fishbone well technology to achieve reservoir stimulation and increase oil and gas production. The device includes a jetting sub and an adjusting sub connected to it. The jetting sub has a through-hole on its sidewall, and the adjusting sub has an internal oil hole for oil and gas to flow from the formation into the extraction well. Initially, a needle tube is installed in the inner cavity of the jetting sub. During the pumping of liquid into the jetting sub, the needle tube extends through the formation to form an extraction channel. However, this method cannot be used in casing wells and can only be applied in open-hole wells, limiting its application scope. Summary of the Invention

[0004] The purpose of this invention is to solve the problems existing in the prior art and provide a fixed-distance directional sliding device, a fishbone completion string and construction method. By taking advantage of the perforation drilling through the casing, and superimposing the jet drilling distance on the premise of the initial hole distance formed by the perforation, it can not only effectively perforate the casing and improve the hole opening efficiency, but also improve the water jet extension limit to connect different reservoirs.

[0005] One of the objectives of this invention is to provide a fixed-distance directional sliding device.

[0006] The second objective of this invention is to provide a fishbone-shaped well completion string.

[0007] The third objective of this invention is to provide a fishbone-shaped well completion construction method.

[0008] This invention is achieved through the following technical solution:

[0009] In a first aspect, the present invention provides a fixed-distance directional sliding device, comprising a central tube, wherein a plurality of sliding grooves parallel to the central axis are provided on the outer wall of the central tube, and a sliding sleeve is fitted on the outer wall of the central tube.

[0010] A further improvement of the present invention is that:

[0011] The sliding sleeve is provided with a plurality of guide sliding pins along the circumferential direction, and the guide sliding pins are located at the position of the sliding groove.

[0012] In a second aspect, the present invention provides a fishbone completion string, comprising a casing, wherein a lower tubing, the aforementioned fixed-distance directional sliding device and an upper tubing are arranged sequentially from bottom to top inside the casing, and a perforating gun and a jet needle are arranged sequentially from bottom to top inside the lower tubing, and the bottom of the lower tubing is plugged.

[0013] A further improvement of the present invention is that:

[0014] The central tube of the fixed-distance directional sliding device is threadedly connected to the bottom of the upper oil pipe and to the top of the lower oil pipe.

[0015] A further improvement of the present invention is that:

[0016] An oil pipe anchor is fitted onto the lower oil pipe. The oil pipe anchor is connected to the sliding sleeve by a thread. By rotating the upper oil pipe, the central pipe and the sliding groove are rotated, which in turn drives the sliding sleeve and the guide sliding pin to rotate. This causes the oil pipe anchor to rotate, opening it up and anchoring it to the casing wall, thus fixing the sliding sleeve onto the casing.

[0017] A further improvement of the present invention is that:

[0018] Four to five rows of injection needle tubes are arranged axially on the lower oil pipe, and three to four injection needle tubes are evenly arranged in each row on the radial section of the lower oil pipe.

[0019] Correspondingly, 4 to 5 perforating guns are arranged axially on the lower oil pipe, and each perforating gun has 3 to 4 perforating projectiles evenly arranged in the radial section.

[0020] A further improvement of the present invention is that:

[0021] The distance between two adjacent perforating guns is the same as the distance between two adjacent rows of injection needles.

[0022] A further improvement of the present invention is that:

[0023] The vertical distance between the injection needle tube and the corresponding perforating gun is not greater than the length of the sliding groove.

[0024] A further improvement of the present invention is that:

[0025] The injection needle is mounted on the lower oil pipe via an orifice slide.

[0026] A through mounting hole is provided on the side wall of the lower oil pipe, and an orifice slide is set in the mounting hole. One end of the injection needle is inserted into the orifice slide and a self-feeding nozzle is set at its end. The other end of the injection needle is located in the inner cavity of the lower oil pipe.

[0027] A third aspect of the present invention provides a method for constructing a fishbone-shaped well completion, specifically comprising the following steps:

[0028] Step 1: First, install the perforating gun and the injection needle tube inside the lower oil pipe. Connect the two ends of the central tube of the fixed-distance and directional sliding device to the upper oil pipe and the lower oil pipe respectively, and anchor the oil pipe onto the lower oil pipe and connect it to the sliding sleeve of the fixed-distance and directional sliding device through threads.

[0029] Step 2: Lower the assembled tubing from Step 1 into the casing, rotate the upper tubing to rotate the tubing anchor so that the tubing anchor opens and anchors to the casing wall, and fix the sliding sleeve to the casing.

[0030] Step 3: By pressurizing inside the pipe, a perforation gun is used to create perforation holes on the casing.

