WO2021057760A1

WO2021057760A1 - Method, device, and system for low-frequency variable-pressure oil reservoir exploitation of remaining oil in pores

Info

Publication number: WO2021057760A1
Application number: PCT/CN2020/116982
Authority: WO
Inventors: 陈兴隆; 韩海水; 俞宏伟; 李思源; 周体尧; 姬泽敏; 张善严; 王敬瑶; 伍家忠
Original assignee: 中国石油天然气股份有限公司
Priority date: 2019-09-24
Filing date: 2020-09-23
Publication date: 2021-04-01
Also published as: RU2768835C1

Abstract

A method, a device, and a system for low-frequency variable-pressure oil reservoir exploitation of remaining oil in pores. The method comprises: acquiring a distribution diagram of gas in an oil reservoir and a pressure distribution diagram during gas injection; determining the position of a shaft device of a low-frequency variable-pressure well in the oil reservoir according to the distribution diagram and the pressure distribution diagram; intermittently raising and lowering a pressure at a preconfigured frequency by using the position of the shaft device of the low-frequency variable-pressure well in the oil reservoir; and exploiting, by means of a steam injection well and an oil production well, remaining oil in the oil reservoir in which a distribution status of the remaining oil has changed. The system comprises: the shaft device, a data analysis device, and an oil production device. The shaft device comprises: a support packer (1), a support sub (2), an oil layer packer (3), a vent sleeve (4), a high-pressure container (5), an electromagnetic pneumatic valve (6), a gas booster unit (7), and a hollow connecting rod (8). Short-term high pressure is achieved in the vicinity of a wellbore, such that the remaining oil is desorbed, and a direction of a main seepage channel is changed, thereby further improving extraction.

Description

Low-frequency variable pressure oil reservoir exploitation method, device and system of remaining oil in pores

Technical field

The invention relates to the technical field of oilfield development, and in particular to a low-frequency variable pressure oil reservoir exploitation method, device and system for remaining oil in pores.

Background technique

Gas injection and oil displacement technology is an advantageous technology in the late stage of water injection development and the development of low-permeability reservoirs. It has the advantages of low seepage resistance, quick recovery of formation pressure, and obvious oil displacement effect. However, it also has disadvantages that are difficult to overcome, that is, gas is easily trapped in the oil. The reservoir flows along the high-permeability channel. Once the gas has entered and formed a channel in the reservoir, it will be difficult for the gas injected in the later stage to play the role of oil displacement after being produced from the production well. However, in oil reservoirs, some pores including channeling channels still contain high-saturation remaining oil. The prior art has a method to plug some channeling channels, but usually it can only solve the near-well zone, and the plugging agent is difficult. Into the deep part of the reservoir, the main function of this method is to change the seepage direction of the injected gas to a certain extent. The purpose is not to increase the remaining oil in the channeling channel and the surrounding pores. Therefore, the existing technology has not used this part of the remaining oil. The better way.

Summary of the invention

The embodiments of the present invention provide a low-frequency variable pressure oil reservoir production method, device and system for remaining oil in pores, which solves the problem that the prior art cannot perform high-saturation remaining oil in some pores of channeling channels. Technical issues of mining.

The embodiment of the present invention provides a low-frequency variable pressure well wellbore device, which includes: a support packer, a support nipple, an oil layer packer, a vent sleeve, a high-pressure vessel, an electromagnetic gas control valve, a gas booster unit, and a hollow connection Rod, support packer, support sub-section, oil layer packer, vent sleeve, high pressure vessel, electromagnetic gas control valve, gas booster unit and hollow connecting rod are located in the casing;

Among them, the supporting packer is used to: expand the card between the inner wall of the casing and the supporting sub to support the supporting sub;

The lower part of the support pup joint is connected with the support packer, and the upper part of the support pup joint is connected with the oil layer packer. The support pup joint is tubular and has holes on the pipe side. The holes are used to allow the gas in the lower oil layer to pass into the oil layer packer. ；

The oil layer packer is used to: isolate the upper oil layer so that gas enters and exits in the lower oil layer;

The lower part of the aeration sleeve and the outside are connected with the oil layer packer, the inside of the aeration sleeve is connected with the high-pressure vessel, and the cylinder wall of the aeration sleeve has through holes, which are the channels for the gas in the oil layer packer to enter the upper casing space ；

The electromagnetic gas control valve is connected to the vent sleeve through the through hole of the vent sleeve, and is used to open and close the through hole, so that the gas in the lower oil layer can enter the high-pressure container and the upper space;

The lower end of the high-pressure container is connected with the inside of the vent sleeve, the upper end of the high-pressure container is connected with the gas booster unit, and the high-pressure container is in the shape of a hollow cylinder;

The gas booster unit is used to compress the low-pressure gas in the high-pressure container into high-pressure gas;

The bottom of the hollow connecting rod is connected to the gas booster unit, and the top of the hollow connecting rod is connected to the external ground control device, which is used to make the external gas enter the low-frequency variable pressure well wellbore device, and the gas in the lower oil layer is discharged from the low-frequency variable pressure well wellbore device .

