A concentric pipe string and process for coordinated oil production by water injection and steam injection huff and puff

Abstract

The present invention discloses a concentric pipe string and process method for coordinated oil production with water injection and steam injection. A water injection pipe string is installed in the casing, a water injection packer is provided between the inner wall of the casing and the outer wall of the water injection pipe string, a steam injection pipe string is installed in the water injection pipe string, the lower part of the steam injection pipe string extends out of the bottom end of the water injection pipe string, a steam injection packer is provided between the outer wall of the steam injection pipe string and the inner wall of the casing, the bottom of the steam injection pipe string is connected to a rod pump seat, and a pen tip is installed at the bottom of the rod pump seat; a sucker rod is installed in the steam injection pipe string, the bottom of the sucker rod is connected to a rod pump, and the rod pump is installed on the rod pump seat. By designing a concentric pipe string for coordinated oil production with water injection and steam injection, water injection is implemented in the thin oil layer, and steam injection is implemented in the thick oil layer and then switched to pumping production, so that two sets of different development layers can be used simultaneously in one oil well, the number of wells can be reduced, and the oil production rate of the block can be increased. At the same time, the tubing string also has the function of negative pressure oil production to increase the liquid production of the oil well.

Description

Technical Field

[0001] The present invention relates to a concentric pipe string and process method for coordinated oil production by water injection and steam injection, in particular to a concentric pipe string and process method for coordinated oil production by water injection and steam injection for multiple oil reservoirs with large oil layer spans and large differences in crude oil viscosity, which require multiple different development methods. Background Art

[0002] For multiple reservoirs with large spans and widely varying crude oil viscosities, requiring diverse development methods, the current approach is to develop separate layers separately. Light oil reservoirs are primarily developed through waterflooding, while heavy oil reservoirs are primarily developed through steam stimulation. These two layers are produced separately at different stages, making simultaneous production impossible. Therefore, a concentric string and process method for coordinated production using waterflooding and steam stimulation was designed. Waterflooding was implemented in the light oil layer, while steam stimulation was performed in the heavy oil layer, followed by pumping. This allows two different development layers to be simultaneously utilized in a single well, reducing the number of wells deployed and increasing oil production rates in the block.

[0003] After reviewing the "Application of Integrated Injection and Production Strings in Super Heavy Oil Wells" published in "Oil and Gas·Petroleum and Natural Gas Science" in 2021, an integrated steam injection and production string process emerged. This string only shortens the operation time from steam injection to pumping of super heavy oil, and reduces the cold damage to the oil layer caused by well washing operations, but still cannot solve problems such as the simultaneous development and production of thin oil and heavy oil layers.

[0004] After checking the CN201910044009.5 patent "A horizontal well water injection and oil production integrated tubing string and process method", an integrated water injection and oil production tubing string appeared. However, this tubing string only realizes general water injection and combined layer oil production, and is only suitable for light oil water injection development. It still cannot solve the problems of steam injection and huff and puff in heavy oil layers and the simultaneous production of light oil and heavy oil according to different development methods.

[0005] After checking the CN201520211846.X patent "A pipe string for an integrated oil production and water injection process", an integrated oil production and water injection process pipe string appeared. However, this pipe string only combines the oil production pipe string and the water injection pipe string into one, and this pipe string is only suitable for light oil water injection development. It still cannot solve the problems of steam injection and huff and puff in heavy oil layers and the simultaneous development of light oil and heavy oil according to different development methods. Summary of the Invention

[0006] In order to solve the problem that multiple layers cannot be simultaneously utilized according to different development methods, the present invention designs a concentric pipe string and process method for coordinated oil production with water injection and steam injection. Water injection is implemented in the thin oil layer, and steam injection is performed on the heavy oil layer before switching to production. In this way, two different development layers can be simultaneously utilized in one oil well, reducing the number of wells and increasing the oil production rate of the block.

[0007] In order to solve the above technical problems, the technical solution of the present invention is: a concentric tubing string for coordinated oil production with water injection and steam injection, comprising a casing, a water injection tubing string installed in the casing, a water injection packer provided between the inner wall of the casing and the outer wall of the water injection tubing string, a steam injection tubing string installed in the water injection tubing string, the lower part of the steam injection tubing string extending out of the bottom end of the water injection tubing string, a steam injection packer provided between the outer wall of the steam injection tubing string and the inner wall of the casing, the bottom of the steam injection tubing string is connected to a rod pump seat, a pen tip is installed at the bottom of the rod pump seat; a sucker rod is installed in the steam injection tubing string, the bottom of the sucker rod is connected to a rod pump, and the rod pump is installed on the rod pump seat.

