An oil-water well pressure test self-unblocking counterweight device and a self-unblocking method

Abstract

The present application belongs to the field of oil-water well pressure testing, and discloses an oil-water well pressure testing self-unjamming counterweight device and a self-unjamming method. A guide cone is threadedly connected with an outer cavity body, the outer cavity body is threadedly connected with an inner cavity body through a lower part of the cavity body, a plunger is lowered from a top of the inner cavity body to a bottom of the cavity body, a lower surface of the plunger is threadedly connected with a bottom of a connecting rod, a pressing cap is used for sealing the inner cavity body to prevent liquid in the inner cavity body from overflowing upward, an inner surface of a sealing limiting part is provided with threads, an upper sealing part is threadedly connected with the outer cavity body, a lower part of an external connecting part is threadedly connected with a top of the connecting rod, an upper part of the external connecting part is provided with internal threads, a pressure gauge is connected to the upper part, through holes of the outer cavity body are distributed on a wall of the outer cavity body, through holes of the inner cavity body and the outer cavity body are located at an upper part of the inner cavity body and a lower part of the sealing limiting part, and two layers of holes are uniformly distributed, serving as a communication passage of the inner cavity body and the outer cavity body. The present application can ensure that a testing device smoothly passes through a wellbore oil column, and avoid oil jamming resistance and steel wire stretching and breaking accidents.

Description

Technical Field

[0001] The invention relates to the field of oil and water well pressure testing, and in particular to a self-releasing counterweight device and a self-releasing method for oil and water well pressure testing. Background Art

[0002] Oil and water well pressure testing is a crucial means of understanding the injection-production balance in a reservoir and evaluating reservoir pressure maintenance. The data obtained is a crucial basis for development adjustments and potential development measures. Wireline testing is the most common method for oil and water well pressure testing. Wireline testing involves suspending the instrument (due to its light weight, the instrument consists of a pressure gauge and a counterweight, which are threaded together, with the counterweight being a solid steel structure) on a wireline using surface testing equipment. After the test is completed, the downhole instrument is retrieved for playback and recording.

[0003] Due to the gravity-induced separation of oil and water, the fluid column in some pressure test wells fluctuates between oil and water. Due to the inherent properties of the oil and crude oil degassing, the oil column in some wells is highly viscous and exhibits significant viscous resistance. During testing, after the test instrument enters the oil column, heavy oil adheres to its surface, sometimes even bonding to the surrounding heavy oil. This viscous resistance within the well makes it difficult to lift the instrument at the end of the test, a challenge that increases the longer the instrument remains in the well. Since pressure gauges are typically around 30 cm long and the counterweight is approximately 100 cm long, the viscous resistance primarily comes from the counterweight. Consequently, the oil card cannot be lifted, and the steel wire breaks under the strain, causing the instrument to frequently fall into the well, forcing salvage operations that consume significant manpower and material resources. Summary of the Invention

[0004] Under normal circumstances, the test instrument can be smoothly removed from the oil column. However, oil sticking is primarily caused by the instrument remaining relatively still in the oil column for too long, resulting in heavy oil adhering to its outer surface and even bonding to the surrounding heavy oil, causing excessive viscous resistance. If the heavy oil adhesion can be removed, the instrument can be smoothly removed using the wireline.

[0005] In order to solve the problem that the testing instrument is affected by the viscous resistance of crude oil in the wellbore and the oil card cannot be lifted up, the present invention designs a double-layer cavity structure, the tops of the inner and outer cavities are connected, and the outer cavity wall is distributed with temporarily sealed channels. A piston that can move up and down is provided in the inner cavity, and a seal and a limit connection are provided on the upper part of the piston connecting rod, and a counterweight device is connected to the pressure gauge body through a thread.

[0006] The above-mentioned object of the present invention is achieved by the following technical solutions:

[0007] A self-releasing counterweight device for oil and water well pressure testing consists of 11 parts: a guide cone, an outer cavity, an inner cavity, a plunger, a connecting rod, a pressure cap, a sealing stopper, an upper seal, an external connector, an outer cavity through-hole, and an inner cavity through-hole. The pressure cap is made of plastic, the sealing stopper is made of hard plastic, and the remaining parts are made of high-density manganese steel. The connection and function of each part are as follows:

[0008] The guide cone is threadedly connected to the outer cavity and is used to guide the instrument down the wellbore;

[0009] The outer cavity is connected to the inner cavity through a thread at the lower part of the cavity, and the inner surface of the bottom of the inner cavity is roughened.

