Self-unfreezing counterweight device and self-unfreezing method for pressure test of oil-water well

Abstract

The invention belongs to the field of oil-water well pressure testing, and discloses an oil-water well pressure testing self-releasing counterweight device and a self-releasing method. A guide cone is in threaded connection with an outer cavity, the outer cavity is in threaded connection with an inner cavity through the lower portion of the cavity, a plunger is lowered to the bottom of the cavity from the top of the inner cavity, and the lower surface of the plunger is in threaded connection with the bottom of a connecting rod; the inner surface of the sealing limiting piece is provided with threads, the upper seal is in threaded connection with the outer cavity, the lower portion of the external connecting piece is in threaded connection with the top of the connecting rod, the upper portion of the external connecting piece is provided with internal threads, and the external connecting piece is connected with a pressure meter and an outer cavity through hole which are distributed in the wall of the outer cavity. According to the invention, it can be ensured that test equipment smoothly passes through a shaft oil column, and accidents of oil blocking, resistance and steel wire tensile fracture are prevented from happening. The inner and outer cavity through holes are formed in the upper part of the inner cavity and the lower part of the sealing limiting piece, and two layers of holes are uniformly distributed and are used as inner and outer cavity communication channels.

Description

Technical Field

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

[0002] Oil and water well pressure testing is an important means to understand the injection and production balance of the reservoir and evaluate the reservoir pressure maintenance. The data obtained is an important basis for development adjustment and potential tapping. The most common method for oil and water well pressure testing is the steel wire test. The instrument (because the pressure gauge body is light, the instrument is composed of a pressure gauge and a counterweight, the two are connected by threads, and the counterweight is a solid steel structure) is hung on the steel wire using ground testing equipment. After the test is completed, the downhole instrument is brought up to play back the recorded data.

[0003] Due to the gravity differentiation of oil and water, the liquid column in some pressure test wells has oil and water in the wellbore. Affected by the properties of the oil itself and the degassing of crude oil, the oil column in some wells has high viscosity and large viscous resistance. During the test construction, after the test instrument enters the oil column, heavy oil will adhere to the surface of the instrument, and even stick to the surrounding heavy oil. Due to the viscous resistance of the heavy oil in the well, it is difficult to lift it up at the end of the construction. The longer the instrument stays in the well, the more difficult it is. Since the pressure gauge is usually about 30cm long and the counterweight part is about 100cm long, the viscous resistance mainly comes from the counterweight part. The oil card cannot be lifted up, and the steel wire breaks due to the effort, resulting in the accident of the instrument falling into the well from time to time, and salvage operations are forced to be carried out, consuming a lot of manpower and material resources. Summary of the invention

[0004] Under normal circumstances, the test instrument can be smoothly lifted out of the oil column. Considering that the main reason for oil sticking is that the instrument is relatively still in the oil column, the stay time is too long, and the outer surface is attached with heavy oil, and even sticks to the surrounding heavy oil, resulting in excessive viscous resistance. If the heavy oil adhesion can be removed, the instrument can be smoothly lifted out by the steel wire.

[0005] In order to solve the problem that the testing instrument cannot be lifted up due to the viscous resistance of crude oil in the wellbore, the present invention designs a double-layer cavity structure, in which 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, which consists of 11 parts, including a guide cone, an outer cavity, an inner cavity, a plunger, a connecting rod, a pressure cap, a sealing limiter, an upper sealing part, an external connection part, an outer cavity through hole, and inner and outer cavity through holes. The pressure cap is made of plastic, the sealing limiter is made of hard plastic, and the other parts are made of manganese steel with a high density. The connection methods and functions of each part are as follows:

[0008] The guide cone is threadedly connected to the outer cavity, and the guide cone is used to guide the instrument to be lowered along the wellbore;

[0009] The outer cavity is connected to the inner cavity through threads 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, which 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 to 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 part. The inner surface of the sealing part 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 seal is threadedly connected to the outer cavity.

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

[0015] The through holes of the outer cavity are distributed on the wall of the outer cavity. The hole distribution method is: one hole is set every 5 cm in the longitudinal direction, one hole is set every 90 degrees along the cavity in the horizontal direction, and the two adjacent holes are rotated 45 degrees and staggered. It is a channel connecting to the outside. Before the instrument is lowered into the well, the through hole 10 of the outer cavity is temporarily blocked with paraffin.

[0016] The through holes of the inner and outer cavities are 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 the communication channels 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, squeezes out a gap between the wellbore crude oil and the outer wall of the counterweight, lubricates the outer wall of the counterweight, reduces viscous resistance, and realizes jam-releasing.

[0018] Before the test, paraffin is used to temporarily block the pores in the outer cavity wall, and lubricating liquid is pre-injected into the inner and outer cavities. When the oil is stuck and cannot be lifted up 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 liquid 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 unstuck and lifted-up of the instrument.

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

[0020] The existing counterweight for oil and water well pressure testing is a solid steel structure. When oil is stuck, the instrument cannot be lifted up and even the steel wire may break. The present invention proposes a counterweight device with a double-layer cavity structure to relieve the adhesion of heavy oil and reduce viscous resistance. When the device encounters resistance when lifting the test equipment, lubricant can be sprayed outward from the inside of the cavity to reduce viscous resistance, ensuring that the test equipment passes through the wellbore oil column smoothly, avoiding oil sticking and resistance and steel wire tension breakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0022] Figure 1 It is a schematic diagram of the structure of the present invention.

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

[0024] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical scheme of the present invention is now described in detail in conjunction with the following specific embodiments, but it should not be understood as limiting the scope of the present invention. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the equipment used can be obtained from commercial channels.

