Underground circulating device and working method thereof

Abstract

The underground circulating device comprises a circulating valve, the circulating valve is arranged at the upper end of an oil pipe and connected with a floating ball arranged at the lower end of the oil pipe, and an electric pump is arranged at the bottom of the oil pipe. The method effectively solves the problem of stable production of the electric pump well with poor reservoir liquid supply capacity or liquid production capacity fluctuating from low to high after later transfer injection, effectively reduces the ground workload, prolongs the service life of the electric pump, saves the cost, and has good economic benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of oil field production and oil and gas recovery, and in particular relates to a downhole circulation device and a working method thereof. Background Art

[0002] There are various types of developed reservoirs at home and abroad, and the development methods are diverse. The liquid production of different reservoirs is different at different stages. Most reservoirs use artificial lift technology. Submersible electric pumps are an important means of artificial lift, but the displacement of the electric pump is determined when the pipe string enters the well, which cannot meet the production needs of the later changes in the liquid production of the oil well. Even if frequency conversion control is currently used, the liquid production range is still not large and is greatly restricted. First, for reservoirs with continuous reservoir development, natural energy is insufficient, and water and gas injection are used to establish a well network for development. In the later stage, liquid lifting and strong production are required. For reservoirs with sufficient natural energy, liquid lifting and strong production are also required in the later stage, and the liquid production will increase significantly. Second, for reservoirs with poor reservoir connectivity and small area, natural energy is insufficient and a well network cannot be established. Exhaustion development is adopted, and the liquid production gradually decreases in the later stage, and the liquid production will decrease significantly.

[0003] At present, there are generally three ways to solve the problem of large fluctuations in liquid production at oil fields.

[0004] One is that the displacement of the electric pump is replaced during maintenance work, and the disadvantage is that it is expensive for oil well operations.

[0005] The second is to add water to the wellhead annulus or to produce by reflux. Adding water to the annulus will cause serious scaling of the tubing, and reflux production requires ground modification and continuous optimization and adjustment on site.

[0006] The third is intermittent production. The disadvantage is that the electric pump is frequently turned on and off, which reduces the life of the electric pump. At the same time, there is a risk of blocking the flow of the electric pump after the pollutants in the wellbore settle during the shutdown period. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a downhole circulation device in view of the deficiencies in the above-mentioned prior art, which is used to solve the technical problems that the liquid production of oil well electric pumps gradually decreases during production, resulting in insufficient liquid supply and shortened life of the electric pumps, and that low liquid production wells, after later water and gas injection development, the liquid production increases and the electric pumps are not suitable for production.

[0008] The present invention adopts the following technical solutions:

[0009] A downhole circulation device comprises a circulation valve, which is arranged at the upper end of an oil pipe and connected to a floating ball arranged at the lower end of the oil pipe. An electric pump is arranged at the bottom of the oil pipe.

[0010] Specifically, the oil pipe is arranged in the casing, and the casing is vertically arranged in the formation.

[0011] Furthermore, the bottom of the casing is located in the oil and gas layer area.

[0012] Furthermore, casing perforations are provided at the bottom of the casing.

[0013] Furthermore, cementing cement is provided on the outside of the casing.

[0014] Furthermore, a first bonding interface is arranged inside the cementing cement, and a second bonding interface is arranged outside the cementing cement.

[0015] Specifically, the circulation valve is connected to the float ball through a connecting rod.

[0016] Specifically, two branches are arranged at the circulation valve, one is connected to the ground, and the other enters the annulus between the oil pipe and the casing.

[0017] Another technical solution of the present invention is a working method of the downhole circulation device, when the liquid level is above the float, the float does not move, the circulation valve is in a closed state, and the liquid lifted by the electric pump is all produced to the surface;

[0018] When the liquid level drops below the float, the float moves downward due to gravity, driving the connecting rod to open the circulation valve. The liquid forms two running paths at the circulation valve, one is directly lifted to the ground, and the other passes through the circulation valve into the annulus between the tubing and casing to replenish the annulus fluid volume.

[0019] Specifically, the details are as follows:

[0020] In the initial stage of hole repair, the float is below the dynamic liquid surface and the circulation valve is in the closed state;

[0021] When the formation is deficient and the fluid supply is insufficient, the dynamic liquid level drops below the float position. The float drives the connecting rod to move under the influence of gravity, and the circulation valve is in the open state. Part of the liquid in the tubing enters the annulus between the tubing and the casing to replenish the liquid volume.

[0022] After water and gas injection development, the formation energy increases, the fluid supply is sufficient, the fluid entering the wellbore from the reservoir increases, the dynamic liquid level rises, the float resets, and drives the connecting rod to close the circulation valve, and all the fluid in the oil pipe is produced.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] A downhole circulation device, in which a circulation valve and a float are linked, can automatically adjust the opening and closing of the circulation valve to prevent the electric pump from idling when the liquid supply is insufficient, causing the electric pump to burn out due to underload, or shut down and affect production capacity.

