CN116104440A - A kind of oil well injection using pipe string and injecting solution huff and puff method - Google Patents

Abstract

The invention discloses a pipe string used for oil well injection and a solution huff and puff method. The tubing string used for oil well injection includes: oil pipe and casing, the top of the oil pipe is provided with an oil discharge pipe, and the top of the space between the oil pipe and the casing is provided with a liquid injection pipe. A high-pressure sealing device is arranged at the wellhead of the oil pipe, and a flow control valve is arranged at the end of the downhole string of the oil pipe. The invention can realize high-frequency intermittent injection and production in the same well, increase the frequency of interaction between the solution and formation crude oil, improve the oil production efficiency of a single huff and puff cycle, reduce the construction period between huff and puff processes, and increase the oil recovery speed.

Description

A kind of oil well injection using pipe string and injecting solution huff and puff method

technical field

The invention relates to a pipe string used for oil well injection and a solution huff and puff method, belonging to the technical field of oilfield development

Background technique

The huff and puff technology of oil production is usually based on gas medium (water vapor). Steam huff and puff is a kind of extraction that first injects a certain amount of steam into the oil well, shuts the well for a period of time, and waits for the thermal energy of the steam to diffuse to the oil layer, and then opens the well for production. Method for increasing production of heavy oil. The process of steam stimulation operation can be divided into three stages, namely, steam injection, brine and recovery. The steam stimulation method is the most commonly used method in the recovery of heavy oil, and it is also the best thermal recovery method for industrial applications. Steam stimulation is also called steam stimulation or cyclic steam injection. Steam huff and puff mainly utilizes the characteristics of strong compression/expansion performance of gas, and its effect is better, but the production cost is high, and the investment cost of gas injection equipment is large.

Compared with the gas injection huff and puff technology, the development effect of the solution injection huff and puff technology is relatively poor, but because of its low cost and easy operation, it is the best development method for specific reservoirs, so this technology has a certain range of applications.

The solution injection huff and puff technology is mainly applied in oil reservoirs that cannot replenish energy, and the corresponding relationship between oil and water wells in this oil reservoir cannot be established due to reasons such as complex oil layer relationships. The solution can have certain functions. For example, for heavy oil, a solution with viscosity-reducing function can be selected.

The solution injection huff and puff technology is to inject solution into the oil well, soak the well for a period of time, and then pump oil for production, and use the partial pressure increased by the injected solution and the oil-carrying capacity of the solution to obtain more production. It can be seen from Fig. 1 that the fluid injected and produced in the latter time basically passes through the path of the previous fluid, and as the number of times increases, the efficiency of the new recovery gradually decreases.

Contents of the invention

In view of the technical defects and drawbacks in the prior art, embodiments of the present invention provide a pipe string for oil well injection and a solution injection method that overcomes the above problems or at least partially solves the above problems.

An embodiment of the present invention provides a high-pressure sealing device, which includes: an outer cylinder, a telescopic sealing bag and a positioning ring sleeved inside the outer cylinder;

The outer cylinder is ring-shaped and can be sleeved on the polished rod, and the bottom is provided with a support platform;

The positioning ring is placed on the top of the telescopic sealing bag to position and fix the telescopic sealing bag;

The telescopic sealing bag is ring-shaped, placed on the support platform, and is in close contact with the polished rod in an extended state to achieve sealing, and not in contact with the polished rod in a contracted state to release the seal.

Another embodiment of the present invention provides a flow direction control valve, which includes: a control valve part and a power part;

The control valve part includes: a valve body, a valve ball and a gear set; the valve ball and the gear set are arranged in the valve body, and a channel for liquid to flow is opened in the valve ball;

The power part includes: a casing and fan blades; the casing is annular and surrounds the valve body, and the fan blades are arranged in the casing;

The gear set is respectively meshed with the valve ball shaft of the valve ball and the fan blade shaft of the fan blade;

When the fan blade rotates in one direction under the impact of the liquid, it drives the gear set to make the valve ball rotate to close the passage; when it rotates in the other direction, it drives the gear set to make the valve ball Turn to open the channel.

