Downhole fluid control device and method of construction

Abstract

The application belongs to the technical field of downhole tools for oil and gas development, and particularly relates to a downhole fluid control device and a construction process. The downhole fluid control device comprises a working cylinder, at least one through hole is arranged on the cylinder wall of the working cylinder, and an opening and closing plate is arranged in the working cylinder, the first end of the opening and closing plate is connected with the working cylinder, and the first end of the opening and closing plate is sealed against the through hole on the outside of the working cylinder; the opening and closing plate is configured to move the second end radially inward in response to the pressure on the outside of the working cylinder, so as to open the through hole.

Description

Technical Field

[0001] This invention belongs to the field of downhole tools technology for oil and gas development, specifically relating to a downhole fluid control device and a construction process. Background Technology

[0002] Oil and gas development is a systematic project covering geology, drilling, well completion, production enhancement, extraction, and transportation. In recent years, with rapid economic development, energy demand has risen sharply, and oil and gas development has shifted from conventional oil and gas resources to unconventional oil and gas such as tight oil and gas, shale oil and gas, and coalbed methane. Horizontal well fracturing technology has become the mainstream technology.

[0003] Unconventional oil and gas resources are often buried deep with low porosity, requiring hydraulic fracturing to establish oil and gas channels in the formation. To improve oil and gas recovery, the hydraulic fracturing operation rate, injection fluid volume, and proppant quantity are typically increased to crush the oil and gas-bearing formation as much as possible. As oil and gas well development enters the middle and late stages, formation energy gradually decreases, and more and more fluid accumulates in the well, leading to a rapid decline in oil and gas production. To address the problem of increased fluid accumulation in oil and gas wells, high-pressure gases such as compressed natural gas and nitrogen are usually injected into the well. The compressed gas is injected into the formation through the annulus or tubing to reduce the fluid density. Then, the compressed gas enters the tubing through a gas lift valve on the tubing string, and under fluid circulation, lifts the fluid in the well to the surface, reducing the resistance of the accumulated fluid to the natural gas in the formation, thereby releasing production capacity.

[0004] However, during the flowback after fracturing and in the later production process, some of the proppant (ceramsite, quartz) squeezed into the formation will enter the wellbore along with oil and gas, and flowback fluid. Currently, conventional gas lift methods do not have sand control functions, which can easily cause blockage of the gas lift valve during production. In order to achieve efficient drainage and gas production in oil and gas wells, this invention provides a downhole fluid control device, a drainage and gas production string, and corresponding construction technology. Summary of the Invention

[0005] In view of the technical problems mentioned above, the present invention aims to provide a downhole fluid control device that can be used to implement drainage gas production processes.

[0006] The present invention also proposes a construction process that uses the downhole fluid control device provided by the present invention.

[0007] According to the present invention, a downhole fluid control device is provided, comprising:

[0008] A working cylinder, wherein at least one through hole is provided on the cylinder wall; and

[0009] An opening and closing plate is disposed inside the working cylinder, the first end of the opening and closing plate is connected to the working cylinder, and the outer side of the first end of the opening and closing plate seals against the through hole;

[0010] The opening and closing plate is configured to move the second end radially inward in response to pressure on the outside of the working cylinder, thereby opening the through hole.

[0011] In a specific embodiment provided by the present invention, a groove is provided on the outer side of the working cylinder wall, the groove is connected to the through hole, and the first end of the opening and closing plate is provided in the groove by means of hinge.

[0012] In a specific embodiment provided by the present invention, a sealing elastic element is provided between the opening and closing plate and the bottom wall of the groove for sealing abutment.

[0013] In a specific embodiment provided by the present invention, the sealing elastic element is made of rubber.

[0014] In a specific embodiment provided by the present invention, the sealing elastic element is fixedly connected to the bottom wall of the groove, and the sealing elastic element is in sealing contact with the opening and closing plate.

[0015] In a specific embodiment provided by the present invention, the thickness of the end of the sealing elastic member near the through hole is greater than that of the end away from the through hole.

[0016] In a specific embodiment provided by the present invention, the opening and closing plate is made of an elastic material, the first end of the opening and closing plate is fixedly connected to the working cylinder, and the outer side of the second end of the opening and closing plate is sealed and abutted against the through hole.

[0017] In a specific embodiment provided by the present invention, a sand-proof mesh is fixedly provided on the outer wall of the working cylinder at the position corresponding to the through hole.

