Shale gas well concentric double tube liquid and sand discharge pipe column structure

Abstract

The utility model discloses a kind of shale gas well concentric double-tube liquid discharge and sand discharge pipe column structures, including casing, big oil pipe, small oil pipe, horn mouth, water distributor, check valve and sand jetting pen tip.Big oil pipe is hung in casing by hanger, and lower end is connected with horn mouth;Small oil pipe is hung in big oil pipe, and lower end is extended to middle and lower part of horizontal well section, and multiple water distributors are installed in its horizontal section, and bottom end is sequentially connected with check valve and rotary jetting sand jetting pen tip.Water distributor has anti-return function, and gas or liquid can be injected in section, for supplementing formation energy and dredging wellbore;Check valve is used for controlling fluid one-way flow, to prevent wellbore sand liquid backflow;Rotary jetting sand jetting pen tip rotates and sprays along inclination under the drive of sand washing liquid, for efficient scouring of wellbore sand.The utility model can form multiple-channel fluid circulation, and give consideration to liquid discharge and sand discharge function, suitable for shallow shale gas well full life cycle drainage production requirement, with the advantages of reducing cost, reducing risk and improving capacity.

Description

Technical Field

[0001] This utility model relates to the field of oil and gas extraction technology, and in particular to a concentric double-pipe fluid and sand discharge tubing structure for shale gas wells. Background Technology

[0002] With the continued development of shale gas in my country, shallow atmospheric shale gas wells (buried at depths of less than 2000 meters) are gradually showing significant exploration and development potential. To effectively release the production capacity of shallow gas wells, fracturing stimulation methods with large sand, fluid, and drainage volumes are typically employed. However, under these methods, due to the low formation closure pressure, rapid fluid drainage rate, and high sand addition intensity, sand production is common in shallow shale gas wells during the oil plugging, testing, and drainage stages. This leads to the formation of sediment and fluid accumulation within the wellbore, potentially resulting in the tubing being buried by sand, well closure, or even production shutdown.

[0003] To address drainage issues, existing technologies primarily employ jet pumps and mechanical pumping. While widely used in conventional gas wells, these methods demonstrate insufficient adaptability in shallow, atmospheric-pressure shale gas wells. This is because when the sand content within the wellbore is high, pumps are prone to clogging, leading to pump failure. This not only affects drainage efficiency but also increases the frequency of pump inspections and replacements, significantly raising development costs. Furthermore, existing technologies are generally single-function, typically only capable of drainage and failing to simultaneously address sand removal, thus failing to meet the comprehensive drainage and sand removal requirements of shallow shale gas wells throughout their entire lifecycle.

[0004] Therefore, there is an urgent need for a downhole process string and its construction method that is simple in structure, highly reliable, can efficiently drain fluid and effectively remove sand, and can adapt to the production needs of shallow shale gas wells throughout their entire life cycle, in order to reduce operational risks, reduce production costs, and improve the productivity and economy of gas wells. Utility Model Content

[0005] The purpose of this invention is to provide a concentric double-pipe drainage and sand removal string structure for shale gas wells, in order to solve the problems of poor adaptability, easy blockage, and high operating costs of existing drainage and production processes in shallow atmospheric pressure shale gas wells, thereby achieving efficient drainage and sand removal throughout the entire life cycle of the gas well.

[0006] This utility model is achieved using the following technical solution: a concentric double-pipe fluid and sand discharge tubing structure for shale gas wells, characterized in that it includes casing; a large tubing, the top end of which is suspended inside the casing via a tubing hanger, and the bottom end connected to a bell mouth; a small tubing, the top end of which is suspended inside the large tubing via a tubing hanger, extending down to the lower part of the horizontal well section; a water distributor installed on the horizontal section of the small tubing, having an anti-backflow function, used for segmented injection of gas or liquid; a one-way valve connected to the bottom end of the small tubing, used to control the unidirectional flow of fluid; and a rotating jet sand-flushing pen tip installed at the bottom of the one-way valve, used to flush and remove sediment in the wellbore during sand flushing operations.

[0007] Furthermore, the lower depth of the horn-shaped opening is located above the position of the last cluster of perforations in the horizontal well.