Yet another embodiment of the present invention provides a tubing string used for oil well injection, including: an oil pipe and a casing, the top of the oil pipe is provided with an oil discharge pipe, and the top of the oil casing ring space formed between the oil pipe and the casing is provided There are filling tubes, which:

The above-mentioned high-pressure sealing device is arranged at the wellhead of the oil pipe, and the above-mentioned flow direction control valve is arranged at the end of the downhole string of the oil pipe.

Another embodiment of the present invention provides a solution injection huff and puff method based on the above-mentioned oil well injection using a pipe string, which includes:

sealing the oil pipe through the high-pressure sealing device;

Inject a solution into the space of the oil collar through the liquid injection pipe to close the flow direction control valve;

When the injection pressure reaches a first threshold, the solution is discharged through the injection pipe until the injection pressure drops to a second threshold, so that the flow direction control valve is opened;

releasing the sealing of the oil pipe through the high-pressure sealing device;

extracting liquid from the oil pipe and discharging through the oil extraction pipe;

Repeat the above process until the predetermined injection-production frequency is reached.

The embodiment of the present invention achieves at least the following technical effects: it can realize high-frequency intermittent injection and production in the same well, increase the frequency of interaction between the solution and formation crude oil, improve the oil production efficiency of a single throughput cycle, and also reduce the construction period between the throughput processes, improving oil recovery rate.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure described in the written description, claims hereof, as well as the appended drawings.

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the description, and are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In the attached picture:

(a) in Fig. 1 is the sectional view of the existing oil well injection solution huff and puff, (b) is the sectional view of the oil reservoir;

Fig. 2 is a structural schematic diagram of a pipe string used for oil well injection provided by an embodiment of the present invention;

(a) shows the unsealed state of high-pressure sealing device among Fig. 3, (b) shows the sealed state;

(a) among Fig. 4 shows the longitudinal sectional view of telescoping sealing bag, and (b) shows top view;

(a) in Fig. 5 shows the longitudinal sectional view of outer tube 31, and (b) shows a top view;

Figure 6 is a schematic diagram of the installation of the flow direction control valve provided by the embodiment of the present invention;

(a) in Fig. 7 shows the longitudinal sectional view of flow direction control valve, and (b) shows a top view;

Fig. 8 is a flow chart of the solution injection throughput method provided by the embodiment of the present invention;

(a) in Fig. 9 shows the structure in which the pumping unit is produced, and (b) shows the structure in which the screw pump is produced.

Detailed ways

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided for more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numerals in different drawings refer to the same or similar elements unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with aspects of the invention as recited in the appended claims.

At first the technical terms of the present invention are briefly introduced:

The original energy of the oil reservoir: refers to the amount of energy that the oil reservoir has when it is not developed. These original energies are a part of the reservoir composition and the condition and foundation of reservoir development, so they become another focus of reservoir description. The original energy of the reservoir can be evaluated by the reservoir energy index. The so-called strength of reservoir energy refers to the difficulty of reservoir fluid flowing into the wellbore. The easier the flow, the stronger the energy of the reservoir; otherwise, the weaker it is.

Shaft: Refers to a vertical or inclined type of project excavated from the ground to the ore body in underground mining or underground engineering construction. The vertical project is called a vertical shaft, and the inclined project is called an inclined shaft. The shaft is the main entrance and exit of the mine to the ground, and it is the throat project for lifting and transporting coal (or gangue), transporting personnel, materials and equipment, ventilation and drainage during mine production.

Oil-water well: refers to the oil production well or water injection well in the oil field, and the water injection well is a well used to inject water into the oil layer. In the process of oil field development, water is injected into the reservoir through special water injection wells to maintain or restore the pressure of the reservoir, so that the reservoir has a strong driving force, so as to increase the production speed and recovery rate of the reservoir.

Dynamic seal: refers to the seal between relative moving parts.

Static seal: refers to the seal between two static surfaces.

Packing box: when the pumping unit is used for production, the wellhead dynamic sealing device is used to seal the annular space between the oil pipe and the polished rod. It adopts multi-stage sealing, which has good sealing effect and high pressure resistance. At the same time, due to the design of the universal joint to adjust the eccentricity and angle, it is especially suitable for oil wells with deviated wellheads.