[0025] Furthermore, casing perforation is a conventional completion method for sandstone reservoirs, which can effectively prevent problems such as sand production and collapse caused by open hole completion.

[0026] Furthermore, cementing can effectively isolate the formation and the fluid in the pipe, ensuring that the drilled formations are not connected to each other, thereby achieving the purpose of independent production of the perforated layer.

[0027] Furthermore, the circulation valve is connected to the float, and the gravity of the float can be used to move up and down. The circulation valve can be automatically opened in the well according to the change of the liquid level, and the fluid in the oil pipe flows into the casing to realize the automatic circulation of the fluid in the well, preventing the electric pump from idling due to insufficient fluid supply, which may cause the electric pump to fail.

[0028] Furthermore, a circulation valve is installed on the oil pipe to utilize a float to automatically open and close, so that when the liquid supply is insufficient, the fluid in the oil pipe automatically flows into the annulus of the oil casing.

[0029] A working method of a downhole circulation device can automatically adjust the circulation valve switch according to the amount of liquid in the well to ensure sufficient submergence and guarantee the normal operation of the machine (electric pump, pumping unit). Avoid frequent start and stop of the electric pump and pumping unit, which may cause pump damage and generate downhole operation costs. Reduce the cost of wellhead process modification and reduce wellhead safety risks.

[0030] In summary, the present invention effectively solves the problem of stable production of electric pump wells with poor reservoir fluid supply capacity or with fluctuating fluid production from low to high after later transfer, effectively reduces ground workload, increases the service life of electric pumps, saves costs, and has good economic benefits.

[0031] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the operation diagram of the sufficient liquid supply stage in the initial stage of production;

[0033] Figure 2 This is a schematic diagram of the operation during the liquid supply shortage stage in the late stage of production;

[0034] Figure 3 Schematic diagram of different states of the circulation valve, where (a) is the open state and (b) is the closed state.

[0035] Among them: 1. Cementing cement; 2. Oil pipe; 3. Circulation valve; 4. Connecting rod; 5. Float; 6. Electric pump; 7. Casing perforation; 8. Formation; 9. Casing; 10. Oil and gas layer. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "one side", "one end", "one side" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0038] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0040] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0041] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0042] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0043] Example 1

[0044] The present invention provides a downhole circulation device, including a circulation valve 3, a connecting rod 4 and a floating ball 5. The circulation valve 3 is arranged at the upper end of the oil pipe 2. The circulation valve 3 is connected to the floating ball 5 arranged at the lower end of the oil pipe 2 through the connecting rod 4. The floating ball 5 is located between the oil pipe 2 and the casing 9. An electric pump 6 is arranged at the bottom of the oil pipe 2.

[0045] In the embodiment of the present invention, the oil pipe 2 is arranged in the casing 9, the casing 9 is arranged in the formation 8, the bottom of the casing 9 is arranged at the oil and gas layer 10, and the bottom of the casing 9 is provided with casing perforations 7.

[0046] In the embodiment of the present invention, cementing cement 1 is disposed on the outside of the casing 9, the inside of the cementing cement 1 is the first bonding interface between the casing 9 and the cement, and the outside of the cementing cement 1 is the second bonding interface between the formation and the cement.

[0047] In the embodiment of the present invention, please refer to Figure 3 Two branches are arranged at the circulation valve 3 , one is connected to the ground, and the other enters the annulus between the oil pipe 2 and the casing 9 .

[0048] Example 2

[0049] The working method of a downhole circulation device of the present invention is as follows:

[0050] When the liquid level is above the float 5, the float 5 does not move due to the buoyancy, the circulation valve 3 is in a closed state, and all the liquid lifted by the electric pump 6 is produced to the ground.

[0051] When the liquid level drops below the float 5, the float 5 moves downward due to gravity, driving the connecting rod 4 to open the circulation valve 3. The liquid forms two running paths at the circulation valve 3, one is directly lifted to the ground, and the other enters the annulus between the oil pipe 2 and the casing 9 through the circulation valve 3 to replenish the annulus fluid volume, ensuring the stable submergence of the electric pump 6 and smooth production.

[0052] Reservoirs with poor reservoir properties are divided into three stages, as follows:

[0053] In the first stage, the initial formation pressure at the beginning of the plugging process has a certain fluid supply capacity, the fluid interface (dynamic liquid surface) is high, and the downhole circulation device operates as follows: Figure 1 As shown, the float 5 is located below the dynamic liquid surface and is not displaced due to the influence of buoyancy, and the circulation valve 3 is in a closed state.

