A gas injection pipe column mechanism and method for multi-layer oil production in the same well

Abstract

The application is suitable for oil and gas exploitation field, and discloses a same-well multi-layer oil extraction and gas injection pipe column mechanism and a method, which comprises the following steps: after a sealing unit is lowered into a designated position in a casing of an oil well and is fixed by setting and sealing, an oil extraction unit is lowered, the oil extraction unit passes through the sealing unit, a sealing space is formed in the sealing unit, the sealing space communicates with a stratum through the casing, carbon dioxide generated in oil field development can be captured, separated and pressurized to a supercritical state of gas-liquid mixture through an injection pipe, and then is injected into a seabed salt water layer for safe storage without leaking into other spaces of the casing, and oil liquid below can enter a platform through a perforated pipe. The process is simple and reliable, realizes independent oil extraction and gas injection, and does not affect each other, can solve the problem of high cost of storing carbon dioxide by using a single well due to valuable well slot resources of offshore oil fields, and can realize the goal of green low-carbon and normal production of oil fields.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas exploitation, and in particular to a same-well multi-layer oil production and gas injection pipe string mechanism and a production and injection method. BACKGROUND

[0002] With the continuous exploration and development of offshore oil and gas, there are more associated gas in the production process. The current treatment method is mainly to burn or empty the associated gas, but this is not conducive to the realization of the "double carbon" target. At the same time, the well slot resources of offshore platforms are valuable, and it is costly to use a single well to store carbon dioxide. Therefore, a new type of pipe string mechanism is needed to realize the injection of carbon dioxide gas into the seabed saline layer for geological storage while producing oil. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a same-well multi-layer oil production and gas injection pipe string mechanism and a production and injection method.

[0004] The technical solution adopted by the present application to solve the technical problem comprises a casing arranged in an oil well, an oil production unit for pumping crude oil from the casing, a gas injection unit for injecting carbon dioxide into the bottom layer, and a pack-off unit arranged at a specified position in the casing; wherein the pack-off unit separates the space above and below the pack-off unit at the specified position of the casing, a pack-off space is formed in the pack-off unit, the gas injection unit is connected to the pack-off space through a pipeline, the pack-off space is connected to the formation through the casing, the oil production unit is arranged in the pack-off unit, and the oil production unit connects the space above and below the pack-off unit.

[0005] In one embodiment, the pack-off unit comprises a bottom packer and a top packer, the bottom packer and the top packer are arranged in the casing, the top packer is arranged above the bottom packer, and the bottom packer and the top packer are abutted to the casing by external contour expansion to form a sealing band.

[0006] In one embodiment, the pack-off unit further comprises a filter blocking assembly, the filter blocking assembly is annularly arranged in the pack-off space, and the filter blocking assembly is sealingly connected to the bottom packer and the top packer.

[0007] In one embodiment, the filter blocking assembly comprises a blind pipe and a sand control screen pipe, the blind pipe is arranged at the upper and lower parts of the filter blocking assembly, the blind pipe is used to block the entry of muddy impurities into the pack-off space, and the sand control screen pipe is arranged at the middle part of the filter blocking assembly, the sand control screen pipe is tubular and connects the inside and outside spaces of the filter blocking assembly, and one end of the sand control screen pipe is provided with a screen.

[0008] In an embodiment, the oil production unit comprises a perforated pipe, an anchoring seal and a positioning seal, the perforated pipe is arranged in the packer unit, the anchoring seal and the positioning seal are arranged on the perforated pipe, the anchoring seal is in sealing connection with the bottom packer, and the positioning seal is in sealing connection with the top packer.

[0009] In an embodiment, the oil production unit further comprises a tank pump assembly, a production packer and a downhole safety valve, the tank pump assembly is arranged on the upper part of the perforated pipe and is used to draw liquid flowing out of the perforated pipe, the production packer is sleeved on the tank pump assembly and is in interference fit with the inner wall of the casing to form a sealing band, and the downhole safety valve is arranged in the tank pump assembly and controls the flow of the tank pump assembly.