The embodiment of the present invention also provides a low-frequency variable pressure oil reservoir production method for the remaining oil in the pores, including:

Obtain the gas distribution map in the reservoir and the pressure distribution map between the injection and production wells during the gas injection process;

Determine the placement position of the low-frequency variable pressure well borehole device in the oil reservoir according to the gas distribution map in the oil reservoir and the pressure distribution map between the injection and production wells during the gas injection process;

The placement position of the low-frequency variable pressure well borehole device in the reservoir is used to intermittently increase and decrease the pressure at a preset frequency to change the remaining oil distribution in the reservoir at the placement position;

Through steam injection wells and oil production wells, the remaining oil in the reservoir that has changed the distribution of the remaining oil is exploited.

The embodiment of the present invention also provides a low-frequency variable pressure oil reservoir production system for remaining oil in pores, including: a low-frequency variable pressure well borehole device, a data analysis device, and an oil production device;

Among them, the data analysis device is used to: obtain the distribution map of the gas in the reservoir, the pressure distribution map between the injection and production wells during the gas injection process, and according to the distribution map of the gas in the reservoir, the injection and production wells during the gas injection process To determine the placement position of the low-frequency variable pressure well borehole device in the reservoir;

The low-frequency variable pressure well borehole device is used to place it in the corresponding position in the oil reservoir, and the placement position in the oil reservoir to intermittently increase and decrease the pressure at a preset frequency, and to change the remaining oil distribution state in the reservoir at the placement position ；

The oil extraction device is used to extract the remaining oil in the reservoir that has changed the distribution of the remaining oil through steam injection wells and oil production wells.

The embodiment of the present invention also provides a computer device including a memory, a processor, and a computer program stored in the memory and capable of running on the processor, and the processor implements the above-mentioned method when the computer program is executed.

The embodiment of the present invention also provides a computer-readable storage medium, and the computer-readable storage medium stores a computer program for executing the above-mentioned method.

In the embodiment of the present invention, according to the gas distribution map in the reservoir and the pressure distribution map between the injection and production wells during the gas injection process, it is determined that the low-frequency variable pressure well bore device is placed in a certain position in the reservoir to preset Increase and decrease the pressure intermittently at the frequency of the system, so as to change the remaining oil distribution state in the reservoir at the placement position. In this way, the remaining oil in the reservoir that has changed the remaining oil distribution state can be exploited through steam injection wells and oil production wells. Improve the degree of recovery.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

Figure 1 is a schematic diagram of gas distribution in the reservoir during gas injection;

Figure 2 is a schematic diagram of the enlarged cross-sectional gas distribution of the gas in the reservoir during the gas injection process;

Figure 3 is a schematic diagram of the remaining oil distribution in the enlarged area during the gas injection process;

Figure 4 is a schematic diagram of pressure distribution between injection and production wells during gas injection;

Fig. 5 is a schematic diagram of a low-frequency variable pressure oil reservoir production method for remaining oil in pores according to an embodiment of the present invention.

Fig. 6 is a schematic diagram of pressure distribution of a low-frequency variable pressure method provided by an embodiment of the present invention;

Figure 7 is a schematic structural diagram of a low-frequency variable pressure well wellbore device provided by an embodiment of the present invention;

Figure 8 is a schematic structural diagram of a vent sleeve provided by an embodiment of the present invention;

Figure 9 is a schematic diagram of the flow of gas through a vent sleeve provided by an embodiment of the present invention;

Figure 10 is a schematic diagram of the structure of a high-pressure vessel provided by an embodiment of the present invention;

Figure 11 is a schematic diagram of a partially assembled structure of a high-pressure vessel provided by an embodiment of the present invention;

Figure 12 is a front view of an electromagnetic pneumatic valve provided by an embodiment of the present invention;

Figure 13 is a top view of an electromagnetic pneumatic valve provided by an embodiment of the present invention;

Figure 14 is a schematic diagram of a gas booster provided by an embodiment of the present invention;

Figure 15 is an abstract diagram of a gas booster provided by an embodiment of the present invention;

Figure 16 is a schematic diagram of a parallel gas booster unit provided by an embodiment of the present invention;

Figure 17 is a schematic view of the hollow connecting rod structure provided by an embodiment of the present invention.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

Gas injection development usually involves injecting gas in injection wells and producing oil in production wells. The main function of gas as a displacing agent for displacing crude oil is its low seepage resistance, especially in low-permeability reservoirs where water injection is difficult, gas injection can achieve better results. It is precisely because of its low seepage resistance that the fingering phenomenon is serious during the oil displacement process. When the production well sees gas, the gas content will rise rapidly, leading to the occurrence of gas channeling. After gas channeling, most of the production wells need to be shut down for treatment, resulting in a short effective period of gas injection and low recovery rate of gas flooding. Gas injection technology cannot be widely used. Figures 1 to 3 show the fluid state in the reservoir during the gas injection process. Figure 1 is a longitudinal section. The main gas channel is formed in the middle of the reservoir, and there is a relatively large volume of gas unswept area around, especially the bottom of the reservoir where the unused volume is the most. Figure 2 shows the shape of the main gas channel and the unaffected area in cross section. Figure 3 is an enlarged effect of the local area in Figure 2, showing that even though most of the pores of the main channel, there is still a considerable amount of remaining oil retained. The reason is that after the gas flows through, a continuous gas phase is formed in the main channel, and the gas flow tends to be stable. Due to the blocking of rock particles, interfacial tension, adsorption, etc., part of the remaining oil cannot flow.

