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WO2024060415A1 - 基于异步周期的采油装置、方法及系统 - Google Patents

基于异步周期的采油装置、方法及系统 Download PDF

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Publication number
WO2024060415A1
WO2024060415A1 PCT/CN2022/137598 CN2022137598W WO2024060415A1 WO 2024060415 A1 WO2024060415 A1 WO 2024060415A1 CN 2022137598 W CN2022137598 W CN 2022137598W WO 2024060415 A1 WO2024060415 A1 WO 2024060415A1
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Prior art keywords
well
oil
gas
pressure
injection
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PCT/CN2022/137598
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English (en)
French (fr)
Inventor
王海涛
孙焕泉
何应付
骆铭
伦增珉
Original Assignee
中国石油化工股份有限公司
中国石油化工股份有限公司石油勘探开发研究院
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Publication of WO2024060415A1 publication Critical patent/WO2024060415A1/zh

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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/25—Methods for stimulating production

Definitions

  • the present invention relates to the technical field of oil and gas field development, and in particular to an asynchronous cycle-based oil production device, method and system.
  • Unconventional oil reservoirs such as shale oil and tight oil are rich in resources and are new areas for future oil strategic succession. Due to the poor reservoir properties of unconventional oil reservoirs such as shale oil and tight oil, the matrix permeability is ⁇ 1mD (overburden permeability ⁇ 0.1mD), and the current main method is to develop through depletion after multi-stage fracturing of horizontal wells, but the recovery rate is low and the decline is large. After large-scale fracturing, there are multi-scale fractures, including natural bedding fractures and artificial fracture fractures. During water injection development, water channeling is serious in areas with fractures, and it is difficult for water injection to enter the dense matrix and mobilize crude oil. It is urgent to overcome efficient development technology and technology to significantly increase recovery rate. In addition, key technologies are also urgently needed to significantly increase recovery rates in complex types of reservoirs such as low permeability reservoirs, fault block reservoirs, heavy oil reservoirs and carbonate reservoirs.
  • Gas injection development is an important technology for improving oil recovery, mainly by injecting gas into the formation to displace oil.
  • Gas types mainly include hydrocarbon gases and non-hydrocarbon gases.
  • Hydrocarbon gases mainly include liquefied petroleum gas, rich gas, dry gas (methane), etc.
  • Non-hydrocarbon gases mainly include CO 2 , N 2 , air, flue gas, etc.
  • gas molecules are smaller and can more easily enter the pores of reservoir rocks, making it easier to establish an effective displacement system to drive crude oil.
  • it becomes miscible with crude oil or reduces multi-phase interfacial tension and expansion. It has significant effects on crude oil and reducing the viscosity of crude oil, and has a completely different oil displacement mechanism from water.
  • gas injection huff and puff, continuous gas displacement, water and gas alternation, etc. are currently the main gas injection development methods.
  • the object of the present invention is to provide an asynchronous cycle oil production device, method and system, which improves the oil production efficiency of heterogeneous oil reservoirs with fractures or high permeability strips.
  • the present invention provides an oil production device based on an asynchronous cycle.
  • the oil production device includes: at least one well group and a control unit.
  • the well group includes a wellbore and at least one horizontal well group.
  • Each of the The horizontal well group at least includes a first well and a second well, the wellbore is vertical to the ground, each well group shares one wellbore, the first well and the second well are both horizontal wells parallel to the ground;
  • a casing, an oil pipe and a packer are provided in the wellbore.
  • the casing is used for gas injection in the first well
  • the oil pipe is used for crude oil production in the second well
  • the packer is used to isolate the the annular space between the oil pipe and the casing
  • the control unit is used to perform the following steps on the well group: Step 1: Inject gas into the first well through the casing, and the second The well is simmered; Step 2: Continue to inject the gas into the first well to displace crude oil to the second well, and at the same time, the second well produces through the oil pipe; Step 3: Inject the The first well and the second well are simmered to allow the gas to enter the low permeability area; step 4: continue to simmer the first well, and the second well produces through the oil pipe.
  • control unit is also used to obtain environmental parameters of the well group in real time to control oil production parameters.
  • control device is also used to determine the formation pressure and the minimum miscible pressure of the formation fluid based on the environmental parameters, and to control the oil production parameters based on the formation pressure and the minimum miscible pressure of the formation fluid.
  • the environmental parameters include at least: the bottom hole pressure and wellbore pressure of the first well, the bottom hole pressure and wellbore pressure of the second well; the oil production parameters at least include injection pressure, the injection rate of the gas, the Gas injection time, well simmering time, production time and production speed.
  • control unit is also configured to perform the following steps: in step 1, when the formation pressure is higher than the preset first target pressure, perform step 2; in step 2, when the local pressure is higher than the preset first target pressure, When the formation pressure is lower than the preset second target pressure, step 3 is performed; in step 3, when the derivative of the average formation pressure is zero, step 4 is performed.
  • the first target pressure is 1.4 times the minimum miscible pressure; the second target pressure is 1.2 times the minimum miscible pressure.
  • control unit is also configured to increase the injection rate and/or the production rate when it is detected that the formation pressure and the minimum miscible pressure of the formation fluid are both less than the pressure target.
  • the injection rate and/or the production rate are reduced.
  • control unit is also configured to repeatedly execute step 1 to step 4 in sequence, and obtain the oil-gas ratio of the crude oil in real time.
  • oil-gas ratio is lower than a preset threshold, the asynchronous periodic oil production is completed.
  • control unit includes: a sensor for collecting environmental information of the well group in real time; a calculator for calculating the formation pressure, the minimum miscible pressure of the formation fluid and the average formation pressure according to the environmental information.
  • the derivative of pressure a controller used to control the oil production parameters and execute the oil production mode formed by step 1 to step 4.
  • the well group includes multiple horizontal well groups, and the angle between two adjacent horizontal well groups is 90°-180°.
  • the first well and the second well of the same horizontal well group are arranged in parallel along the longitudinal direction of the wellbore, and the distance between the first well and the second well is twice the half height of a single well fracture. .
  • the gas is hydrocarbon gas and/or non-hydrocarbon gas, wherein the hydrocarbon gas is at least one of liquefied petroleum gas, rich gas and dry gas, and the non-hydrocarbon gas is at least one of CO 2 , N 2 , air and flue gas.
  • hydrocarbon gas is at least one of liquefied petroleum gas, rich gas and dry gas
  • non-hydrocarbon gas is at least one of CO 2 , N 2 , air and flue gas.
  • a chemical agent for inhibiting gas channeling is added to the gas, and the chemical agent is foam or gel.
  • the oil area to be produced is an unconventional oil reservoir or a conventional oil reservoir, wherein the unconventional oil reservoir is selected from shale oil and tight oil, and the conventional oil reservoir is selected from low permeability oil reservoirs and fault block oil. At least one of a heavy oil reservoir, a heavy oil reservoir and a carbonate reservoir.
  • the first wells of the plurality of horizontal well groups operate asynchronously, and/or the second wells of the plurality of horizontal well groups operate asynchronously.
  • the present invention also provides an oil recovery method based on asynchronous cycles, which is implemented according to the oil recovery device as described above, wherein the oil recovery method includes: Step 1: Set at least A well group, the well group includes a wellbore and at least one horizontal well group, each horizontal well group includes at least a first well and a second well, the wellbore is vertical to the ground, and each well group shares one wellbore , the first well and the second well are both horizontal wells parallel to the ground, and the wellbore is provided with a casing for gas injection in the first well and an oil pipe for crude oil production in the second well.
  • Step 2 Inject gas into the first well through the casing, and perform well boiling in the second well;
  • Step 3 Continue to inject the gas into the first well to displace crude oil to the second well, while the second well produces through the oil pipe;
  • Step 4 Inject the first well and the third well The second well is simmered to allow the gas to enter the low permeability area;
  • step 5 continue to simmer the first well, and the second well is produced through the oil pipe.
  • the oil recovery method further includes: repeatedly executing steps 2 to 5 in sequence, and obtaining the oil-gas ratio of the crude oil in real time.
  • the oil-gas ratio is lower than a preset threshold, the asynchronous periodic oil recovery is completed.
  • the well group includes multiple horizontal well groups, and the angle between two adjacent horizontal well groups is 90°-180°.
  • the first well and the second well of the same horizontal well group are arranged in parallel along the longitudinal direction of the wellbore, and the distance between the first well and the second well is twice the half height of a single well fracture. .
  • the gas is a hydrocarbon gas and/or a non-hydrocarbon gas, wherein the hydrocarbon gas is at least one of liquefied petroleum gas, rich gas, and dry gas, and the non-hydrocarbon gas is CO 2 , N 2 , at least one of air and flue gas.
  • the hydrocarbon gas is at least one of liquefied petroleum gas, rich gas, and dry gas
  • the non-hydrocarbon gas is CO 2 , N 2 , at least one of air and flue gas.
  • a chemical agent for inhibiting gas channeling is added to the gas, and the chemical agent is foam or gel.
  • the oil area to be produced is an unconventional oil reservoir or a conventional oil reservoir, wherein the unconventional oil reservoir is selected from shale oil and tight oil, and the conventional oil reservoir is selected from low permeability oil reservoirs and fault block oil. At least one of a heavy oil reservoir, a heavy oil reservoir and a carbonate reservoir.
  • the first wells of the plurality of horizontal well groups operate asynchronously, and/or the second wells of the plurality of horizontal well groups operate asynchronously.
  • the present invention provides an asynchronous cycle-based oil production system, which includes: the asynchronous cycle-based oil production device as described above; and a gas recovery device for realizing the control of outflow from the well group. gas separation and recovery.
  • one or more embodiments of the above solutions may have the following advantages or beneficial effects:
  • the control unit performs the following four steps on the well group: Step 1: Inject gas into the first well through the casing, and the second well is soaked; Step 2: Continue to inject gas into the first well to drive Transfer crude oil to the second well, and at the same time, the second well produces through oil pipes; Step 3: The first well and the second well are simmered to allow the gas to enter the low permeability area; Step 4: The first well continues to simmer, and the second well produces through tubing.
  • step 1 and step 2 inject gas into the first well, that is, between other two adjacent steps, for example, between step 2 and step 3, there is no operation of injecting gas into the first well; thus, the mechanisms of pressurized mixed phase production of crude oil, displacement of crude oil, well diffusio n, expansion production of crude oil, and depressurized dissolved gas driving crude oil are brought into play, breaking through the technical bottleneck of CO2 injection to develop unconventional oil reservoirs such as shale oil and tight oil, and realizing efficient gas injection development of heterogeneous oil reservoirs with fractures or high permeability bands.
  • Figure 1 is an application example diagram of an asynchronous cycle-based oil production device according to an embodiment of the present application.