[0010] In an embodiment, the gas injection unit comprises a gas supply system and an injection pipe, the gas supply system is connected to the injection pipe; the gas supply system comprises a carbon dioxide injection pump and a corrosion inhibitor injection pump, the carbon dioxide injection pump and the corrosion inhibitor injection pump are connected to the injection pipe in parallel, and a pressure gauge is arranged at the parallel connection of the injection pipe, and the injection pipe is connected to the packer space.

[0011] The present application also provides a method for oil production and gas injection of a same-well multi-layer oil production and gas injection pipe column mechanism, which comprises the following steps:

[0012] Step S1, lowering the packer unit into the casing to a specified depth and setting the packer unit;

[0013] Step S2, lowering the oil production unit into the packer unit and arranging the oil production unit in the packer unit in a sealing manner;

[0014] Step S3, the oil production unit pumps crude oil below the packer unit to the space above the packer unit and supplies the crude oil to the oil production platform;

[0015] Step S4, starting the gas injection unit to inject carbon dioxide into the packer space and into the formation through the casing.

[0016] In an embodiment, after the packer unit is set in the step S1, sealing test is needed, that is, a pressure greater than the maximum gas injection pressure of the gas injection unit is used to test the sealing of the packer unit, if there is no obvious pressure drop of the packer unit, the setting is qualified, and the step S2 can be continued.

[0017] In an embodiment, in the steps S1 to S4, when emergency shutdown is needed, the gas injection unit needs to be closed first, and then the oil production unit is shut down.

[0018] The same well multi-layer oil production and gas injection pipe column mechanism has the following beneficial effects: after the sealing unit is lowered into the casing of the oil well to the designated position and is fixed by setting, the oil production unit is lowered, the oil production unit passes through the sealing unit, a sealing space is formed in the sealing unit, the sealing space communicates with the stratum through the casing, the carbon dioxide generated in the oil field development can be captured, separated and pressurized to the supercritical state of gas-liquid mixture through the injection pipe, and is injected into the submarine salt water layer for safe storage without leaking into other spaces of the casing, and the oil liquid below can enter the platform through the perforated pipe. The process is simple and reliable, realizes independent oil production and gas injection, does not affect each other, solves the high cost problem of storing carbon dioxide by using a single well, and realizes the green low-carbon and normal production target of the oil field.

[0019] The same well multi-layer oil production and gas injection pipe column mechanism has the following beneficial effects: the sealing unit and the oil production unit are installed, and the gas injection and oil production are simultaneously performed on the mechanism without affecting each other, and the production efficiency and the carbon dioxide injection efficiency are greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the present application, the present application will be further described below in combination with the drawings and examples. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor. In the drawings:

[0021] Figure 1 is a structure diagram of the same well multi-layer oil production and gas injection pipe column mechanism in an embodiment of the present application;

[0022] Figure 2 is a gas circuit diagram of the same well multi-layer oil production and gas injection pipe column mechanism in an embodiment of the present application;

[0023] Figure 3 is a whole structure diagram of the same well multi-layer oil production and gas injection pipe column mechanism in an embodiment of the present application;

[0024] Figure 4 is a flowchart of the installation method of the same well multi-layer oil production and gas injection pipe column mechanism in an embodiment of the present application;

[0025] Figure 5 is a flowchart of the same well multi-layer oil production and gas injection pipe column mechanism in an embodiment of the present application;

[0026] Reference Signs

[0027] 1 bottom packer; 2 blind pipe; 3 sand control screen; 4 top packer; 5 round plug; 6 perforated pipe; 7 anchor seal; 8 positioning seal; 9 canned pump assembly; 10 production packer; 11 circulation sliding sleeve; 12 downhole safety valve; 13 tubing hanger; 14 carbon dioxide injection pump; 15 first regulating valve; 16 three-way mixer; 17 second regulating valve; 18 corrosion inhibitor injection pump; 19 on-off valve; 20 pressure gauge; 21 injection pipe; 22 packoff space; 23 casing. DETAILED DESCRIPTION

[0028] In order to make the technical features, objectives and effects of the present application clearer, the specific embodiments of the present application will be described in detail below. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "upper", "lower", "left", "right", "vertical", "horizontal", "vertical", "horizontal", "top", "bottom", "inner", "outer", "head", "tail" and the like are based on the directions or positional relationships shown in the drawings, constructed and operated in a particular direction, and are only for the convenience of describing the technical solutions, and should not be understood as indicating that the devices or elements referred to must have a particular direction, and therefore should not be understood as limiting the present application.