Figure 4 shows the pressure distribution along the length between injection and production wells when gas injection is stably produced. The injection well has the highest pressure Pin and the production pressure has the lowest Pout. At the bottom of the injection well, the pressure drop funnel is obvious, that is, the pressure drop gradient is larger, then the pressure tends to be flat, and the difference ΔP between the pressure Pi and Pout at position i is small. Curve 1 and curve 2 respectively show the pressure distribution of high-permeability and low-permeability reservoirs. The low-permeability reservoir with differential pressure at position i is smaller than that of the high-permeability reservoir, so that there is more remaining oil in the pores. That is, the lower the reservoir permeability, the more serious the impact of gas channeling, the higher the remaining oil saturation, and the lower the degree of recovery.

According to the remaining oil distribution position and force characteristics in the reservoir pores, a low-frequency variable pressure method is proposed. As shown in Figure 5, the method includes:

Step 501: Obtain the gas distribution map in the reservoir and the pressure distribution map between the injection and production wells during the gas injection process;

Step 502: Determine the placement position of the low-frequency variable pressure well bore device in the oil reservoir according to the gas distribution map in the oil reservoir and the pressure distribution map between the injection and production wells during the gas injection process;

Step 503: Use the placement position of the low-frequency variable pressure well borehole device in the reservoir to intermittently increase and decrease the pressure at a preset frequency, and change the remaining oil distribution state in the reservoir at the placement position;

Step 504: Exploit the remaining oil in the oil reservoir whose distribution state of the remaining oil has been changed through the steam injection well and the oil production well.

That is, the low-frequency variable pressure well borehole device is used to intermittently increase and decrease the pressure at a certain frequency at a low pressure position (ie, the placement position), which causes the pressure within a certain range around the position to change. This effect causes the original stable gas flow to be changed, and the gas seepage direction undergoes a reversal change within a frequency, thereby changing the state of the remaining oil in the pores of the affected area, and a part of the remaining oil reaches the flowing state and is produced, which improves Extraction degree. At the same time, the change of the remaining state and the low-frequency gas injection well will cause the redistribution of the seepage resistance in the affected area, resulting in a change in the shape and direction of the main seepage channel originally formed, which will expand the swept volume of gas flooding and increase the degree of recovery more significantly.

Figure 6 shows that a low-frequency variable pressure well is set in the middle of the injection-production well. The gas injected into the well causes the pressure to rise, and then the well quickly discharges the gas to cause the pressure to drop. When the speed is higher, the pressure will be lower than the initial pressure . The analysis of the corresponding pressure curves (injection pressure line and discharge pressure line) shows that the seepage state in the affected area is inevitably affected by pressure changes, where P _fimax is the maximum injection pressure and P _fomin is the minimum discharge pressure.

In the embodiment of the present invention, the key to the realization of the principle of the low-frequency variable pressure method lies in the design of the wellbore device of the low-frequency variable pressure well. In order to achieve the effect of gas flowing at a high velocity and causing short-term high pressure in the near-well zone, the present invention designs a corresponding low-frequency variable pressure well wellbore device, as shown in Figure 7.

The low-frequency variable pressure well borehole devices from bottom to top are: support packer 1, support short section 2, oil layer packer 3, vent sleeve 4, high pressure vessel 5, electromagnetic gas control valve 6, gas booster unit 7 It is composed of hollow connecting rod 8, including supporting packer 1, supporting short section 2, oil layer packer 3, vent sleeve 4, high pressure vessel 5, electromagnetic gas control valve 6, gas booster unit 7 and hollow connecting rod 8 is located inside the sleeve 9.

Among them, the support packer 1 is a commonly used equipment in oilfields. Its function is to be clamped on the inner wall of the casing 9 by the slip mechanical device, and the sealing rubber tube is expanded to isolate the upper and lower spaces, and the whole also supports the upper part. The role of the pipe string. There are many models, and the present invention can choose a model with simple operation and good packing effect. The upper part adopts the Y445 packer and the lower part adopts the Y221 packer.

The supporting sub 2 is a design device, tubular, with perforations on the side. The lower part is connected with the supporting packer 1, and the upper part is connected with the oil layer packer 3. The function of the hole is to allow the gas in the lower oil layer to pass into the oil layer packer 3 without obstruction.

The oil layer packer 3 plays the role of isolating the oil layer, the upper oil layer is separated by the packing rubber, and the gas enters and exits in the lower oil layer.

The vent sleeve 4, the high-pressure vessel 5, the electromagnetic gas control valve 6, the gas booster unit 7 and the hollow connecting rod 8 are the core design components.

