A volumetric fracturing string assembly

Abstract

The application provides a volume fracturing pipe column assembly, which comprises a first pipe body and a volume fracturing pipe column; the volume fracturing pipe column is accommodated in the pipe cavity of the first pipe body; the outer peripheral wall of a first injection valve is provided with a first valve port; the outer peripheral wall of the first injection valve is sleeved with a first connecting ring, a first spring and a first sleeve ring; the first sleeve ring covers the first valve port and forms a first sealing space together with the outer peripheral wall of the first injection valve; the first sealing space is communicated with the first valve port; the first spring is sleeved with the outer peripheral wall of the first injection valve and elastically abuts against the first connecting ring and the first sleeve ring; at this time, the first sleeve ring continuously covers the first valve port under the elastic action of the first spring and maintains the first sealing space, and the first valve port is in a closed state; fracturing fluid enters the first valve port along a flow channel and is injected into the first sealing space; the fracturing fluid in the first sealing space expands the first sleeve ring upward and overcomes the elastic force of the first spring on the first sleeve ring to lift the first sleeve ring upward.

Description

Technical Field

[0001] This application belongs to the technical field of volumetric fracturing tubing, and particularly relates to a volumetric fracturing tubing assembly. Background Technology

[0002] With the development of technology, tubing strings have been gradually applied in petroleum engineering. The tubing string is a channel that passes through the formation and is positioned at a certain location in the channel. At this time, the tubing string is filled with fracturing fluid, and the flow rate of the fracturing fluid is controlled by a throttle device. The throttle device throttles and reduces the flow rate of the fracturing fluid. Therefore, the fracturing fluid is throttled before it is injected outward along the valve port of the tubing string, and the flow rate of the fracturing fluid is controlled to reach the preset flow rate. At this time, the flow rate of the fracturing fluid is controlled by the throttle device, so that the fracturing fluid can only enter the tubing string when the flow rate of the fracturing fluid meets the preset flow rate range. Summary of the Invention

[0003] This application provides a volumetric fracturing tubing assembly to address the problem that the flow rate of fracturing fluid in a volumetric fracturing tubing is controlled by a flow throttle.

[0004] In a first aspect, embodiments of this application provide a volumetric fracturing tubing assembly, comprising:

[0005] The first pipe body penetrates the stratum vertically and has a cavity; the outer surface of the first pipe body is attached to the stratum.

[0006] A volumetric fracturing string is housed within the cavity and penetrates the cavity under external force. The volumetric fracturing string includes a string body, a first injection valve, a second injection valve, and a first expansion separator. The first injection valve, the first expansion separator, and the second injection valve are connected to the string body and arranged sequentially from bottom to top. The string body has a flow channel through which the first injection valve, the second injection valve, and the first expansion separator pass.

[0007] The first injection valve has a first valve port on its outer peripheral wall. A first connecting ring, a first spring, and a first collar are sleeved on the outer peripheral wall of the first injection valve. The first collar is arranged relative to the first valve port, covering the first valve port and forming a first sealing space with the outer peripheral wall of the first injection valve. The first sealing space is connected to the first valve port. The first spring is sleeved on the outer peripheral wall of the first injection valve and elastically abuts against the first connecting ring and the first collar. At this time, the first collar continuously covers the first valve port under the elastic action of the first spring and maintains the first sealing space. The first valve port is in a closed state.

[0008] The fracturing fluid enters the first valve port along the flow channel and is sprayed into the first sealed space. The fracturing fluid in the first sealed space expands upward to open the first collar and overcomes the elastic force of the first spring on the first collar to push the first collar upward. At this time, the first valve port is adjusted from the closed state to the open state, allowing the fracturing fluid entering through the flow channel to be sprayed into the formation.

[0009] Optionally, the first collar is movably fitted onto the outer peripheral wall of the first injection valve; the end of the first collar facing away from the first spring is provided with a first conical surface; the outer peripheral wall of the tubular body is provided with a second conical surface.

[0010] Optionally, the first conical surface seals against the second conical surface under the elastic force of the first spring, and the first sealing space is formed between the first collar, the outer peripheral wall of the tubular body and the outer peripheral wall of the first injection valve. The first sealing space is connected to the first valve port and the first valve port is the only opening in the first sealing space.

[0011] Optionally, the first collar is provided with a first annular groove and a first sealing ring. The first sealing ring is disposed between the first collar and the outer peripheral wall of the first injection valve and is sealed within the first annular groove.

[0012] The first annular groove is disposed on the upper side of the first sealed space, and the first sealing ring sleeved in the first annular groove blocks the fracturing fluid sprayed upward from the first sealed space.

[0013] Optionally, the first collar is provided with a second annular groove and a second sealing ring. The second sealing ring is disposed between the first collar and the outer peripheral wall of the first injection valve and is sealed within the first annular groove.