[0031] Step 4: Lower the oil pipe. The central tube moves downward along the sliding groove in a directional and fixed distance. However, the central tube cannot rotate during the translation to ensure that the orientation remains unchanged during sliding. The downward movement of the central tube drives the injection needle tube to move downward until it is aligned with the position of the perforation hole.

[0032] Step 5: The ground pump truck pressurizes the oil pipe, and the high-pressure fluid is jetted through the injection needle. The injection needle automatically enters the perforation hole under its own propulsion force. Driven by the ground high-pressure pump, the injection needle advances along the water jet through the perforation hole to break the rock.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] During construction, this invention first uses a perforating gun to create a preliminary channel within the casing. Then, the tubing is lowered, causing the central tube to move downwards, which in turn moves the jetting needle downwards to align with the initial channel formed by the perforation. Finally, a high-pressure pump pressurizes the system, and the needle drills along the jet stream from the borehole. This technology not only effectively perforates the casing and improves drilling efficiency but also increases the water jet extension limit, enabling the connection of different reservoirs.

[0035] This invention combines perforation ejection drilling with hydraulic jet drilling to achieve a drilling process of perforation first and then jetting, avoiding the problem of cutting the casing wall, improving the drilling efficiency, and making multi-branch fishbone well technology applicable to casing wells. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of a fixed-distance directional sliding device in this invention;

[0037] Figure 2This is a schematic diagram of a fishbone-shaped well completion string provided by the present invention;

[0038] Figure 3 This is a diagram showing the assembly structure of the injection needle tube on the lower oil pipe;

[0039] Figure 4 This is a schematic diagram of a self-priming nozzle.

[0040] In the picture,

[0041] 1. Orientation and spacing sliding device; 101. Sliding sleeve; 102. Guide sliding pin; 103. Sliding groove.

[0042] 104. Central tube,

[0043] 2. Spray needle tube,

[0044] 3. Perforation gun,

[0045] 4. Hole track,

[0046] 5. Self-feeding nozzle, 501. Housing, 502. Rear nozzle, 503. Forward nozzle. Detailed Implementation

[0047] The present invention will now be described in further detail with reference to the accompanying drawings:

[0048] The main idea of ​​this invention is to combine perforation jet drilling with water jet drilling to achieve a perforation-first, jet-later drilling process. During construction, a perforating gun is first used to create a preliminary channel within the casing. Then, the tubing is lowered, causing the central tube to move downwards, which in turn moves the jetting needle downwards to align with the initial channel formed by the perforation. Finally, a high-pressure pump pressurizes the system, and the needle drills along the jet stream from the perforation hole. This technology not only effectively perforates the casing and improves drilling efficiency but also increases the water jet extension limit, enabling the connection of different reservoirs.

[0049]

Example 1

[0050] This embodiment provides a fixed-distance directional sliding device, such as... Figure 1 As shown, the device includes a central tube 104. The outer wall of the central tube 104 is provided with multiple sliding grooves 103 parallel to the central axis. Preferably, four sliding grooves 103 are evenly arranged along the outer wall of the central tube 104. A sliding sleeve 101 is fitted onto the central tube 104. Multiple guide sliding pins 102 are arranged circumferentially on the sliding sleeve 101, and the guide sliding pins 102 are located at the positions of the sliding grooves 103. The guide sliding pins 102 cooperate with the sliding grooves 103 and can be used to restrict the vertical movement of the central tube 104.

[0051] The sliding sleeve 101 is fitted onto the outer wall of the central tube 104 and fixed by the guide sliding pin 102. The guide sliding pin 102 serves as a limit, restricting the vertical movement of the central tube 104 within the length of the sliding groove 103. Specifically, the limiting function of the guide sliding pin 102 is as follows: when the central tube 104 moves up or down to the upper or lower end of the sliding groove 103, the guide limiting pin 102 is blocked by the sliding groove 103, thus restricting its movement. The guide sliding pin 102 also serves as a guide because it is positioned within the sliding groove, allowing the central tube 104 to move vertically but not rotate.

[0052] The outer walls of both the upper and lower ends of the central tube 104 are provided with external threads, so that the upper and lower ends of the central tube 104 are respectively connected to the oil pipe through the threads.