①Vent sleeve 4

The lower part of the vent sleeve 4 has a short section on the outside (the short section is a commonly used accessory in industrial pipe connections. The common threaded section is divided into double-ended outer wires, single-ended outer wires, and flat-end outer wires. ) Is connected to the oil layer packer 3, and the inside is connected to the high-pressure vessel 5 through an inner thread 41. Its structure is shown in Figure 8. The cylinder wall 42 of the vent sleeve 4 has a through hole 43, which is a passage for the gas in the bottom oil layer packer 3 to enter the upper casing space. See Figure 9, a schematic diagram of gas flow. The through hole at the connection position of the high-pressure vessel 5 has good roundness and smooth inner wall. The through hole is matched with the rubber column of the electromagnetic pneumatic valve 6 and has a valve function.

②High pressure vessel 5

The high-pressure vessel 5 has a simple structure, a hollow cylindrical shape, and the end caps at both ends are built-in, that is, are connected to the inside of the vent sleeve 4 through an inner thread 51, and both ends of the outer cylinder are both outer threads 52, as shown in FIG. One end of the high-pressure container 5 is connected to the inside of the vent sleeve 4, and the other end of the high-pressure container 5 is connected to the gas booster unit 7. After the bottom end cover is connected to the vent sleeve 4, a constant pressure valve 53 is installed, as shown in Fig. 11. An electromagnetic air control valve 6 is installed below the constant pressure valve 53. When the constant pressure valve 53 reaches the design pressure, its high-pressure air outlet 54 is opened and kept open until the internal and external fluid pressures are balanced, and then closed.

Since the inner diameter of the casing at the bottom of the well is only 10 cm, if the volume of the high-pressure vessel is increased, the only way to extend it is to extend it, and its maximum length is the depth of the wellbore. Generally, the depth of the oil reservoir in our country is greater than 1000m, and if the inner diameter of the container is 6cm, the space volume of the 1000m equal-diameter long pipe is about 3m ³ .

Therefore, the length of the high-pressure container is determined according to the specific casing usage of the oil well to maximize it. Generally, casing is divided into surface casing, technical casing and oil casing, and its length varies with well conditions. The minimum inner diameters of surface casing, technical casing and oil layer casing are 21.6cm, 15.0cm and 10.0cm respectively. Assuming that the reservoir depth is 2000m, the surface casing is 200m, the technical casing is 1600m, and the oil casing is 200m, the high-pressure vessel can also be designed to gradually thicken from bottom to top. Corresponding to different casing types, the inner diameter of the high-pressure vessel is respectively 12.0cm, 9.0cm and 6.0cm, if the length is the same as the corresponding sleeve, the space volume of the trapezoidal high-pressure vessel is about 15m ³ .

Since the low-frequency variable pressure method needs to establish a condition of 2 times the annulus pressure in the high-pressure vessel, the existing casing cannot be used as the vessel. Its wall thickness is within 5-10mm, and the pressure resistance is not strong. The container designed by this method is made of 316 steel, the wall thickness is within 10-20mm, and the maximum pressure resistance can reach 70MPa.

Due to on-site operating conditions, a single high-pressure vessel has a length of 10m, which is gradually connected in series by connecting the two ends with a sealed coupling. In the reducing section, the sealing coupling can be reduced in diameter. This technology is a mature technology and will not be repeated here.

③Electromagnetic pneumatic control valve 6

The electromagnetic air control valve 6 includes a plurality of piston-type cone plugs 61, as shown in FIG. 12, the piston-type cone plugs are L-shaped, and the plurality of piston-type cone plugs 61 are connected by a multi-way air joint 62. The piston-type cone plug 61 includes a cone plug 611, a connecting rod 612, a magnetic piston 613, an electromagnetic block 614, and an L-shaped frame; among them, the cone plug 611, the connecting rod 612, and the magnetic piston 613 are connected in sequence , The connecting rod 612, the magnetic piston 613 and the electromagnetic block 614 are located in the L-shaped frame.

The electromagnetic gas control valve 6 uses part of the energy when the high-pressure gas is discharged to push the piston-type cone plug to move upward. The cone plug 611 is blocked at the position of the through hole 43 of the vent sleeve 4, so that the gas cannot pass through the vent sleeve. 4 Enter the upper space, but can only enter the formation. When the high-pressure gas is relieved and the outlet gas pressure is balanced with the ambient pressure, the magnetic piston 613 is driven by the connecting rod 612 to move the cone plug 611 downward under the electromagnetic suction force of the electromagnetic block 614, and the piston-type cone plug When the head returns to the original position by its own gravity, the electromagnetic gas control valve 6 is opened, and the low-pressure gas discharged from the oil layer enters the upper space. The number of plugs of the electromagnetic air control valve 6 is used in conjunction with the vent sleeve 4. See Figure 12 for the front view and Figure 13 for the top view.