[0010] The plunger is a hollow part that is lowered from the top of the inner cavity to the bottom of the cavity. The lower surface of the plunger is roughened and is threadedly connected to the bottom of the connecting rod.

[0011] The rubber pressure cap is used to seal the inner cavity and prevent the liquid in the inner cavity from overflowing upward.

[0012] The function of the sealing limiter is to seal the outer cavity to prevent the liquid in the cavity from overflowing upwards, and secondly, to serve as a limit load-bearing component. The inner surface of the seal is provided with threads, and the connecting rod part in contact with the limiter is roughened. The friction with the connecting rod is used to limit the upward movement of the piston, while bearing the weight of the counterweight body.

[0013] The upper sealing member is threadedly connected to the outer cavity.

[0014] The lower part of the external connection piece is connected with the top of the connecting rod by thread, and the upper part of the external connection piece is provided with an internal thread and is connected with a pressure gauge.

[0015] The external cavity through-holes are distributed along the wall of the cavity. Holes are spaced every 5 cm vertically and every 90 degrees horizontally along the cavity, with adjacent holes staggered 45 degrees. These holes communicate with the outside world. Before lowering the instrument into the well, the external cavity through-holes 10 are temporarily sealed with paraffin.

[0016] The through hole of the inner cavity is located at the upper part of the inner cavity and the lower part of the sealing limiter, and two layers of holes are evenly distributed as a communication channel between the inner and outer cavities.

[0017] The jam-releasing method of the present invention utilizes lubricating liquid pre-injected into the cavity to be sprayed outward through the temporary sealing hole of the outer cavity, thereby squeezing out a gap between the wellbore crude oil and the outer wall of the counterweight, lubricating the outer wall of the counterweight, reducing viscous resistance, and achieving jam-releasing.

[0018] Before the test, paraffin wax is used to temporarily block the pores in the outer cavity wall, and lubricating fluid is pre-injected into the inner and outer cavities. When the oil jam is unable to be lifted due to the viscous resistance of the crude oil, the connecting rod overcomes the friction resistance of the limiter and drives the plunger to move upward relative to the outer cavity, squeezing the lubricating fluid in the cavity. The liquid in the cavity is ejected outward, reducing the viscous resistance between the crude oil and the instrument, and realizing the release and lifting of the instrument.

[0019] The beneficial effects of the present application compared with the prior art are:

[0020] The existing oil-water well pressure test weight is a solid steel structure, and when oil sticking occurs, the instrument cannot be lifted, and even causes steel wire fracture accidents. The present application proposes a weight device with a double-cavity structure, which can spray lubricant from the inside to the outside of the cavity when the test equipment encounters resistance, reduces the viscous resistance, ensures the smooth passage of the test equipment through the wellbore oil column, and avoids oil sticking resistance and steel wire stretching and fracture accidents. BRIEF DESCRIPTION OF DRAWINGS

[0021] The present application will be further described below in conjunction with the drawings and examples.

[0022] Figure 1 The present application is a structural schematic diagram.

[0023] 1 guide cone, 2 outer cavity, 3 inner cavity, 4 plunger, 5 connecting rod, 6 pressure cap, 7 sealing limiting piece, 8 upper sealing piece, 9 external connecting piece, 10 outer cavity through hole, 11 inner cavity through hole. DETAILED DESCRIPTION

[0024] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present application, the technical solutions of the present application will be described in detail below in conjunction with the following specific examples, but it should not be understood as limiting the scope of the present application. Unless otherwise specified, the experimental methods used in the present application are conventional methods, and the equipment used can be obtained from commercial channels. EXAMPLE

[0025] The structure of the device of the present application is as follows:

[0026] The guide cone 1 is threadedly connected with the outer cavity 2, the outer cavity 2 is threadedly connected with the inner cavity 3 through the threads at the lower part of the cavity, the plunger 4 is a hollow piece, which is lowered from the top of the inner cavity 3 to the bottom of the cavity, the lower surface of the plunger 4 is threadedly connected with the bottom of the connecting rod 5, the pressure cap 6 is used to seal the inner cavity to prevent the liquid in the inner cavity from overflowing upward, the inner surface of the sealing limiting piece 7 is provided with threads, which are used to limit the upward movement of the piston by friction with the connecting rod 5, and also bear the weight of the weight body, the upper sealing piece 8 is threadedly connected with the outer cavity 2, the lower part of the external connecting piece 9 is threadedly connected with the top of the connecting rod 5, and the upper part of the external connecting piece 9 is provided with internal threads, which are connected with a pressure gauge, the outer cavity through holes 10 are distributed on the wall of the outer cavity, and the inner cavity through holes 11 are located at the upper part of the inner cavity 3 and the lower part of the sealing limiting piece 7, and are evenly distributed in two layers of 8 holes as the communication channels between the inner and outer cavities.

[0027] 1 Preparation before testing:

[0028] (1) threadedly connect the guide cone 1, the outer cavity 2 and the inner cavity 3 in sequence;

[0029] (2) Connect the plunger and connecting rod: lower the plunger 4 to the bottom of the inner cavity, insert the connecting rod 5 into the inner cavity, and connect it to the plunger thread by friction with the bottom of the inner cavity 3;

[0030] (3) Use paraffin wax to temporarily seal the outer cavity through hole 10.

[0031] (4) Lubricating liquid (such as a surfactant that does not react with or dissolve paraffin) is injected into the inner and outer cavities, and the injection height is not higher than the through hole 11 of the inner cavity.

[0032] (5) The pressure cap 6 is inserted through the top of the connecting rod 5 and sits on the top of the inner cavity.

[0033] (6) Insert the sealing limiter 7 through the top of the connecting rod 5 and press it onto the pressure cap 6.

[0034] (7) The top end of the connecting rod 5 is inserted into the upper sealing member 8 and is threadedly connected to the outer cavity 2. The sealing limiter with an internal thread locks the connecting rod with a roughened contact section under the pressure of the upper sealing member 8, thereby limiting the relative movement between the connecting rod and the counterweight body.

[0035] (8) The top end of the connecting rod 5 is threadedly connected to the external connector 9. The connecting rod 5 is connected to the pressure gauge through the thread on the external connector to form a test instrument.

[0036] 2. Lowering test: The above-mentioned test instrument is suspended on a steel wire and lowered into the well for testing using ground testing equipment. During the lowering process, the weight of the counterweight device is borne by the friction between the sealing limiter and the connecting rod.

[0037] 3. After the test, if you encounter resistance when pulling up, you can release the card by yourself.

[0038] (1) The test instrument cannot be lifted due to the viscous resistance of the oil column in the wellbore.

[0039] (2) As the lifting force increases, the piston connecting rod 5 overcomes the friction resistance of the sealing limiter 7 and moves relative to the counterweight body (guide cone 1, outer cavity 2, inner cavity 3), driving the plunger 4 to move upward.

[0040] (3) The upward-moving plunger 4 squeezes the lubricating liquid (such as a surfactant that does not react with or cannot dissolve paraffin) pre-filled in the inner cavity 3. The lubricating liquid in the inner cavity transmits pressure to the outer cavity through the inner and outer cavity channels. The double-cavity design connected at the top ensures that the lubricating liquid in the outer cavity is relatively evenly stressed. Under the action of pressure, the lubricating liquid in the outer cavity breaks through the temporarily sealed hole in the outer cavity wall and sprays outward, squeezing out a gap between the outer wall of the counterweight and the crude oil in the wellbore, and lubricating the outer wall of the counterweight, reducing viscous resistance, and the instrument is unstuck and lifted up.

[0041] (4) Due to the radial pressure of the oil column in the wellbore and the vacuum negative pressure at the bottom of the piston, the outward injection speed of the liquid in the cavity is objectively limited. The outer wall of the counterweight and the crude oil in the wellbore are always isolated by lubricating liquid, ensuring that the test equipment can pass through the wellbore oil column smoothly, avoiding oil jams and wire breakage accidents.