[0053] Both ends of the sliding sleeve 103 are provided with external threads to facilitate the threaded connection between the sliding sleeve 101 and the tubing anchor. During assembly, the central tube 104 is connected to the tubing via threads, and then the tubing anchor is placed over the tubing. The sliding sleeve 101 is threadedly connected to the tubing anchor. By rotating the tubing, the tubing anchor is opened and anchored to the casing wall, thus fixing the sliding sleeve to the casing. A guide sliding pin 102 is fixed on the sliding sleeve 101. The guide sliding pin 102 cooperates with the sliding groove 103 to restrict the vertical movement of the central tube 104. The sliding sleeve 101 is located at the bottom of the sliding groove 103, so that the downward movement of the tubing causes the central tube 104 to move downward, ensuring that the central tube 104 can only move downward a certain distance, which is the length of the sliding groove 103.

[0054]

Example 2

[0055] This embodiment provides a fishbone-shaped well completion string, such as... Figure 2 As shown, the device includes a casing, and inside the casing, from bottom to top, are arranged a lower oil pipe, the fixed-distance directional sliding device 1 described in Example 1, and an upper oil pipe. Inside the lower oil pipe, from bottom to top, are arranged a perforating gun 3 and a jet needle tube 2. The bottom of the lower oil pipe is plugged.

[0056] Among them, the central tube 104 of the fixed-distance directional sliding device 1 is connected to the bottom of the upper oil pipe by a thread and to the top of the lower oil pipe by a thread.

[0057] An oil pipe anchor is fitted onto the lower oil pipe. The oil pipe anchor is connected to the sliding sleeve 101 by a thread. By rotating the upper oil pipe, the central pipe 104 and the sliding groove 103 are rotated, which in turn drives the sliding sleeve 101 and the guide sliding pin 102 to rotate. This causes the oil pipe anchor to rotate, opening and anchoring it to the casing wall, thus fixing the sliding sleeve to the casing. At this time, the central pipe 104 can move up and down.

[0058] The injection needle tubes 2 are arranged in 16 to 20 units on the lower oil pipe. Preferably, 4 to 5 rows of injection needle tubes 2 are arranged axially on the lower oil pipe, and 3 to 4 injection needle tubes 2 are evenly arranged in each row on the radial cross section of the lower oil pipe. Correspondingly, 4 to 5 perforating guns 3 are arranged axially on the lower oil pipe, and 3 to 4 perforating projectiles are evenly arranged in the radial cross section of each perforating gun 3. The distance between two adjacent perforating guns 3 is the same as the distance between two adjacent rows of injection needle tubes 2.

[0059] Preferably, the perforating gun 3 is installed within a range of 20m-30m from the bottom of the lower oil pipe, and the injection needle tubes 2 are installed on the perforating gun 3 within a range of 10m-20m. Note that the perforating bullets and the orifices of the injection needle tubes 2 should be precisely installed in the same orientation on the ground. Specifically, the number of perforations is the same as the number of injection needle tubes and corresponds one-to-one. One perforating gun contains 3 to 4 perforating bullets, and the number of perforating bullets is the same as the number of injection needle tubes, because the perforating bullets form the perforation holes, and the injection needle tubes drill along the perforation holes.

[0060] Among them, the vertical distance between the injection needle tube 2 and the corresponding perforation gun 3 is not greater than the length of the sliding groove. For example, counting from bottom to top, the vertical distance between the first row of injection needle tubes 2 and the first injection gun 3 is not greater than the length of the sliding groove, the vertical distance between the second row of injection needle tubes 2 and the second injection gun 3 is not greater than the length of the sliding groove, and so on. Since the downward movement distance of the center tube is at most the length of the sliding groove (when the sliding sleeve 101 is located at the lower end of the sliding groove), the length of the sliding groove 103 should be greater than or equal to the distance between the injection needle tube 2 and the perforation hole. This ensures that the downward movement of the center tube drives the injection needle tube 2 to move downward and automatically aligns with the blast hole generated by the perforation.

[0061] During construction, a perforating gun 3 is first used to create a preliminary channel within the casing. Then, the tubing is lowered, causing the central tube 104 to move downwards, which in turn moves the jetting needle 2 downwards to align with the initial channel created by the perforation. Finally, a high-pressure pump is used to pressurize the system, and the jetting needle 2 drills along the jet stream from the borehole. This technology not only effectively perforates the casing and improves drilling efficiency but also increases the water jet extension limit, enabling the connection of different reservoirs.

[0062]

Example 3

[0063] like Figure 3 As shown, the injection needle tube 2 is installed on the lower oil pipe through the orifice slide 4. Specifically, a through mounting hole is provided on the side wall of the lower oil pipe, the orifice slide 4 is installed in the mounting hole, one end of the injection needle tube 2 is inserted into the orifice slide 4 and a self-propelled nozzle 5 is installed at its end, and the other end of the injection needle tube 2 is located in the inner cavity of the lower oil pipe. Liquid is pumped into the lower oil pipe from the ground by a pump truck. Driven by the high-pressure liquid, the injection needle tube breaks the rock and drills under the action of the self-propelled nozzle, gradually extending to form a jet channel.

