CN101769140A - Device for displacing oil underground, preventing reflow and automatically relieving pressure - Google Patents

Abstract

A downhole oil flooding prevention backflow and automatic pressure relief device, which is mainly composed of a body, a sealing ball cover, a sealing ball, a slider, a spring, a limit block and a spring seat. There are several limit blocks on the inner periphery of the upper part, female threads on the inner periphery of the lower part, and a cylindrical slide with a core hole in the center of the upper end with a sealing ball cover in the middle of the body and a sealing ball on the upper part of the center hole. There is a coil spring in the middle and lower part, and a spring seat threaded with the body in the lower part, and several oil drain holes in the middle of the body; the dynamic sealing fit between the slider and the body; the male thread at the lower end of the body and the underground lifting The outlet pipe of the pump is connected with thread, and the upper end of the male thread is connected with the tubing string. The invention has the advantages of simple structure, reliable sealing, no soft seals, long service life, no need to replace, reduces the number of oil pipe lifting, and saves workover costs.

Description

Downhole oil flooding prevention backflow and automatic pressure relief device

1. Technical field

The invention relates to a downhole oil displacement preventing backflow and automatic pressure relief device which can timely release excess energy accumulated in the well after downhole oil displacement lifting equipment stops working, prevent backflow, prevent motor reversal and release the pressure of the tubing string in time.

2. Background technology

In the downhole driving and lifting crude oil process production, when the shutdown is shut down, the energy accumulated in the production process will be released, and the fluid stored in the tubing will generate elastic energy, and the output fluid in the tubing and the output pipeline will form with the fluid in the casing. Pressure difference, etc. cause the drive pump to become a hydraulic motor, which not only damages the components of the drive device but also endangers the safety of the equipment. At present, for oil wells with too low formation energy, a one-way valve is generally installed on the surface pipeline near the wellhead to prevent the pipeline fluid from backflowing into the oil well after shutdown, and a one-way valve is installed on the upper end of the driving equipment to prevent pipeline fluid from Backfilling of the oil well prevents the motor from reversing due to the backflow of the fluid. At the same time, it is equipped with an oil drain for pressure relief. This requires that the oil drain has a high airtightness during normal production, and the oil pipe must be pulled out after the pressure is relieved. Updating the downhole oil drainer increases redundant operating procedures and unnecessary economic investment,

3. Contents of the invention

The purpose of the present invention is to provide a downhole flooding oil backflow prevention and automatic pressure relief device to solve the above-mentioned problems in the prior art.

The invention is mainly composed of a body, a sealing ball cover, a sealing ball, a slider, a spring, a limit block and a spring seat. Block limit block, the inner circumference of the lower part is provided with a female thread, and the middle part of the body is provided with a cylindrical slider with a core hole in the center with a sealing ball cover at the upper end and a sealing ball at the upper part of the center hole, and a coil spring at the middle and lower part , the lower part is provided with a spring seat threaded with the main body, and several oil drain holes are provided in the middle part of the main body; the dynamic sealing fit between the slider and the main body; The male thread is connected with the tubing string.

The diameter of the upper end of the slider is smaller than the diameter below the upper end, and the upper end is provided with a horse-tooth button, and the upper end of the central hole is provided with a 45° chamfer.

The sealing spherical cover is set as a circular concave shape, and the outer surface of the sealing spherical cover is provided with an internal and external communication hole, and a horse tooth button matching the horse tooth button on the slider is provided at the lower end of the sealing spherical cover.

The invention is installed on the outlet pipe of the downhole lift pump, which can prevent backflow and reverse rotation of the motor when the lift pump stops working, and can also drain the crude oil in the oil pipe into the casing when the oil well is in operation, preventing the oil pipe from being pulled up. The crude oil in the tubing is sprayed to the ground to pollute the environment. The invention has the advantages of simple structure, reliable sealing, no soft seals, long service life and no replacement, which reduces the times of pulling up the tubing and saves workover costs.

4. Description of drawings

Accompanying drawing - is a kind of structural representation of the present invention

In the figure 1-body 2 sealing ball cover 3-sealing ball 4-limiting block 5-slider 6-spring 7-spring seat 8-oil drain hole

5. Specific implementation

In order to further disclose the technical solutions of the present invention, the following will be described in detail through examples in conjunction with the accompanying drawings:

The present invention is mainly composed of a body 1, a sealing ball cover 2, a sealing ball 3, a slider 5, a spring 6, a limit block 4 and a spring seat 7. Thread, the inner circumference of the upper part is provided with a number of limit blocks 4, the inner circumference of the lower part is provided with female threads, and the center of the upper end with a sealing ball cover 2 is provided with a core hole and the upper part of the center hole is provided with a sealing ball 3 in the middle of the body. The cylindrical slider 5 has a coil spring 6 at the middle and lower part, and a spring seat 7 threadedly connected with the body at the lower part, and several oil drain holes are arranged at the middle part of the body; the dynamic sealing fit between the slider and the body; the lower end of the body The male thread is connected with the outlet pipe thread of the downhole lift pump, and the upper end male thread is connected with the tubing string.