[0042] It is necessary to add that:

[0043] 1. The lubricating liquid is not limited to surfactants that do not react with paraffin or cannot dissolve paraffin;

[0044] 2. The seal stopper 7 can be replaced with an independent connector, connected by a threaded rod and placed between the seal stopper 7 and the upper seal 8. It will break or fail under stress. The test wire diameter is 2.083mm to 3.810mm, with a minimum breaking force of 5380N. The designed limit resistance limit of the limit connection is 500N, meaning that the limit connection fails under a tensile force of 50kg. The limit force can be adjusted by adjusting the threads of the seal stopper 7.

[0045] 3. Temporary sealing: When the formation temperature is <50℃, use paraffin wax for sealing. When the formation temperature is >50℃, add polyethylene wax to the paraffin wax to increase the melting point.

[0046] By adding 5% polyethylene wax, the melting point of paraffin can be increased to 90°C.

[0047] The above-described embodiments are only preferred embodiments of the present invention, and are not intended to be all feasible embodiments of the present invention. Any obvious modifications made by a person skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A self-releasing counterweight device for oil and water well pressure testing, characterized in that: The guide cone (1) is threadedly connected to the outer cavity (2), and the outer cavity (2) is threadedly connected to the inner cavity (3) through the thread at the bottom of the cavity. The plunger (4) is a hollow part, which is lowered from the top of the inner cavity (3) to the bottom of the cavity. The lower surface of the plunger (4) is threadedly connected to the bottom of the connecting rod (5). The pressure cap (6) is used to seal the inner cavity to prevent the liquid in the inner cavity from overflowing upward. The inner surface of the sealing limiter (7) is provided with a thread, and the friction between it and the connecting rod (5) is used to limit the upward movement of the piston and at the same time bear the weight of the counterweight body. The upper sealing member (8) is threadedly connected to the outer cavity (2), and the lower part of the external member (9) is threadedly connected to the top of the connecting rod (5). The upper part of the external member (9) is provided with an internal thread and is connected to a pressure gauge. The outer cavity through hole (10) is distributed on the outer cavity wall, and the inner cavity through hole (11) is located at the upper part of the inner cavity (3) and the lower part of the sealing limiter (7). There are 8 holes evenly distributed in two layers, which serve as a communication channel between the inner and outer cavities. Before the instrument is lowered into the well, lubricating liquid is added to the inner cavity (3) in advance, and the through hole (10) of the outer cavity is temporarily blocked. When the instrument encounters resistance, the piston connecting rod (5) overcomes the friction resistance of the sealing limiter (7), and moves relative to the guide cone (1), the outer cavity (2), and the inner cavity (3), driving the plunger (4) to move upward; the upward moving plunger (4) squeezes the lubricating liquid pre-filled in the inner cavity (3), and the lubricating liquid in the inner cavity transmits pressure to the outer cavity through the inner and outer cavity channels. The double cavity design connected at the top ensures that the lubricating liquid in the outer cavity is relatively evenly stressed. Under the action of pressure, the lubricating liquid in the outer cavity breaks through the temporarily sealed hole of the outer cavity wall and sprays outward, squeezing out a gap between the outer wall of the counterweight and the crude oil in the wellbore, and plays a lubricating role on the outer wall of the counterweight, reducing the viscous resistance, and the instrument is unstuck and lifted up.

2. The self-releasing counterweight device for oil and water well pressure testing according to claim 1 is characterized in that: The inner surface of the bottom of the inner cavity (3), the lower surface of the plunger (4), and the portion of the connecting rod (5) in contact with the sealing limiter (7) are all roughened.

3. The self-releasing counterweight device for oil and water well pressure testing according to claim 1 is characterized in that: The hole distribution of the outer cavity through hole (10) is as follows: a hole is provided every 5 cm in the longitudinal direction, one hole is provided every 90 degrees along the cavity in the horizontal direction, and the upper and lower adjacent holes are rotated 45 degrees and staggered.