  • FIG. 2 is a schematic top view of a first example of an asynchronous cycle-based oil production device according to the embodiment of the present application.
  • Figure 3 is a schematic top view of a second example of an asynchronous cycle-based oil production device according to the embodiment of the present application.
  • Figure 4 is a schematic flowchart of the asynchronous cycle-based oil production method according to the embodiment of the present application.
  • Figure 5 is a schematic diagram of the periodic recovery rate in the asynchronous period-based oil recovery method according to the embodiment of the present application.
  • the steps illustrated in the flowcharts of the figures may be performed in a computer system, such as a set of computer-executable instructions. Also, although a logical order is shown in the flowchart diagrams, in some cases the steps shown or described may be performed in a different order than herein.
  • Unconventional oil reservoirs such as shale oil and tight oil are rich in resources and will be a new area for future petroleum strategic succession. Due to poor physical properties of unconventional oil reservoirs such as shale oil and tight oil, with matrix permeability ⁇ 1mD (overburden permeability ⁇ 0.1mD), horizontal wells are currently mainly developed using multi-stage fracturing followed by depletion, but the recovery rate is low. , the decrease is large. After large-scale fracturing, multi-scale fractures exist, including natural bedding fractures and artificial fracturing fractures. During water injection development, water channeling is severe in areas with fractures, making it difficult for water injection to enter the tight matrix and utilize crude oil. There is an urgent need to overcome high-efficiency development technology and greatly increase oil recovery technology. In addition, key technologies are urgently needed to significantly improve oil recovery in complex types of reservoirs such as low permeability reservoirs, fault block reservoirs, heavy oil reservoirs and carbonate reservoirs.
  • Gas injection development is an important technology for improving oil recovery in oil fields. It mainly injects gas into the formation to drive oil.
  • Gas types mainly include hydrocarbon gas and non-hydrocarbon gas.
  • Hydrocarbon gas mainly includes liquefied petroleum gas, rich gas, dry gas (methane), etc.
  • Non-hydrocarbon gas mainly includes CO2, N2, air, flue gas, etc.
  • gas molecules are smaller and can more easily enter the pores of reservoir rocks, making it easier to establish an effective displacement system to drive crude oil.
  • it becomes miscible with crude oil or reduces multi-phase interfacial tension and expansion. It has significant effects on crude oil and reducing the viscosity of crude oil, and has a completely different oil displacement mechanism from water.
  • gas injection huff and puff, continuous gas displacement, water and gas alternation, etc. are currently the main gas injection development methods.
  • the invention provides an oil production device based on asynchronous cycles.
  • the oil production device includes: at least one well group and a control unit.
  • Each well group includes a wellbore and at least one horizontal well group, and each horizontal well group includes at least a first well and a second well.
  • the wellbore is vertical to the ground, and each well group shares one wellbore.
  • the first well and the second well are both horizontal wells parallel to the ground.
  • the wellbore is provided with casing, oil pipe and packer.
  • the casing is used for gas injection in the first well
  • the oil pipe is used for crude oil production in the second well
  • the packer is used for isolation.
  • the annular space of the tubing and casing is used for isolation.
  • the packer is used to seal the annular space between the oil pipe and casing of the wellbore to ensure that the gas injected from the casing enters the horizontal well section of the first well.
  • the control unit is used to perform the following operations on the well group: Step 1: Inject gas into the first well through the casing, and perform simmering on the second well; Step 2: Continue to inject gas into the The first well is used to displace crude oil to the second well, while the second well produces through oil pipes; Step 3: Stew the first well and the second well to allow the gas to enter the low Penetration area; Step 4: The first well continues to simmer, and the second well produces through tubing. Wherein, during the execution of steps 1 and 4, only the steps 1 and 2 inject gas into the first well. That is, between other two adjacent steps, for example, between step 2 and step 3, there is no operation of injecting gas into the first well.
  • control device is also configured to repeatedly execute steps 2 to 4 in sequence, and obtain the oil-gas ratio of the crude oil in real time.
  • oil-gas ratio is lower than a preset threshold, the asynchronous periodic oil production task is completed.
  • This invention can effectively reduce the drilling cost of a single well by vertically deploying two horizontal wells: the first well and the second well, and the two wells share the vertical section wellbore.
  • the horizontal sections of the two wells are parallel, and staged fracturing is implemented.
  • the vertical distance is twice the height of the single-well fracturing half-fracture to ensure control of more reserves and maximize single-well EUR (Estimated Ultimate Recovery).
  • Step 1 Inject gas into the first well through the casing, and perform simmering in the second well; the injected gas may be hydrocarbon gas and/or non-hydrocarbon gas, and the hydrocarbon gas may be liquefied petroleum gas, Rich gas, dry gas, etc., and the non-hydrocarbon gases are CO 2 , N 2 , air, flue gas, etc.
  • the specific location and connection status of the first well and the second well are determined based on the stratigraphic conditions of the specific oil production area.
  • the main purpose of stewing the second well is to prevent the injected gas from being produced through the second well, so that the injected gas remains in the reservoir and increases the pressure of the reservoir. At this time, the gas Continue to spread into the reservoir pores.
  • This step 1 can increase the pressure of the entire formation.
  • the increase in pressure can realize the miscibility of the injected gas and the formation crude oil, while reducing the stress sensitivity of the reservoir and improving the seepage capacity and oil displacement efficiency.
  • the casing is made of different grades of steel according to different strengths.
  • Step 2 Continue to inject gas into the first well to displace crude oil to the second well, and at the same time, the second well produces through the oil pipe; according to a preferred embodiment.
  • Producing the second well includes extracting the crude oil in the second well and outputting it for collection.
  • the oil production operation is performed in the same manner as the gas injection operation of the first well.
  • This step 2 can establish effective displacement between wells, exert the displacing effect of gas between wells, efficiently displace crude oil in fractures or high permeability channels, quickly extract crude oil from easy-flow areas, and at the same time increase the injection rate of gas.
  • the contact area with the matrix or low permeability area effectively improves the utilization rate of crude oil in the matrix or low permeability area.
  • the casing is made of different grades of steel according to different strengths.
  • Step 3 Stew the first well and the second well to allow the gas to enter the low permeability area.
  • This step 3 mainly exerts the diffusion effect of gas during the well stewing process.
  • the gas enters the crude oil through diffusion, expands the crude oil, and reduces the multi-phase interfacial tension and crude oil viscosity. Since it is a well stewing process, step 3 can weaken the channeling effect of gas, realize the diffusion of gas into the matrix or low permeability area, exert the mechanism of expansion, reduce interfacial tension, and reduce the viscosity of crude oil, and effectively utilize the matrix and low permeability area. of crude oil.
  • Step 4 The first well continues to simmer, and the second well produces through tubing.
  • the first well is continued to be simmered because when the first well is in a closed state, no gas will be injected and produced from the first well, so that part of the gas near the first well It continues to spread into the pores of the reservoir, while the other part flows and displaces towards the second well.
  • This step 4 is used for the gas to displace the remaining crude oil to the second well.
  • step 1 and step 4 inject gas into the first well.
  • step 2 when the formation pressure in step 1 is higher than the preset first target pressure, step 2 is executed; when the formation pressure in step 2 is lower than the preset second target pressure, step 2 is executed. 3; When the derivative of the average formation pressure in step 3 is zero, perform step 4.
  • the first target pressure is 1.4 times the minimum miscible pressure; the second target pressure is 1.2 times the minimum miscible pressure.
  • Performing steps 1 to 4 in sequence constitutes one oil production cycle.
  • the injection wells and production wells in adjacent oil production cycles can be interchanged.
  • the first well is the injection well and the second well is the production well.
  • the first well can be changed to the production well and the second well is the injection well.
  • the entire development and production process can keep the injection wells of all well groups synchronized, and the production wells of all well groups also synchronized; several well groups can also be combined into a large well group, and the wells in the combined large well group can be synchronized, or
  • the well group performs asynchronous cycle injection and production development in sequential, reverse or irregular order.
  • the first wells of the plurality of horizontal well groups operate asynchronously
  • the second wells of the plurality of horizontal well groups operate asynchronously.
  • chemical agents for inhibiting gas channeling can be added during the injection process of the injection well.
  • the chemical agent can be a foam system, a gel system or other substances that can effectively inhibit gas channeling. Channeling system.
  • methods such as alternating gas and water can also be used to effectively suppress gas channeling.
  • the oil area to be produced is an unconventional oil reservoir or a conventional oil reservoir.
  • the unconventional oil reservoir is selected from shale oil and tight oil
  • the conventional oil reservoir is selected from at least one of low permeability oil reservoir, fault block oil reservoir, heavy oil oil reservoir and carbonate rock oil reservoir. .
  • the control unit is also used to obtain the environmental parameters of the well group in real time to control the oil production parameters. Specifically, the formation pressure and the minimum miscible pressure of the formation fluid are determined according to the environmental parameters, and then the oil production parameters are controlled according to the formation pressure and the minimum miscible pressure of the formation fluid. For example, when the average formation pressure is lower than the minimum miscible pressure, the injection volume is controlled in real time with 1.4MMP as the target pressure, and the injection speed is designed to be no higher than 90% of the maximum injection speed of the injection pump. When the average formation pressure is higher than 1.4MMP, the first process is skipped and the second process is directly entered.
  • the environmental parameters at least include: the bottom hole pressure and wellbore pressure of the first well, the bottom hole pressure and wellbore pressure of the second well; the oil production parameters at least include injection pressure, gas injection rate, gas injection duration, well soaking Duration, production time and production speed.
  • the first well and the second well of the same horizontal well group are arranged in parallel along the longitudinal direction of the wellbore, and the distance between the first well and the second well is twice the half height of a single well fracture.
  • two horizontal wells are deployed vertically: the injection well m and the production well n.
  • the two wells share the vertical section of the wellbore.
  • the two horizontal wells can use depletion development in the initial stage, or they can directly enter asynchronous development. Periodic injection and production development stage. If depletion development is adopted, the first well produces from the annular space of tubing j and casing i, and the second well produces from tubing j.
  • the first well is used as the injection well m
  • the second well is used as the production well n.
  • a packer k is used to seal the annular space of the tubing and casing.
  • control unit a includes: during the CO 2 asynchronous cycle injection and production process, automatic control is carried out through the control unit a of the intelligent injection and production of the wellhead Christmas tree.
  • the control unit a includes sensors, calculators and controllers. Wherein, the sensor is used to collect environmental information of the well group in real time; the calculator is used to calculate the formation pressure, the minimum miscible pressure of the formation fluid and the derivative of the average formation pressure based on the collected environmental information; the controller is used to control oil production parameters, and execute the oil production method formed by steps 1 to 4 above.