[0054] In the second stage, as the production volume continues to increase, the formation becomes depleted and the fluid supply is insufficient. The dynamic liquid level drops below the position of the float 5. The float 5 is affected by gravity and drives the connecting rod 4 to move. The circulation valve 3 is in an open state (the circulation valve 3 is equipped with an oil nozzle to control the reflux volume and to perform ground fishing and change the working system). A part of the liquid in the oil pipe 2 enters the annulus of the oil casing to supplement the liquid volume. The downhole circulation device operates as follows: Figure 2 .

[0055] In the third stage, after water and gas injection development, the formation energy increases, the fluid supply changes from insufficient to sufficient, the fluid entering the wellbore from the reservoir increases, the dynamic liquid level rises, the float resets, driving the connecting rod to close the circulation valve, and all the fluid in the oil pipe is produced.

[0056] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0057] See also Figure 1 In the initial stage, the liquid supply is sufficient, the float is affected by the buoyancy, and the circulation valve is linked to close the circulation valve. The fluid in the oil pipe is directly lifted to the ground along the oil pipe, and the electric pump or oil pumping unit works normally.

[0058] See also Figure 2 For some reservoirs, the initial fluid supply is sufficient, but as the development progresses, the fluid supply becomes worse and worse. The current conventional practice is to perform downhole operations and replace electric pumps or pumping units with smaller displacement. Figure 2 As shown, when the liquid supply is insufficient, in order to ensure the normal operation of the electric pump or the oil pumping unit, when the liquid supply is insufficient, the liquid level drops below the float, and the float moves downward under the influence of gravity, driving the circulation valve to open, and part of the fluid in the oil pipe enters the annulus of the oil casing, ensuring that the dynamic liquid level is always kept near the float, ensuring that there is sufficient sinking degree, and ensuring that the electric pump or the oil pumping unit is not underloaded.

[0059] In summary, the present invention provides a downhole circulation device and a working method thereof, which effectively solves the problem of stable production of electric pump wells with poor reservoir fluid supply capacity or with fluctuating fluid production from low to high after late transfer, thereby effectively reducing ground workload and increasing the service life of electric pumps.

[0060] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A downhole circulation device, characterized in that: The oil pipe (2) comprises a circulation valve (3), which is arranged at the upper end of the oil pipe (2), the circulation valve (3) is connected to a floating ball (5) arranged at the lower end of the oil pipe (2), and an electric pump (6) is arranged at the bottom of the oil pipe (2).

2. The downhole circulation device according to claim 1, characterized in that: The oil pipe (2) is arranged in a casing (9), and the casing (9) is vertically arranged in a stratum (8).

3. The downhole circulation device according to claim 2, characterized in that: The bottom of the casing (9) is located in the oil and gas layer (10) area.

4. The downhole circulation device according to claim 3, characterized in that: The bottom of the casing (9) is provided with casing perforations (7).

5. The downhole circulation device according to claim 2, characterized in that: Well cementing cement (1) is arranged on the outside of the casing (9).

6. The downhole circulation device according to claim 5, characterized in that: A first bonding interface is arranged on the inner side of the cementing cement (1), and a second bonding interface is arranged on the outer side of the cementing cement (1).

7. The downhole circulation device according to claim 1, characterized in that: The circulation valve (3) is connected to the float (5) via a connecting rod (4).

8. The downhole circulation device according to claim 1, characterized in that: Two branches are arranged at the circulation valve (3), one of which is connected to the ground and the other of which enters the annulus between the oil pipe (2) and the casing (9).

9. The working method of the downhole circulation device according to claim 1, characterized in that: When the liquid level is above the float (5), the float (5) does not move, the circulation valve (3) is in a closed state, and all the liquid lifted by the electric pump (6) is produced to the ground; When the liquid level drops below the float (5), the float (5) moves downward due to gravity, driving the connecting rod (4) to open the circulation valve (3). The liquid forms two running paths at the circulation valve (3), one of which is directly lifted to the ground, and the other passes through the circulation valve (3) into the annulus between the oil pipe (2) and the casing (9), thereby replenishing the annulus fluid volume.

10. The working method of the downhole circulation device according to claim 9, characterized in that: The details are as follows: In the initial stage of hole repair, the float (5) is located below the dynamic liquid surface, and the circulation valve (3) is in a closed state; When the formation is deficient and the liquid supply is insufficient, the dynamic liquid level drops below the position of the float (5), and the float (5) drives the connecting rod (4) to move due to the influence of gravity, and the circulation valve (3) is in an open state, and a part of the liquid in the oil pipe (2) enters the annulus between the oil pipe (2) and the casing (9) to replenish the liquid volume; After water and gas injection development, the formation energy rises, the fluid supply is sufficient, the fluid entering the wellbore from the reservoir increases, the dynamic liquid level rises, the float (5) resets, drives the connecting rod (4) to close the circulation valve (3), and all the fluid in the oil pipe is produced.

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