[0025] Example 1

[0026] The structure of the device of the present invention is as follows:

[0027] 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 lower part 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, while bearing the weight of the counterweight body. The upper seal 8 is threadedly connected to the outer cavity 2, and the lower part of the external connection 9 is threadedly connected to the top of the connecting rod 5. The upper part of the external connection 9 is provided with an internal thread, and a pressure gauge is connected to it. The outer cavity through holes 10 are distributed on the outer cavity wall, and the inner and outer cavity through holes 11 are located at the upper part of the inner cavity 3 and the lower part of the sealing limiter 7. Two layers of 8 holes are evenly distributed as the connecting channel between the inner and outer cavities.

[0028] 1. Preparation before the test:

[0029] (1) The guide cone 1, the outer cavity 2, and the inner cavity 3 are threadedly connected in sequence;

[0030] (2) Connecting 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 the plunger with the plunger thread by friction with the bottom of the inner cavity 3;

[0031] (3) Use paraffin wax to temporarily seal the outer cavity through hole 10.

[0032] (4) Lubricating liquid (such as a surfactant that does not react with or cannot 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 and outer cavities.

[0033] (5) The pressure cap 6 is inserted through the top of the connecting rod 5 and sits on the top of the inner cavity.

[0034] (6) The sealing limiter 7 is inserted through the top end of the connecting rod 5 and pressed onto the pressure cap 6.

[0035] (7) The upper sealing member 8 is inserted into the top end of the connecting rod 5 and is threadedly connected to the outer cavity 2. The limiting sealing member 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.

[0036] (8) The top end of the connecting rod 5 is threadedly connected to the external connection part 9. The top end of the connecting rod 5 is threadedly connected to the pressure gauge through the thread on the external connection part to form a test instrument.

[0037] 2 Lowering test: The above test instruments are hung on the steel wire and lowered into the well for testing through the ground test equipment. During the lowering process, the weight of the counterweight device is borne by the friction between the sealing limiter and the connecting rod.

[0038] 3. After the test, the upward pull encounters resistance and the card is released automatically

[0039] (1) The test instrument cannot be lifted due to the viscous resistance of the oil column in the wellbore.

[0040] (2) As the lifting force increases, the piston connecting rod 5 overcomes the friction resistance of the limit seal 7, and moves relative to the counterweight body (guide cone 1, outer cavity 2, inner cavity 3), driving the plunger 4 to move upward.

[0041] (3) The upwardly 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, thereby reducing viscous resistance and unblocking the instrument and lifting it up.

[0042] (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 separated by lubricating liquid, ensuring that the test equipment can pass through the wellbore oil column smoothly and avoiding oil jams and wire breakage accidents.

[0043] It is necessary to add that:

[0044] 1. The lubricating liquid is not limited to surfactants that do not react with paraffin or cannot dissolve paraffin;

[0045] 2. The sealing limiter 7 can be replaced by an independent connector, which is connected by thread and connecting rod, placed between the sealing limiter 7 and the upper sealing member 8, and fails due to stress fracture or wear. The test wire specification diameter is 2.083mm~3.810mm, the minimum breaking force is 5380N, and the design limit connection resistance limit is 500N, that is, when subjected to a tensile force of 50kg, the limit connection fails, and the limit force is adjusted by adjusting the thread of the sealing limiter 7.

[0046] 3. Temporary sealing: When the formation temperature is <50℃, use paraffin wax to seal. When the formation temperature is >50℃, add polyethylene wax to the paraffin wax to increase the melting point.

[0047] By adding 5% polyethylene wax, the melting point of paraffin can be increased to 90°C.

[0048] The above-described embodiments are only preferred embodiments of the present invention, but not all feasible embodiments of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in 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 lower part 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 the sealing limiter (7) and the connecting rod (5) is used to limit the upward movement of the piston, while bearing the weight of the counterweight body. The upper seal (8) is threadedly connected to the outer cavity 2, and the lower part of the external connection (9) is threadedly connected to the top of the connecting rod (5). The upper part of the external connection (9) is provided with an internal thread and is connected to a pressure gauge. The outer cavity through holes (10) are distributed on the outer cavity wall, and the inner and outer cavity through holes (11) are located at the upper part of the inner cavity (3) and the lower part of the sealing limiter (7). Two layers of 8 holes are evenly distributed as the inner and outer cavity communication channels.

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 through holes (10) of the outer cavity is as follows: a hole is arranged every 5 cm in the longitudinal direction, and one hole is arranged every 90 degrees along the cavity in the horizontal direction, and two 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 component (8), and the external connecting component (9) are made of manganese steel with a relatively high density.

8. A self-unblocking 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; (2) Lowering test: The above-mentioned test instruments are hung on the steel wire and lowered 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 limit seal 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 upwardly 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 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, thereby reducing viscous resistance and unblocking the instrument and lifting it 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 passes through the wellbore oil column smoothly and avoiding oil jams and wire breakage accidents.

9. The self-unlocking method for oil and water well pressure testing according to claim 8, characterized in that: The steps of assembling the self-releasing counterweight device include: ① The guide cone (1), the outer cavity (2), and the inner cavity (3) are sequentially threadedly connected; ② Connecting 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 the plunger with the plunger thread by friction with 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 higher than the through hole (11) of the inner and outer cavities; ⑤ Insert the pressure cap (6) through the top of the connecting rod (5) and seat it 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 upper sealing member (8) is inserted into the top end of the connecting rod (5) and threadedly connected to the outer cavity (2). The limiting sealing member 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; ⑧ The top end of the connecting rod (5) is threadedly connected to the external connection member (9), and is connected to the pressure gauge through the thread on the external connection member to form a testing 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 the paraffin.

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