1) In the attached drawing, the elastic force of the selected spring is greater than or equal to the gravity of the slider and the ball valve, and the stress conditions to be satisfied are:

f ₁ ≥m ₁ ×g+m ₂ ×g (1)

f ₁ =-k×Δx ₀ (2)

Among them, f ₁ - spring force of spring 6 at no load, N; m ₁ - mass of slider 5, kg; m ₂ - mass of sealing ball, kg; k - spring stiffness coefficient, N/m; Δx ₀ - The compressed length of the spring under no load, m; g-the acceleration due to gravity, 9.8N/kg.

Suppose: A _u - the area of the upper part of the slider 5, m ² ; A _d - the area of the bottom of the slider 5, m ² ; A _r - the area of the center hole, m ² .

It can be seen from the drawings that A _d = A _u (actually A _d ≥ A _u all meet the conditions), when the device is lowered to the predetermined position, both ends of the body will be filled with downhole fluid, according to the liquid pressure formula and formula (1) The pressure on the lower part of the valve body is greater than that on the upper part, and the pressure relief port of the valve is closed at this time.

2) When normal production input starts

p _d =p _out >>p _u =ρgh (3)

In the formula, p _out - pump outlet pressure, P _d ; h - liquid height above the device, m.

When starting normal production, the initial value of h is very small. At this time, the sealing ball is opened, and the fluid in the lower part of the device enters the tubing through the center hole. When the downhole fluid fills the tubing, the pressure difference between the two ends basically remains stable after the surface starts to flow out. The stress situation of the present invention is:

f ₁ +p _d ×A _d >m ₁ ×g+p _u ×A _u A _u (4)

In normal production, the force at both ends always satisfies the formula (4), the sealing ball will remain open, and the underground fluid will continuously enter the oil pipe at the upper end of the valve from the center hole, and the pressure relief port of the valve will always be closed at this time.

3) During the pressure relief process:

When the downhole unit stops or cannot operate normally, the pressure p _d on the lower part of the present invention drops rapidly to close to the pump inlet pressure due to the sudden loss of the pressure energy supplied by the downhole unit. Rapid release forms a high pressure, and the fluid will flow back through the center hole, causing the sealing ball to close quickly. At this time, p _u is much higher than p _d , so that the two ends of the present invention form a very high pressure difference, and the slider starts due to unbalanced force. Sliding down, the oil drain hole is opened, and the fluid in the upper oil pipe begins to flow from the pressure relief port to the annular space of the oil casing, until the force on the upper end of the present invention is equal to or less than the force on the bottom, the slider moves up, and the oil drain hole is sealed and stops Drain.

Claims (3)

1. displacing oil underground, preventing reflow and automatic decompression device, mainly by body, the sealing ball cover, ball sealer, slide block, spring, limited block and spring base are formed, it is cylindrical to it is characterized in that body is made as, the upper and lower periphery is provided with male thread, be provided with some limited blocks in the top week, week is provided with box thread in the bottom, the center that the middle part is provided with upper end band sealing ball cover in body is provided with the cylindrical slider that heart hole and centre bore top are provided with ball sealer, the middle and lower part is provided with helical spring, the bottom is provided with the spring base that is threaded with body, is provided with several draining holes at the middle part of body; Movable sealing cooperates between slide block and the body; Body lower end male thread is connected with down-hole lifting delivery side of pump gas thread, and the upper end male thread is connected with tubing string.

2. displacing oil underground, preventing reflow according to claim 1 and automatic decompression device is characterized in that described upper end of slide block portion diameter less than the following diameter in upper end, and the upper end is provided with the gingival cyst of mucous gland in the newborn button, are provided with 45 ° of chamferings in the centre bore upper end.

3. displacing oil underground, preventing reflow according to claim 1 and 2 and automatic decompression device, it is characterized in that described ball sealer is covered with is round concave shape, be provided with inside and outside intercommunicating pore in sealing ball cover appearance, sealing ball cover lower end be provided with slide block on the gingival cyst of mucous gland in the newborn button that is complementary of gingival cyst of mucous gland in the newborn button.

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