[0014] Optionally, the second annular groove is disposed on the side of the first annular groove facing away from the first sealing space, and is spaced apart from the first annular groove; the second sealing ring and the first sealing ring enclose a secondary sealing space, which is located above the sealing space.

[0015] Optionally, the first connecting ring is sleeved on the outer peripheral wall of the first injection valve, and the inner wall of the first connecting ring is threaded to the outer peripheral wall of the first injection valve. Under the action of external force, it rotates relative to the outer peripheral wall of the first injection valve to adjust the position of the first connecting ring and adjust the resistance force of the first connecting ring against the first spring.

[0016] Optionally, when the fracturing fluid does not enter the first valve port, the first collar moves downward under the elastic force of the first spring and blocks the first valve port, thus adjusting the first valve port from the open state to the closed state.

[0017] Optionally, the second injection valve is disposed above the first injection valve;

[0018] Optionally, the outer peripheral wall of the second injection valve is provided with a second valve port. The outer peripheral wall of the second injection valve is fitted with a second connecting ring, a second spring, and a second sleeve ring. The second sleeve ring is arranged relative to the second valve port, covering the second valve port and forming a second sealing space with the outer peripheral wall of the second injection valve. The second sealing space is connected to the second valve port. The second spring is sleeved on the outer peripheral wall of the second injection valve and elastically abuts against the second connecting ring and the second sleeve ring. At this time, the second sleeve ring continuously covers the second valve port under the elastic action of the second spring and maintains the second sealing space. The second valve port is in a closed state.

[0019] Optionally, the inner peripheral wall of the second injection valve is connected to a first sliding sleeve, which is movably connected to the inner peripheral wall of the second injection valve and covers the second valve port; the upper surface of the first sliding sleeve is provided with a first support portion, which is used to support the first ball entering through the flow channel. Under the impact of the first ball, the first sliding sleeve moves downward and separates from the first ball from the second valve port. At this time, the second valve port is in a through state, and the fracturing fluid entering through the flow channel is sprayed into the second sealed space through the second valve port.

[0020] Optionally, the first ball seals against the first sliding sleeve and, together with the first sliding sleeve, blocks the flow path between the second injection valve and the first injection valve;

[0021] The first expansion separator is located between the second injection valve and the first injection valve, and above the first sliding sleeve; the fracturing fluid entering through the flow channel is delivered to the top of the first sliding sleeve and passes through the groove on the inner wall of the first expansion separator to expand the first expansion separator. At this time, the first expansion separator is adjusted from a contracted state to an expanded state and is in sealing contact with the inner wall of the lumen to separate the external space of the second injection valve and the external space of the first injection valve.

[0022] Optionally, the volumetric fracturing string further includes a second expansion separator, which is located above the first expansion separator and is positioned on both sides of the second injection valve.

[0023] The second expansion separator in the expanded state and the first expansion separator in the expanded state form a metering space for storing a metered amount of fracturing fluid.

[0024] Optionally, the volumetric fracturing string further includes a pressure relief valve and a second sliding sleeve. The pressure relief valve is disposed on the side of the second expansion separator opposite to the second injection valve. The outer peripheral wall of the pressure relief valve is provided with a third valve port. The second sliding sleeve is movably sleeved on the inner side wall of the pressure relief valve and covers the third valve port.

[0025] The second sliding sleeve is provided with a second supporting part, which is used to support the second ball entering through the flow channel. The second sliding sleeve moves downward under the impact of the second ball and separates from the third valve port. At this time, the third valve port is in a through state. The fracturing fluid entering through the flow channel is sprayed to the outside of the pressure relief valve through the third valve port and the fracturing fluid is discharged. At this time, the second expansion separator in the expansion state and the first expansion separator in the expansion state gradually contract.

[0026] Optionally, the volumetric fracturing string further includes an anchor body, which is connected to the main body of the string and retracts inward under the action of rotation or lifting, so that the anchor claw of the anchor body disengages from the first string body.

[0027] This application provides a volumetric fracturing tubing assembly in which fracturing fluid enters along a flow channel to a first valve port and is injected into a first sealed space. The fracturing fluid in the first sealed space expands upwards, pushing against the elastic force of a first spring on the first sleeve. At this point, the first valve port changes from a closed state to an open state, allowing the fracturing fluid entering through the flow channel to be injected into the formation. In this case, the fracturing fluid does not need to be regulated by a flow throttle, and its flow rate does not need to be limited; it only needs to overcome the elastic force of the first spring on the first sleeve. The first sleeve ring is lifted upward within the first sealed space to adjust the opening state of the first valve port. This allows fracturing fluid to be injected into the formation through the open valve port for volumetric fracturing without affecting the flow rate of the fracturing fluid into the flow channel. When the fracturing fluid does not enter the first valve port, the first sleeve ring moves downward under the elastic force of the first spring and blocks the first valve port, adjusting it from the open state to the closed state. The first sleeve ring also prevents external debris from entering the first valve port, thus providing external protection for the first valve port. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings. In the following description, the same reference numerals denote the same parts.

