A pumping pipe string and construction method for a pressure-free well after oil and gas well fracturing

Abstract

The present invention discloses a pumping string for a well without pressure reduction after the fracturing of an oil and gas well, comprising an upper string and a lower string; the upper string comprises a tubular oil pump and a salvage male joint, the salvage male joint is connected to the lower end of the tubular oil pump; the lower string comprises a bridge plug and a salvage female joint, the salvage female joint is connected to the top of the bridge plug, and the salvage female joint is adapted to the salvage male joint; a sealing mechanism is provided on the outer side of the bridge plug, a hollow cavity is provided in the middle of the bridge plug, a thread plug is connected to the bottom of the cavity, a pressure plug is connected to the sliding seal in the cavity, and a shear pin is provided between the pressure plug and the bridge plug, and a liquid inlet hole is provided on the part of the bridge plug between the pressure plug and the thread plug. By sealing the bridge plug seat on the upper part of the fracturing layer, the oil layer pressure is temporarily sealed below the bridge plug, and the pumping operation and wellhead facility installation can be directly carried out, thereby avoiding the cumbersome steps of first pressure reduction before installing the wellhead facility and pumping operation in the traditional operation.

Description

Technical Field

[0001] The invention relates to the technical field of downhole construction, and in particular to a pumping pipe column and a construction method for a pressure-free well after fracturing of an oil and gas well. Background Art

[0002] In order to improve the effect of reservoir transformation, many wells use casing fracturing. After fracturing, there is residual pressure at the wellhead at the end of the blowout. According to well control requirements, the well must be pressurized before pumping operations can be carried out.

[0003] The traditional well-killing method requires many equipment, facilities, and labor costs such as pump trucks, well-killing fluid, operation construction equipment, and operators. This method also has the problems of high well-killing cost, long time, easy pollution of oil layer, and difficult treatment of mixed well-killing fluid. In addition, when the fluid is discharged after well-killing, the amount of liquid discharged is large, and the discharged liquid contains a large amount of hazardous substances such as oil, gas, and chemical materials. Due to environmental protection requirements, these liquids are difficult to handle, which increases the cost of waste liquid treatment and correspondingly increases the operating production cost.

[0004] Therefore, according to the current requirements for improving quality and efficiency, a pumping string and construction method for pressure-free wells after fracturing of oil and gas wells is urgently needed on site to improve the problems existing on site. Summary of the invention

[0005] The purpose of the present invention is to address the defects of the prior art and to provide a pumping tubing string and construction method for oil and gas wells that do not need to be pressurized after fracturing. By sealing the bridge plug seat on the upper part of the fracturing layer, the oil layer pressure is temporarily sealed below the bridge plug, and pumping operations and wellhead facilities can be directly carried out, thereby avoiding the cumbersome steps of first pressing the well, installing the wellhead facilities and pumping operations in traditional operations, thereby improving the efficiency of the operation and reducing the production cost.

[0006] The technical solution of the present invention is:

[0007] A pumping string for a pressure-free well after fracturing of an oil and gas well, characterized in that it comprises an upper string and a lower string;

[0008] The upper tubular column includes a tubular oil pump and a salvage male connector, and the salvage male connector is connected to the lower end of the tubular oil pump;

[0009] The lower tubular column comprises a bridge plug and a salvage female joint, wherein the salvage female joint is connected to the top of the bridge plug, and the salvage female joint is adapted to the salvage male joint;

[0010] A sealing mechanism is provided on the outside of the bridge plug, a hollow cavity is provided in the middle of the bridge plug, a thread plug is connected to the bottom of the cavity, a pressure plug is slidingly sealed in the cavity, a shear pin is provided between the pressure plug and the bridge plug, and a liquid inlet hole is provided on the part of the bridge plug located between the pressure plug and the thread plug.

[0011] Preferably, three steps are provided in the cavity of the bridge plug, and an upper cavity, a middle cavity and a lower cavity with gradually increasing inner diameters are formed in the cavity of the bridge plug through the three steps, the upper end of the pressure plug is adapted to the upper cavity, and the lower end of the pressure plug is adapted to the middle cavity.

[0012] Preferably, the tubular oil pump comprises a pump rod, a pump body and a tubular pump casing, the pump body is slidably connected in the tubular pump casing, and the top of the pump body is connected to the bottom of the pump rod.

[0013] Preferably, a group of annular grooves are provided on the outer peripheral surface of the pressing plug, and a sealing ring is sleeved in the annular groove.

[0014] Preferably, the distance between the wire plug and the liquid inlet hole is greater than the height of the pressure plug.