  • the senor is used to collect the second pressure gauge f, the first pressure gauge d of the casing at the wellhead, the oil pipe gas composition analysis system e, the third pressure gauge f of the injection well m, and the fourth pressure gauge h of the production well n.
  • MMP minimum miscible pressure
  • the controller is also used to optimize the injection rate and production rate using built-in model calculations based on the minimum miscible pressure (MMP) of the formation fluid calculated in real time and combined with the pressure target. For example: when the minimum miscible pressure of the formation fluid and the formation pressure are both less than the pressure target, then increase the injection rate and/or production rate; when the minimum miscibility pressure of the formation fluid and the formation pressure are both greater than the pressure target, then Reduce injection speed and/or production speed.
  • MMP minimum miscible pressure
  • the controller controls the injection pump, the injection port c of the wellhead Christmas tree and the production nozzle b of the wellhead Christmas tree in real time to perform intelligent injection and production control and achieve efficient development of the reservoir.
  • each well group may include multiple horizontal well groups, and the angle between two adjacent horizontal well groups is 90°-180°.
  • FIG. 2 is a schematic top view of a first example of an asynchronous cycle-based oil production device according to the embodiment of the present application.
  • Figure 3 is a schematic top view of a second example of an asynchronous cycle-based oil production device according to the embodiment of the present application. As shown in Figure 2, it is a top view of a well group in an oil production device.
  • the well group includes a first wellbore 300, a first horizontal well group 301, a second horizontal well group 302, a third horizontal well group 303 and a fourth Horizontal well groups 304, each horizontal well group only includes a first well and a second well, and the angle between two adjacent horizontal well groups is 90 degrees.
  • the well group includes a second wellbore 400, a fifth horizontal well group 401 and a sixth horizontal well group 402. The angle between two adjacent horizontal well groups is 180 degrees.
  • the asynchronous periodic oil production device of the present invention realizes efficient, automatic and intelligent control, and designs a low-cost three-dimensional development injection and production well model for the asynchronous periodic gas injection and oil production method.
  • the oil production device also exerts the mechanisms of pressurizing miscible crude oil, displacing crude oil, well diffusion, expanding crude oil, and depressurizing dissolved gas to drive crude oil.
  • the oil displacement efficiency exceeds 90%, breaking through the CO2 injection to develop shale oil.
  • the technical bottleneck of unconventional reservoirs such as tight oil has achieved efficient development of gas injection in heterogeneous reservoirs with fractures or high permeability strips; among the four processes in a single cycle, only the first and second processes Gas is injected from the injection well, and there is no need to inject gas in the other two injection processes.
  • the injection and production well model is developed, and two horizontal wells are deployed vertically.
  • the two wells share the vertical section of the wellbore, which can effectively reduce the drilling cost of a single well.
  • the injection and production of two horizontal wells are integrated by using casing gas injection and tubing production, which improves the efficiency of the injection and production wells.
  • Efficiency; the present invention also integrates sensors, calculators, and controllers on the production tree through intelligent control to achieve real-time calculation and precise control of average formation pressure, minimum miscible pressure of formation fluid, target formation pressure, injection rate, and production rate.
  • the present invention also proposes an oil production method based on asynchronous cycle.
  • the oil production method is implemented according to the above-mentioned asynchronous period-based oil production device.
  • This oil production method is mainly used in unconventional resources such as shale oil and tight oil, low permeability reservoirs, heavy oil reservoirs, integrated reservoirs, fault block reservoirs, high water content reservoirs, high temperature and high salt reservoirs, carbonic acid reservoirs, etc. Development of salt rock reservoirs and other special lithology reservoirs.
  • FIG. 4 is a schematic flowchart of the asynchronous cycle-based oil production method according to the embodiment of the present application.
  • step S101 is: setting up at least one well group in the oil production area, each well group includes a wellbore and at least one horizontal well group, and each horizontal well group includes at least a first well and a second well, The wellbore is perpendicular to the ground, and each well group shares one wellbore.
  • the first well and the second well are both horizontal wells parallel to the ground.
  • the first well may be an injection well
  • the second well may be a production well.
  • Each well group may include multiple first wells and multiple second wells, and the first well and the second well may include
  • the injection and production methods can be different, and the injection and production cycles can be asynchronous.
  • the first well and the second well of the same horizontal well group are arranged in parallel along the longitudinal direction of the wellbore, and the distance between the first well and the second well is twice the half height of a single well fracture.
  • Each well group may include multiple horizontal well groups. Preferably, the angle between two adjacent horizontal well groups is 180°.
  • the wellbore is provided with casing, oil pipe and packer.
  • the casing is used for gas injection of the first well
  • the oil pipe is used for crude oil production of the second well
  • the packer is used for isolation.
  • the tubing and casing are used for gas injection of the first well, the oil pipe is used for crude oil production of the second well, and the packer is used for isolation.
  • the tubing and casing are used for gas injection of the first well, the oil pipe is used for crude oil production of the second well, and the packer is used for isolation.
  • This invention can effectively reduce the drilling cost of a single well by vertically deploying two horizontal wells: the first well and the second well, and the two wells share the vertical section wellbore.
  • the horizontal sections of the two wells are parallel, and staged fracturing is implemented.
  • the vertical distance is twice the height of the single-well fracturing half-fracture to ensure control of more reserves and maximize single-well EUR (Estimated Ultimate Recovery).
  • Step S102 is: injecting gas into the first well through the casing, and performing well boiling on the second well.
  • the injected gas can be hydrocarbon gas and/or non-hydrocarbon gas.
  • the hydrocarbon gas is liquefied petroleum gas, rich gas, dry gas, etc.
  • the non-hydrocarbon gas is CO 2 , N 2 , air, flue Qi and so on.
  • the specific location and connection status of the first well and the second well are determined based on the stratigraphic conditions of the specific oil production area.
  • This step S102 can increase the pressure of the entire formation.
  • the increase in pressure can achieve miscibility of the injected gas and the formation crude oil, while reducing reservoir stress sensitivity and improving seepage capacity and oil recovery efficiency.
  • Step S103 is: continuing to inject gas into the first well to displace crude oil to the second well, while the second well produces through the oil pipe.
  • Producing the second well includes extracting crude oil in the second well and exporting it for collection.
  • This step S103 can establish effective displacement between wells, exert the displacing effect of gas between wells, efficiently displace crude oil in fractures or high permeability channels, quickly extract crude oil from easy-flow areas, and at the same time increase the injection rate of gas.
  • the contact area with the matrix or low permeability area effectively improves the utilization rate of crude oil in the matrix or low permeability area.
  • Step S104 is: the first well and the second well are soaked to allow the gas to enter the low permeability area.
  • This step mainly plays the role of gas diffusion during the soaking process.
  • the gas diffuses into the crude oil, expands the crude oil, and reduces the multiphase interface tension and crude oil viscosity. Since it is a soaking process, this step can weaken the cross-flow effect of the gas, realize the diffusion of the gas into the matrix or low permeability area, play the role of expansion, reduce the interface tension, and reduce the viscosity of the crude oil, and efficiently mobilize the crude oil in the matrix and low permeability area.
  • Step S105 is: the first well continues to simmer, and the second well produces through oil pipes. This step S105 is used for the gas to displace the remaining crude oil to the second well.
  • This step S105 is used for the gas to displace the remaining crude oil to the second well.
  • steps 102 and 105 During the execution of steps 102 and 105, only steps 102 and 103 are used to inject gas into the first well. Between other adjacent steps, for example, between steps 103 and 104, no gas is injected into the first well. The operation of injecting gas into a well.
  • step 103 when the formation pressure in step 102 is higher than the preset first target pressure, step 103 is executed; when the formation pressure in step 103 is lower than the preset second target pressure, step 104 is executed; when the derivative of the average formation pressure in step 104 is zero, step 105 is executed.
  • Executing steps S101 to S105 in sequence constitutes one oil production cycle.
  • the injection wells and production wells in adjacent oil production cycles can be interchanged.
  • the first well is the injection well and the second well is the production well.
  • the second oil production cycle the first well can be changed to the production well and the second well is the injection well.
  • the entire development and production process can keep the injection wells of all well groups synchronized, and the production wells of all well groups also synchronized; several well groups can also be combined into a large well group, and the wells in the combined large well group can be synchronized, or
  • the well group performs asynchronous cycle injection and production development in sequential, reverse or irregular order.
  • the first wells of the plurality of horizontal well groups operate asynchronously
  • the second wells of the plurality of horizontal well groups operate asynchronously.
  • chemical agents can be added to inhibit gas channeling during the injection process of the injection well.
  • the chemical agent can be a foam system, a gel system, or other systems that can effectively inhibit gas channeling.
  • methods such as alternating gas and water can also be used to effectively suppress gas channeling.
  • the oil production method also includes obtaining environmental parameters of the well group in real time for controlling oil production parameters. Specifically, it includes determining the formation pressure and the minimum miscible pressure of the formation fluid based on environmental parameters; controlling the oil production parameters based on the formation pressure and the minimum miscible pressure of the formation fluid. For example, when the average formation pressure is lower than the minimum miscible pressure, the injection volume is controlled in real time with a target pressure of 1.4MMP, and the injection rate is designed to be no higher than 90% of the maximum injection rate of the injection pump. When the average formation pressure is higher than 1.4MMP, the first process is skipped and the second process is entered directly.
  • the environmental parameters at least include: bottom hole pressure and wellbore pressure of the first well and the second well; the oil production parameters at least include gas injection pressure, gas injection speed, gas injection time, well soaking time, production time and Production speed.
  • the control unit a includes a sensor, a calculator and a controller.
  • the sensor is used to collect real-time data of the second pressure gauge f, the first pressure gauge d of the casing at the wellhead, the oil pipe gas composition analysis system e, the third pressure gauge f of the injection well m, and the fourth pressure gauge h of the production well n.
  • the calculator shown is used to collect bottom hole pressure gauge data in real time, and calculates the average formation pressure in real time through the built-in mathematical model; using the collected oil pipe gas composition, subtracting the oil pipe gas composition from the original formation fluid composition, the current formation fluid composition is obtained.
  • MMP minimum miscible pressure
  • the controller controls the injection pump, the injection port c of the wellhead Christmas tree and the production nozzle b of the wellhead Christmas tree in real time to perform intelligent injection and production control to achieve efficient development of the reservoir.
  • Process 1 The sensor of the control unit a of the wellhead Christmas tree intelligent injection and production collects the bottom hole pressure gauge data of two horizontal wells, and its calculator calculates the average of the bottom hole pressure of the two horizontal wells in real time to obtain the average formation pressure, which is calculated as 1.4 times the minimum miscible pressure (MMP) as the target average formation pressure, calculate and optimize the injection rate, and start CO 2 injection.