Seal box: A device used to seal the wellhead when a screw pump is used for production.

This embodiment provides a tubing string used for oil well injection, as shown in Figure 1, comprising: an oil pipe 10 and a casing 20, an oil discharge pipe 11 is arranged on the top of the oil pipe 10, and an oil collar is formed between the oil pipe 10 and the casing 20 space, a liquid injection pipe 21 is arranged on the top of the oil collar.

A high-pressure sealing device 30 is arranged at the wellhead of the tubing 10 , and a flow control valve 40 is arranged at the end of the downhole string of the tubing 10 . Specifically, the high-pressure sealing device 30 may be disposed below the oil pipe sealing member 60 at the top of the oil pipe 10 . As shown in Figure 9(a) described later, in the case of using a pumping unit for production, the oil pipe sealing member 60 is specifically a packing box; as shown in Figure 9(b) described later, when using When the screw pump is in production, the oil pipe sealing component 60 is specifically a sealing box.

The specific structure based on the high-pressure sealing device 30 and the flow direction control valve 40 will be described in detail below in conjunction with the accompanying drawings:

As shown in FIG. 3 , the high-pressure sealing device 30 includes: an outer cylinder 31 , a telescopic sealing bag 32 and a positioning ring 33 sleeved inside the outer cylinder 31 . The outer cylinder 31 is ring-shaped and can be fitted over the shaft member 50 for oil pumping. As shown in Figure 9(a) described later, in the case of using a pumping unit for production, the rod shaft part 50 for oil pumping is a polished rod; in the case of using a screw pump for production, the rod for oil pumping is The shaft member 50 is a smooth shaft. In order to simplify the space, the polished rod 50 is taken as an example for description below, and this description is also applicable to the case of a smooth shaft, so no additional details are given here.

The bottom of the outer cylinder 31 is provided with a supporting table 34, the telescopic sealing bag 32 is ring-shaped, placed on the supporting table 34, and the positioning ring 33 is placed on the top of the telescopic sealing bag 32, and the telescopic sealing bag 32 is positioned and fixed. The telescoping sealing bag 32 is in close contact with the polished rod 50 to achieve sealing when it is stretched, and is not in contact with the polished rod 50 to release the seal when it is contracted.

Specifically, in order to realize the expansion and contraction of the telescopic sealing bag 32 , a through hole 35 is opened on the side wall of the outer tube 31 at a position corresponding to the telescopic sealing bag 32 , and through the through hole 35 , the inflatable air is injected into or discharged into the telescopic sealing bag 32 . The flexible sealing bag 32 is expanded and contracted by liquid.

Optionally, there may be multiple telescopic sealing capsules 32 , which are spaced apart by spacer rings 36 . Correspondingly, each telescopic sealing capsule 32 corresponds to a through hole 35 , and the positioning ring 33 is placed on the top of the telescopic sealing capsule 32 located on the top. The diameter of the middle hole of the spacer ring 36 and the positioning ring 33 is preferably larger than the diameter of the polished rod 50 in the range of 4-6 mm, which can not only ensure that there is no contact with the polished rod 50 to cause scratches, but also maintain effective support for the telescopic sealing bag 32.

As shown in Figure 4, it is a concrete structural schematic diagram of the telescopic sealing bag 32, wherein, Fig. 4 (a) shows a longitudinal sectional view of the telescopic sealing bag 32, and Fig. 4 (b) shows a top view of the telescopic sealing bag 32,

The optional material of the telescopic sealing bag 32 is rubber, which has good wear resistance and certain elasticity, and its thickness is not less than 2 mm. As shown in the figure, the telescopic sealing bag 32 is ring-shaped, with corrugated structures on both ends, and corrugated surfaces are formed on both sides of the straight surface, and the telescopic distance range in the axial direction is ±5mm. An expansion fluid delivery tube 47 is connected to the outer side of the telescopic sealing bag 32 and protrudes from the through hole 35 on the side of the outer cylinder 31 .