[0029] It should also be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing", "setting" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements or the interaction relationship between two elements. When an element is referred to as "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there can be one or more intervening elements. The terms "first", "second", "third" and the like are only for the convenience of describing the technical solutions, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features, therefore, the features with "first", "second", "third" and the like can explicitly or implicitly include one or more of the features. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0030] Figures 1 to 3A kind of same well multi-layer oil production gas injection pipe column mechanism in one embodiment of the present application is shown, which can be used for carbon dioxide gas re-injection to seabed salt water layer for geological storage while oil production, which can include casing 23 arranged in oil well, oil production unit for pumping crude oil from casing 23, gas injection unit for re-injecting carbon dioxide into bottom layer and pack-off unit arranged at specified position in casing 23;Wherein, the pack-off unit isolates the space above and below the pack-off unit at the specified position of the casing 23, and the pack-off space 22 is formed in the pack-off unit, the gas injection unit is communicated to the pack-off space 22 through the pipeline, the pack-off space 22 is communicated with the formation through the casing 23, and the oil production unit is arranged in the pack-off unit, which communicates the space above and below the pack-off unit.

[0031] After the pack-off unit is lowered into the casing 23 of the oil well and fixed by setting at the specified position, the oil production unit is lowered, which passes through the pack-off unit, and the pack-off space 22 is formed in the pack-off unit, which is communicated with the formation through the casing 23, and the carbon dioxide associated with oil field development can be captured, separated, pressurized to gas-liquid mixed supercritical state through the injection pipe 21, and re-injected to the seabed salt water layer for safe storage without leaking into other space of the casing 23, while the oil liquid below can enter the platform through the perforated pipe 6. The process is simple and reliable, realizes independent oil production and gas injection, and does not affect each other, which can solve the problem of high cost of storing carbon dioxide with a single well in valuable offshore oil field well slot, and achieve the goal of green low-carbon and normal production of oil field.

[0032] It can be understood that the space between the casing 23 and the formation is communicated with each other, and the high-pressure carbon dioxide in the casing 23 can enter the formation through the casing 23, dissolve with salt water and be stored in the salt water.

[0033] In a specific embodiment, the supercritical pressure of carbon dioxide gas-liquid is determined according to the environmental temperature and other environmental parameters.

[0034] Further, the output pressure of carbon dioxide does not exceed 18 MPa.

[0035] Figure 2 The pack-off unit in one embodiment can include bottom packer 1 and top packer 4, which are arranged in the casing 23, and the top packer 4 is arranged above the bottom packer 1, and the bottom packer 1 and the top packer 4 are expanded to abut to the casing 23 through the outer circular contour, forming a sealing band.

[0036] Figure 2The packoff unit can include a filter blocking assembly in one embodiment, the filter blocking assembly is annularly arranged in the packoff space 22, and the filter blocking assembly is sealingly connected to the bottom packer 1 and the top packer 4. The filter assembly can prevent the salty water mixed with the sand from being back-flushed into the packoff space 22.

[0037] Figure 2 The filter blocking assembly can include a blind pipe 2 and a sand control screen pipe 3 in one embodiment. The blind pipe 2 is arranged at the upper and lower portions of the filter blocking assembly, and the blind pipe 2 is used to block the muddy impurities from entering the packoff space 22. The sand control screen pipe 3 is arranged at the middle portion of the filter blocking assembly, and the sand control screen pipe 3 is tubular and connects the inside and outside of the filter blocking assembly. The sand control screen pipe 3 is provided with a screen at one end. The blind pipe 2 can block the muddy impurities from entering the inside at the upper and lower portions, and the screen can block the sand of a certain size from entering, and the liquid can smoothly pass through the screen and enter the inside.