[0015] Preferably, there are at least two liquid inlet holes, which are distributed circumferentially on the bridge plug.

[0016] Preferably, the liquid inlet hole is in a rectangular shape.

[0017] A method for constructing a pumping string for a pressure-free well after fracturing of an oil and gas well, comprising the following steps:

[0018] (1) First, lower the tubular column into the casing, and seal the lower tubular column seat at the upper part of the fracturing layer through the sealing mechanism outside the bridge plug, at this time, the oil layer pressure is temporarily sealed below the bridge plug;

[0019] (2) Connect the tubular oil pump to the lower end of the oil pipe, use the oil pipe to lower the upper pipe string into the casing and position it above the lower pipe string;

[0020] (3) Install a suction device at the wellhead;

[0021] (4) Pressurize the casing. The pressure drives the pressure plug to move downward and cut off the shear pin. Then the pressure plug falls to the bottom of the bridge plug cavity.

[0022] (5) Start the tubing pump. The oil layer liquid below the bridge plug passes through the liquid inlet hole and the cavity of the bridge plug and is pumped to the wellhead for collection by the tubing pump.

[0023] (6) After pumping is completed, continue to deepen the upper pipe string downward so that the salvage female joint fits with the salvage male joint, and then fish out the upper and lower pipe strings together.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] The present invention seals the bridge plug seat on the upper part of the fracturing layer and temporarily seals the oil layer pressure below the bridge plug, so that pumping operations and wellhead facilities can be directly carried out, thereby avoiding the cumbersome steps of first killing the well and then installing the wellhead facilities and pumping operations in traditional operations, thereby improving the efficiency of the operation and reducing the production cost.

[0026] After the wellhead facilities are installed, the casing is used to pressurize the lower part of the hollow bridge plug, so that the cavity and the liquid inlet hole of the hollow bridge plug are connected to the lower oil layer and the tubing pump, and then production can be started.

[0027] After the pumping is completed, the entire pipe string can be salvaged more conveniently and quickly by deepening the upper pipe string and using the salvage male connector and the salvage female connector. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of the present invention;

[0029] Figure 2 is a schematic diagram of the structure of the bridge plug;

[0030] In the figure: 1, tubular oil pump, 2, pump rod, 3, pump body, 4, tubular pump casing, 5, salvage male joint, 6, salvage female joint, 7, sealing mechanism, 8, bridge plug, 9, sealing ring, 10, shear pin, 11, pressure plug, 12, liquid inlet hole, 13, thread plug, 14, oil pipe, 15, casing, 16, cavity, 17, upper cavity, 18, middle cavity, 19, lower cavity. DETAILED DESCRIPTION

[0031] The present invention is further described below with reference to the accompanying drawings and embodiments.

[0032] Example 1

[0033] See also Figure 1 and Figure 2 The invention discloses a pumping string for a pressure-free well after fracturing of an oil and gas well, comprising an upper string and a lower string.

[0034] The upper pipe string comprises a tubular oil pump 1 and a salvage male connector 5 , and the salvage male connector 5 is connected to the lower end of the tubular oil pump 1 .

[0035] The tubular oil pump 1 comprises a pumping rod 2 , a pump body 3 and a tubular pump casing 4 . The pump body 3 is slidably connected in the tubular pump casing 4 , and the top of the pump body 3 is connected to the bottom of the pumping rod 2 .

[0036] The lower tubular string comprises a bridge plug 8 and a salvage female joint 6 . The salvage female joint is connected to the top of the bridge plug 8 , and the salvage female joint is adapted to the salvage male joint 5 .

[0037] A sealing mechanism 7 is provided on the outer side of the bridge plug 8 , a hollow cavity 16 is provided in the middle of the bridge plug 8 , and a wire plug 13 is connected to the bottom of the cavity 16 .

[0038] A pressure plug 11 is slidably and sealably connected in the cavity 16 , and a shear pin 10 is provided between the pressure plug 11 and the bridge plug 8 . A liquid inlet hole 12 is provided in a portion of the bridge plug 8 between the pressure plug 11 and the wire plug 13 .

[0039] The construction method of the present invention comprises the following steps:

[0040] (1) First, lower the tubular column into the casing 15, and seal the lower tubular column seat at the upper part of the fracturing layer through the sealing mechanism 7 outside the bridge plug 8, thereby temporarily sealing the oil layer pressure below the bridge plug 8.

[0041] (2) Connect the tubular oil pump 1 to the lower end of the oil pipe 14, and use the oil pipe 14 to lower the upper pipe string into the casing 15 to a position above the lower pipe string.

[0042] (3) Install a suction device such as a Christmas tree at the wellhead.