[0018] In a specific embodiment provided by the present invention, the sand-proof mesh is fixed to the working cylinder by pins.

[0019] According to the present invention, a construction process is also provided, comprising the following steps:

[0020] The downhole fluid control device provided according to the present invention is connected to the tubing and inserted into the well to the water-flooded section;

[0021] Insert a pipe into the oil pipe to the flooded section;

[0022] Gas is injected into the annulus between the pipeline and the oil pipe, or into the pipeline, to perform drainage and gas extraction.

[0023] Compared with the prior art, the advantages of this application are as follows.

[0024] This invention includes a working cylinder and a hinged plate. One end of the hinged plate is connected to the working cylinder, and the outer side of the other end of the hinged plate abuts against the inner wall of the working cylinder, sealing the through-hole of the working cylinder. During construction, the external pressure of the downhole fluid control device (i.e., formation pressure) is transmitted to the hinged plate through the through-hole, causing the hinged plate to move radially inward and open the through-hole. At this time, downhole fluid can enter the working cylinder through the through-hole. In addition, since the inner side of the hinged plate of this invention is connected to the inner cavity of the working cylinder, the pressure inside the working cylinder can be transmitted to the inner side of the hinged plate. When the pressure inside the working cylinder is sufficiently high, it can prevent the hinged plate from opening, thereby enabling more reliable implementation of the construction process provided by this invention. Attached Figure Description

[0025] The invention will now be described with reference to the accompanying drawings.

[0026] Figure 1 A schematic diagram showing the initial state of an embodiment of the downhole fluid control device according to the present invention;

[0027] Figure 2 A schematic diagram showing the working state of an embodiment of the downhole fluid control device according to the present invention is provided.

[0028] Figure 3 A cross-sectional schematic diagram of the downhole fluid control device according to the present invention is shown;

[0029] Figure 4 A three-dimensional structural diagram of the downhole fluid control device according to the present invention is shown;

[0030] Figure 5 A schematic diagram of the disassembled structure of the downhole fluid control device according to the present invention is shown;

[0031] Figure 6 A schematic diagram of the drainage gas extraction construction process according to the present invention is shown.

[0032] In the picture:

[0033] 1. Working cylinder; 11. Through hole; 12. Groove; 13. Groove bottom wall;

[0034] 2. Pins;

[0035] 3. Sand control netting;

[0036] 4. Sealing elastic element;

[0037] 5. Hinging plate; 51. First end; 52. Second end;

[0038] 6. Connecting pin;

[0039] 100. Downhole fluid control device.

[0040] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0041] The invention will now be described with reference to the accompanying drawings.

[0042] It should be noted that in this application, the direction near the wellhead after the well is entered according to the present invention is described as "up," "forward," or similar terms, that is... Figure 1 Above; the direction away from the wellhead after the well is entered according to the present invention is described as "below", "after" or similar terms, i.e. Figure 1 Below. These are not used to define the absolute position of the components involved, but can vary depending on the specific circumstances.

[0043] In this application, "inner" refers to the direction of the working cylinder 1 closer to the central axis, and "outer" refers to the direction of the working cylinder 1 away from the central axis.

[0044] Example 1:

[0045] Figure 1 The structure of a downhole fluid control device 100 according to the present invention is shown. (See diagram below.) Figure 1 As shown, the downhole fluid control device 100 includes a working cylinder 1 and an opening / closing plate 5.

[0046] In this embodiment, the working cylinder 1 is generally cylindrical in shape, and both axial ends of the working cylinder 1 are provided with connectors for connecting to oil pipes. In a specific embodiment, the two axial ends of the working cylinder 1 are respectively provided with male threads and female threads.

[0047] At least one through hole 11 is provided on the wall of the working cylinder 1, and the through hole 11 connects the outer side of the working cylinder 1 and the inner cavity. In a preferred embodiment, such as Figure 3 As shown, three through holes 11 are uniformly arranged along the circumferential direction on the wall of the working cylinder 1, and the phase angle between adjacent through holes 11 is 120°.

[0048] The opening and closing plate 5 is installed inside the working cylinder 1. The first end 51 of the opening and closing plate 5 is connected to the working cylinder 1, and the outer side of the second end 52 of the opening and closing plate 5 is sealed against the through hole 11. After the downhole fluid control device 100 enters the well, the formation pressure can be transmitted to the second end 52 of the opening and closing plate 5 through the through hole 11, thereby pushing the second end 52 of the opening and closing plate 51 to move radially inward, thereby opening the through hole 11, so that the formation fluid can enter the inner cavity of the working cylinder 1 through the through hole 11.