[0038] Figure 2 The production unit can include a perforated pipe 6, an anchoring sealing member 7 and a positioning sealing member 8 in one embodiment. The perforated pipe 6 is arranged in the packoff unit, the anchoring sealing member 7 and the positioning sealing member 8 are arranged on the perforated pipe 6, the anchoring sealing member 7 is sealingly connected to the bottom packer 1, and the positioning sealing member 8 is sealingly connected to the top packer 4. After the sealing connection, the casing 23 is completely sealed to form a packoff space 22.

[0039] In a specific embodiment, the bottom packer 1 and the top packer 4 are provided with a light hole at the center, and the anchoring sealing member 7 and the positioning sealing member 8 are cylindrical. The anchoring sealing member 7 and the positioning sealing member 8 are directly inserted into the light hole, and the sealing ring and the light hole are matched to form a sealing band.

[0040] It can be understood that the perforated pipe 6 is provided with a plurality of holes, and the holes are arranged below the bottom packer 11. The holes are used to suck the liquid below and supply the liquid above the top packer 4.

[0041] In a specific embodiment, the perforated pipe 6 is further provided with a round plug 5 at the lower portion of the perforated pipe 6. The round plug 5 is located at the lowermost end of the perforated pipe 6, and the round plug 5 has the functions of plugging and sand setting.

[0042] Figure 2 The production unit can further include a tank pump assembly 9, a production packer 10 and a downhole safety valve 12 in one embodiment. The tank pump assembly 9 is arranged at the upper portion of the perforated pipe 6, and is used to draw the liquid flowing out of the perforated pipe 6. The production packer 10 is sleeved on the tank pump assembly 9 and is in interference fit with the inner wall of the casing 23 to form a sealing band. The downhole safety valve 12 is arranged in the tank pump assembly and controls the flow of the tank pump assembly 9. The liquid flowing into the oil pipe through the perforated pipe 6 can be transported to the offshore platform through the tank pump assembly 9, so as to achieve the purpose of oil production.

[0043] Figure 3 The injection unit can include a gas supply system and an injection pipe 21 in one embodiment, the gas supply system is communicated with the injection pipe 21; the gas supply system includes a carbon dioxide injection pump 14 and a corrosion inhibitor injection pump 18, the carbon dioxide injection pump 14 and the corrosion inhibitor injection pump 18 are connected to the injection pipe 21 in parallel, a pressure gauge 20 is arranged at the parallel position of the injection pipe 21, and the injection pipe 21 is communicated into the sealing space 22.

[0044] It can be understood that the corrosion inhibitor is mainly used to slow down the corrosion of the carbon dioxide and the acidic substance formed by the water to the casing 23 and other components.

[0045] In a specific embodiment, the outlet of the injection pipe 21 is arranged in the circular space surrounded by the filter blocking assembly, because the liquid filtered in advance will not cause serious damage to the injection pipe 21 and back flushing.

[0046] In a specific embodiment, the first minimum flow valve can include a carbon dioxide injection assembly including a carbon dioxide injection pump 14 and a first regulating valve 15, the carbon dioxide injection pump 14 is connected to the first regulating valve 15 and the injection pipe 21 in sequence through a pipeline, and a corrosion inhibitor injection assembly including a corrosion inhibitor injection pump 18 and a second regulating valve 17, the corrosion inhibitor injection pump 18 is connected to the second regulating valve 17 and the injection pipe 21 in sequence through a pipeline.

[0047] Further, the second regulating valve 17 is a one-way valve, which is used to prevent the high-pressure carbon dioxide from back flushing into the corrosion inhibitor injection pump 18.

[0048] Further, a three-way mixer 16 is arranged at the parallel position of the carbon dioxide injection assembly and the corrosion inhibitor injection assembly, and the carbon dioxide injection assembly, the corrosion inhibitor injection assembly and the injection pipe 21 are communicated to the three-way mixer 16.