④Gas booster unit 7

The gas booster unit 7 is composed of multiple gas boosters in parallel. The gas booster is a conventional application device, and its function is to compress low-pressure gas into high-pressure gas under the condition that the air compressor provides power. Its structure and main components are shown in Figure 14. Among them, the power gas outlet 71 and power gas inlet 72 of each gas turbocharger are located above, and the high-pressure gas outlet 73 of each gas turbocharger is located below, and each gas increases The low-pressure gas inlet 74 of the compressor is located below the outer wall, and the high-pressure gas outlet 73, power gas outlet 71 and power gas inlet 72 of a single gas booster connected in parallel have collecting pipes to make the gas booster units work synchronously. Gas enters the power gas space 75 through the power gas inlet 72. Below the power gas space 75 is the low pressure end 76 of the piston. Below the high pressure end 77 of the piston is the high pressure space 78. The high pressure space 78 includes two ports: a high pressure gas outlet 73 and a low pressure gas inlet 74 A flow control valve 79 is included between the low-pressure gas inlet 74 and the high-pressure space 78. The space below the low-pressure end 76 of the piston is connected with a piston retreat gas passage 80. There is a power gas conversion passage 81 between the power gas outlet 71 and the power gas inlet 72. The principle of the pressurization process is in a mature application state, so I will not repeat it here.

Due to the special applicability of the present invention, the shape and component specifications of the gas booster need to meet the conditions in the wellbore, see FIG. 15.

In the present invention, a connecting protective sleeve 82 is designed to wrap and protect the main body of the gas booster, and play the role of connecting with the upper and lower devices.

Wherein, the opening position of the low pressure gas inlet 74 is designed on the outer wall of the connecting protective sleeve 82 to facilitate gas entry.

The high-pressure gas outlet 73 is located directly below the connecting protective sleeve 82, which is convenient for connection with the high-pressure container.

The power gas inlet 72 and the power gas outlet 71 are both arranged at the top position of the connecting protective sleeve 82 to facilitate connection with the upper part (other gas boosters or hollow connecting rod 8).

The multiple gas boosters are also connected by respective high-pressure gas collection pipes 83, power gas outlet collection pipes 84 and power gas inlet collection pipes 85. A sub-section 86 is installed on the uppermost gas booster, which is connected to the hollow connecting rod through this sub-section.

In the application process of the present invention ^{, 10,000-20,000 Nm 3 of} compressed gas is accumulated per frequency, and the designed single turbocharger has a small displacement, less than 20 NL/min. Therefore, multiple turbochargers are required in parallel to form a unit to increase the displacement. The single turbocharger of the present invention has such conditions for parallel connection, and the combination is shown in Fig. 16. The high-pressure gas, power gas outlet and power gas inlet of a single turbocharger connected in parallel have collecting pipes to make the unit work synchronously.

⑤Hollow connecting rod 8

The hollow connecting rod 8 has a simple structure, as shown in Figure 17. Two ends are mating connectors, one end is a female buckle connector 87, and the other end is a male buckle connector 88, which can be connected in sequence. The hollow connecting rod 8 plays a role of bearing the weight of the bottom part, and the hollow pipe 89 is also a channel for the power gas outlet and the power gas inlet collecting pipe. The bottom of the hollow connecting rod 8 is connected to the gas booster unit 7, and the top is connected to an external ground control device (wellhead device).

In the embodiment of the present invention, the working process of the low-frequency variable pressure well borehole device is as follows (that is, step 503 specifically includes):

Take the low-frequency variable pressure method for low-permeability reservoirs with gas injection and oil displacement as an example. Low-permeability reservoirs have low permeability and complex pore structure, leading to high water injection pressure, resulting in difficulty in water injection, and common problems of non-injection. This type of reservoir is produced by gas injection and usually low injection rate to prevent fingering.

The reservoir depth is 2000m, and the daily gas injection is 3 cubic meters (3000Nm ³ ) under the condition of the bottom hole fluid pressure of 10MPa. According to the single-frequency gas injection of 10 cubic meters (formation pressure 10MPa), the goal of 1 frequency in 7 days is to implement high-pressure radial injection into the reservoir.

The core device size of the low-frequency variable pressure well bore device is as follows:

The inner diameter of the high-pressure vessel is 6cm, the total length in series is 1000m, and the total volume is 3m ³ ;

The gas booster unit consists of 10 gas boosters. The maximum working pressure of a single gas booster is 60MPa, the discharge flow is 200L/min, and the ratio of work to rest time is 2:1. The fluid in the high-pressure container can be compressed to 50MPa within 6 days.

The outer diameter of the hollow connecting rod is 3cm, and the total length of the series is about 1000m.

The power gas is provided by an ordinary air pump. Because it works on the ground, it can be connected in parallel to meet the displacement requirements, and the output pressure is greater than 0.8MPa.

The calculation parameters are as follows:

The density of gas under normal pressure is about one-thousandth of the density of water, such as nitrogen 1.25g/L. At 50°C, the density of 10MPa and 50MPa nitrogen is 0.1g/mL and 0.38g/mL, respectively. That is, in a high-pressure vessel with a length of 1000 m, when the bottom pressure is 50 MPa, the top pressure is only 46 MPa. When converted to 10 MPa, the volume is 14.0 m ³ .