[0030] Figure 1 This is a schematic diagram showing the opening of the first valve port of a volumetric fracturing tubing assembly provided in an embodiment of this application.

[0031] Figure 2 This is a schematic diagram showing the opening of the second valve port of a volumetric fracturing tubing assembly provided in an embodiment of this application.

[0032] Figure 3 This is a schematic diagram showing the opening of the third valve port of a volumetric fracturing tubing assembly provided in an embodiment of this application.

[0033] Figure 4 This is a schematic diagram of the first injection valve of a volumetric fracturing tubing assembly provided in an embodiment of this application.

[0034] Figure 5 Figure 4 A magnified view of a section in direction A.

[0035] Figure 6 This is a schematic diagram showing the opening of the second injection valve of a volumetric fracturing tubing assembly provided in an embodiment of this application.

[0036] Figure 7 Figure 6 A magnified view of the area along the B-axis.

[0037] Figure 8 This is a schematic diagram of a pressure relief valve for a volumetric fracturing tubing assembly provided in an embodiment of this application.

[0038] Figure 9 This is a schematic diagram of the anchor body of a volumetric fracturing tubing assembly provided in an embodiment of this application. Detailed Implementation

[0039] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0040] This application provides a volumetric fracturing tubing assembly to address the problem that the flow rate of fracturing fluid in existing volumetric fracturing tubing is controlled by a flow throttle.

[0041] refer to Figures 1 to 9 This application provides a volumetric fracturing tubing assembly, which includes a first tubing body 10 and a volumetric fracturing tubing 20.

[0042] The first tube 10 penetrates the formation vertically and has a cavity 11. The outer surface of the first tube 10 is attached to the formation and is sealed to the formation. At this time, the first tube 10 provides lateral support to the formation and maintains the vertical state of the first tube 10 so that the volumetric fracturing string 20 can enter the bottom layer along the first tube 10.

[0043] The volumetric fracturing string 20 is housed in the lumen 11 and penetrates the lumen 11 under the action of external force. At this time, the volumetric fracturing string 20 enters the lumen 11 and enters the formation along the lumen 11. Optionally, the external force can be gravity.

[0044] The volumetric fracturing string 20 includes a string body 21, a first injection valve 22, a second injection valve 23, and a first expansion separator 24. The first injection valve 22, the first expansion separator 24, and the second injection valve 23 are connected to the string body 21 and are arranged sequentially from bottom to top.

[0045] The tubing string body 21 is provided with a flow channel through which a first injection valve 22, a second injection valve 23, and a first expansion separator 24 pass. The flow channel is used to supply fracturing fluid and passes through the first injection valve 22, the first expansion separator 24, and the second injection valve 23. The first expansion separator 24 is located between the first injection valve 22 and the second injection valve 23.

[0046] The outer peripheral wall of the first injection valve 22 is provided with a first valve port 221. The outer peripheral wall of the first injection valve 22 is fitted with a first connecting ring 222, a first spring 223 and a first collar 224. The first collar 224 is arranged relative to the first valve port 221, covers the first valve port 221, and forms a first sealing space 22a with the outer peripheral wall of the first injection valve 22. The first sealing space 22a is connected to the first valve port 221.

[0047] At this time, the first sleeve ring 224 is provided with a groove, which is arranged relative to the first valve port 221 and is sealed to the first valve port 221. A first sealing space 22a is formed between the groove and the first valve port 221, and the first sleeve ring 224 is sealed to the outer peripheral wall of the first injection valve 22, so that the first sleeve ring 224 can block the first valve port 221 in the initial state and form a switch for fracturing fluid to be injected outward through the valve port without the need for the control of the flow throttle and the need to control the flow rate of the fracturing fluid. At this time, the reason for the flow control is that it is hoped that a sufficient pressure difference will be generated on both sides of the flow throttle so that the packer can be sealed (the expansion packer requires the internal pressure to be greater than the external pressure to achieve a seal).

[0048] The first spring 223 is sleeved on the outer peripheral wall of the first injection valve 22 and elastically abuts against the first connecting ring 222 and the first collar 224. At this time, the first collar 224 continuously covers the first valve port 221 under the elastic action of the first spring 223 and maintains the first sealing space 22a. The first valve port 221 is in the closed state. At this time, the first collar 224 is sealed to the outer peripheral wall of the first injection valve 22 under the action of elastic force, and the sealing effect is good. At this time, the fracturing fluid enters the first sealing space 22a from the first valve port 221 and acts upward on the first collar 224. Only when the force of the fracturing fluid on the first collar 224 is greater than the force of the first spring 223 on the first collar 224 can the fracturing fluid expand upward on the first collar 224 in the first sealing space 22a. The force exerted by the first spring 223 on the first ring 224 is greater than the force exerted by the first spring 223 on the first ring 224, which serves as the opening factor for the first ring 224. This eliminates the need to separately control the flow rate of the fracturing fluid, avoids the application of a flow throttle, improves the accuracy and effectiveness of the volume fracturing string 20, and ensures that the flow rate of the fracturing fluid is not lost.