[0008] Furthermore, the flared end is connected to the large oil pipe via an oil pipe buckle, and its inner diameter is consistent with that of the large oil pipe.

[0009] Furthermore, the coupling of the small oil pipe is chamfered with a chamfer angle greater than 45°.

[0010] Furthermore, the rotating jet sandblasting pen tip jets sandblasting liquid at an angle of approximately 60°.

[0011] Furthermore, the one-way valve achieves unidirectional fluid flow through the sealing structure between the valve disc and the valve seat, and keeps the small tubing filled with air when not in operation. A pressure gauge is connected to the wellhead to monitor downhole pressure changes.

[0012] Furthermore, the large oil pipe has an outer diameter of 73mm or 89mm; the small oil pipe has an outer diameter of 48.0mm and is a standard oil pipe.

[0013] The beneficial effects of the concentric double-pipe fluid and sand discharge tubing structure for shale gas wells described in this utility model include: It is highly adaptable to shallow, atmospheric pressure shale gas wells with sand production. The small tubing can be run to a greater depth than the large tubing, enabling gas lift, fluid drainage, and sand flushing. The tubing does not need to be connected to other mechanical drainage and gas production processes.

[0014] The bell mouth connects to the large oil pipe via a tubing clamp. Its inner diameter is the same as that of the large oil pipe, which can effectively guide the flow, reduce flow resistance, and prevent sand accumulation, ensuring smooth liquid flow in the tubing string.

[0015] The water distributor determines the installation location and number of installation stages based on the gas well's production status. It can implement segmented gas and liquid injection, which can not only replenish formation energy and unclog the wellbore, but also increase the gas flow rate and efficiently discharge liquid and fracturing sand.

[0016] The one-way valve controls the flow direction of fluid through the seal between the valve disc and the valve seat. Liquid and fracturing sand in the wellbore cannot flow back into the small tubing, thus ensuring the smooth flow of the small tubing injection channel. When not in operation, the small tubing is filled with gas. A pressure gauge is connected to the wellhead to facilitate monitoring of downhole pressure changes and timely adjustment of the drainage and production operation system.

[0017] The rotating jet sand-washing pen tip, driven by a large volume of sand-washing fluid, generates a rotational motion and accelerates the sand-washing fluid out along the sand-washing pipe column at a 60° angle, thereby achieving the purpose of efficient sand-washing. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 A schematic diagram of a concentric double-pipe fluid and sand discharge tubing structure for a shale gas well; In the diagram, 1-small oil pipe; 2-large oil pipe; 3-casing; 4-flare mouth; 5-water distributor; 6-water distributor; 7-sandblasting pen tip. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Example

[0022] like Figure 1 As shown, this embodiment provides a concentric double-pipe drainage and sand removal tubing structure for shale gas wells, including casing 3, large tubing 2, small tubing 1, bell mouth 4, water distributor 5, check valve 6, and rotating jet sand removal tip 7.

[0023] Specifically, the main tubing 2 has an outer diameter of 73mm or 89mm. Its top end is suspended inside the casing 3 via a tubing hanger, and its bottom end is connected to the bell mouth 4. The lower depth of the bell mouth 4 is located above the last cluster of perforations in the horizontal well. It is connected to the main tubing 2 via a tubing coupling. The inner diameter of the bell mouth 4 is the same as that of the main tubing 2. It is used for flow guidance, reducing flow resistance, and preventing fracturing sand from accumulating at the bottom.

[0024] Small tubing 1 is a standard tubing with an outer diameter of 48.0 mm. Its top end is suspended inside the large tubing 2 via a tubing hanger, extending down to the lower part of the horizontal well section. The coupling of small tubing 1 is chamfered with a chamfer angle greater than 45° to reduce the risk of obstruction during tubing string insertion or retrieval.

[0025] Multiple water distributors 5 are installed on the horizontal section of the small tubing 1. The water distributors 5 are connected to the small tubing 1 via variable couplings and have an anti-backflow function, which can prevent formation sand and fluid from flowing back into the small tubing 1 during liquid or gas injection. The water distributors 5 can inject gas or liquid in stages to replenish formation energy, clear the wellbore, and increase the gas flow rate in the wellbore, thereby carrying fracturing sand and fluid to the surface.