[0064] like Figure 4 As shown, the self-propelled nozzle 5 includes a housing 501, which is a trumpet-shaped structure. The smaller opening end of the housing 501 is connected to the end of the needle tube, and a backward nozzle 502 is installed inside the smaller opening end of the housing 501. The backward nozzle 502 is inclined from the side wall of the housing towards the axis, and the angle between the backward nozzle 502 and the axis of the housing is 30-45°. A forward nozzle 503 is installed inside the larger opening end of the housing 501, and the forward nozzle 503 is parallel to the axis of the housing 501. When there is pressure buildup in the downhole tubing, the pressure is transmitted from the injection needle tube 2 to the self-propelled nozzle 5. The self-propelled nozzle 5 breaks the rock through the forward nozzle 503, and the backward nozzle 502 propels it forward continuously. The injection needle tube 2, driven by the self-propelled nozzle 5, breaks the rock and drills along the orifice slide, extending to form a jet channel.

[0065] The needle tube and self-feeding nozzle in this invention can also be based on existing technologies, as long as they can achieve their functions. For details, please refer to existing published literature, which will not be elaborated here.

[0066]

Example 4

[0067] This embodiment provides a fishbone-style well completion construction method, which specifically includes the following steps:

[0068] Step 1: First, install the perforating gun and the injection needle tube inside the lower oil pipe. Connect the two ends of the central tube of the fixed-distance and directional sliding device to the upper oil pipe and the lower oil pipe respectively, and anchor the oil pipe onto the lower oil pipe and connect it to the sliding sleeve of the fixed-distance and directional sliding device through threads; plug the bottom of the lower oil pipe.

[0069] Preferably, 16 to 20 injection needle tubes 2 are arranged on the lower oil pipe. More preferably, 4 to 5 rows of injection needle tubes 2 are arranged axially on the lower oil pipe, and each row of injection needle tubes has 3 to 4 tubes evenly arranged on the radial cross section of the lower oil pipe. Correspondingly, 4 to 5 perforating guns are arranged axially on the lower oil pipe, and each perforating gun has 3 to 4 perforating projectiles evenly arranged on its radial cross section. The distance between two adjacent perforating guns is the same as the distance between two adjacent rows of injection needle tubes.

[0070] Preferably, the perforating gun is installed within a range of 20m-30m from the bottom of the lower oil pipe, and the injection needles are installed on the perforating gun within a range of 10m-20m. It is important to ensure that the perforating bullets and the injection needle orifices are precisely installed in the same orientation on the ground. Specifically, the number of perforations is the same as the number of injection needles and they correspond one-to-one. One perforating gun contains 3 to 4 perforating bullets, and the number of perforating bullets is the same as the number of injection needles, because the perforating bullets form the perforation holes, and the injection needles drill along the perforation holes.

[0071] Among them, the vertical distance between the injection needle tube 2 and the corresponding perforating gun 3 is not greater than the length of the sliding groove 103. For example, counting from bottom to top, the vertical distance between the first row of injection needle tubes and the first injection gun is not greater than the length of the sliding groove, the vertical distance between the second row of injection needle tubes and the second injection gun is not greater than the length of the sliding groove, and so on. Since the downward movement distance of the center tube is at most the length of the sliding groove (when the sliding sleeve is located at the lower end of the sliding groove), the length of the sliding groove should be greater than or equal to the distance between the injection needle tube and the perforation hole. This ensures that the downward movement of the center tube drives the needle tube orifice to move downward and automatically align with the blast hole generated by the perforation.

[0072] Step 2: Lower the assembled tubing from Step 1 into the casing, rotate the upper tubing to rotate the tubing anchor so that the tubing anchor opens and anchors to the casing wall, and fix the sliding sleeve to the casing.

[0073] Step 3: By pressurizing inside the pipe, a perforation gun is used to create perforation holes on the casing.

[0074] Step 4: Lower the oil pipe. The central tube can move downward along the sliding groove in a directional and fixed distance. However, the central tube cannot rotate during translation to ensure that the orientation remains unchanged during sliding. The downward movement of the central tube drives the injection needle tube to move downward to the position aligned with the perforation hole.

[0075] Step 5: The ground pump truck pressurizes the oil pipe, and the high-pressure fluid is jetted through the injection needle. The injection needle automatically enters the perforation hole under its own propulsion force. Driven by the ground high-pressure pump, the injection needle advances along the water jet through the perforation hole to break the rock.