[0043] (4) Pressurize the casing 15 . The pressure drives the pressure plug 11 to move downward and cut the shear pin 10 . Then, the pressure plug 11 falls into the bottom of the cavity 16 of the bridge plug 8 .

[0044] (5) The tubing pump 1 is started. The oil layer liquid below the bridge plug 8 passes through the liquid inlet hole 12 and the cavity 16 of the bridge plug 8 and is then pumped to the wellhead for collection by the tubing pump 1.

[0045] (6) After the pumping is completed, the upper tubular column is further deepened downward so that the salvage female joint cooperates with the salvage male joint 5, and then the upper tubular column and the lower tubular column are fished out together. In this step, the bridge plug 8 can be unsealed using an unsealing tool, or a bridge plug 8 with a soluble sealing mechanism 7 can be directly selected.

[0046] The present invention seals the bridge plug 8 on the upper part of the fracturing layer, temporarily sealing the oil layer pressure below the bridge plug 8, and can directly carry out pumping operations and install wellhead facilities, thereby avoiding the cumbersome steps of first killing the well and then installing wellhead facilities and pumping operations in traditional operations, thereby improving the efficiency of the operation and reducing the production cost.

[0047] After the wellhead facilities are installed, the casing 15 is used to pressurize and knock down the pressure plug 11 at the bottom of the hollow bridge plug 8, so that the cavity 16 and the liquid inlet hole 12 of the hollow bridge plug 8 are connected to the lower oil layer and the tubular oil pump 1, and then production can be started.

[0048] After the pumping is completed, by deepening the upper pipe string and using the salvage male connector 5 and the salvage female connector 6 to cooperate, the entire pipe string can be salvaged more conveniently and quickly.

[0049] Example 2

[0050] See also Figure 1 and Figure 2 The invention discloses a pumping string for a pressure-free well after fracturing of an oil and gas well, comprising an upper string and a lower string.

[0051] The upper pipe string comprises a tubular oil pump 1 and a salvage male connector 5 , and the salvage male connector 5 is connected to the lower end of the tubular oil pump 1 .

[0052] The lower tubular string comprises a bridge plug 8 and a salvage female joint 6 . The salvage female joint is connected to the top of the bridge plug 8 , and the salvage female joint is adapted to the salvage male joint 5 .

[0053] A sealing mechanism 7 is provided on the outer side of the bridge plug 8 , a hollow cavity 16 is provided in the middle of the bridge plug 8 , and a wire plug 13 is connected to the bottom of the cavity 16 .

[0054] A pressure plug 11 is slidably and sealably connected in the cavity 16 , and a shear pin 10 is provided between the pressure plug 11 and the bridge plug 8 . A liquid inlet hole 12 is provided in a portion of the bridge plug 8 between the pressure plug 11 and the wire plug 13 .

[0055] The construction method of the present invention comprises the following steps:

[0056] (1) First, lower the tubular column into the casing 15, and seal the lower tubular column seat at the upper part of the fracturing layer through the sealing mechanism 7 outside the bridge plug 8, thereby temporarily sealing the oil layer pressure below the bridge plug 8.

[0057] (2) Connect the tubular oil pump 1 to the lower end of the oil pipe 14, and use the oil pipe 14 to lower the upper pipe string into the casing 15 to a position above the lower pipe string.

[0058] (3) Install a suction device at the wellhead.

[0059] (4) Pressurize the casing 15 . The pressure drives the pressure plug 11 to move downward and cut the shear pin 10 . Then, the pressure plug 11 falls into the bottom of the cavity 16 of the bridge plug 8 .

[0060] (5) The tubing pump 1 is started. The oil layer liquid below the bridge plug 8 passes through the liquid inlet hole 12 and the cavity 16 of the bridge plug 8 and is then pumped to the wellhead for collection by the tubing pump 1.

[0061] (6) After the pumping is completed, continue to deepen the upper pipe string downward so that the salvage female joint fits with the salvage male joint 5, and then fish out the upper and lower pipe strings together.

[0062] As a further preferred method of this embodiment, specifically:

[0063] Three steps are provided in the cavity 16 of the bridge plug 8, and an upper cavity 17, a middle cavity 18 and a lower cavity 19 with gradually increasing inner diameters are formed in the cavity 16 of the bridge plug 8 through the three steps. The upper end of the pressure plug 11 is adapted to the upper cavity 17, and the lower end of the pressure plug 11 is adapted to the middle cavity 18.