The expansion liquid is, for example, lubricating oil. After injection, the telescopic sealing bag 32 expands, stretches in the axial direction and makes close contact with the polished rod 50, and continues to increase the pressure to the design pressure difference to complete the sealing operation, as shown in Figure 3(b). When sealing is not required and the up and down movement of the polished rod 50 is not affected, the lubricating oil inside the telescopic sealing bag 32 is discharged by the expansion fluid delivery pipe 47 and sucked by a vacuum pump so that the telescopic sealing bag 32 is in a contracted state, as shown in Fig. 3(a) .

As shown in FIG. 5 , it is a schematic structural view of the outer cylinder 31 , wherein FIG. 5( a ) shows a longitudinal section view of the outer cylinder 31 , and FIG. 5 ( b ) shows a top view of the outer cylinder 31 .

The outer cylinder 31 can be made of stainless steel with a smooth inner wall, which is conducive to improving the sealing performance of the telescopic sealing bag 32. The two ends of the outer cylinder 31 are tapered joints with inner threads, the lower part is connected with the oil pipe 10, and the upper part is connected with the oil pipe sealing part (packing box or sealed box) connection. There is a support platform 34 at the bottom of the outer cylinder 31, the first telescopic sealing bag 32 is placed, the spacer ring 36 is placed on it, the second sealing bag 32 is rotated, and the positioning ring 33 is put into the top, so that the working space of the telescopic sealing bag 32 conforms to Design requirements.

Fig. 7(a) shows a longitudinal sectional view of the flow direction control valve, and Fig. 7(b) shows a top view. As shown in FIG. 7 , the flow direction control valve 40 includes: a control valve part and a power part. The control valve part includes: valve body 41 , valve ball 42 and gear set 43 ; the power part includes: housing 44 and fan blade 45 .

Wherein, the valve ball 42 and the gear set 43 are arranged in the valve body 41 , and the valve ball 42 is provided with a channel 46 for liquid to flow through. Specifically, the valve ball 42 can be arranged in the valve body 41 through a supporting bearing 48 . The casing 44 is annular and surrounds the valve body 41, and the fan blade 45 is arranged in the casing 44; the gear set 43 is respectively connected with the valve ball shaft 47 of the valve ball 42 and the fan blade shaft of the fan blade 45 (not shown in the figure) Mesh.

Specifically, the top of the valve body 41 may be provided with an upper joint 49 for connecting with the oil pipe 10 . As shown in FIG. 6 , the flow control valve 40 is connected to the end of the downhole string of the tubing 10 through an upper joint 49 , so that the flow control valve 40 is installed on the tubing 10 . The housing 44 has a larger diameter than the oil pipe 10 , so that when the valve body 41 is installed on the oil pipe 10 , the fan blade 45 can be exposed outside the radial range of the oil pipe 10 .

When working, when the fan blade 45 rotates in one direction under the impact of the liquid, it drives the gear set 43 to make the valve ball 42 rotate to close the channel 46; when it rotates in the other direction, it drives the gear set 43 to make the valve ball 42 rotate to open Channel 46.

The flow direction control valve 40 is used in conjunction with the high pressure sealing device 30 to more precisely control the flow direction of the fluid.

When the flow direction control valve 40 is not used in the prior art, during the injection process, the solution not only enters the oil layer but also enters the oil pipe 10, and enters the oil pipe 10 and the sucker rod annulus in the reverse direction along the oil well pump, and its pressure is different from the injection pressure. Likewise, the high-pressure sealing device 30 undertakes all pressure-resistant sealing functions.

When the flow control valve 40 is used in this embodiment, when the flow control valve 40 is closed during the injection of the solution, the solution only enters the oil layer, and the high-pressure sealing device 30 hardly assumes the role of pressure-resistant sealing. In the production stage, the flow direction control valve 40 is opened, so that formation outflow fluid can enter the tubing 10 . When the formation is prone to sand production or blockages, the flow direction control valve 40 can reduce the situation of the inlet blockage of the oil well pump.

If the high-pressure sealing device 30 fails, the downhole fluid can also be controlled downhole through the flow direction control valve 40 .

The following will be described in conjunction with the accompanying drawings, based on an embodiment of a solution injection huff and puff method for oil well injection with a high-pressure sealing device 30 and a flow control valve 40 using a pipe string. As shown in FIG. 8, the method includes the following steps:

Step 100 , sealing the oil pipe 10 through the high-pressure sealing device 30 .