[0008] Furthermore, the water injection packer is located above the water injection layer.

[0009] Furthermore, the steam injection packer is located between the water injection layer and the oil production layer.

[0010] Furthermore, the water injection string adopts an insulated oil pipe.

[0011] A process for coordinated oil recovery by water injection and steam injection, having a concentric pipe string, comprises the following steps:

[0012] A. First, run the steam injection string with the steam injection packer and rod pump seat to the predetermined position and seat the steam injection packer;

[0013] B. Run the water injection string with the water injection packer into the predetermined position, seal the water injection packer and protect the casing;

[0014] C. Inject water into the thin oil injection layer through the water injection string;

[0015] D. Carry out steam injection into the heavy oil layer through the steam injection string;

[0016] E. After the steam injection is completed, the sucker rod assembly with the rod pump is lowered into the steam injection string, and the well is opened for production.

[0017] Furthermore, water is injected into the thin oil injection layer according to the water injection requirements through the water injection string to replenish the formation energy and drive the thin oil to be produced from the corresponding oil well; the heat dissipated by the steam injection string can heat the injected water in the water injection string; at the same time, the steam entering the heavy oil layer rises due to the overlying, which can heat the upper water injection layer, further reduce the viscosity of the thin oil and improve the mobility ratio.

[0018] Furthermore, the steam injection column is used to steam the heavy oil layer according to the steam injection intensity, thereby heating the heavy oil layer to facilitate the flow of the heavy oil.

[0019] Furthermore, the sucker rod assembly with the rod pump is lowered into the steam injection string, and the well is opened for production; due to the presence of the steam injection packer, when the sucker rod assembly with the rod pump pumps up and down, negative pressure is formed near the rod pump seat, thereby improving the liquid supply capacity of the oil-producing layer.

[0020] This invention utilizes a concentric string designed for coordinated water and steam injection production. This allows for separate water injection into thin oil layers and steam injection into thick oil layers, followed by transition to production through pumping. This allows for simultaneous activation of two distinct development zones within a single well, reducing the number of wells deployed and increasing oil production rates. Furthermore, the string also features negative pressure production, increasing well production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the water injection-steam injection string;

[0022] Figure 2 It is a schematic diagram of the water injection-oil production string.

[0023] Among them: 1. Casing; 2. Steam injection string; 3. Water injection string; 4. Water injection packer; 5. Steam injection packer; 6. Rod pump seat; 7. Pen tip; 8. Sucker rod. DETAILED DESCRIPTION

[0024] The following is combined with Figure 1 、 2 The specific embodiments of the present invention are further described.

[0025] A concentric tubing string for coordinated water and steam injection huff-and-puff oil production comprises a casing 1, a water injection string 3 installed within the casing 1, a water injection packer 4 disposed between the inner wall of the casing 1 and the outer wall of the water injection string 3, a steam injection string 2 installed within the water injection string 3, the lower portion of the steam injection string 2 extending beyond the bottom end of the water injection string 3, a steam injection packer 5 disposed between the outer wall of the steam injection string 2 and the inner wall of the casing 1, a rod pump seat 6 connected to the bottom of the steam injection string 2, a pen tip 7 mounted at the bottom of the rod pump seat 6, a sucker rod 8 installed within the steam injection string 2, the bottom of the sucker rod 8 connected to a rod pump mounted on the rod pump seat 6. The water injection packer 4 is located above the water injection layer, and the steam injection packer 5 is located between the water injection layer and the oil production layer.

[0026] A process for coordinated oil recovery by water injection and steam injection, having a concentric pipe string, comprises the following steps:

[0027] A. First, run the steam injection string 2 with the steam injection packer 5 and the rod pump seat 6 to the predetermined position and seal the steam injection packer 5;

[0028] B. Lowering the water injection string 3 with the water injection packer 4 to the predetermined position, sealing the water injection packer 4 and protecting the casing 1;

[0029] C. Inject water into the thin oil injection layer through the water injection string 3;

[0030] D. inject steam into the heavy oil layer through the steam injection string 2;

[0031] E. After the steam injection is completed, the sucker rod 8 with the rod pump is lowered into the steam injection string 2, and the well is opened for production.

[0032] Water injection string 3 is used to inject water into the thin oil injection zone according to the injection requirements, replenishing formation energy and driving thin oil production from the corresponding production well. Heat dissipated by steam injection string 2 heats the injected water within injection string 3. Simultaneously, steam entering the heavy oil zone, due to its overlying rise, heats the upper injection zone, further reducing the viscosity of the thin oil and improving the mobility ratio.