[0049] The fracturing fluid enters the first valve port 221 along the flow channel and is sprayed into the first sealed space 22a; the fracturing fluid in the first sealed space 22a expands upward to open the first collar 224 and overcomes the first spring 223's pressure on the first collar 224. The elastic force of the first spring 223 pushes the first collar 224 upward, at which point the first valve port 221 changes from a closed state to an open state, allowing fracturing fluid entering through the flow channel to be injected into the formation. At this time, the fracturing fluid does not need to be regulated by a throttle, nor does its flow rate need to be limited. It only needs to overcome the elastic force of the first spring 223 on the first collar 224, and by pushing the first collar 224 upward within the first sealed space 22a, the opening state of the first valve port 221 can be adjusted. This facilitates the injection of fracturing fluid through the open first valve port 221 into the formation for volumetric fracturing, without affecting the flow rate of the fracturing fluid entering the flow channel. Furthermore, when the fracturing fluid does not enter the first valve port 221, the first collar 224 is... Under the action of elastic force, it moves downward and blocks the first valve port 221, adjusting the first valve port 221 from the open state to the closed state, and blocking external debris from entering the first valve port 221 through the first collar 224, thereby achieving external protection of the first valve port 221.

[0050] The first ring 224 is movably sleeved on the outer peripheral wall of the first injection valve 22 and moves along the central axis of the first injection valve 22 to move relative to the first valve port 221, thereby realizing the opening or closing of the first valve port 221.

[0051] The first ring 224 has a first conical surface 2241 at the end facing away from the first spring 223; the outer peripheral wall of the tubing body 21 has a second conical surface 211. At this time, the first conical surface 2241 and the second conical surface 211 are in contact, and the first conical surface 2241 seals against the second conical surface 211 under the elastic force of the first spring 223. The contact between the first conical surface 2241 and the second conical surface 211 ensures the sealing of the first sealing space 22a. The conical surface fit reduces the gap between the mating surfaces, ensuring the sealing of the first sealing space 22a as much as possible, and can also better withstand the impact of fracturing fluid on the first ring 224. At this time, the first ring 224 can prevent the fracturing fluid from being directly sprayed onto the casing, reducing the erosion of the casing.

[0052] The first sealing space 22a is formed by the outer peripheral wall of the first ring 224, the tubing body 21, and the outer peripheral wall of the first injection valve 22. The first sealing space 22a is connected to the first valve port 221, and the first valve port 221 is the only opening in the first sealing space 22a. At this time, the fracturing fluid can only enter the first sealing space 22a along the first valve port 221. As the first valve port 221 is the only opening in the first sealing space 22a, the complete sealing of the first sealing space 22a is ensured, and the loss of fracturing fluid in the first sealing space 22a is reduced.

[0053] The first sleeve ring 224 is provided with a first annular groove 2241 and a first sealing ring 2242. The first sealing ring 2242 is disposed between the first sleeve ring 224 and the outer peripheral wall of the first injection valve 22, and is sealed within the first annular groove 2241. The first annular groove 2241 is disposed on the upper side of the first sealed space 22a. The first sealing ring 2242 disposed within the first annular groove 2241 blocks the fracturing fluid sprayed upward from the first sealed space 22a. At this time, the first sealing ring 2242 disposed within the first annular groove 2241 acts as the first barrier wall of the first sealed space 22a, and blocks the fracturing fluid in the first sealed space 22a from seeping into the first sleeve ring 224. The loss of fracturing fluid ensures the impact of fracturing fluid on the first sleeve ring 224 and maintains the sealing performance of the first sealed space 22a.

[0054] In addition, the first sleeve ring 224 is provided with a second annular groove 2243 and a second sealing ring 2244. The second sealing ring 2244 is disposed between the outer peripheral wall of the first sleeve ring 224 and the first injection valve 22, and is sealed within the first annular groove 2241. The second annular groove 2243 is disposed on the side of the first annular groove 2241 facing away from the first sealing space 22a, and is spaced apart from the first annular groove 2241. The second sealing ring 2244 and the first sealing ring enclose a secondary sealing space 2244a, which is located on the upper side of the sealing space.

[0055] At this time, the second sealing ring 2244 and the first sealing ring form a secondary sealing space 2244a. This secondary sealing space 2244a serves as a secondary sealing space 2244a of the first sealing space 22a, further ensuring that the fracturing fluid in the first sealing space 22a blocks the seepage of the first ring 224. It can also serve as a second protective space after the first sealing ring 2242, greatly ensuring the all-round output of fracturing fluid to the first ring 224.