  • MMP minimum miscible pressure
  • the intelligent injection and production control system controls the production nozzle b to open and enter the first Second process.
  • the main purpose of process one is to increase the pressure and achieve miscibility.
  • Process 2 With the average formation pressure reaching 1.2 times MMP as the target pressure, the intelligent injection-production displacement process is carried out. CO 2 is injected into the injection well and produced by the production well.
  • the production-injection ratio is set in the calculator of the intelligent injection-production control system, and the production wells are produced according to the production speed results calculated by the intelligent injection-production control system and the constant liquid volume to control the size of the nozzle.
  • the average formation pressure gradually decreases during the entire displacement process.
  • the intelligent injection-production ratio is set in the calculator of the intelligent injection-production control system.
  • the calculator of the injection and production control system calculates the average formation pressure in real time. When the average formation pressure drops to 1.2 times MMP, both the injection well and the production well are closed and enter the next process.
  • the main purpose of process two is to use pressure difference to displace crude oil and gravity to displace crude oil, thereby expanding the spread of CO 2 in the reservoir.
  • Process 3 Two horizontal wells are shut in and soaked at the same time.
  • the intelligent injection and production control system determines in real time whether the derivative of the average formation pressure is zero. When it reaches zero, the soaking ends and the next process begins.
  • the main purpose of process 3 is to allow CO2 to diffuse into the matrix during the soaking process, and the crude oil in the mobilized crude oil and fractures flows to the production well under the action of gravity.
  • Process 4 The injection well continues to be shut in, and the production well goes into production.
  • the intelligent injection and production control system calculates the real-time average formation pressure. When the average formation pressure drops to 0.8 times MMP, the production well is shut down.
  • the four processes of the first cycle end and enter the next cycle.
  • the main purpose of process four is to displace crude oil by dissolved gas and displace oil by gravity.
  • An output CO 2 separation and recovery device can be added at the wellhead to separate CO 2 from the output fluid of the production well and reinject it through the injection well, thus achieving separation and reinjection at the same wellhead, recycling CO 2 and reducing CO 2 costs.
  • a certain shale reservoir to be tested is 90 meters thick and is developed in two layers.
  • the horizontal section of the first well in a horizontal well group is 15 meters from the bottom.
  • the horizontal section is 500 meters long.
  • Fracturing is carried out in 10 sections.
  • Microseismic Monitoring shows that the half-fracture of the horizontal well's pressure fracture is 15 meters high.
  • the horizontal section of the second well travels 45 meters from the bottom.
  • the horizontal section is 500 meters long.
  • the fracturing is carried out in 10 sections.
  • Microseismic monitoring shows that the horizontal well's pressure fracture is 15 meters high.
  • the seam height is 15 meters.
  • the horizontal sections of the two horizontal wells are parallel and share the vertical well section.
  • CO2 is injected from the casing into the upper horizontal well, and crude oil and other produced fluids are produced from the tubing of the lower horizontal well.
  • the wellhead Christmas tree is equipped with an intelligent injection and production control system, which directly uses asynchronous cycles. Developed by injection-mining development method.
  • the original reservoir pressure is 17MPa, and the original reservoir temperature is 80 degrees Celsius.
  • the experimentally measured minimum miscible pressure of formation crude oil and CO2 at the reservoir temperature is 20MPa.
  • Step 1 The sensors of the intelligent injection and production control system of the wellhead Christmas tree collect the bottom hole pressure of the two horizontal wells to be 17MPa.
  • the average formation pressure at the beginning is 17MPa.
  • the target average formation pressure is 1.4 times the minimum miscible pressure (MMP) of 28MPa.
  • MMP minimum miscible pressure
  • the CO2 injection is calculated and optimized to start at an injection rate of 60 tons/day.
  • the calculator of the intelligent injection and production control system calculates the average formation pressure in real time. When the average formation pressure reaches 28MPa, the signal is transmitted to the production end of the wellhead Christmas tree, the production nozzle is opened, and the second process begins.
  • Step 2 With the average formation pressure 1.2 times MMP24MPa as the target pressure, carry out the intelligent injection and production displacement process. Inject CO 2 into the injection well and maintain the injection rate at 60 tons/day.
  • the calculator of the intelligent injection and production control system the injection and production The ratio is set to 1.1, and the production well is produced according to 66 tons/day and the size of the nozzle is controlled by a constant liquid volume. The entire process gradually reduces the average formation pressure.