[0049] Further, a switch valve 19 is further arranged on the injection pipe 21, and the switch valve 19 can control the flow of the injection pipe 21.

[0050] Figure 4 A method for extracting and injecting oil by using a same-well multi-layer oil extraction injection pipe column mechanism is shown, which includes the following steps:

[0051] Step S1, the sealing unit is lowered into the casing 23 and reaches a specified depth, and the sealing unit is set;

[0052] Step S2, the oil extraction unit is lowered and arranged in the sealing unit, and the oil extraction unit is sealed with the sealing unit;

[0053] Step S3, the oil extraction unit sucks the crude oil below the sealing unit to the space above the sealing unit and supplies it to the oil extraction platform;

[0054] Step S4, the gas injection unit is started to inject carbon dioxide into the isolation space 22 and into the formation through the casing 23.

[0055] Figure 5 In one embodiment, the steps include:

[0056] Step S11, the bottom packer 1 and the top packer 4 are connected in sequence and then lowered into the casing 23 and reach the designated depth, and the bottom packer 1 and the top packer 4 are set.

[0057] Step S12, the perforating pipe 6, the anchoring sealing member 7, the positioning sealing member 8, the canning pump assembly 9, the production packer 10 and the downhole safety valve 12 are lowered into the casing 23 in sequence, and the perforating pipe 6 is arranged in the bottom packer 1 and the top packer 4.

[0058] Step S13, the anchoring sealing member 7 is sealingly connected with the bottom packer 1, the positioning sealing member 8 is sealingly connected with the top packer 4, the production packer 10 is set with the casing 23, and the injection pipe 21 is arranged in the production packer 10 and the top packer 4 in sequence.

[0059] Step S21, the liquid enters into the pipe through the perforating pipe 6 of the central production pipe column, is lifted to the oil production platform by the canning pump assembly 9, and the downhole safety valve 12 is in the pressurized opening state.

[0060] Step S22, the carbon dioxide injection pump 14 and the corrosion inhibitor injection pump 18 are started respectively, and when the output pressure of the carbon dioxide injection pump 14 and the corrosion inhibitor injection pump 18 is stable, pressure test is performed.

[0061] Step S23, after the pressure test is completed, the output pressure of the first adjusting valve 15 and the second adjusting valve 17 is opened and adjusted, the carbon dioxide gas-liquid supercritical body and the corrosion inhibitor form a mixed liquid which enters into the injection pipe 21, the mixed liquid flows through the injection pipe 21 and the isolation space 22, and finally flows into the formation and the salt water layer for storage.

[0062] Figure 4 In one embodiment, step S1 can include that after the isolation unit is set, sealing test needs to be performed, that is, a sealing test is performed on the isolation unit by using a maximum gas injection pressure greater than that of the gas injection unit, and if there is no obvious pressure drop of the isolation unit, the setting is qualified, and step S2 can be continued.

[0063] Figure 4 In one embodiment, steps S1 to S4 can include that when emergency shutdown is needed, the gas injection unit needs to be slowly closed first, and then the oil production unit is shut down.

[0064] In a specific embodiment, the carbon dioxide injection pump 1414 and the corrosion inhibitor injection pump 18 are first closed, then the first regulating valve 15 and the second regulating valve 17 are closed, and finally the downhole safety valve 12 is closed.

[0065] It can be understood that the above embodiments only express the preferred embodiments of the present application, which are described in a more specific and detailed manner, but cannot be understood as a limitation to the patent scope of the present application; it should be pointed out that the above technical features can be freely combined without departing from the concept of the present application for those skilled in the art, and several modifications and improvements can be made, which all belong to the protection scope of the present application; therefore, any equivalent transformation and modification within the scope of the claims of the present application shall belong to the scope of the claims of the present application.