[0056] The first connecting ring 222 is sleeved on the outer peripheral wall of the first injection valve 22. The inner wall of the first connecting ring 222 is threaded to the outer peripheral wall of the first injection valve 22. Under the action of external force, it rotates relative to the outer peripheral wall of the first injection valve 22 to adjust the position of the first connecting ring 222 and the resistance force of the first connecting ring 222 against the first spring 223. At this time, the first connecting ring 222 is threaded relative to the outer peripheral wall of the first injection valve 22 under external action, and the position of the first connecting ring 222 relative to the outer peripheral wall of the first injection valve 22 is adjusted. At this time, the first connecting ring 222 pre-compresses the first spring 223 at different positions and adjusts the resistance force of the first spring 223 to adjust the force of the first spring 223 against the first sleeve ring 224. Therefore, the sealing force of the first sleeve ring 224 relative to the outer peripheral wall of the first injection valve 22 is achieved, so that the corresponding first sleeve ring 224 can be opened by fracturing fluid with different impact forces. Conversely, it controls the fracturing fluid pressure in the oil sleeve and simplifies the flow control of fracturing fluid.

[0057] When the fracturing fluid does not enter the first valve port 221 or when injection stops, the first collar 224 moves downward under the elastic force of the first spring 223 and blocks the first valve port 221. The first valve port 221 is adjusted from the open state to the closed state. At this time, the fracturing fluid in the first sealed space 22a does not impact the first collar 224 and does not apply sufficient upward force to the first collar 224. The upward force applied by the fracturing fluid to the first collar 224 is less than the elastic force of the first spring 223 on the first collar 224. The first collar 224, driven by the first spring 223, adheres to the outer peripheral wall of the first injection valve 22 and maintains the sealed fit of the first conical surface 2241 and the second conical surface 211, thus maintaining the first sealed space 22a. This achieves automatic closure of the first collar 224 relative to the first valve port 221 without the need for additional closure control.

[0058] Furthermore, a second injection valve 23 is disposed above the first injection valve 22. The outer peripheral wall of the second injection valve 23 has a second valve port 231. A second connecting ring 232, a second spring 233, and a second sleeve ring 234 are fitted onto the outer peripheral wall of the second injection valve 23. The second sleeve ring 234 is arranged relative to the second valve port 231, covering the second valve port 231 and forming a second sealing space 23a with the outer peripheral wall of the second injection valve 23. The second sealing space 23a communicates with the second valve port 231. The second spring 233 is sleeved on the outer peripheral wall of the second injection valve 23 and elastically abuts against the second connecting ring 232 and the second sleeve ring 234. At this time, under the elastic action of the second spring 233, the second sleeve ring 234 continuously covers the second valve port 231 and maintains the second sealing space 23a, keeping the second valve port 231 closed. The function of the second sleeve ring 234 and the second injection valve 23 is the same as the function of the first sleeve ring 224 and the first injection valve 22.

[0059] The difference is that the inner peripheral wall of the second injection valve 23 is connected to a first sliding sleeve 235. The first sliding sleeve 235 is movably connected to the inner peripheral wall of the second injection valve 23 and covers the second valve port 231. The upper surface of the first sliding sleeve 235 is provided with a first support portion 236, which is used to support the first ball 237 entering through the flow channel. Under the impact of the first ball 237, the first sliding sleeve 235 moves downward and separates from the first ball 237 from the second valve port 231. At this time, the second valve port 231 is in a through state, and the fracturing fluid entering through the flow channel is sprayed into the second sealed space 23a through the second valve port 231.

[0060] In this process, the first ball 237 impacts the first sliding sleeve 235, causing the first sliding sleeve 235 to disengage from the second valve port 231. This allows the second valve port 231 to be adjusted from a covered state to a through state, enabling the fracturing fluid to enter the second sealed space 23a along the second valve port 231. Meanwhile, the first ball 237 blocks the first sliding sleeve 235 and prevents the fracturing fluid from being transported downwards. This ensures that the fracturing fluid, with the first ball 237 blocking the first sliding sleeve 235, fully impacts the second collar 234 along the second valve port 231. This allows the fracturing fluid to open the second collar 234 within the second sealed space 23a for the second stage of injection. At this time, there is a distance between the second valve port 231 and the first valve port 221, and the fracturing fluid fracturing the formation at different locations. This allows for the gradual fracturing of formations at multiple different locations, improving the fracturing effect of the volumetric fracturing string 20 on the formation and ensuring the oil production effect of the formation.