  • the calculator of the intelligent injection and production control system calculates the average formation pressure in real time. When the average formation pressure When it drops to 24MPa, both the injection well and the production well are closed and the next process is entered.
  • Step 3 The two horizontal wells are shut in at the same time and the intelligent injection and production control system determines in real time whether the derivative of the average formation pressure is zero. After 30 days of well soaking, the derivative of the average formation pressure reaches zero, and the well soaking is completed and the next process is entered.
  • Step 4 The injection well continues to be shut in, and the production well produces according to 66 tons/day, constant liquid volume, and controlled nozzle size.
  • the intelligent injection and production control system calculates the real-time average formation pressure. When the average formation pressure drops to 0.8 times MMP16MPa, the production well Close the well. The four processes of the first cycle end and enter the next cycle.
  • FIG5 is a schematic diagram of the cycle recovery rate in the asynchronous cycle-based oil recovery method of the embodiment of the present application. As shown in FIG5, after 6 cycles, the recovery rate is as high as 34%, and the effect of significantly improving the recovery rate is clearly seen. From the cycle recovery rate characteristics, as the number of cycles increases, the recovery rate shows a trend of first increasing rapidly and then increasing slowly. Among them, the recovery rate of the first cycle is the largest, reaching 15.5%.
  • the asynchronous cycle oil production method of the present invention brings into play the mechanism of boosting mixed phase to produce crude oil, displacing crude oil, soaking well diffusion, expanding crude oil, gravity oil drainage, and depressurized dissolved gas to drive crude oil, with an oil recovery efficiency of more than 90%, breaking through the technical bottleneck of injecting CO2 to develop unconventional oil reservoirs such as shale oil and tight oil, and realizing efficient gas injection development of heterogeneous oil reservoirs with fractures or high permeability bands; in the four processes of a single cycle, gas is injected from the injection well only in the first process and the second process, and gas injection is not required in the other two injection processes, so that better oil production effect can be achieved with less injected gas, and the oil-gas ratio and economy are effectively improved; and the low-cost three-dimensional development injection and production well mode of the present invention deploys two horizontal wells in the vertical direction, and the two wells share a vertical section wellbore, which can effectively reduce the drilling cost of a single well, and realizes the integration of injection
  • the present invention also provides an oil production system based on asynchronous cycles.
  • the oil production system includes the above-mentioned oil production device and gas recovery device.
  • the gas recovery device is used to separate and recover gas flowing out of the well group.
  • CO 2 is injected from the injection end c of the wellhead Christmas tree into the annular space of the tubing and casing, and enters the horizontal section of injection well A; when production well B is producing, the produced fluid flows into the horizontal section of horizontal well B
  • the oil pipe is extracted from the production nozzle b of the wellhead Christmas tree. It realizes gas injection and oil production in the same well, realizing a low-cost three-dimensional development injection and production well model.

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Abstract

本发明公开了一种异步周期采油装置、方法及系统，包括：至少一个井组及控制单元，每个井组包括井筒和至少一个水平井组，每个水平井组至少包括第一井和第二井，井筒与地面垂直，每个井组共用一个井筒，第一井和第二井均为与地面平行的水平井；井筒中设有套管、油管和封隔器；控制单元用于对井组执行以下步骤：通过套管注入气体至第一井，第二井进行焖井；继续注入气体至第一井，以驱替原油至第二井，同时第二井通过油管进行生产；第一井和第二井进行焖井，以使气体进入低渗透区域；第一井继续焖井，第二井通过油管进行生产。本发明提高了具有裂缝或高渗透条带的非均质油藏的采油效率。

Description

基于异步周期的采油装置、方法及系统 技术领域
本发明涉及油气田开发技术领域，尤其是涉及一种基于异步周期的采油装置、方法及系统。
背景技术
页岩油、致密油等非常规油藏资源丰富，是未来石油战略接替新领域。由于页岩油、致密油等非常规油藏储层物性差，基质渗透率≤1mD(覆压渗透率≤0.1mD)，目前主要采用水平井多级压裂后衰竭开发，但采收率低，递减大。大规模压裂后，存在多尺度裂缝，包括天然层理缝、人工压裂裂缝。注水开发时，有裂缝的区域水窜严重，注水难以进入致密基质、动用原油，亟需攻克高效开发技术和大幅度提高采收率技术。此外低渗透油藏、断块油藏、稠油油藏和碳酸盐岩油藏等复杂类型油藏，大幅度提高采收率也亟需关键技术。
注气开发是油田提高采收率的重要技术，主要是通过向地层注入气体驱油。气体种类主要包括烃类气体和非烃类气体。烃类气体主要包括液化石油气、富气、干气(甲烷)等，非烃类气体主要包括CO 2、N 2、空气、烟道气等。
从驱油机理来看，与注水相比，气体分子小，能够更加容易进入油藏岩石孔隙，更容易建立有效驱替系统驱动原油，同时注气后与原油混相或降低多相界面张力、膨胀原油、降低原油粘度等效果显著，具有与水完全不同的驱油机理。从注气方式来看，注气吞吐、气体连续驱替、水气交替等方式是目前主要的注气开发方式。
但是由于气体流动性强，容易在地层中发生气窜，且油藏中的裂缝和油藏的非均质性加剧了气窜，这些大大降低了开发效果，限制了注气技术在不同类型油藏中的应用与推广，尤其是针对页岩油、致密油等非常规油藏和低渗透油藏，大规模压裂形成的裂缝导致了非常严重的气窜，这些均使得注气方式的创新成为亟待解决的问题。
发明内容
本发明的目的在于：需要提供一种异步周期的采油装置、方法及系统，所述采油装置提高了裂缝或高渗透条带的非均质油藏的采油效率。
为了解决上述技术问题，本发明提供了一种基于异步周期的采油装置，所述采油装置包括：至少一个井组及控制单元，所述井组包括井筒和至少一个水平井组，每个所述水平井组至少包括第一井和第二井，所述井筒与地面垂直，每个井组共用一个所述井筒，所述第一井和第二井均为与地面平行的水平井；所述井筒中设有套管、油管和封隔器，所述套管用于所述第一井的气体注入，所述油管用于所述第二井的原油生产，所述封隔器用于隔离所述油管与所述套管之间的环形空间；所述控制单元用于对所述井组按照如下步骤来执行：步骤1：通过所述套管注入气体至所述第一井，所述第二井进行焖井；步骤2：继续注入所述气体至所述第一井，以驱替原油至所述第二井，同时所述第二井通过所述油管进行生产；步骤3：对所述第一井和所述第二井进行焖井，以使所述气体进入低渗透区域；步骤4：对所述第一井继续进行焖井，所述第二井通过所述油管进行生产。
优选地，所述控制单元还用于实时获取所述井组的环境参数，以控制采油参数。
优选地，所述控制装置还用于根据所述环境参数确定地层压力及地层流体的最小混相压力，并根据所述地层压力及地层流体的最小混相压力控制所述采油参数。
优选地，所述环境参数至少包括：第一井的井底压力及井筒压力、第二井的井底压力及井筒压力；所述采油参数至少包括注入压力、所述气体的注入速度、所述气体的注入时长、焖井时长、生产时长及生产速度。