[0064] The gradually enlarged inner cavity formed by the three steps facilitates the installation of the pressure plug 11. At the same time, when pressure is applied in the casing 15, the inner diameter of the lower cavity 19 is larger than that of the pressure plug 11, which makes it easier for the pressure plug 11 to fall into the bottom of the cavity 16 of the bridge plug 8.

[0065] Example 3

[0066] See also Figure 1 and Figure 2 The invention discloses a pumping string for a pressure-free well after fracturing of an oil and gas well, comprising an upper string and a lower string.

[0067] The upper pipe string comprises a tubular oil pump 1 and a salvage male connector 5 , and the salvage male connector 5 is connected to the lower end of the tubular oil pump 1 .

[0068] The lower tubular string comprises a bridge plug 8 and a salvage female joint 6 . The salvage female joint is connected to the top of the bridge plug 8 , and the salvage female joint is adapted to the salvage male joint 5 .

[0069] A sealing mechanism 7 is provided on the outer side of the bridge plug 8 , a hollow cavity 16 is provided in the middle of the bridge plug 8 , and a wire plug 13 is connected to the bottom of the cavity 16 .

[0070] A pressure plug 11 is slidably and sealably connected in the cavity 16 , and a shear pin 10 is provided between the pressure plug 11 and the bridge plug 8 . A liquid inlet hole 12 is provided in a portion of the bridge plug 8 between the pressure plug 11 and the wire plug 13 .

[0071] The construction method of the present invention comprises the following steps:

[0072] (1) First, lower the tubular column into the casing 15, and seal the lower tubular column seat at the upper part of the fracturing layer through the sealing mechanism 7 outside the bridge plug 8, thereby temporarily sealing the oil layer pressure below the bridge plug 8.

[0073] (2) Connect the tubular oil pump 1 to the lower end of the oil pipe 14, and use the oil pipe 14 to lower the upper pipe string into the casing 15 to a position above the lower pipe string.

[0074] (3) Install a suction device at the wellhead.

[0075] (4) Pressurize the casing 15 . The pressure drives the pressure plug 11 to move downward and cut the shear pin 10 . Then, the pressure plug 11 falls into the bottom of the cavity 16 of the bridge plug 8 .

[0076] (5) The tubing pump 1 is started. The oil layer liquid below the bridge plug 8 passes through the liquid inlet hole 12 and the cavity 16 of the bridge plug 8 and is then pumped to the wellhead for collection by the tubing pump 1.

[0077] (6) After the pumping is completed, continue to deepen the upper pipe string downward so that the salvage female joint fits with the salvage male joint 5, and then fish out the upper and lower pipe strings together.

[0078] As a further preferred method of this embodiment, specifically:

[0079] A group of annular grooves are provided on the outer peripheral surface of the pressure plug 11, and a sealing ring 9 is sleeved in the annular grooves.

[0080] The sealing effect between the pressure plug 11 and the cavity 16 of the bridge plug 8 is increased by a set of sealing rings 9 .

[0081] The distance between the wire plug 13 and the liquid inlet hole 12 is greater than the height of the pressure plug 11 .

[0082] This design can prevent the pressure plug 11 from falling into the bottom of the cavity 16 of the bridge plug 8 and blocking the liquid inlet 12, so that the liquid flows through the liquid inlet 12 into the cavity 16 of the bridge plug 8 more smoothly.

[0083] Example 4

[0084] See also Figure 1 and Figure 2 The invention discloses a pumping string for a pressure-free well after fracturing of an oil and gas well, comprising an upper string and a lower string.

[0085] The upper pipe string comprises a tubular oil pump 1 and a salvage male connector 5 , and the salvage male connector 5 is connected to the lower end of the tubular oil pump 1 .

[0086] The lower tubular string comprises a bridge plug 8 and a salvage female joint 6 . The salvage female joint is connected to the top of the bridge plug 8 , and the salvage female joint is adapted to the salvage male joint 5 .

[0087] A sealing mechanism 7 is provided on the outer side of the bridge plug 8 , a hollow cavity 16 is provided in the middle of the bridge plug 8 , and a wire plug 13 is connected to the bottom of the cavity 16 .

[0088] A pressure plug 11 is slidably and sealably connected in the cavity 16 , and a shear pin 10 is provided between the pressure plug 11 and the bridge plug 8 . A liquid inlet hole 12 is provided in a portion of the bridge plug 8 between the pressure plug 11 and the wire plug 13 .

[0089] The construction method of the present invention comprises the following steps:

[0090] (1) First, lower the tubular column into the casing 15, and seal the lower tubular column seat at the upper part of the fracturing layer through the sealing mechanism 7 outside the bridge plug 8, thereby temporarily sealing the oil layer pressure below the bridge plug 8.