[0061] The first ball 237 seals against the first sliding sleeve 235 and, together with the first sliding sleeve 235, blocks the flow channel between the second injection valve 23 and the first injection valve 22; the first expansion separator 24 is located between the second injection valve 23 and the first injection valve 22 and is located above the first sliding sleeve 235; the fracturing fluid entering through the flow channel is transported to the top of the first sliding sleeve 235 and passes through the groove on the inner wall of the first expansion separator 24 to expand the first expansion separator 24. At this time, the first expansion separator 24 is adjusted from a contracted state to an expanded state and is in sealed contact with the inner wall of the cavity 11 to separate the external space of the second injection valve 23 and the external space of the first injection valve 22.

[0062] The first expansion separator 24 separates the external space of the first valve port 221 and the external space of the second valve port 231, allowing the fracturing fluid to contact the outside. Moreover, the first expansion separator 24 expands synchronously with the flow of fracturing fluid in its groove, ensuring the timely operation of the first expansion separator 24. Furthermore, the sealing of the first expansion separator 24 and the first ball 237 on the first sliding sleeve 235 is performed sequentially, ensuring automatic sliding control of the volumetric fracturing string 20 under the physical structure and improving the automation effect of the volumetric fracturing string 20.

[0063] Optionally, the volumetric fracturing string 20 also includes a second expansion separator 25, which is located above the first expansion separator 24 and is positioned on both sides of the second injection valve 23. The second expansion separator 25 in the expanded state and the first expansion separator 24 in the expanded state form a metering space, which is used to store a metered amount of fracturing fluid.

[0064] Since the distance between the second expansion separator 25 and the first expansion separator 24 is determinable, and the volume between the second expansion separator 25 and the first expansion separator 24 is also determinable, when we control the position of the first expansion separator 24, the position of the second expansion separator 25 is also determined accordingly. This facilitates the calculation of the working area of ​​the single volumetric fracturing string 20 based on the position of the first expansion separator 24, thereby improving the effectiveness of the calculation of the working area of ​​the volumetric fracturing string 20.

[0065] Furthermore, the volumetric fracturing string 20 also includes a pressure relief valve 26 and a second sliding sleeve 27. The pressure relief valve 26 is located on the side of the second expansion separator 25 facing away from the second injection valve 23. The outer peripheral wall of the pressure relief valve 26 is provided with a third valve port. The second sliding sleeve 27 is movably sleeved on the inner side wall of the pressure relief valve 26 and covers the third valve port. The second sliding sleeve 27 is provided with a second support portion, which is used to support the second ball 28 entering through the flow channel. Under the impact of the second ball 28, the second sliding sleeve 27 moves downward and separates from the third valve port. At this time, the third valve port is in a through state, and the fracturing fluid entering through the flow channel is sprayed to the outside of the pressure relief valve 26 through the third valve port. At this time, the second expansion separator 25 and the first expansion separator 24, which are in an expanded state, gradually contract. Optionally, the diameter of the second ball 28 is larger than the diameter of the first ball 237.

[0066] In addition, the volumetric fracturing string 20 also includes an anchor body 29, which is connected to the string body 21 and retracts inward under the action of rotation or lifting, causing the anchor claws of the anchor body 29 to disengage from the first string body 10. The anchor body 29 is a hydraulic anchor.

[0067] Anchor body 29 enters the anchoring state:

[0068] The fracturing fluid in the flow channel enters the inner cavity through the small hole at the lower end of the first connector 291. When the hydraulic pressure reaches about 7 MPa, the first pin is sheared. Under the action of hydraulic pressure, the second connector 292 moves upward, pushing the first lower cone 2912 upward. The first lower cone 2912 has a conical surface, and the conical surface actuates the slip 2914 to extend outward. At this time, the slip 2914 extends outward under the combined action of the conical surface of the first lower cone 2912 and the conical surface of the first upper cone 2913, and the teeth are anchored on the casing to ensure the stable operation of the anchor.

[0069] Entering anchored state:

[0070] The fracturing fluid in the flow channel enters the inner cavity through the small hole at the lower end of the first connector 291. When the hydraulic pressure reaches about 7 MPa, the pin of the second connector 292 is sheared. Under the action of hydraulic pressure, the third connector 293, the fourth connector 294, the fifth connector 295, the sixth connector 296, and the seventh connector 297 move upward, pushing the first lower cone 2912 upward. The slip 2914 extends upward under the combined action of the first upper cone 2913 and the first lower cone 2912, and the teeth are anchored on the casing. The seventh connector 297 has a one-way locking function, which can prevent the first lower cone 2912 from moving to the right and ensure the stable operation of the anchor.

[0071] Release anchoring status:

[0072] 1. Lift up to release the anchoring state. At this time, the connecting nail will not be cut off (the nail head can be thickened), but the connecting nail will be cut off.