优选地，所述控制单元还用于执行如下步骤：在所述步骤1中，当地层压力高于预设的第一目标压力时，则执行所述步骤2；在所述步骤2中，当地层压力低于预设的第二目标压力时，则执行所述步骤3；在所述步骤3中，当平均地层压力的导数为零时，则执行所述步骤4。
优选地，所述第一目标压力为1.4倍的最小混相压力；所述第二目标压力为1.2倍的最小混相压力。
优选地，所述控制单元还用于在检测到所述地层压力、以及所述地层流体的 最小混相压力均小于压力目标时，调大所述注入速度和/或所述生产速度，在检测到所述地层压力、以及所述地层流体的最小混相压力均大于压力目标时，调小所述注入速度和/或所述生产速度。
优选地，所述控制单元还用于依次反复执行所述步骤1至所述步骤4，并实时获取所述原油的油气比，当所述油气比低于预设阈值时，则完成异步周期采油。
优选地，所述控制单元包括：传感器，其用于实时采集所述井组的环境信息；计算器，其用于根据所述环境信息计算所述地层压力、地层流体的最小混相压力和平均地层压力的导数；控制器，其用于控制所述采油参数，并执行所述步骤1-所述步骤4所形成的采油方式。
优选地，所述井组包括多个所述水平井组，相邻两个水平井组之间的夹角为90°-180°。
优选地，同一水平井组的所述第一井和第二井沿所述井筒的纵向上平行设置，所述第一井和所述第二井的距离为单井裂缝半缝高的两倍。
优选地，所述气体为烃类气体和/或非烃类气体，其中，所述烃类气体为液化石油气、富气、干气中的至少一种，所述非烃类气体为CO 2、N 2、空气、烟道气中的至少一种。
优选地，所述气体还加入用于抑制气窜的化学剂，所述化学剂为泡沫或凝胶。
优选地，所述待采油区为非常规油藏或常规油藏，其中，所述非常规油藏选自页岩油和致密油，所述常规油藏选自低渗透油藏、断块油藏、稠油油藏和碳酸盐岩油藏中的至少一种。
优选地，多个水平井组的第一井异步工作，和/或多个水平井组的第二井异步工作
另一方面，本发明还提供了一种基于异步周期的采油方法，所述采油方法根据如上述所述的采油装置来实现，其中，所述采油方法包括：步骤1：在待采油区设置至少一个井组，所述井组包括井筒和至少一个水平井组，每个所述水平井组至少包括第一井和第二井，所述井筒与地面垂直，每个井组共用一个所述井筒，所述第一井和第二井均为与地面平行的水平井，所述井筒中设有用于所述第一井的气体注入的套管、用于所述第二井的原油生产的油管和用于隔离所述油管与所 述套管之间的环形空间的封隔器；步骤2：通过所述套管注入气体至所述第一井，所述第二井进行焖井；步骤3：继续注入所述气体至所述第一井，以驱替原油至所述第二井，同时所述第二井通过所述油管进行生产；步骤4：对所述第一井和所述第二井进行焖井，以使所述气体进入低渗透区域；步骤5：对所述第一井继续进行焖井，所述第二井通过所述油管进行生产。
优选地，所述采油方法还包括：依次反复执行所述步骤2至所述步骤5，并实时获取所述原油的油气比，当所述油气比低于预设阈值时，则完成异步周期采油。
优选地，所述井组包括多个所述水平井组，相邻两个水平井组之间的夹角为90°-180°。
优选地，同一水平井组的所述第一井和第二井沿所述井筒的纵向上平行设置，所述第一井和所述第二井的距离为单井裂缝半缝高的两倍。
优选地，所述气体为烃类气体和/或非烃类气体，其中，所述烃类气体为液化石油气、富气、干气中的至少一种，所述非烃类气体为CO 2、N 2、空气、烟道气中的至少一种。
优选地，所述气体还加入用于抑制气窜的化学剂，所述化学剂为泡沫或凝胶。
优选地，所述待采油区为非常规油藏或常规油藏，其中，所述非常规油藏选自页岩油和致密油，所述常规油藏选自低渗透油藏、断块油藏、稠油油藏和碳酸盐岩油藏中的至少一种。
优选地，多个水平井组的第一井异步工作，和/或多个水平井组的第二井异步工作。
此外，本发明提供了一种基于异步周期的采油系统，所述采油系统包括：如上述所述的基于异步周期的采油装置；以及气体回收装置，其用于实现对从所述井组中流出的气体的分离和回收。
与现有技术相比，上述方案中的一个或多个实施例可以具有如下优点或有益效果：
控制单元对井组执行以下4个步骤：步骤1：通过套管注入气体至所述第一 井，所述第二井进行焖井；步骤2：继续注入气体至所述第一井，以驱替原油至所述第二井，同时所述第二井通过油管进行生产；步骤3：所述第一井和第二井进行焖井，以使所述气体进入低渗透区域；步骤4：所述第一井继续焖井，所述第二井通过油管进行生产。
由于在步骤1和步骤4的执行过程中，仅所述步骤1和步骤2注入气体至所述第一井，即，在其他相邻两步骤之间，例如，在步骤2至步骤3之间，不涉及向第一井注入气体的操作；由此，发挥了升压混相动用原油、驱替原油、焖井扩散、膨胀动用原油、降压溶解气驱动原油机理，突破了注CO 2开发页岩油、致密油等非常规油藏技术瓶颈，实现了存在裂缝或高渗透条带的非均质油藏注气高效开发。
另外，在单周期的四个过程中，只有第一个过程和第二个过程中从注入井注入气体，其余两个注入过程中均不需要注入气体，这样可以用更少的注入气体实现更好的采油效果，有效的提高了油气比和经济性；并且本发明的低成本立体开发注采井模式，纵向上部署两口水平井，两口井共用垂直段井筒，可以有效的降低单井钻井成本，利用套管注气、油管采油，实现了两口水平井注采一体化，提高了驱油效率。
本发明的其它特征和优点将在随后的说明书中阐述，并且，部分地从说明书中变得显而易见，或者通过实施本发明而了解。本发明的目的和其他优点可通过在说明书、权利要求书以及附图中所特别指出的结构来实现和获得。
附图说明
附图用来提供对本发明的进一步理解，并且构成说明书的一部分，与本发明的实施例共同用于解释本发明，并不构成对本发明的限制。在附图中：
图1是本申请实施例的基于异步周期的采油装置的应用示例图。
图2是本申请实施例的基于异步周期的采油装置的第一个示例的俯视示意图。
图3是本申请实施例的基于异步周期的采油装置的第二个示例的俯视示意图。
图4是本申请实施例的基于异步周期的采油方法中的流程示意图。
图5是本申请实施例的基于异步周期的采油方法中的周期采收率情况示意图。
具体实施方式
以下将结合附图及实施例来详细说明本发明的实施方式，借此对本发明如何应用技术手段来解决技术问题，并达成技术效果的实现过程能充分理解并据以实施。需要说明的是，只要不构成冲突，本发明中的各个实施例以及各实施例中的各个特征可以相互结合，所形成的技术方案均在本发明的保护范围之内。
另外，附图的流程图示出的步骤可以在诸如一组计算机可执行指令的计算机系统中执行。并且，虽然在流程图中示出了逻辑顺序，但是在某些情况下，可以以不同于此处的顺序执行所示出或描述的步骤。
页岩油、致密油等非常规油藏资源丰富，是未来石油战略接替新领域。由于页岩油、致密油等非常规油藏储层物性差，基质渗透率≤1mD(覆压渗透率≤0.1mD)，目前主要采用水平井多级压裂后衰竭开发，但采收率低，递减大。大规模压裂后，存在多尺度裂缝，包括天然层理缝、人工压裂裂缝。注水开发时，有裂缝的区域水窜严重，注水难以进入致密基质、动用原油，亟需攻克高效开发技术和大幅度提高采收率技术。此外低渗透油藏、断块油藏、稠油油藏和碳酸盐岩油藏等复杂类型油藏，大幅度提高采收率也亟需关键技术。
注气开发是油田提高采收率的重要技术，主要是通过向地层注入气体驱油。气体种类主要包括烃类气体和非烃类气体。烃类气体主要包括液化石油气、富气、干气(甲烷)等，非烃类气体主要包括CO2、N2、空气、烟道气等。
从驱油机理来看，与注水相比，气体分子小，能够更加容易进入油藏岩石孔隙，更容易建立有效驱替系统驱动原油，同时注气后与原油混相或降低多相界面张力、膨胀原油、降低原油粘度等效果显著，具有与水完全不同的驱油机理。从注气方式来看，注气吞吐、气体连续驱替、水气交替等方式是目前主要的注气开发方式。
但是由于气体流动性强，容易在地层中发生气窜，且油藏中的裂缝和油藏的非均质性加剧了气窜，这些大大降低了开发效果，限制了注气技术在不同类型油藏中的应用与推广，尤其是针对页岩油、致密油等非常规油藏和低渗透油藏，大 规模压裂形成的裂缝导致了非常严重的气窜，这些均使得注气方式的创新成为亟待解决的问题。
本发明提供了一种基于异步周期的采油装置。采油装置包括：至少一个井组及控制单元。每个井组包括井筒和至少一个水平井组，每个水平井组至少包括第一井和第二井。井筒与地面垂直，每个井组共用一个所述井筒，所述第一井和第二井均为与地面平行的水平井。所述井筒中设有套管、油管和封隔器，所述套管用于所述第一井的气体注入，所述油管用于所述第二井的原油生产，所述封隔器用于隔离所述油管和套管的环形空间。具体的，所述封隔器用于对井筒的油管与套管之间的环形空间进行封隔，确保从套管注入的气体进入第一井的水平井井段。所述控制单元用于对所述井组按照如下操作来执行：步骤1：通过套管注入气体至所述第一井，所述第二井进行焖井；步骤2：继续注入气体至所述第一井，以驱替原油至所述第二井，同时所述第二井通过油管进行生产；步骤3：对所述第一井和第二井进行焖井，以使所述气体进入低渗透区域；步骤4：所述第一井继续焖井，所述第二井通过油管进行生产。其中，在步骤1和步骤4的执行过程中，仅所述步骤1和步骤2注入气体至所述第一井。即，在其他相邻两步骤之间，例如，在步骤2至步骤3之间，不涉及向第一井注入气体的操作。
可选的，所述控制装置还用于依次反复执行步骤2至步骤4，并实时获取所述原油的油气比，当所述油气比低于预设阈值时，则完成异步周期采油任务。
本发明通过纵向上部署两口水平井：第一井和第二井，且两口井共用垂直段井筒，可以有效降低单井钻井成本，两口井水平段平行，实施分段压裂，两口水平井的垂向距离为单井压裂半缝高的两倍，以保证控制更多的储量，实现单井EUR(Estimated Ultimate Recovery单井评估的最终可采储量)最大化。
步骤1：通过套管注入气体至所述第一井，所述第二井进行焖井；注入的气体可以为烃类气体和/或非烃类气体，所述烃类气体为液化石油气、富气、干气等，所述非烃类气体为CO 2、N 2、空气、烟道气等。所述第一井和第二井的具体位置和连通情况根据具体的采油区地层情况确定。在步骤1中，对第二井进行焖井的主要作用是使注入气体不会通过第二井产出，从而使得所注入的气体保留在油藏内，提高油藏的压力，此时，气体持续向油藏孔隙内扩散。该步骤1能够提高整个地层的压力，压力的升高可以实现注入气体与地层原油的混相，同时减小 储层应力敏感，提高渗流能力和驱油效率。根据承受的强度不同，所述套管的材质为不同等级的钢材。
步骤2：继续注入气体至所述第一井，以驱替原油至所述第二井，同时所述第二井通过油管进行生产；按照一种优选的实施方式。所述第二井进行生产包括提取所述第二井中的原油并输出收集，采油操作的执行与第一井的注入气体操作相同执行。该步骤2可以建立井间的有效驱替，发挥气体在井间的驱替作用，高效驱替裂缝或高渗透通道内的原油，将易流动区域的原油快速采出，同时增大了注入气体与基质或低渗透区域的接触面积，有效提高了基质或低渗透区域内原油的动用率。根据承受的强度不同，所述套管的材质为不同等级的钢材。
步骤3：对所述第一井和第二井进行焖井，以使所述气体进入低渗透区域。该步骤3主要发挥焖井过程中气体的扩散作用，气体通过扩散进入原油、膨胀原油、降低多相界面张力和原油粘度。由于是焖井过程，所以该步骤3可以减弱气体的窜流作用，实现气体扩散进入基质或者低渗透区域，发挥膨胀、降低界面张力作用、降低原油粘度的作用机理，高效动用基质和低渗透区域的原油。
步骤4：所述第一井继续焖井，所述第二井通过油管进行生产。在步骤4中，继续对第一井进行焖井，是由于在第一井处于关闭状态时，不会有气体从第一井来进行注入和产出，使得第一井附近的气体中的一部分继续向油藏孔隙内扩散，而另一部分向第二井进行流动、驱替。该步骤4用于所述气体驱替剩余原油至所述第二井。通过生产井的降压衰竭开发，充分发挥溶解气驱的作用机理，实现基质、低渗透区域和井间剩余油的高效开发，同时这个过程不需要注入气体，可以节省注入成本，增加油气比，提高经济性。
在步骤1和步骤4的执行过程中，仅所述步骤1和步骤2注入气体至所述第一井。
执行上述步骤过程中，当步骤1中的地层压力高于预设的第一目标压力时，则执行步骤2；当步骤2中的地层压力低于预设的第二目标压力时，则执行步骤3；当步骤3中平均地层压力的导数为零时，则执行步骤4。所述第一目标压力为1.4倍的最小混相压力；所述第二目标压力为1.2倍的最小混相压力。
依次执行一遍步骤1至步骤4为一个采油周期，当执行多个采油周期时，相 邻采油周期的注入井和生产井可以进行互换。比如第一采油周期中的第一井为注入井，第二井为生产井，第二采油周期时可改成第一井为生产井，第二井为注入井。
整个开发采油过程可以将所有井组的注入井保持同步，所有井组的生产井也保持同步；也可以将几个井组进行组合成大井组，组合后的大井组内的井保持同步，或者井组按照顺序、倒序或者不规则的顺序依次进行异步周期注采开发。优选的，多个水平井组的第一井异步工作，和/或多个水平井组的第二井异步工作。