[0026] The bottom end of the small tubing 1 is connected to a one-way valve 6. The one-way valve 6 controls the unidirectional flow of fluid through the seal between the valve disc and the valve seat, allowing the fluid to flow smoothly from the small tubing 1 into the wellbore, while preventing the liquid and fracturing sand in the wellbore from flowing back into the small tubing 1. In the non-operating state, the small tubing 1 is kept aerated, and a pressure gauge can be connected to the wellhead for monitoring downhole pressure and guiding the drainage and production system.

[0027] The bottom of the single-flow valve 6 is connected to the rotating jet sand-flushing pen tip 7. During the sand-flushing operation, a large volume of sand-flushing fluid is injected through the small oil pipe 1 and drives the sand-flushing pen tip 7 to rotate. The sand-flushing fluid is sprayed onto the well wall at an angle of about 60° to the axial direction of the tubing, achieving efficient flushing and removal of deposited sand particles and ensuring unobstructed well.

[0028] Through the above structural design, the process tubing in this embodiment can form a multi-channel fluid circulation using the concentric structure of the large tubing 2 and the small tubing 1. This enables both early-stage gas lift drainage and induction of flow, efficient sand carrying during mid-stage self-flowing production, and later-stage sand flushing operations via the small tubing 1 in conjunction with the rotating jet sand flushing tip 7. A single tubing run can meet the full lifecycle operation requirements of drainage, sand removal, and sand flushing, reducing production costs and improving the development efficiency and safety of shallow shale gas wells.

[0029] The above embodiments describe the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Modifications and variations made by those skilled in the art without departing from the spirit and scope of this utility model should be protected within the scope of the appended claims.

Claims

1. A concentric double-pipe fluid and sand discharge tubing structure for shale gas wells, characterized in that, Includes casing (3); large tubing (2), the top end of which is hung inside casing (3) by tubing hanger and the bottom end is connected to bell mouth (4); small tubing (1), the top end of which is hung inside large tubing (2) by tubing hanger and extends down to the middle and lower part of horizontal well section; water distributor (5) set on the horizontal section of small tubing (1), which has anti-backflow function and is used for segmented injection of gas or liquid; one-way valve (6) connected to the bottom end of small tubing (1), which is used to control the unidirectional flow of fluid; and rotating jet sand-washing pen tip (7) set at the bottom of one-way valve (6), which is used to flush and remove sand in wellbore during sand-washing operation.

2. The concentric double-pipe fluid and sand discharge tubing structure for shale gas wells according to claim 1, characterized in that, The lower depth of the horn-shaped opening (4) is above the position of the last cluster of perforations in the horizontal well.

3. The concentric double-pipe fluid and sand discharge tubing structure for shale gas wells according to claim 1, characterized in that, The flared mouth (4) is connected to the large oil pipe (2) through an oil pipe buckle, and its inner diameter is consistent with the inner diameter of the large oil pipe (2).

4. The concentric double-pipe fluid and sand discharge tubing structure for shale gas wells according to claim 1, characterized in that, The coupling of the small oil pipe (1) is chamfered, and the chamfer angle is greater than 45°.

5. The concentric double-pipe fluid and sand discharge tubing structure for shale gas wells according to claim 1, characterized in that, The rotating jet sandblasting pen tip (7) sprays sandblasting liquid at an angle of approximately 60°.

6. The concentric double-pipe fluid and sand discharge tubing structure for shale gas wells according to claim 1, characterized in that, The one-way valve (6) achieves unidirectional fluid flow through the sealing structure between the valve disc and the valve seat, and keeps the small oil pipe (1) filled with air in the non-working state. A pressure gauge is connected to the wellhead to monitor downhole pressure changes.

7. The concentric double-pipe fluid and sand discharge tubing structure for shale gas wells according to claim 1, characterized in that, The large oil pipe (2) has an outer diameter of 73mm or 89mm; the small oil pipe (1) has an outer diameter of 48.0mm and is a standard oil pipe.

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