As shown in FIG. 5 , the expansion liquid is injected into the telescopic sealing bag 32 through the through hole 35 of the high-pressure sealing device 30 , so that the telescopic sealing bag 32 stretches until it comes into close contact with the polished rod 50 , thereby sealing the oil pipe 10 . Under the support of the internal liquid, the telescopic sealing bag 32 is in close contact with the polished rod 50 to realize the ring surface sealing, and the pressure difference can reach more than 10MPa, so it can withstand the high pressure in the process of injecting the solution, so that the internal and external pressure difference of the oil well pump or screw pump is at Balanced state.

In contrast, if only the existing oil pipe sealing parts (packing box or sealing box) are used to achieve sealing, the effective pressure of the seal under dynamic sealing conditions is not greater than 1MPa; the effective pressure under static sealing conditions is not greater than 3Mpa, unable to withstand the high pressure in the process of injecting the solution.

Step 200, inject solution into the space of the oil collar through the injection pipe, and close the flow direction control valve 40 .

Specifically, prefluid and displacement fluid may be injected sequentially. Prefluid usually has special functions, such as viscosity reduction, solubilization, etc.; displacement fluid is usually formation water or injection water.

As mentioned above, when the solution is injected into the oil collar space, the fan blade 45 is impacted downward by the solution, causing the fan blade 45 to rotate counterclockwise, driving the gear set 43 to rotate the valve ball 42, and after closing the channel 46, the gear set 43 stops The fan blade 45 is stopped to continue to rotate, so that the flow direction control valve 40 is closed. At this time, the solution will only enter the oil layer, but not the oil pipe 10 .

Step 300, when the injection pressure reaches the first threshold, discharge the solution through the injection pipe until the injection pressure drops to the second threshold, so that the flow direction control valve is opened.

This step is a pressure relief process. The first threshold is, for example, 10 MPa, and the second threshold is, for example, 3 MPa. When the fluid in the oil layer passes through the space of the oil collar to discharge pressure and release pressure, the fan blade 45 is impacted upward by the fluid, and the fan blade 45 rotates clockwise, driving the gear set 43 to rotate the valve ball 42, opening the channel 46, and the gear set 43 limits the fan The lobe 45 stops rotating, thereby opening the flow direction control valve 40 .

Step 400 , release the sealing of the oil pipe through the high-pressure sealing device 30 .

As shown in FIG. 3 , the expansion liquid inside the telescopic sealing bag can be discharged through the through hole 35 , so that the telescopic sealing bag 32 shrinks and leaves the polished rod, thereby releasing the sealing of the oil pipe. When the telescopic sealing bag 32 shrinks, it keeps a gap with the polished rod 50 without friction, and does not affect the normal work of the packing box or the sealing box above.

Step 500, extracting liquid from the oil pipe 10 and discharging it through the oil extraction pipe.

Specifically, the oil pump pumps liquid from the oil pipe 10 , and when the oil pump is working, the fan blade 45 is always impacted upward by the fluid, so the flow direction control valve 40 is always in an open state. This design avoids construction problems such as cable layout of electric control valves.

The above process is repeated until a predetermined injection-production frequency is reached, for example, 3 injection-production frequencies.

An example is given below to illustrate the specific implementation process of the method for injecting solution in the present invention.

(1) Install equipment

Initial installation requires tripping of the well tubing string. After installing the oil well injection pipe string, connect the high-pressure pump truck and related injection solution and other supporting equipment at the wellhead casing valve, see Figure 2

(2) High-pressure sealing device implements sealing

Lubricating oil is added to the two liquid injection pipes, and the external pipeline is connected with the liquid injection pipes to form a seal with the outer cylinder. When the pressure is displayed as 17MPa, stop filling and observe the pressure change. If it remains stable, it means that the high-pressure sealing device is in working condition.

(3) Inject the solution and close the flow control valve

In this example, 20m ^{3 of} prefluid and 40m ³ of displacement fluid were used in the first round of throughput.