[0073] Lifting the oil pipe causes the eighth connector 298, the ninth connector 299, and the tenth connector 2910 to move upwards. The tenth connector 2910, through a connecting pin, causes the eighth connector 2910, the tenth connector 2910, the seventh connector 297, and the eleventh connector 2911 to move upwards. Since the first lower cone 2912 is limited by the slip 2914, the connecting pin is sheared when the lifting force is increased. At this time, the first lower cone 2912 is in a free state and moves to the right under the action of gravity. The tenth connector 2910 causes the first upper cone 2913 to move to the left. The slip 2914 is retracted under the rebound force of the spring plate of the eighth connector 298, releasing the anchoring state.

[0074] 2. Rotate clockwise to release the anchoring state. At this time, the connecting nail will not be cut off (the nail head can be thickened), but the connecting nail will be cut off.

[0075] Rotating the oil pipe clockwise on the ground causes the eighth connector 298 to rotate, which in turn drives the ninth connector 299 to cut the connecting pin. Since the slip 2914 is in an anchored state, the first upper cone 2913 is also relatively anchored and cannot rotate. The eighth and tenth connectors 2910 are relatively anchored, so rotating the ninth connector 299 allows relative rotation with the tenth connector 2910, causing the connecting buckle to disengage. Once the buckle is completely disengaged, the tenth connector 2910, connected to the first lower cone 2912, is in a free state and moves to the right under gravity. The ninth connector 299 drives the first upper cone 2913 to move to the left. The slip 2914 retracts under the restoring force of the spring plate of the eighth connector, releasing the anchored state.

[0076] This application provides a volumetric fracturing string assembly in which fracturing fluid enters the first valve port 221 along the flow channel and is injected into the first sealed space 22a. The fracturing fluid in the first sealed space 22a expands upward to open the first collar 224 and overcomes the elastic force of the first spring 223 on the first collar 224, thus pushing the first collar 224 upward. At this time, the first valve port 221 is adjusted from a closed state to an open state, allowing the fracturing fluid entering through the flow channel to be injected into the formation. At this time, the fracturing fluid does not need to be regulated by a flow throttle and its flow rate does not need to be limited; it only needs to overcome the elastic force of the first spring 223 on the first collar 224. The first sleeve 224 is pushed upward within the first sealed space 22a by the fracturing force, thereby adjusting the opening state of the first valve port 221. This allows the fracturing fluid to be injected into the formation through the open valve port 221 for volumetric fracturing. In addition, when the fracturing fluid does not enter the first valve port 221, the first sleeve 224 moves downward under the elastic force of the first spring 223 and blocks the first valve port 221, adjusting it from the open state to the closed state. The first sleeve 224 also prevents external debris from entering the first valve port 221, thus achieving external protection for the first valve port 221.

[0077] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0078] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more features.

[0079] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A volumetric fracturing tubing assembly, characterized in that, include: The first pipe body penetrates the stratum vertically and has a cavity; the outer surface of the first pipe body is attached to the stratum. A volumetric fracturing string is housed within the cavity and penetrates the cavity under external force. The volumetric fracturing string includes a string body, a first injection valve, a second injection valve, and a first expansion separator. The first injection valve, the first expansion separator, and the second injection valve are connected to the string body and arranged sequentially from bottom to top. The string body has a flow channel through which the first injection valve, the second injection valve, and the first expansion separator pass. The first injection valve has a first valve port on its outer peripheral wall. A first connecting ring, a first spring, and a first collar are sleeved on the outer peripheral wall of the first injection valve. The first collar is arranged relative to the first valve port, covering the first valve port and forming a first sealing space with the outer peripheral wall of the first injection valve. The first sealing space is connected to the first valve port. The first spring is sleeved on the outer peripheral wall of the first injection valve and elastically abuts against the first connecting ring and the first collar. At this time, the first collar continuously covers the first valve port under the elastic action of the first spring and maintains the first sealing space. The first valve port is in a closed state. The fracturing fluid enters the first valve port along the flow channel and is sprayed into the first sealed space; the fracturing fluid in the first sealed space expands the first collar upward and overcomes the elastic force of the first spring on the first collar to push the first collar upward. At this time, the first valve port is adjusted from the closed state to the open state, allowing the fracturing fluid entering through the flow channel to be sprayed into the formation. The first collar is movably sleeved on the outer peripheral wall of the first injection valve; the end of the first collar facing away from the first spring is provided with a first conical surface; the outer peripheral wall of the tubular body is provided with a second conical surface; The first conical surface seals against the second conical surface under the elastic force of the first spring. The first sealing space is formed between the first collar, the outer peripheral wall of the main body of the tubing, and the outer peripheral wall of the first injection valve. The first sealing space is connected to the first valve port, and the first valve port is the only opening in the first sealing space.

2. The volumetric fracturing tubing assembly according to claim 1, characterized in that, The first sleeve ring is provided with a first annular groove and a first sealing ring. The first sealing ring is disposed between the first sleeve ring and the outer peripheral wall of the first injection valve, and is sealed within the first annular groove. The first annular groove is disposed on the upper side of the first sealed space, and the first sealing ring sleeved in the first annular groove blocks the fracturing fluid sprayed upward from the first sealed space.