Provided bottomhole pressure 10MPa remains stable, then injected into the formation after the pressure vessel, the bottom remains 10MPa pressure, top pressure of about 9MPa, the volume of remaining gas in the container 3m ^3, i.e., injected into the formation 11.0m ^3.

If the calculation accurately considers the influence of temperature and pressure gradient, and the influence of unstable gas flow at the bottom of the wellbore, the actual volume of gas injected into the formation is slightly larger than 10m ³ .

①Setup before the device enters the well

Adjust the working pressure of the gas booster to 50MPa; adjust the pressure of the constant pressure valve of the high-pressure vessel to 50MPa.

The ground control electromagnetic pneumatic valve opens and closes.

②System installation of the overall device

According to the structure shown in Figure 7, downhole operations and installation are carried out.

③Implement low-frequency transformation operation

In the late stage of gas injection, a large amount of gas is seen in the production wells, and after gas channeling is formed, the gas injection and production wells can be temporarily closed to stop the injection process. When there is no formation of gas channeling or a small amount of produced gas, that is, the implementation of low-frequency variable pressure operation has a better oil-increasing effect.

Carry out the above design plan:

First, the ground control electromagnetic gas control valve is opened, and under the action of the existing formation pressure, the gas in the oil reservoir quickly enters the high-pressure vessel, and enters the upper annulus space through the vent sleeve. Usually in a short period of time (1h), the gas fills the above-mentioned space, the pressure is distributed stably, and the bottom pressure maintains the pressure of the formation fluid at 10MPa.

Secondly, the external ground control device controls the injection of power gas and keeps the power gas outlet open to the atmosphere. At this time, the gas booster unit starts to work, the working time is long, the total time is 6 days, and the ground program controls the rest period of the unit. During the working process, the gas in the upper annulus enters the high-pressure vessel, and the internal gas pressure continues to rise. At the same time, the gas in the reservoir flows into the upper annulus, and the gas pressure decreases slightly. Because the gas injection volume of the formation is much larger than the volume in the annulus, the pressure change is small. This process is the process of gas discharge from the reservoir, and the pressure change is seen as the discharge Pressure line.

Third, when the external ground control device monitors that the pressure in the high-pressure vessel reaches 47 MPa, the ground control closes the electromagnetic gas control valve, and the upper space gas is isolated from the gas near the lower oil layer. The high-pressure gas booster unit continues to work until the pressure in the high-pressure vessel reaches 50MPa, the constant-pressure valve in the high-pressure vessel opens, and the high-pressure gas enters the formation at high speed, causing high pressure near the well and changing the previously formed remaining oil distribution. At the same time, the ground automatic control system shuts off the power gas injection, and the booster unit stops working.

Finally, when the gas pressure in the high-pressure container is equal to the pressure of the fluid at the bottom of the well (about less than 1 h), the constant pressure valve of the high-pressure container is closed, and the injection and boosting process ends.

The above operations have completed a frequency transformation process. If you need to implement it again, repeat the above steps.

④Continue the gas injection process

When the low-frequency variable pressure well bore device stops working, the original gas injection and production wells continue to work. Within a certain period, the production wells will increase oil to a certain extent, and the gas-oil ratio will drop significantly. The process is also positive. It is the key stage to improve the recovery factor.

Based on the same inventive concept, the embodiments of the present invention also provide a low-frequency variable pressure oil reservoir production system with remaining oil in the pores, as described in the following embodiments. Since the problem-solving principle of the low-frequency variable pressure reservoir production system for the remaining oil in the pores is similar to that of the low-frequency variable pressure reservoir production method for the remaining oil in the pores, the implementation of the low-frequency variable pressure reservoir production system for the remaining oil in the pores can be found in the pore The implementation of the low-frequency variable pressure reservoir production method for the remaining oil in the interior, the repetition will not be repeated.

The low-frequency variable pressure oil reservoir production system of the remaining oil in the pore includes: low-frequency variable pressure well borehole device, data analysis device, and oil production device;

In the embodiment of the present invention, it further includes: an external surface control device, which is used to control the wellbore device of the low-frequency variable pressure well.

In summary, 1. The present invention proposes a low-frequency variable pressure reservoir development and application method that can effectively drive the remaining oil in the pore; the high flow rate generated by the proposed low-frequency variable pressure well bore device can cause short-term high pressure near the well zone, Realize the desorption of remaining oil and change the direction of the main seepage channel;

2. The used low-frequency variable pressure well wellbore device makes full use of the injected gas, and does not need to inject and exhaust gas repeatedly, and its economic benefits are significant;

3. The gas compression process in the proposed low-frequency variable pressure well bore device does not require manual intervention;

4. This method continues to increase the recovery level by more than 5% by expanding the swept volume after the gas drive channeling.

Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

The present invention is described with reference to flowcharts and/or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and/or block in the flowchart and/or block diagram, and the combination of processes and/or blocks in the flowchart and/or block diagram can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing equipment to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing equipment are generated It is a device that realizes the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.

These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing equipment to work in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction device. The device implements the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.