The solution is continuously injected into the space of the oil-annulus without intermission between the pre-fluid and the displacement fluid. The solution has a large drop in the initial stage in the space of the oil sleeve ring, and the kinetic energy is strong; when it enters the formation, it still maintains a flow rate of 30m ³ /d. Under the impact of this flow, the fan blade flowing to the control valve rotates counterclockwise and closes the control valve so that the solution does not enter the oil pipe.

After the injection is completed, observe the change of the injection pressure. If the pressure drops slowly, it means that the absorption state of the formation is saturated. If the rate of decrease is fast, it means that the formation energy has not been replenished in place, which provides a reference for the next throughput design.

(4) High-frequency intermittent injection and production in the first throughput cycle

In the prior art, after the solution is injected, the well starts to soak, and waits for the injection pressure to drop to about 3MPa, and then the pipe string operation can be implemented. And this method cancels the stewing well operation. After the solution is injected, the injection-production operation starts repeatedly, that is, high-frequency intermittent injection-production.

Set the injection pressure after injecting the solution as 10MPa, change the injection direction at the wellhead, and discharge the liquid from the casing valve to the liquid storage tank of the high-pressure pump truck. When the liquid is discharged, the fan blade of the downhole flow control valve rotates clockwise and opens the flow control valve, so that part of the solution enters the tubing. When the casing discharge pressure reaches 3MPa, close the flow control valve and stop the discharge. Open the valve of the liquid injection pipe of the high-pressure sealing device, release the pressure, and when it is lower than 3MPa, suck to shrink the sealing bag and prevent it from contacting the polished rod.

When the pumping unit is turned on, the extracted oil-free solution can enter the pump truck. When the pumped liquid contains oil, the pumping unit is turned off or the liquid enters the production output pipeline. The structure produced by pumping unit is shown in Figure 9(a), and the structure produced by screw pump is shown in Figure 9(b).

When the total discharge volume reaches 40m ³ , enter the next injection stage of this throughput round.

Repeat related operations from steps (2) to (4) until the design frequency is completed, for example, 3 injection-production frequencies. With the prolongation of the throughput period, the frequency of injection and production decreases gradually.

(5) Oil well pump works, continuous production

After completing the designed injection and production frequency, it has entered the normal production state. Do a good job in production dynamic monitoring, judge the effectiveness of this method and formulate the next step work plan based on the water content change of the produced fluid, cumulative oil production and other information.

(6) Implement the second throughput cycle

When the production of the oil well drops to the design level of the scheme, the second huff and puff scheme will be implemented. Refer to the relevant operations in (1) to (5) for the steps, and it is no longer necessary to lift and lower the pipe string.

In the existing solution injection huff and puff technology, the tubing string in the oil well is first pulled out, and the solution (including functional solvent) is injected into the formation along the tubing or oil/casing annulus through a high-pressure pump truck until the injection pressure is increased to Pin, and then stewed. well. When the pressure drops to Pou, a certain amount of liquid is discharged from the injection port, and then the pumping operation is carried out. After the pumping unit or the screw pump is installed, the mechanical oil production method is carried out. It usually takes at least 10 days to soak the well, mainly to wait for the injection pressure to drop to a recoverable level. When the pressure is higher than Pou, the seal between the pumping unit packing box and the polished rod, and the sealing box of the screw pump and the motor shaft will be closed. Ineffective, resulting in leakage, puncture leakage and even uncontrolled spraying.

The oil well injection pipe string provided by the embodiment of the present invention realizes high-pressure sealing by setting a high-pressure sealing device, which can not only shorten the soaking time, but also eliminate the need to lift out components such as oil pumps in the oil well. That is, after the solution is injected into the space of the oil collar, the production of the oil well pump can be started at any time. Therefore, the present invention has the following advantages:

1. The high-frequency intermittent injection-production method in the same well has been realized, so that the functional solution interacts with the formation crude oil at a high frequency during one huff and puff process, changing from one contact to reciprocating contact with a controllable number of times, and the oil production efficiency of a single huff and puff cycle is improved more than 2 times;

2. It makes it easier to implement the high-frequency intermittent injection-production method in the same well, reduces the construction period between the huff and puff processes, improves the oil recovery speed, and greatly reduces the production cost. In the case of high throughput pressure in the existing technology, it is necessary to operate the pipe string, and the construction period and waiting time for pressure recovery are at least 1 month;

3. Improve the application efficiency and production stimulation effect of solution injection huff and puff technology, so that this technology can be popularized and applied in reservoirs with complex small fault blocks and poor oil quality/pressure cannot be replenished.