3. The volumetric fracturing tubing assembly according to claim 2, characterized in that, The first sleeve is provided with a second annular groove and a second sealing ring. The second sealing ring is disposed between the first sleeve and the outer peripheral wall of the first injection valve and is sealed within the first annular groove.

4. The volumetric fracturing tubing assembly according to claim 3, characterized in that, The second annular groove is disposed on the side of the first annular groove facing away from the first sealing space, and is spaced apart from the first annular groove; the second sealing ring and the first sealing ring enclose a secondary sealing space, which is located above the sealing space.

5. A volumetric fracturing tubing assembly according to claim 4, characterized in that, The first connecting ring is sleeved on the outer peripheral wall of the first injection valve. The inner wall of the first connecting ring is threaded to the outer peripheral wall of the first injection valve and rotates relative to the outer peripheral wall of the first injection valve under the action of external force to adjust the position of the first connecting ring and adjust the resistance force of the first connecting ring against the first spring.

6. The volumetric fracturing tubing assembly according to claim 5, characterized in that, When the fracturing fluid does not enter the first valve port, the first collar moves downward under the elastic force of the first spring and blocks the first valve port, thus adjusting the first valve port from the open state to the closed state.

7. A volumetric fracturing tubing assembly according to claim 6, characterized in that, The second injection valve is located above the first injection valve.

8. A volumetric fracturing tubing assembly according to claim 7, characterized in that, The second injection valve has a second valve port on its outer peripheral wall. A second connecting ring, a second spring, and a second sleeve ring are fitted onto the outer peripheral wall of the second injection valve. The second sleeve ring is arranged relative to the second valve port, covering the second valve port and forming a second sealing space with the outer peripheral wall of the second injection valve. The second sealing space is connected to the second valve port. The second spring is fitted onto the outer peripheral wall of the second injection valve and elastically abuts against the second connecting ring and the second sleeve ring. At this time, the second sleeve ring continuously covers the second valve port under the elastic action of the second spring and maintains the second sealing space. The second valve port is in a closed state.

9. A volumetric fracturing tubing assembly according to claim 8, characterized in that, The inner peripheral wall of the second injection valve is connected to a first sliding sleeve, which is movably connected to the inner peripheral wall of the second injection valve and covers the second valve port. The upper surface of the first sliding sleeve is provided with a first support portion, which is used to support the first ball entering through the flow channel. The first sliding sleeve moves downward under the impact of the first ball and separates from the second valve port. At this time, the second valve port is in a through state, and the fracturing fluid entering through the flow channel is sprayed into the second sealed space through the second valve port.

10. A volumetric fracturing tubing assembly according to claim 9, characterized in that, The first ball seals against the first sliding sleeve, and together with the first sliding sleeve, blocks the flow channel between the second injection valve and the first injection valve; The first expansion separator is located between the second injection valve and the first injection valve, and above the first sliding sleeve; the fracturing fluid entering through the flow channel is delivered to the top of the first sliding sleeve and passes through the groove on the inner wall of the first expansion separator to expand the first expansion separator. At this time, the first expansion separator is adjusted from a contracted state to an expanded state and is in sealing contact with the inner wall of the lumen to separate the external space of the second injection valve and the external space of the first injection valve.

11. A volumetric fracturing tubing assembly according to claim 10, characterized in that, The volumetric fracturing string also includes a second expansion separator, which is located above the first expansion separator and is positioned on both sides of the second injection valve. The second expansion separator in the expanded state and the first expansion separator in the expanded state form a metering space for storing a metered amount of fracturing fluid.

12. A volumetric fracturing tubing assembly according to claim 11, characterized in that, The volumetric fracturing string also includes a pressure relief valve and a second sliding sleeve. The pressure relief valve is located on the side of the second expansion separator facing away from the second injection valve. The outer peripheral wall of the pressure relief valve is provided with a third valve port. The second sliding sleeve is movably sleeved on the inner side wall of the pressure relief valve and covers the third valve port. The second sliding sleeve is provided with a second support portion, which is used to support the second ball entering through the flow channel. The second sliding sleeve moves downward under the impact of the second ball and separates from the third valve port. At this time, the third valve port is in a through state. The fracturing fluid entering through the flow channel is sprayed to the outside of the pressure relief valve through the third valve port, and the fracturing fluid is discharged. At this time, the second expansion separator in the expansion state and the first expansion separator in the expansion state gradually contract.

13. A volumetric fracturing tubing assembly according to claim 12, characterized in that, The volumetric fracturing string also includes an anchor body, which is connected to the main body of the string and retracts inward under rotation or lifting, causing the anchor claws of the anchor body to detach from the first string body.

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