Claims

1. A multi-layer oil production and gas injection tubing system for a single well, characterized in that, include: The well includes a casing (23), an oil production unit for drawing crude oil from the casing (23), an injection unit for injecting carbon dioxide back into the bottom layer, and a packer unit located at a designated position within the casing (23). The packer unit isolates the space above and below the packer unit at a designated position on the casing (23), forming a packer space (22) within the packer unit. The gas injection unit is connected to the packer space (22) through a pipeline. The packer space (22) is connected to the formation through the casing (23). The oil production unit is installed in the packer unit and connects the space above and below the packer unit. The sealing unit includes a bottom packer (1) and a top packer (4). The bottom packer (1) and the top packer (4) are disposed inside the sleeve (23). The top packer (4) is disposed above the bottom packer (1). The bottom packer (1) and the top packer (4) abut against the sleeve (23) through the expansion of their outer circumferences to form a sealing strip. The oil production unit includes a perforated pipe (6), an anchoring seal (7), and a positioning seal (8). The perforated pipe (6) passes through the packer unit. The anchoring seal (7) and the positioning seal (8) are sleeved on the perforated pipe (6). The anchoring seal (7) is sealed to the bottom packer (1), and the positioning seal (8) is sealed to the top packer (4). The gas injection unit includes a gas supply system and an injection pipe (21). The gas supply system is connected to the injection pipe (21). The gas supply system includes a carbon dioxide injection pump (14), a corrosion inhibitor injection pump (18), and a pressure gauge (20). The carbon dioxide injection pump (14) and the corrosion inhibitor injection pump (18) are connected in parallel to the injection pipe (21). The pressure gauge (20) is located at the parallel connection point of the injection pipe (21). The injection pipe (21) is connected to the enclosure space (22).

2. The multi-layer oil production and gas injection tubing system according to claim 1, characterized in that, The sealing unit also includes a filter blocking assembly, which is arranged in a ring within the sealing space (22) and is sealed to the bottom packer (1) and the top packer (4).

3. The multi-layer oil production and gas injection tubing system according to claim 2, characterized in that, The filter blocking assembly includes a blind tube (2) and a sand-proof screen tube (3). The blind tube (2) is disposed at the upper and lower parts of the filter blocking assembly. The blind tube (2) is used to block muddy impurities from entering the sealed space (22). The sand-proof screen tube (3) is disposed in the middle of the filter blocking assembly. The sand-proof screen tube (3) is tubular and connects the internal and external spaces of the filter blocking assembly. One end of the sand-proof screen tube (3) is provided with a screen.

4. The multi-layer oil production and gas injection tubing system according to claim 1, characterized in that, The oil production unit is also equipped with a canister pump assembly (9), a production packer (10), and a downhole safety valve (12). The canister pump assembly (9) is located on the upper part of the perforated pipe (6) and is used to draw the liquid flowing out of the perforated pipe (6). The production packer (10) is sleeved on the canister pump assembly (9) and forms a sealing band with an interference fit with the inner wall of the casing (23). The downhole safety valve (12) is located inside the canister pump assembly (9) and controls the flow rate of the canister pump assembly (9).

5. A method for the production and injection of a multi-layered gas injection tubing system in a single well, applied to the multi-layered gas injection tubing system in a single well as described in any one of claims 1-4, characterized in that, Includes the following steps: Step S1: Lower the packer unit into the sleeve (23) to the specified depth and set the packer unit. Step S2: The oil production unit is lowered and inserted into the packer unit, and the oil production unit is sealed to the packer unit; Step S3: The oil production unit draws the crude oil below the packer unit into the space above the packer unit and supplies it to the oil production platform. Step S4: Start the gas injection unit to inject carbon dioxide into the sealed space (22) and enter the formation through the casing (23).

6. The production and injection method of a multi-layer oil and gas production tubing system in the same well according to claim 5, characterized in that, In step S1, after the packer unit is set, a seal test is required. That is, the packer unit is tested for seal using a pressure greater than the maximum injection pressure of the injection unit. If the packer unit does not have a significant pressure drop, the setting is qualified, and step S2 continues.

7. The production and injection method of a multi-layer oil and gas production tubing system in the same well according to claim 5, characterized in that, In steps S1 to S4, if an emergency shutdown is required, the gas injection unit must be shut down first, followed by the oil production unit.

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