[0033] The steam injection string 2 is used to inject steam into the heavy oil layer according to the steam injection intensity, thereby heating the heavy oil layer to facilitate the flow of the heavy oil.

[0034] The sucker rod 8 with rod pump is lowered into the steam injection string 2, and the well is started for production. Due to the presence of the steam injection packer 5, the sucker rod 8 with rod pump creates negative pressure near the rod pump seat 6 when pumping up and down, thereby improving the fluid supply capacity of the oil-producing layer.

[0035] The present invention employs a concentric dual-tube structure to separately inject water and steam into the thin oil and heavy oil reservoirs. The water injection string 3 utilizes insulated tubing, while the steam injection string 2 utilizes conventional tubing. A rod pump base 6 is pre-installed in the steam injection string 2. A lower packer is used to isolate the thin oil and heavy oil reservoirs. A packer is then lowered into the top of the thin oil reservoir to protect the casing 1. After steam injection into the heavy oil reservoir, the production phase begins. A rod pump and sucker rod 8 are then directly lowered for negative pressure oil production, enabling simultaneous development of water injection into the thin oil reservoir and steam injection into the heavy oil reservoir.

[0036] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention within the technical scope disclosed in the present invention, and they should be covered by the scope of protection of the present invention.

Claims

1. A concentric string for coordinated oil production with water injection and steam injection, characterized in that: The invention comprises a casing (1), a water injection pipe column (3) is installed in the casing (1), a water injection packer (4) is provided between the inner wall of the casing (1) and the outer wall of the water injection pipe column (3), a steam injection pipe column (2) is installed in the water injection pipe column (3), the lower part of the steam injection pipe column (2) extends out of the bottom end of the water injection pipe column (3), a steam injection packer (5) is provided between the outer wall of the steam injection pipe column (2) and the inner wall of the casing (1), the bottom of the steam injection pipe column (2) is connected to a rod pump seat (6), and a pen tip (7) is installed at the bottom of the rod pump seat (6); a sucker rod (8) is installed in the steam injection pipe column (2), the bottom of the sucker rod (8) is connected to a rod pump, and the rod pump is installed on the rod pump seat (6).

2. The concentric string for coordinated oil production with water injection and steam injection huff and puff according to claim 1, characterized in that: The water injection packer (4) is located above the water injection layer.

3. The concentric tubing string for coordinated oil production with water injection and steam injection huff and puff according to claim 1, characterized in that: The steam injection packer (5) is located between the water injection layer and the oil production layer.

4. The concentric tubing string for coordinated oil production with water injection and steam injection huff and puff according to claim 1, characterized in that: The water injection pipe column (3) adopts a heat-insulated oil pipe.

5. A process for coordinated oil recovery by water injection and steam injection, characterized in that: The concentric tubular column according to any one of claims 1 to 4 comprises the following steps: A. First, the steam injection string (2) with the steam injection packer (5) and the rod pump seat (6) is lowered to the predetermined position and the steam injection packer (5) is seated; B. lowering the water injection string (3) with the water injection packer (4) to the predetermined position, sealing the water injection packer (4) and protecting the casing (1); C. injecting water into the thin oil injection layer through the water injection string (3); D. injecting steam into the heavy oil layer through the steam injection column (2); E. After the steam injection is completed, the sucker rod (8) with the rod pump is lowered into the steam injection string (2) and the well is opened for production.

6. The process for coordinated oil production by water injection and steam injection huff and puff according to claim 5, characterized in that: In the step C, water is injected into the thin oil injection layer through the water injection string (3) according to the water injection requirements, so as to replenish the formation energy and drive the thin oil to be produced from the corresponding oil production well; the heat dissipated by the steam injection string (2) can heat the injected water in the water injection string (3); at the same time, the steam entering the heavy oil layer can heat the upper water injection layer due to the overlying rise, further reducing the viscosity of the thin oil and improving the mobility ratio.

7. The process for coordinated oil production by water injection and steam injection huff and puff according to claim 5, characterized in that: In the step D, steam injection is performed on the heavy oil layer according to the steam injection intensity through the steam injection column (2), thereby heating the heavy oil layer to facilitate the flow of the heavy oil.

8. The process for coordinated oil production by water injection and steam injection huff and puff according to claim 5, characterized in that: In the step E, the sucker rod (8) assembly with the rod pump is lowered into the steam injection string (2) to start the well pumping and production; due to the presence of the steam injection packer (5), when the sucker rod (8) assembly with the rod pump pumps up and down, negative pressure is formed near the rod pump seat (6), thereby improving the liquid supply capacity of the oil-producing layer.

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