在异步周期注采过程中，根据生产井的气窜情况，可以在注入井的注入过程中加入用于抑制气窜的化学剂，化学剂可以是泡沫体系、凝胶体系或者其他可以有效抑制气窜的体系。在单周期中的注入井的注入过程也可以采用气水交替等有效抑制气窜的方式。
进一步，待采油区为非常规油藏或常规油藏。其中，所述非常规油藏选自页岩油和致密油，所述常规油藏选自低渗透油藏、断块油藏、稠油油藏和碳酸盐岩油藏中的至少一种。
单周期内各个过程中，气体的注入压力、注入速度、注入时间、焖井时间、生产时间、生产速度等关键参数采用室内物理模拟或者数值模拟进行优化。
所述单周期的四个过程中，只有第一个过程和第二个过程中从注入井注入气体，其余两个注入过程中均不需要注入气体，这样可以用更少的注入气体实现更好的采油效果，有效的提高了油气比和经济性。
所述控制单元还用于实时获取所述井组的环境参数，以控制采油参数。具体地，根据环境参数确定地层压力及地层流体的最小混相压力，再根据地层压力及地层流体的最小混相压力控制采油参数。比如，当平均地层压力低于最小混相压力时，以1.4MMP为目标压力实时控制注入量，注入速度的设计以不高于注入泵最大注入速度的90％进行配注。当平均地层压力高于1.4MMP时，跳过第一个过程，直接进入第二个过程。
所述环境参数至少包括：第一井的井底压力及井筒压力、第二井的井底压力及井筒压力；所述采油参数至少包括注入压力、气体的注入速度、气体的注入时长、焖井时长、生产时长及生产速度。同一水平井组的所述第一井和第二井沿所 述井筒的纵向上平行设置，所述第一井和第二井的距离为单井裂缝半缝高的两倍。
按照一种具体的实施方式，如图1所示，纵向上部署两口水平井：注入井m和生产井n，两口井共用垂直段井筒，两口水平井初期可以采用衰竭开发，也可以直接进入异步周期注采开发阶段。如果采用衰竭开发，第一井从油管j和套管i环形空间进行生产，第二井从油管j进行生产。
异步周期注采开发时，第一井作为注入井m，第二井作为生产井n，在井筒的垂直段，采用封隔器k密封油管和套管的环形空间。注入开始时，CO 2从井口采油树的注入端c注入到油管和套管的环形空间，进入注入井m的水平段；生产井n生产时，产出流体流入生产井n的油管，从井口采油树的生产油嘴b采出。
具体包括：在注CO 2异步周期注采过程中，通过井口采油树智能注采的控制单元a进行自动控制。所述控制单元a包括传感器、计算器及控制器。其中，所述传感器用于实时采集井组的环境信息；所述计算器用于根据所采集的环境信息计算地层压力、地层流体的最小混相压力和平均地层压力的导数；所述控制器用于控制采油参数，并执行上述步骤1-步骤4所形成的采油方式。进一步，所述传感器用于采集井口的套管第二压力表f、第一压力表d、油管气组成分析系统e、注入井m的第三压力表f、生产井n的第四压力表h的实时数据；所述计算器用于实时采集的井底压力计数据，通过内置数学模型实时计算平均地层压力；以及，基于采集的油管气组成，利用原始地层流体组成减掉油管产出气的组成，得到当前地层流体组成，而后通过当前地层流体组成计算得到相应的分子量，进一步利用如下数据模型来实时计算地层流体的最小混相压力(MMP)：MMP＝[(7.727×MW×1.005 T)-4.377×MW-329]/145，其中，MW为分子量，T为油藏温度。而且，计算器还用于实时计算平均地层压力的导数。
另外，所述控制器还用于根据实时计算的地层流体的最小混相压力(MMP)，结合压力目标，利用内置模型计算优化确定注入速度和生产速度。例如：当地层流体的最小混相压力和地层压力均小于所述压力目标时，则调大注入速度和/或生产速度；当地层流体的最小混相压力和地层压力均大于所述压力目标时，则调小注入速度和/或生产速度。
进一步，所述控制器按照异步周期注采开发方式的要求，实时控制注入泵、井口采油树注入端c和井口采油树的生产油嘴b，进行智能注采调控，实现油藏高效开发。
另外，优选的，每个井组可以包括多个所述水平井组，相邻两个水平井组之间的夹角90°-180°。图2是本申请实施例的基于异步周期的采油装置的第一个示例的俯视示意图。图3是本申请实施例的基于异步周期的采油装置的第二个示例的俯视示意图。如图2所示，其为采油装置中井组的其中一种俯视图，该井组包括第一井筒300、第一水平井组301、第二水平井组302、第三水平井组303及第四水平井组304，每组水平井组均只是包括第一井和第二井，相邻两个水平井组之间的夹角为90度。如图3所示，该井组包括第二井筒400、第五水平井组401和第六水平井组402，相邻两个水平井组之间的夹角为180度。
本发明的异步周期的采油装置实现了高效、自动、智能控制，并且为异步周期注气采油方法配套设计了低成本立体开发注采井模式。
所述采油装置还发挥了升压混相动用原油、驱替原油、焖井扩散、膨胀动用原油、降压溶解气驱动原油机理，驱油效率超过90％，突破了注CO 2开发页岩油、致密油等非常规油藏技术瓶颈，实现了存在裂缝或高渗透条带的非均质油藏注气高效开发；在单周期的四个过程中，只有第一个过程和第二个过程中从注入井注入气体，其余两个注入过程中均不需要注入气体，这样可以用更少的注入气体实现更好的采油效果，有效的提高了油气比和经济性；并且本发明的低成本立体开发注采井模式，纵向上部署两口水平井，两口井共用垂直段井筒，可以有效的降低单井钻井成本，利用套管注气、油管采油，实现了两口水平井注采一体化，提高了效率；本发明还通过智能化控制将传感器、计算器、控制器集成在采油树上，实现平均地层压力、地层流体最小混相压力、目标地层压力的、注入速度、生产速度实时计算与精准控制。
基于上述基于异步周期的采油装置，本发明还提出了一种基于异步周期的采油方法。该采油方法根据上述基于异步周期的采油装置来实现。该采油方法主要用于页岩油、致密油等非常规资源、低渗透油藏、稠油油藏、整装油藏、断块油藏、高含水油藏、高温高盐油藏、碳酸盐岩油藏等特殊岩性油藏的开发。
图4是本申请实施例的基于异步周期的采油方法中的流程示意图。如图4所示，步骤S101为：在待采油区设置至少一个井组，每个井组包括井筒和至少一个水平井组，每个所述水平井组至少包括第一井和第二井，所述井筒与地面垂直，每个井组共用一个所述井筒，所述第一井和第二井均为与地面平行的水平井。其 中，所述第一井可以为注入井，第二井可以为生产井，所述每个井组可以包括多个第一井和多个第二井，所述第一井和第二井的注采方式可以不相同、注采周期可以不同步。同一水平井组的所述第一井和第二井沿所述井筒的纵向上平行设置，所述第一井和第二井的距离为单井裂缝半缝高的两倍。每个井组可以包括多个所述水平井组，优选的，相邻两个水平井组之间的夹角为180°。
所述井筒中设有套管、油管和封隔器，所述套管用于所述第一井的气体注入，所述油管用于所述第二井的原油生产，所述封隔器用于隔离所述油管和套管。
本发明通过纵向上部署两口水平井：第一井和第二井，且两口井共用垂直段井筒，可以有效降低单井钻井成本，两口井水平段平行，实施分段压裂，两口水平井的垂向距离为单井压裂半缝高的两倍，以保证控制更多的储量，实现单井EUR(Estimated Ultimate Recovery单井评估的最终可采储量)最大化。
步骤S102为：通过套管注入气体至所述第一井，所述第二井进行焖井。注入的气体可以为烃类气体和/或非烃类气体，所述烃类气体为液化石油气、富气、干气等，所述非烃类气体为CO 2、N 2、空气、烟道气等。所述第一井和第二井的具体位置和连通情况根据具体的采油区地层情况确定。
该步骤S102能够提高整个地层的压力，压力的升高可以实现注入气体与地层原油的混相，同时减小储层应力敏感，提高渗流能力和驱油效率。
步骤S103为：继续注入气体至所述第一井，以驱替原油至所述第二井，同时所述第二井通过油管进行生产。按照一种优选的实施方式。所述第二井进行生产包括提取所述第二井中的原油并输出收集。
该步骤S103可以建立井间的有效驱替，发挥气体在井间的驱替作用，高效驱替裂缝或高渗透通道内的原油，将易流动区域的原油快速采出，同时增大了注入气体与基质或低渗透区域的接触面积，有效提高了基质或低渗透区域内原油的动用率。
步骤S104为：所述第一井和第二井进行焖井，以使所述气体进入低渗透区域。该步骤主要发挥焖井过程中气体的扩散作用，气体通过扩散进入原油、膨胀原油、降低多相界面张力和原油粘度。由于是焖井过程，所以该步骤可以减弱气体的窜流作用，实现气体扩散进入基质或者低渗透区域，发挥膨胀、降低界面张 力作用、降低原油粘度的作用机理，高效动用基质和低渗透区域的原油。
步骤S105为：所述第一井继续焖井，所述第二井通过油管进行生产。该步骤S105用于所述气体驱替剩余原油至所述第二井。通过生产井的降压衰竭开发，充分发挥溶解气驱的作用机理，实现基质、低渗透区域和井间剩余油的高效开发，同时这个过程不需要注入气体，可以节省注入成本，增加油气比，提高经济性。
在步骤102和步骤105的执行过程中，仅所述步骤102和步骤103注入气体至所述第一井，在其他相邻步骤之间，例如，步骤103至步骤104之间，不涉及向第一井注入气体的操作。
在上述步骤执行过程中，当步骤102中的地层压力高于预设的第一目标压力时，则执行步骤103；当步骤103中的地层压力低于预设的第二目标压力时，则执行步骤104；当步骤104中平均地层压力的导数为零时，则执行步骤105。
依次执行一遍步骤S101至步骤S105为一个采油周期，当执行多个采油周期时，相邻采油周期的注入井和生产井可以进行互换。比如第一采油周期中的第一井为注入井，第二井为生产井，第二采油周期时可改成第一井为生产井，第二井为注入井。
整个开发采油过程可以将所有井组的注入井保持同步，所有井组的生产井也保持同步；也可以将几个井组进行组合成大井组，组合后的大井组内的井保持同步，或者井组按照顺序、倒序或者不规则的顺序依次进行异步周期注采开发。优选的，多个水平井组的第一井异步工作，和/或多个水平井组的第二井异步工作。
异步周期注采过程中，根据生产井的气窜情况，可以在注入井的注入过程中加入化学剂抑制气窜，化学剂可以是泡沫体系、凝胶体系或者其他可以有效抑制气窜的体系。在单周期中的注入井的注入过程也可以采用气水交替等有效抑制气窜的方式。
单周期内各个过程中，气体的注入压力、注入速度、注入时间、焖井时间、生产时间、生产速度等关键参数采用室内物理模拟或者数值模拟进行优化。
所述单周期的四个过程中，只有第一个过程和第二个过程中从注入井注入气体，其余两个注入过程中均不需要注入气体，这样可以用更少的注入气体实现更好的采油效果，有效的提高了油气比和经济性。
所述采油方法还包括实时获取所述井组的环境参数，用于控制采油参数。具体包括根据环境参数确定地层压力及地层流体的最小混相压力；根据地层压力及地层流体的最小混相压力控制采油参数。比如，当平均地层压力低于最小混相压力时，以1.4MMP为目标压力实时控制注入量，注入速度的设计以不高于注入泵最大注入速度的90％进行配注。当平均地层压力高于1.4MMP时，跳过第一个过程，直接进入第二个过程。所述环境参数至少包括：第一井、第二井的井底压力及井筒压力；所述采油参数至少包括气体的注入压力、气体的注入速度、气体的注入时长、焖井时长、生产时长及生产速度。
具体包括：在注CO 2异步周期注采过程中，通过井口采油树智能注采的控制单元a进行自动控制，所述控制单元a包括传感器、计算器及控制器。所述传感器用于采集井口的套管第二压力表f、第一压力表d、油管气组成分析系统e、注入井m的第三压力表f、生产井n的第四压力表h的实时数据；所示计算器用于实时采集的井底压力计数据，通过内置数学模型实时计算平均地层压力；利用采集的油管气组成，利用原始地层流体组成减掉油管气组成，得到目前地层流体组成，通过组成计算得到分子量，通过内置如下数学模型：MMP＝[(7.727×MW×1.005 T)-4.377×MW-329]/145，其中，MW为分子量，T为油藏温度。实时计算地层流体的最小混相压力(MMP)，根据压力目标，利用内置模型计算优化确定注入速度和生产速度；实时计算平均地层压力的导数。所述控制器按照异步周期注采开发方式的要求，实时控制注入泵、井口采油树注入端c和井口采油树的生产油嘴b，进行智能注采调控，实现油藏高效开发。
例如：过程一：井口采油树智能注采的控制单元a的传感器采集两口水平井的井底压力计数据，其计算器实时计算两口水平井井底压力的平均值，得到平均地层压力，以1.4倍的最小混相压力(MMP)为目标平均地层压力，计算、优化确定注入速度，开始CO 2注入，待平均地层压力达到1.4倍的MMP时，智能注采控制系统控制生产油嘴b打开，进入第二过程。过程一的主要目的为升高压力，实现混相。
过程二：以平均地层压力达到1.2倍MMP为目标压力，进行智能注采驱替过程，注入井注入CO 2，生产井进行生产。智能注采控制系统的计算器中设定采注比，生产井按照智能注采控制系统计算的生产速度结果、定液量控制油嘴大小 进行生产，整个驱替过程中平均地层压力逐渐降低，智能注采控制系统的计算器实时计算平均地层压力，当平均地层压力降至1.2倍MMP时，注入井和生产井都关闭，进入下一过程。过程二的主要目的是利用压差驱替原油和重力驱替原油，扩大了CO 2在油藏中的波及。