These computer program instructions can also be loaded on a computer or other programmable data processing equipment, so that a series of operation steps are executed on the computer or other programmable equipment to produce computer-implemented processing, so as to execute on the computer or other programmable equipment. The instructions provide steps for implementing the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.

The foregoing descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the embodiments of the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

A low-frequency variable pressure well wellbore device, which is characterized in that, from bottom to top, it includes: a support packer, a support short section, an oil layer packer, a vent sleeve, a high-pressure vessel, an electromagnetic gas control valve, a gas booster unit and a hollow Connecting rod, supporting packer, supporting sub-section, oil layer packer, vent sleeve, high pressure vessel, electromagnetic gas control valve, gas booster unit and hollow connecting rod are located in the casing;

Among them, the supporting packer is used to: expand the card between the inner wall of the casing and the supporting sub to support the supporting sub;

The lower part of the support pup joint is connected to the support packer, and the upper part of the support pup joint is connected to the oil layer packer. The support pup joint is tubular and has holes on the pipe side. The holes are used to allow the gas in the lower oil layer to pass into the oil layer packer. ；

The oil layer packer is used to: isolate the upper oil layer so that gas enters and exits in the lower oil layer;

The lower part of the aeration sleeve and the outside are connected with the oil layer packer, the inside of the aeration sleeve is connected with the high-pressure vessel, and the cylinder wall of the aeration sleeve has through holes, which are the channels for the gas in the oil layer packer to enter the upper casing space ；

The electromagnetic gas control valve is connected to the vent sleeve through the through hole of the vent sleeve, and is used to open and close the through hole, so that the gas in the lower oil layer can enter the high-pressure container and the upper space;

The lower end of the high-pressure container is connected with the inside of the vent sleeve, the upper end of the high-pressure container is connected with the gas booster unit, and the high-pressure container is in the shape of a hollow cylinder;

The gas booster unit is used to compress the low-pressure gas in the high-pressure container into high-pressure gas;

The bottom of the hollow connecting rod is connected to the gas booster unit, and the top of the hollow connecting rod is connected to the external ground control device, which is used to make the external gas enter the low-frequency variable pressure well wellbore device, and the gas in the lower oil layer is discharged from the low-frequency variable pressure well wellbore device .
The low-frequency variable pressure well wellbore device of claim 1, wherein the outside of the vent sleeve is connected with the oil layer packer through a short section, and the inside of the vent sleeve is threadedly connected with the high-pressure container.
The low-frequency variable pressure well wellbore device of claim 1, wherein the end caps at both ends of the high-pressure container are in-line, and the gas booster unit and the vent sleeve are connected through the in-line type; the high-pressure container Both ends of the outer cylinder are external threaded fasteners, which are connected to the inside of the vent sleeve through the external threaded fasteners.
The low-frequency variable pressure well wellbore device of claim 3, wherein the high-pressure container includes a constant-pressure valve, and the bottom end cap of the high-pressure container is installed with a constant-pressure valve after being connected to a vent sleeve. An electromagnetic air control valve is installed below, and the constant pressure valve is used to open when the preset pressure is reached, and keep it open until the fluid pressure inside and outside the high-pressure vessel is balanced, and then close.
The low-frequency variable pressure well wellbore device according to claim 1, 3, or 4, wherein the high-pressure container includes a plurality of pieces, and the two are connected by a sealing coupling.
The low-frequency variable pressure well wellbore device of claim 5, wherein the inner diameters of the multiple high-pressure containers are different, and the high-pressure containers with different inner diameters are connected by a sealed reducing coupling.
The low-frequency variable pressure well wellbore device of claim 1, wherein the electromagnetic pneumatic control valve includes a plurality of piston-type cone plugs, the piston-type cone plugs are L-shaped, and the plurality of Piston cone plugs are connected by multi-way vent joints;

The piston-type cone plug includes a cone plug, a connecting rod, a magnetic piston, an electromagnetic block, and an L-shaped frame; wherein the cone plug, a connecting rod, and a magnetic piston are connected in sequence, and the connecting rod, The magnetic piston and the electromagnetic block are located in the L-shaped frame; the magnetic piston is driven to push the connecting rod and the conical plug by the energization of the electromagnetic block, so that the through hole in the vent sleeve is opened and closed.
The low-frequency variable pressure well wellbore device of claim 7, wherein the number of through holes in the high-pressure container is the same as the number of the piston cone plugs.
The low-frequency variable pressure well wellbore device of claim 1, wherein the gas booster unit comprises a plurality of gas boosters in parallel, and the power gas outlet and power gas inlet of each gas booster are located above, The high-pressure gas outlet of each gas booster is located below, the low-pressure gas inlet of each gas booster is located below the outer wall, and the high-pressure gas outlet, power gas outlet and power gas inlet of a single gas booster connected in parallel are collected Pipe, make the gas booster unit work synchronously.
The low-frequency variable pressure well wellbore device according to claim 9, further comprising: a connecting protective sleeve for wrapping and protecting the gas booster, and connecting with the upper and lower connecting protective sleeves;

An opening for a low-pressure gas inlet is provided on the outer wall of the connecting protective sleeve to facilitate gas entry;