The technical effect of the present invention is further illustrated by comparative experiments below.

When injecting the solution, the compressibility of the solution is basically the same as that of water in the range of 4.0-5.0×10 ^-4 MPa ^-1 (temperature 20°-120°, pressure 7-42MPa). From the isothermal compressibility formula (1):

Among them, the isothermal compressibility coefficient refers to the volume change rate of gas with pressure change under isothermal conditions. When the pressure difference is estimated to be 10MPa, the volume compression of the solution is less than 1%, that is, the energy storage capacity of the liquid is weak, and the main function of the pressure difference is to propel the liquid in the reservoir. The kinetic energy released by the energy stored in the liquid is also very low when the pressure difference decreases. Therefore, the solution injection huff and puff method is basically to inject the amount of liquid and then approximate the same amount of recovery. A small amount of crude oil is produced by using the action of the injected solution and the crude oil in the pores. And with the increase of throughput rounds, the action distance is getting farther and farther, and the invalid flow time is getting longer and longer.

Taking the solution huff and puff of a well as an example, assuming that the well depth is 1000m, the reservoir thickness is 5m, the effective reserve radius is 50m, the porosity is 30%, and the oil saturation in newly swept pores is 70%, the calculated oil reserve Qt is 8242m ³ . Inject the highest pressure wellhead of 15MPa, and after the wellhead pressure is 3MPa after brine, the oil will be pumped for production.

The calculation results are shown in Table 1:

Table 1 Parameter analysis of existing solution injection technology

It can be seen from the data that if the existing technology is used for solution injection, as the number of throughputs increases, the efficiency of a single throughput decreases rapidly, and the construction time is prolonged. In Table 1, the recovery factor after 4 puffs is only 8%.

In contrast, using the solution injection technology provided by the present invention limits the efficiency of a single oil production, but the efficiency of a single oil production can be significantly improved by accelerating the frequency of interaction between the solution and crude oil, that is, after the injected fluid reaches a predetermined pressure, take The method of pressure relief and pressurization makes the front edge of the injected solution (the functional solution part) contact with high-saturation crude oil for many times, and at the same time, the fluid in the pores of the integral flow channel involved in the injected fluid also reciprocates, which enhances the oil film stripping effect . So as to achieve the effect of greatly increasing production within one throughput round.

According to the principles of the present invention, the calculation results of the above example are shown in Table 2:

Table 2 The parameter analysis of the solution injection technology of the present invention

From the above data shown in Table 2, it can be seen that when the solution injection huff and puff technology of the present invention is adopted, the efficiency of a single huff and puff is greatly improved, and the recovery rate after 4 huffs and puffs is increased to 15%, and the construction time for tripping and lowering the pipe string is saved and stewing well time.

Those skilled in the art should understand that the embodiments of the present invention may be provided as methods, systems, or computer program products. Accordingly, the present invention can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It should be understood that each procedure and/or block in the flowchart and/or block diagram, and a combination of procedures and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions may be provided to a general purpose computer, special purpose computer, embedded processor, or processor of other programmable data processing equipment to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing equipment produce a An apparatus for realizing the functions specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to operate in a specific manner, such that the instructions stored in the computer-readable memory produce an article of manufacture comprising instruction means, the instructions The device realizes the function specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions can also be loaded onto a computer or other programmable data processing device, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby The instructions provide steps for implementing the functions specified in the flow chart or blocks of the flowchart and/or the block or blocks of the block diagrams.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (16)

1. A high pressure seal, comprising: the outer cylinder is sleeved with a telescopic sealing bag and a positioning ring inside the outer cylinder;

the outer cylinder is annular and can be sleeved on the polish rod, and a supporting table is arranged at the bottom of the outer cylinder;

the positioning ring is placed at the top of the telescopic sealing bag and is used for positioning and fixing the telescopic sealing bag;

the telescopic sealing bag is annular and is placed on the supporting table, and is tightly contacted with the polish rod in an extending state so as to realize sealing, and is not contacted with the polish rod in a contracting state so as to release sealing.