4. The self-releasing counterweight device for oil and water well pressure testing according to claim 1 is characterized in that: Before the instrument is lowered into the well, the through hole (10) of the outer cavity is temporarily blocked with paraffin.

5. The self-releasing counterweight device for oil and water well pressure testing according to claim 1 is characterized in that: The material of the pressure cap (6) is plastic.

6. The self-releasing counterweight device for oil and water well pressure testing according to claim 1 is characterized in that: The sealing limiter (7) is made of hard plastic.

7. The self-releasing counterweight device for oil and water well pressure testing according to claim 1 is characterized in that: The guide cone (1), the outer cavity (2), the inner cavity (3), the plunger (4), the connecting rod (5), the upper sealing member (8), and the external connecting member (9) are made of manganese steel with a relatively high density.

8. A self-unlocking method for oil and water well pressure testing, characterized in that: The steps include: (1) Preparation before testing: Assemble the self-releasing counterweight device described in claim 1 and connect it to the pressure gauge through the threads on the external parts to form a test instrument; (2) Lowering test: Hang the above-mentioned test instruments on the steel wire and lower them into the well for testing through the ground test equipment; (3) After the test, if the card is blocked, it will be released automatically: ①The test instrument cannot be lifted due to the viscous resistance of the oil column in the wellbore; ② As the lifting force increases, the piston connecting rod (5) overcomes the friction resistance of the sealing limiter (7), and moves relative to the guide cone (1), the outer cavity (2), and the inner cavity (3), driving the plunger (4) to move upward; ③ The upward-moving plunger (4) squeezes the lubricating liquid pre-filled in the inner cavity (3). The lubricating liquid in the inner cavity transmits pressure to the outer cavity through the inner and outer cavity channels. The double-cavity design connected at the top ensures that the lubricating liquid in the outer cavity is relatively evenly stressed. Under the action of pressure, the lubricating liquid in the outer cavity breaks through the temporary sealing hole of the outer cavity wall and sprays outward, squeezing out a gap between the outer wall of the counterweight and the crude oil in the wellbore, and lubricating the outer wall of the counterweight, reducing viscous resistance, and the instrument is unstuck and lifted up; ④ Due to the radial pressure of the oil column in the wellbore and the vacuum negative pressure at the bottom of the piston, the outward injection speed of the liquid in the cavity is objectively limited. The outer wall of the counterweight and the crude oil in the wellbore are always isolated by lubricating liquid, ensuring that the test equipment can pass through the wellbore oil column smoothly, avoiding oil jams and steel wire breakage accidents.

9. The self-unlocking method for oil and water well pressure testing according to claim 8, characterized in that: Assembling the self-releasing counterweight device includes the following steps: ① Thread the guide cone (1), the outer cavity (2), and the inner cavity (3) in sequence; ② Connect the plunger and connecting rod: lower the plunger (4) to the bottom of the inner cavity, insert the connecting rod (5) into the inner cavity, and connect it to the plunger thread by friction between the plunger (4) and the bottom of the inner cavity (3); ③ Use paraffin wax to temporarily seal the through hole of the outer cavity (10); ④ Inject lubricating liquid into the inner and outer cavities, with the injection height not exceeding the through hole (11) of the inner cavity; ⑤ Insert the pressure cap (6) through the top of the connecting rod (5) and sit on the top of the inner cavity; ⑥ Insert the sealing limiter (7) through the top of the connecting rod (5) and press it onto the pressure cap (6); ⑦ The top end of the connecting rod (5) is inserted into the upper sealing member (8) and threadedly connected to the outer cavity (2). The sealing limiter provided with an internal thread locks the connecting rod with a roughened contact section under the pressure of the upper sealing member (8), thereby limiting the relative movement of the connecting rod (5) and the counterweight body; ⑧The top end of the connecting rod (5) is connected to the external connection piece (9) by thread, and is connected to the pressure gauge through the thread on the external connection piece to form a test instrument.

10. The self-unlocking method for oil and water well pressure testing according to claim 8 or 9, characterized in that: The lubricating liquid is a surfactant that does not react with or dissolve paraffin.

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