[0049] According to the present invention, the inner side of the opening and closing plate 5 is connected to the inner cavity of the working cylinder 1, that is, the inner side of the opening and closing plate 5 can be directly subjected to the pressure of the inner cavity of the working cylinder 1. This arrangement allows for better integration with the construction process provided by the present invention, as detailed below.

[0050] In this embodiment, a groove 12 is provided on the outer side of the working cylinder 1. The groove 12 communicates with the through hole 11. The first end 51 of the opening and closing plate 5 is provided in the groove 12 by means of hinge. Specifically, the groove 12 is provided below the through hole 11. The groove 12 is opened on the outer wall of the working cylinder 1 and does not penetrate the inner wall of the working cylinder 1. That is to say, the inner wall of the working cylinder 1 forms the bottom wall 13 of the groove 12. The lower end of the bottom wall 13 is the cylinder wall of the working cylinder 1, and the upper part of the bottom wall 13 is the through hole 11.

[0051] The hinge plate 5 is roughly strip-shaped, with its lower end being the first end 51 and its upper end being the second end 52. The hinge plate 5 is located within the groove 12, and its first end 51 is connected to the working cylinder 1 via a hinge. Figure 1 As shown, in the initial state, the outer side of the second end 52 of the opening and closing plate 5 abuts against the position of the through hole 11 on the inner wall of the working cylinder 1, thereby sealing the through hole 11.

[0052] In a specific embodiment, such as Figure 1 and Figure 5 As shown, the opening / closing plate 5 is hinged to the working cylinder 1 by a connecting pin 6, and the central axis of the connecting pin 6 is perpendicular to the central axis of the working cylinder 1. With this configuration, the opening / closing plate 5 can swing around the connecting pin 6.

[0053] In one specific embodiment, a sealing elastic element 4 is provided to seal against the opening and closing plate 5 and the bottom wall 13 of the groove 12. The sealing elastic element 4 seals the opening and closing plate 5 against the bottom wall 13, preventing fluid from the outside of the working cylinder 1 from entering the inner cavity of the working cylinder 1 through the gap between the opening and closing plate 5 and the bottom wall 13. Furthermore, the sealing elastic element 4 provides a radially outward preload to the opening and closing plate 5, allowing it to abut against the inner wall of the working cylinder 1 without external force, thereby blocking the through hole 11 at the second end 52 of the opening and closing plate 5.

[0054] In one specific embodiment, the sealing elastic element 4 is made of rubber. The sealing elastic element 4 is fixedly connected to the bottom wall 13 of the groove, and the sealing elastic element 4 abuts against the opening and closing plate 5. With this configuration, after the downhole fluid control device 100 enters the well, as... Figure 1 As shown, in the initial state, the opening / closing plate 5 closes the through hole 11 under the action of the sealing elastic element 4. Figure 2As shown, in the working state, the formation pressure is transmitted to the opening and closing plate 5 through the through hole 11, thereby pushing the opening and closing plate 5 to overcome the elastic force of the sealing elastic element 4. The second end 52 of the opening and closing plate 5 moves radially inward, thereby opening the through hole 11, and the accumulated liquid in the formation can enter the inner cavity of the working cylinder 1 through the through hole 11.

[0055] In a preferred embodiment, the thickness of the end of the sealing elastic element 4 near the through hole 11 is greater than that of the end away from the through hole 11. For example... Figure 1 As shown, the sealing elastic element 4 is constructed into a small-angle wedge shape that is thick at the top and thin at the bottom. Under the elastic deformation of the sealing elastic element 4, the outer surface of the sealing elastic element 4 is in contact with the inner surface of the opening and closing plate 5.

[0056] According to a preferred embodiment of the present invention, a sand-proof mesh 3 is fixedly provided on the outer wall of the working cylinder 1 at a position corresponding to the through hole 11. Further, since the groove 12 communicates with the through hole 11, in this embodiment, as... Figures 1-5 As shown, the sand control mesh 3 covers the groove 12 and the through hole 11. With this setup, formation fluids need to be filtered by the sand control mesh 3 before entering the downhole fluid control device 100 through the through hole 11, thereby preventing blockage inside the downhole fluid control device 100 and improving the efficiency of drainage and gas production.