2. The high pressure seal of claim 1, wherein: and a through hole is formed in the side wall of the outer cylinder at a position corresponding to the telescopic sealing bag, and the telescopic sealing bag is expanded and contracted by injecting or discharging expansion liquid into the telescopic sealing bag through the through hole.

3. The high pressure seal of claim 1 wherein said bellows seal is a plurality of bellows seal pockets spaced from one another by spacer rings.

4. The high pressure seal of claim 1 wherein the ends of the bellows seal bladder have a bellows configuration.

5. A flow direction control valve, comprising: a control valve portion and a power portion;

the control valve portion includes: valve body, valve ball and gear set; the valve ball and the gear set are arranged in the valve body, and a channel for liquid to flow through is formed in the valve ball;

the power section includes: a housing and fan blades; the shell is annular and surrounds the valve body, and the fan blades are arranged in the shell;

the gear sets are respectively meshed with a valve ball shaft of the valve ball and a fan blade shaft of the fan blade;

the fan blades drive the gear set to enable the valve ball to rotate to close the channel under the condition that the fan blades rotate towards one direction under the impact of liquid; and in the state of rotating in the other direction, the gear set is driven to enable the valve ball to rotate to open the channel.

6. The flow direction control valve of claim 5, wherein the valve ball is disposed in the valve body by a support bearing.

7. The flow direction control valve according to claim 5, wherein the top of the valve body is provided with an upper joint for connection with an oil pipe.

8. An oil well string comprising: oil pipe and sleeve pipe, the oil pipe top is provided with arranges oil pipe with the top in the oily lantern ring space that forms between the sleeve pipe is provided with notes liquid pipe, its characterized in that:

a high pressure seal as claimed in any one of claims 1 to 4 provided at the wellhead of the tubing and a flow control valve as claimed in any one of claims 5 to 7 provided at the end of the tubing string.

9. The well string for injecting oil according to claim 8, wherein: the high-pressure sealing device is arranged below an oil pipe sealing part at the top of the oil pipe, and an outer cylinder of the high-pressure sealing device is sleeved on a rod shaft part for oil pumping penetrating through the oil pipe sealing part.

10. The well string for injecting oil according to claim 8, wherein: and the upper joint of the flow direction control valve is connected with the tail end of the underground pipe column of the oil pipe.

11. A method of handling injection solutions based on the tubing string for oil well injection according to any one of claims 8 to 10, comprising:

sealing the oil pipe by the high-pressure sealing device;

injecting a solution into the oil collar space through the liquid injection pipe to close the flow direction control valve;

when the injection pressure reaches a first threshold value, discharging the solution through the liquid injection pipe until the injection pressure is reduced to a second threshold value, so that the flow direction control valve is opened;

unsealing the oil pipe by the high-pressure sealing device;

withdrawing fluid from said tubing and draining it through said sucker tube;

repeating the above process until the preset injection and production frequency is reached.

12. The method of claim 11, wherein said sealing said tubing by said high pressure sealing means comprises: and injecting an expansion liquid into the telescopic sealing bag through the through hole, so that the telescopic sealing bag stretches until the telescopic sealing bag is in close contact with the sucker rod shaft component, and the oil pipe is sealed.

13. The method of claim 11, wherein the injecting a solution into the oil collar space comprises: and sequentially injecting a pre-liquid and a displacement liquid.

14. The method of claim 11, wherein said closing said flow control valve comprises: the solution injected into the oil collar space rotates the fan blades in the flow direction control valve in a direction to close the passage in the valve ball.

15. The method of claim 11, wherein said causing the flow direction control valve to open comprises: the solution discharged through the liquid injection pipe rotates the fan blade in the flow direction control valve in the other direction so as to open the channel in the valve ball.

16. The method of claim 11, wherein said unsealing of said tubing by said high pressure seal comprises: and discharging the expansion liquid in the telescopic sealing bag through the through hole, so that the telescopic sealing bag is contracted and separated from the sucker rod shaft component, and the sealing of the oil pipe is released.

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