[0076] This invention combines perforation ejection drilling with hydraulic jet drilling to achieve a drilling process of perforation first and then jetting, avoiding the problem of cutting the casing wall, improving the drilling efficiency, and making multi-branch fishbone well technology applicable to casing wells.

[0077] In the description of this invention, 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 this invention according to the specific circumstances.

[0078] In the description of this invention, unless otherwise stated, the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0079] The above technical solution is only one embodiment of the present invention. For those skilled in the art, based on the principles disclosed in the present invention, it is easy to make various types of improvements or modifications, and not limited to the technical solutions described in the specific embodiments of the present invention. Therefore, the foregoing description is only a preferred option and is not restrictive.

Claims

1. A fishbone-shaped well completion string, characterized in that, The casing includes a lower oil pipe, a fixed-distance and directional sliding device, and an upper oil pipe arranged sequentially from bottom to top inside the casing. A perforating gun and a jet needle are arranged sequentially from bottom to top inside the lower oil pipe, and the bottom of the lower oil pipe is blocked. The fixed-distance directional sliding device includes a central tube, and multiple sliding grooves parallel to the central axis are provided on the outer wall of the central tube. A sliding sleeve is fitted on the outer wall of the central tube, and multiple guide sliding pins are provided on the sliding sleeve along the circumferential direction, and the guide sliding pins are located at the position of the sliding grooves. The two ends of the central tube are connected to the upper oil pipe and the lower oil pipe, respectively. An oil pipe anchor is sleeved on the lower oil pipe and the oil pipe anchor is connected to the sliding sleeve.

2. The fishbone completion string according to claim 1, characterized in that, The central tube is threaded to the bottom of the upper oil pipe and threaded to the top of the lower oil pipe.

3. The fishbone completion string according to claim 1, characterized in that, The tubing anchor and the sliding sleeve are connected by threads. By rotating the upper tubing, the central tube and the sliding groove are rotated, which in turn rotates the sliding sleeve and the guide sliding pin, causing the tubing anchor to rotate so that the tubing anchor opens and anchors to the casing wall, thus fixing the sliding sleeve to the casing.

4. The fishbone completion string according to claim 1, characterized in that, Four to five rows of injection needle tubes are arranged axially on the lower oil pipe, and three to four injection needle tubes are evenly arranged in each row on the radial section of the lower oil pipe. Correspondingly, four to five perforating guns are arranged axially on the lower oil pipe, and three to four perforating projectiles are evenly arranged in the radial section of each perforating gun.

5. The fishbone completion string according to claim 4, characterized in that, The distance between two adjacent perforating guns is the same as the distance between two adjacent rows of injection needles.

6. The fishbone completion string according to claim 4, characterized in that, The vertical distance between the injection needle tube and the corresponding perforating gun is not greater than the length of the sliding groove.

7. The fishbone completion string according to claim 1, characterized in that, The injection needle is mounted on the lower oil pipe via an orifice slide. A through mounting hole is provided on the side wall of the lower oil pipe, and an orifice slide is set in the mounting hole. One end of the injection needle is inserted into the orifice slide and a self-feeding nozzle is set at its end. The other end of the injection needle is located in the inner cavity of the lower oil pipe.

8. A method for well completion using a fishbone-shaped beam, characterized in that, Specifically, the following steps are included: Step 1: First, install the perforating gun and the injection needle tube inside the lower oil pipe. Connect the two ends of the central tube of the fixed-distance and directional sliding device to the upper oil pipe and the lower oil pipe respectively, and anchor the oil pipe onto the lower oil pipe and connect it to the sliding sleeve of the fixed-distance and directional sliding device through threads. Step 2: Lower the assembled tubing from Step 1 into the casing, rotate the upper tubing to rotate the tubing anchor so that the tubing anchor opens and anchors to the casing wall, and fix the sliding sleeve to the casing. Step 3: By pressurizing inside the pipe, a perforation gun is used to create perforation holes on the casing. Step 4: Lower the oil pipe. The central tube moves downward along the sliding groove in a directional and fixed distance. However, the central tube cannot rotate during the translation to ensure that the orientation remains unchanged during sliding. The downward movement of the central tube drives the injection needle tube to move downward until it is aligned with the position of the perforation hole. Step 5: The ground pump truck pressurizes the oil pipe, and the high-pressure fluid is jetted through the injection needle. The injection needle automatically enters the perforation hole under its own propulsion force. Driven by the ground high-pressure pump, the injection needle advances along the water jet through the perforation hole to break the rock.

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