[0091] (2) Connect the tubular oil pump 1 to the lower end of the oil pipe 14, and use the oil pipe 14 to lower the upper pipe string into the casing 15 to a position above the lower pipe string.

[0092] (3) Install a suction device at the wellhead.

[0093] (4) Pressurize the casing 15 . The pressure drives the pressure plug 11 to move downward and cut the shear pin 10 . Then, the pressure plug 11 falls into the bottom of the cavity 16 of the bridge plug 8 .

[0094] (5) The tubing pump 1 is started. The oil layer liquid below the bridge plug 8 passes through the liquid inlet hole 12 and the cavity 16 of the bridge plug 8 and is then pumped to the wellhead for collection by the tubing pump 1.

[0095] (6) After the pumping is completed, continue to deepen the upper pipe string downward so that the salvage female joint fits with the salvage male joint 5, and then fish out the upper and lower pipe strings together.

[0096] As a further preferred method of this embodiment, specifically:

[0097] There are at least two liquid inlet holes 12, which are distributed around the bridge plug 8, and the shape of the liquid inlet holes 12 is rectangular.

[0098] This design allows the liquid in the oil layer to flow more smoothly into the cavity 16 of the bridge plug 8 through the liquid inlet hole 12, and the rectangular opening is not easily blocked by impurities.

[0099] Example 5

[0100] This embodiment is further optimized on the basis of embodiment 4, specifically:

[0101] A filter screen may be installed on the liquid inlet hole 12 to further prevent the liquid inlet hole 12 from being blocked by impurities in the oil layer liquid.

Claims

1. A pumping string for a pressure-free well after fracturing of an oil and gas well, characterized in that: It includes an upper pipe string and a lower pipe string; The upper tubular column includes a tubular oil pump and a salvage male connector, and the salvage male connector is connected to the lower end of the tubular oil pump; The lower tubular column comprises a bridge plug and a salvage female joint, wherein the salvage female joint is connected to the top of the bridge plug, and the salvage female joint is adapted to the salvage male joint; A sealing mechanism is provided on the outside of the bridge plug, a hollow cavity is provided in the middle of the bridge plug, a wire plug is connected to the bottom of the cavity, a pressure plug is slidably sealed in the cavity, a shear pin is provided between the pressure plug and the bridge plug, and a liquid inlet hole is provided on the portion of the bridge plug between the pressure plug and the wire plug; The cavity of the bridge plug is provided with three steps, and an upper cavity, a middle cavity and a lower cavity with gradually increasing inner diameters are formed in the cavity of the bridge plug through the three steps, the upper end of the pressure plug is adapted to the upper cavity, and the lower end of the pressure plug is adapted to the middle cavity; A group of annular grooves are provided on the outer peripheral surface of the pressing plug, and a sealing ring is sleeved in the annular groove.

2. A pumping string for a pressure-free well after fracturing of an oil and gas well according to claim 1, characterized in that: The tubular oil pump comprises a pump rod, a pump body and a tubular pump casing. The pump body is slidably connected in the tubular pump casing, and the top of the pump body is connected to the bottom of the pump rod.

3. The pumping string for a pressure-free well after fracturing of an oil and gas well according to claim 1, characterized in that: The distance between the wire plug and the liquid inlet hole is greater than the height of the pressure plug.

4. A pumping string for a pressure-free well after fracturing of an oil and gas well according to claim 1, characterized in that: There are at least two liquid inlet holes, which are distributed circumferentially on the bridge plug.

5. A pumping string for a pressure-free well after fracturing of an oil and gas well according to claim 4, characterized in that: The shape of the liquid inlet hole is rectangular.

6. A method for constructing a pumping string for a pressure-free well after fracturing of an oil and gas well according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) First, lower the tubular column into the casing, and seal the lower tubular column seat at the upper part of the fracturing layer through the sealing mechanism outside the bridge plug, at this time, the oil layer pressure is temporarily sealed below the bridge plug; (2) Connect the tubular oil pump to the lower end of the oil pipe, use the oil pipe to lower the upper pipe string into the casing and position it above the lower pipe string; (3) Install a suction device at the wellhead; (4) Pressurize the casing. The pressure drives the pressure plug to move downward and cut off the shear pin. Then the pressure plug falls to the bottom of the bridge plug cavity. (5) Start the tubing pump. The oil layer liquid below the bridge plug passes through the liquid inlet hole and the cavity of the bridge plug and is pumped to the wellhead for collection by the tubing pump. (6) After pumping is completed, continue to deepen the upper pipe string downward so that the salvage female joint fits with the salvage male joint, and then fish out the upper and lower pipe strings together.

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