[0057] Specifically, the sandproof net 3 is constructed in the shape of a long strip. The outer surface of the working cylinder 1 at the corresponding through hole 11 and groove 12 is provided with a step for installing the sandproof net 3. The sandproof net 3 is installed in the step, and the two ends of the sandproof net 3 are fixed to the working cylinder 1 by pins 2.

[0058] According to the present invention, the assembly steps of the downhole fluid control device 100 are as follows: Figure 5 As shown, first install the sealing elastic element 4 on the bottom wall 13 of the groove 12, then insert the opening and closing plate 5 into the groove 12 and insert the connecting pin 6, and finally install the sandproof mesh 3 and tighten the pin 2.

[0059] Example 2:

[0060] In another embodiment of the present invention, the opening and closing plate 5 is made of an elastic material. The first end 51 of the opening and closing plate 5 is fixedly connected to the working cylinder 1, and the outer side of the second end 52 of the opening and closing plate 5 is sealed and abutted against the through hole 11. In this configuration, it is not necessary to provide the groove 12, the sealing elastic element 4, etc.; it is only necessary to fix the first end 51 of the opening and closing plate 5 to the inner wall of the working cylinder 1, and the outer side of the second end 52 is sealed and abutted against the through hole 11.

[0061] Example 3:

[0062] In one embodiment of the present invention, a construction process for drainage gas extraction is provided, such as... Figure 6As shown, the steps are as follows:

[0063] The downhole fluid control device 100 provided according to the present invention is connected to the tubing 81 and inserted into the well to the water-flooded section;

[0064] Insert pipe 82 into oil pipe 81 to the water-flooded section;

[0065] Gas is injected into the annulus between pipe 82 and oil pipe 81 or into pipe 82 to perform drainage and gas extraction.

[0066] In a specific embodiment, such as Figure 6 As shown, at least one downhole fluid control device 100 is first connected in series to the tubing 81 and lowered into the vertical or horizontal section of the well that is flooded with water. At this time, the bottom end of the tubing 81 is sealed. Then, a pipe 82 (usually a small-sized continuous tubing) is lowered into the tubing 81. The pipe 82 is inserted into the bottom end of the tubing 81, and the bottom end of the pipe 82 is open.

[0067] When the formation energy is sufficient, under the action of formation energy (formation pressure, natural gas pressure, etc.), the opening and closing plate 5 of the downhole fluid control device 100 can be pushed radially inward by the formation energy, thereby causing the accumulated liquid in the large annulus between the tubing 81 and the wellbore 10 to be squeezed into the small annulus between the tubing 81 and the pipe 82 or into the pipe 82 through the through hole 11 of the downhole fluid control device 100. Formation compressed gas (natural gas, etc.) enters the small annulus together and moves towards the surface along the tubing 81. During the movement, the natural gas expands in volume, continuously carrying the accumulated liquid to the surface, thereby achieving the effect of drainage and gas production.

[0068] When the formation energy is insufficient, the fluid accumulated in the large annulus between the tubing 81 and the wellbore 10 can enter the small annulus between the tubing 81 and the pipe 82 through the downhole fluid control device 100, but its energy is insufficient to transport it to the surface along the tubing 81. In the above situation, when there is no fluid in the tubing 81, the pressure of the fluid in the large annulus can push the second end 52 of the opening and closing plate 5 to move radially inward, thereby opening the through hole 11. The fluid in the large annulus can enter the tubing 81. As the fluid in the large annulus continuously enters the tubing 81, the pressure in the large annulus gradually decreases. Eventually, the pressure in the large annulus decreases to a level insufficient to push the opening and closing plate 5 to overcome the elastic force of the sealing elastic element 4, thereby closing the through hole 11. At this point, nitrogen, natural gas, or other gases are injected into pipe 82 (or the small annulus between pipe 82 and oil pipe 81) via a ground-based gas lift vehicle to pressurize it. Due to the pressure difference inside and outside pipe 82, the liquid accumulated in oil pipe 81 will move from the small annulus between pipe 82 and oil pipe 81 (or from pipe 82) to the ground. The compressed gas expands in volume during the movement, continuously carrying the liquid accumulated in oil pipe 81 to the ground, thereby achieving the effect of drainage and gas extraction. When the liquid in the large annulus is replenished again to the point where it can push the third working cylinder 3 upward, the above steps are repeated.