The top position of the connecting protective sleeve is provided with openings for a power gas outlet and a power gas inlet;

An opening for a high-pressure gas outlet is provided directly below the connection protective sleeve, which is convenient for connection with a high-pressure container.
The low-frequency variable pressure well wellbore device of claim 1, wherein two ends of the hollow connecting rod are mating joints, one end is a female buckle joint, the other is a male buckle joint, and the hollow connecting rod passes through the middle through pipe Make external air enter the low-frequency variable pressure well borehole device.
A low-frequency variable pressure oil reservoir exploitation method for remaining oil in pores, which is characterized in that it comprises:

Obtain the gas distribution map in the reservoir and the pressure distribution map between the injection and production wells during the gas injection process;

According to the distribution map of the gas in the reservoir and the pressure distribution map between the injection and production wells during the gas injection process, determine the placement position of the low-frequency variable pressure well borehole device of any one of claims 1 to 11 in the reservoir ；

The placement position of the low-frequency variable pressure well borehole device in the reservoir is used to intermittently increase and decrease the pressure at a preset frequency to change the remaining oil distribution in the reservoir at the placement position;

Through steam injection wells and oil production wells, the remaining oil in the reservoir that has changed the distribution of the remaining oil is exploited.
The low-frequency variable pressure reservoir production method of remaining oil in pores according to claim 12, characterized in that the placement position of the low-frequency variable pressure well borehole device in the reservoir is used to intermittently increase and decrease the pressure at a preset frequency. , Change the remaining oil distribution state in the reservoir at the placement position, including:

Through the external ground control device to control the opening of the electromagnetic gas control valve, the gas in the oil reservoir enters the high-pressure container, and enters the upper annulus space through the vent sleeve;

The external ground control device controls the power gas to be injected through the gas booster unit to keep the power gas outlet of the gas booster unit open to the atmosphere;

The gas booster unit starts to work, the gas in the upper annulus enters the high-pressure container, the gas pressure rises, and the gas in the oil reservoir flows into the upper annulus;

When the gas pressure in the high-pressure container reaches the first preset pressure, the external ground control device controls the electromagnetic gas control valve to close, and the gas booster unit continues to work until the gas pressure in the high-pressure container reaches the second preset pressure. The constant pressure valve inside opens, and high-pressure gas enters the reservoir, changing the remaining oil distribution in the reservoir;

The external ground control device closes the power gas injection. When the gas pressure in the high-pressure container is equal to the fluid pressure in the oil reservoir, the constant-pressure valve of the high-pressure container is closed.
A low-frequency variable pressure oil reservoir production system for remaining oil in pores, characterized by comprising: the low-frequency variable pressure well wellbore device, data analysis device, and oil production device according to any one of claims 1 to 11;

Among them, the data analysis device is used to: obtain the distribution map of the gas in the reservoir, the pressure distribution map between the injection and production wells during the gas injection process, and according to the distribution map of the gas in the reservoir, the injection and production wells during the gas injection process To determine the placement position of the low-frequency variable pressure well borehole device in the reservoir;

The low-frequency variable pressure well borehole device is used to place it in the corresponding position in the oil reservoir, and the placement position in the oil reservoir to intermittently increase and decrease the pressure at a preset frequency, and to change the remaining oil distribution state in the reservoir at the placement position ；

The oil extraction device is used to extract the remaining oil in the reservoir that has changed the distribution of the remaining oil through steam injection wells and oil production wells.
The low-frequency variable pressure reservoir production system for remaining oil in the pores of claim 14, further comprising: an external surface control device for controlling the low-frequency variable pressure well borehole device.
The low-frequency variable pressure oil reservoir production system for remaining oil in the pores of claim 15, wherein the low-frequency variable pressure well borehole device is specifically used for:

Through the external ground control device to control the opening of the electromagnetic gas control valve, the gas in the oil reservoir enters the high-pressure container, and enters the upper annulus space through the vent sleeve;

The external ground control device controls the power gas to be injected through the gas booster unit to keep the power gas outlet of the gas booster unit open to the atmosphere;

The gas booster unit starts to work, the gas in the upper annulus enters the high-pressure container, the gas pressure rises, and at the same time, the gas in the oil reservoir flows into the upper annulus;

When the gas pressure in the high-pressure container reaches the first preset pressure, the external ground control device controls the electromagnetic gas control valve to close, and the gas booster unit continues to work until the gas pressure in the high-pressure container reaches the second preset pressure. The constant pressure valve inside opens, and high-pressure gas enters the reservoir, changing the remaining oil distribution in the reservoir;

At the same time, the external ground control device closes the power gas injection. When the gas pressure in the high-pressure container is equal to the fluid pressure in the oil reservoir, the constant-pressure valve of the high-pressure container is closed.
A computer device comprising a memory, a processor, and a computer program stored on the memory and running on the processor, wherein the processor implements the computer program described in any one of claims 12 to 13 when the processor executes the computer program.述方法。 Said method.
A computer-readable storage medium, wherein the computer-readable storage medium stores a computer program for executing the method according to any one of claims 12 to 13.