[0069] Since the inner surface of the opening and closing plate 5 of the downhole fluid control device 100 of the present invention is connected to the inner cavity of the working cylinder 1, the pressure in the inner cavity of the working cylinder 1 can be transmitted to the inner surface of the opening and closing plate 5. Therefore, when nitrogen, natural gas or other gases are injected into the pipeline 82 (or the small annulus between the pipeline 82 and the tubing 81) by the ground gas lift vehicle for pressurization, the pressure in the inner cavity of the working cylinder 1 increases, which can apply a radially outward pressure to the opening and closing plate 5. This avoids the formation pressure (liquid in the large annulus) from being replenished too quickly during this process, which would cause the valve disc 41 to open prematurely, thereby making the construction process provided by the present invention more reliable.

[0070] Example 4:

[0071] In this embodiment, at least one downhole fluid control device 100 is first connected in series to the tubing 81 and lowered into the vertical or horizontal section of the well that is flooded with water. At this time, the bottom end of the tubing 81 is blocked. Then, a pipe 82 (usually a small-sized continuous tubing) is lowered into the tubing 81. The pipe 82 is inserted into the bottom end of the tubing 81, and the bottom end of the pipe 82 is open.

[0072] When the formation energy is insufficient, the accumulated fluid in the large annulus between the tubing 81 and the wellbore 10 can enter the small annulus between the tubing 81 and the pipe 82 through the downhole fluid control device 100, but its energy is insufficient to transport it to the surface along the tubing 81.

[0073] Nitrogen, natural gas, or other gases are injected into pipe 82 (or the small annulus between pipe 82 and oil pipe 81) via a ground gas lift vehicle to pressurize it. Since the inner surface of the opening and closing plate 5 can directly respond to the internal pressure of the working cylinder 1, when the pressure in oil pipe 81 is transmitted to the internal cavity of the working cylinder 1, it can directly push the opening and closing plate 5 to close, thereby preventing the fluid in oil pipe 81 from flowing back to the formation through the through hole 11. Therefore, the difference between this embodiment and embodiment three is that this embodiment does not need to wait for the formation pressure to drop to a level insufficient to push the opening and closing plate 5 to overcome the elastic force of the sealing elastic element 4 to close the through hole 11. It can directly inject nitrogen, natural gas, or other gases into pipe 82 (or the small annulus between pipe 82 and oil pipe 81) via a ground gas lift vehicle to pressurize it, draining the accumulated liquid in oil pipe 81. After the accumulated liquid in oil pipe 81 is drained, the ground gas lift vehicle stops working. It resumes working after the accumulated liquid in oil pipe 81 accumulates again, thereby achieving the effect of drainage and gas extraction.

[0074] In the description of this invention, it should be understood that 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 indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0075] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0076] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0077] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A construction technique, characterized in that, Using a downhole fluid control device, the downhole fluid control device includes: A working cylinder (1) has at least one through hole (11) on its wall and a groove (12) on the outer side of its wall, the groove (12) communicating with the through hole (11); and The opening and closing plate (5) is installed inside the working cylinder (1). The first end (51) of the opening and closing plate (5) is connected to the working cylinder (1). The first end (51) of the opening and closing plate (5) is installed in the groove (12) by hinge. The second end (52) of the opening and closing plate (5) is sealed and abuts against the through hole (11) on the outside. A sealing elastic element (4) is sealed and abuts between the opening and closing plate (5) and the bottom wall (13) of the groove (12). The opening and closing plate (5) is configured to move the second end (52) radially inward in response to the pressure on the outside of the working cylinder (1), thereby opening the through hole (11). The construction process includes: The downhole fluid control device is connected to the tubing and lowered into the well to the water-flooded section, with the lower end of the tubing in a plugged state. A pipe is inserted into the oil pipe to the water-flooded section, with the bottom end of the pipe open. Gas is injected into the annulus between the pipeline and the oil pipe, or into the pipeline, to perform drainage and gas extraction.

2. The construction process according to claim 1, characterized in that, The sealing elastic element (4) is made of rubber.

3. The construction process according to claim 2, characterized in that, The sealing elastic element (4) is fixedly connected to the bottom wall (13) of the groove, and the sealing elastic element (4) is in sealing contact with the opening and closing plate (5).

4. The construction process according to claim 3, characterized in that, The thickness of the end of the sealing elastic element (4) near the through hole (11) is greater than that of the end away from the through hole (11).

5. The construction process according to any one of claims 1 to 4, characterized in that, A sand-proof mesh (3) is fixedly installed on the outer wall of the working cylinder (1) at the position corresponding to the through hole (11).

6. The construction process according to claim 5, characterized in that, The sandproof net (3) is fixed to the working cylinder (1) by pins (2).

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