过程三：两口水平井同时关井焖井，智能注采控制系统实时判断平均地层压力的导数是否为零，当达到零时，焖井结束，进入下一过程。过程三的主要目的是焖井过程CO 2扩散进入基质、动用原油和裂缝中的原油在重力作用下向生产井流动。
过程四：注入井继续关井，生产井进行生产，智能注采控制系统计算实时平均地层压力，当平均地层压力降低到0.8倍MMP时，生产井关井。第一个周期的四个过程结束，进入下一周期。过程四主要目的是溶解气驱替原油和重力作用驱油。
重复以上周期的四个过程，并实时获取所述原油的油气比值，直至油气比低于设定的阈值，则完成采油，只要产量高于经济极限产量，生产继续，否则，开发过程停止。
在井口可以增加产出CO 2分离回收装置，从生产井的产出流体中分离得到CO 2，通过注入井回注，实现了同井台分离、回注，循环利用了CO 2，降低了CO 2成本。
实施例一：
某待测页岩油藏厚度90米，分两层立体开发，一口水平井组中第一井的水平段穿行轨迹距底15米，水平段长500米，分10段进行压裂，微地震监测显示该水平井压裂缝的半缝高15米，第二井的水平段穿行轨迹距底45米，水平段长500米，分10段进行压裂，微地震监测显示该水平井压裂缝的缝高15米。两口水平井的水平段平行，共用直井段，CO 2从套管注入上部水平井，原油等产出流体从下部水平井的油管进行生产，井口采油树安装智能注采控制系统，直接采用异步周期注采开发方式进行开发。
油藏原始压力17MPa，原始油藏温度80摄氏度，实验测得油藏温度下地层 原油与CO 2的最小混相压力为20MPa。
异步周期注采开发步骤：
步骤一：井口采油树智能注采控制系统的传感器采集得到两口水平井的井底压力为17MPa，开始时平均地层压力为17MPa，以1.4倍的最小混相压力(MMP)28MPa为目标平均地层压力，计算、优化确定以注入速度60吨/天开始CO 2注入，智能注采控制系统的计算器实时计算平均地层压力，待平均地层压力达到28MPa时，信号传到井口采油树的生产端，生产油嘴打开，进入第二过程。
步骤二：以平均地层压力1.2倍MMP24MPa为目标压力，进行智能注采驱替过程，注入井注入CO 2，注入速度保持在60吨/天，在智能注采控制系统的计算器中，采注比被设定为1.1，生产井按照66吨/天、定液量控制油嘴大小进行生产，整个过程逐渐降低平均地层压力，智能注采控制系统的计算器实时计算平均地层压力，当平均地层压力降至24MPa时，注入井和生产井都关闭，进入下一过程。
步骤三：两口水平井同时关井焖井，智能注采控制系统实时判断平均地层压力的导数是否为零，焖井30天后，平均地层压力的导数达到零，焖井结束，进入下一过程。
步骤四：注入井继续关井，生产井按照66吨/天、定液量控制油嘴大小进行生产，智能注采控制系统计算实时平均地层压力，当平均地层压力降低到0.8倍MMP16MPa时，生产井关井。第一个周期的四个过程结束，进入下一周期。
重复六个周期，此时油气比为0.05，开发过程停止。
图5是本申请实施例的基于异步周期的采油方法中的周期采收率情况示意图。如图5所示，经过6个周期之后，采收率高达34％，明显的见到了大幅度提高采收率的效果。从周期采收率特征来看，随着周期数的增加，采收率呈现先快速增加，后缓慢增加的趋势。其中，第一周期的采收率数值最大，达到了15.5％。本发明的异步周期的采油方法发挥了升压混相动用原油、驱替原油、焖井扩散、膨胀动用原油、重力泄油、降压溶解气驱动原油机理，驱油效率超过90％，突破了注CO 2开发页岩油、致密油等非常规油藏技术瓶颈，实现了存在裂缝或高渗透条带的非均质油藏注气高效开发；在单周期的四个过程中，只有第一个过程和 第二个过程中从注入井注入气体，其余两个注入过程中均不需要注入气体，这样可以用更少的注入气体实现更好的采油效果，有效的提高了油气比和经济性；并且本发明的低成本立体开发注采井模式，纵向上部署两口水平井，两口井共用垂直段井筒，可以有效的降低单井钻井成本，利用套管注气、油管采油，实现了两口水平井注采一体化，提高了效率；本发明还通过智能化控制将传感器、计算器、控制器集成在采油树上，实现平均地层压力、地层流体最小混相压力、目标地层压力的、注入速度、生产速度实时计算与精准控制。
另一方面，本发明还提供一种基于异步周期的采油系统。该采油系统包括上述所述的采油装置及气体回收装置。所述气体回收装置用于实现对从井组中流出的气体的分离和回收。该采油系统在注入开始时，CO 2从井口采油树的注入端c注入到油管和套管的环形空间，进入注入井A的水平段；生产井B生产时，产出流体流入水平井B的油管，从井口采油树的生产油嘴b采出。实现在同井注气和采油，实现了低成本立体开发注采井模式。
以上所述，仅为本发明较佳的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉该技术的人员在本发明所揭露的技术范围内，可轻易想到的变化或替换，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应该以权利要求的保护范围为准。
应该理解的是，本发明所公开的实施例不限于这里所公开的特定结构、处理步骤或材料，而应当延伸到相关领域的普通技术人员所理解的这些特征的等同替代。还应当理解的是，在此使用的术语仅用于描述特定实施例的目的，而并不意味着限制。
说明书中提到的“一个实施例”或“实施例”意指结合实施例描述的特定特征、结构或特性包括在本发明的至少一个实施例中。因此，说明书通篇各个地方出现的短语“一个实施例”或“实施例”并不一定均指同一个实施例。
虽然本发明所披露的实施方式如上，但所述的内容只是为了便于理解本发明而采用的实施方式，并非用以限定本发明。任何本发明所属技术领域内的技术人员，在不脱离本发明所揭露的精神和范围的前提下，可以在实施的形式上及细节上作任何的修改与变化，但本发明的专利保护范围，仍须以所附的权利要求书所界定的范围为准。

Claims (24)

  1. 一种基于异步周期的采油装置，其特征在于，所述采油装置包括：至少一个井组及控制单元，
    所述井组包括井筒和至少一个水平井组，每个所述水平井组至少包括第一井和第二井，所述井筒与地面垂直，每个井组共用一个所述井筒，所述第一井和第二井均为与地面平行的水平井；
    所述井筒中设有套管、油管和封隔器，所述套管用于所述第一井的气体注入，所述油管用于所述第二井的原油生产，所述封隔器用于隔离所述油管与所述套管之间的环形空间；
    所述控制单元用于对所述井组按照如下步骤来执行：
    步骤1：通过所述套管注入气体至所述第一井，所述第二井进行焖井；
    步骤2：继续注入所述气体至所述第一井，以驱替原油至所述第二井，同时所述第二井通过所述油管进行生产；
    步骤3：对所述第一井和所述第二井进行焖井，以使所述气体进入低渗透区域；
    步骤4：对所述第一井继续进行焖井，所述第二井通过所述油管进行生产。
  2. 根据权利要求1所述的采油装置，其特征在于，所述控制单元还用于实时获取所述井组的环境参数，以控制采油参数。
  3. 根据权利要求2所述的采油装置，其特征在于，
    所述控制装置还用于根据所述环境参数确定地层压力及地层流体的最小混相压力，并根据所述地层压力及地层流体的最小混相压力控制所述采油参数。
  4. 根据权利要求2或3所述的采油装置，其特征在于，
    所述环境参数至少包括：第一井的井底压力及井筒压力、第二井的井底压力及井筒压力；
    所述采油参数至少包括注入压力、所述气体的注入速度、所述气体的注入时 长、焖井时长、生产时长及生产速度。
  5. 根据权利要求3或4所述的采油装置，其特征在于，所述控制单元还用于执行如下步骤：
    在所述步骤1中，当地层压力高于预设的第一目标压力时，则执行所述步骤2；
    在所述步骤2中，当地层压力低于预设的第二目标压力时，则执行所述步骤3；
    在所述步骤3中，当平均地层压力的导数为零时，则执行所述步骤4。
  6. 根据权利要求5所述的采油装置，其特征在于，
    所述第一目标压力为1.4倍的最小混相压力；
    所述第二目标压力为1.2倍的最小混相压力。
  7. 根据权利要求4-6中任一项所述的采油装置，其特征在于，所述控制单元还用于在检测到所述地层压力、以及所述地层流体的最小混相压力均小于压力目标时，调大所述注入速度和/或所述生产速度，在检测到所述地层压力、以及所述地层流体的最小混相压力均大于压力目标时，调小所述注入速度和/或所述生产速度。
  8. 根据权利要求1-7中任一项所述的采油装置，其特征在于，所述控制单元还用于依次反复执行所述步骤1至所述步骤4，并实时获取所述原油的油气比，当所述油气比低于预设阈值时，则完成异步周期采油。
  9. 根据权利要求2-7中任一项所述的采油装置，其特征在于，所述控制单元包括：
    传感器，其用于实时采集所述井组的环境信息；
    计算器，其用于根据所述环境信息计算所述地层压力、地层流体的最小混相 压力和平均地层压力的导数；
    控制器，其用于控制所述采油参数，并执行所述步骤1-所述步骤4所形成的采油方式。
  10. 根据权利要求1-9中任一项所述的采油装置，其特征在于，所述井组包括多个所述水平井组，相邻两个水平井组之间的夹角为90°-180°。
  11. 根据权利要求1-10中任一项所述的采油装置，其特征在于，
    同一水平井组的所述第一井和第二井沿所述井筒的纵向上平行设置，所述第一井和所述第二井的距离为单井裂缝半缝高的两倍。
  12. 根据权利要求1-11中任一项所述的采油装置，其特征在于，所述气体为烃类气体和/或非烃类气体，其中，所述烃类气体为液化石油气、富气、干气中的至少一种，所述非烃类气体为CO 2、N 2、空气、烟道气中的至少一种。
  13. 根据权利要求12所述的采油装置，其特征在于，所述气体还加入用于抑制气窜的化学剂，所述化学剂为泡沫或凝胶。
  14. 根据权利要求1-13中任一项所述的采油装置，其特征在于，所述待采油区为非常规油藏或常规油藏，其中，所述非常规油藏选自页岩油和致密油，所述常规油藏选自低渗透油藏、断块油藏、稠油油藏和碳酸盐岩油藏中的至少一种。
  15. 根据权利要求1-14中任一项所述的采油装置，其特征在于，
    多个水平井组的第一井异步工作，和/或多个水平井组的第二井异步工作。
  16. 一种基于异步周期的采油方法，其特征在于，所述采油方法根据如权利要求1～15中任一项所述的采油装置来实现，其中，所述采油方法包括：
    步骤1：在待采油区设置至少一个井组，所述井组包括井筒和至少一个水平 井组，每个所述水平井组至少包括第一井和第二井，所述井筒与地面垂直，每个井组共用一个所述井筒，所述第一井和第二井均为与地面平行的水平井，所述井筒中设有用于所述第一井的气体注入的套管、用于所述第二井的原油生产的油管和用于隔离所述油管与所述套管之间的环形空间的封隔器；
    步骤2：通过所述套管注入气体至所述第一井，所述第二井进行焖井；
    步骤3：继续注入所述气体至所述第一井，以驱替原油至所述第二井，同时所述第二井通过所述油管进行生产；
    步骤4：对所述第一井和所述第二井进行焖井，以使所述气体进入低渗透区域；
    步骤5：对所述第一井继续进行焖井，所述第二井通过所述油管进行生产。
  17. 根据权利要求16所述的采油方法，其特征在于，所述采油方法还包括：
    依次反复执行所述步骤2至所述步骤5，并实时获取所述原油的油气比，当所述油气比低于预设阈值时，则完成异步周期采油。
  18. 根据权利要求16或17所述的采油方法，其特征在于，所述井组包括多个所述水平井组，相邻两个水平井组之间的夹角为90°-180°。
  19. 根据权利要求16-18中任一项所述的采油方法，其特征在于，
    同一水平井组的所述第一井和第二井沿所述井筒的纵向上平行设置，所述第一井和所述第二井的距离为单井裂缝半缝高的两倍。
  20. 根据权利要求16-19中任一项所述的采油方法，其特征在于，所述气体为烃类气体和/或非烃类气体，其中，所述烃类气体为液化石油气、富气、干气中的至少一种，所述非烃类气体为CO 2、N 2、空气、烟道气中的至少一种。
  21. 根据权利要求20所述的采油方法，其特征在于，所述气体还加入用于抑制气窜的化学剂，所述化学剂为泡沫或凝胶。
  22. 根据权利要求16-21中任一项所述的采油方法，其特征在于，所述待采油区为非常规油藏或常规油藏，其中，所述非常规油藏选自页岩油和致密油，所述常规油藏选自低渗透油藏、断块油藏、稠油油藏和碳酸盐岩油藏中的至少一种。
  23. 根据权利要求16-22中任一项所述的采油方法，其特征在于，
    多个水平井组的第一井异步工作，和/或多个水平井组的第二井异步工作。
  24. 一种基于异步周期的采油系统，其特征在于，所述采油系统包括：
    如权利要求1-15中任一项所述的基于异步周期的采油装置；以及气体回收装置，其用于实现对从所述井组中流出的气体的分离和回收。
PCT/CN2022/137598 2022-09-21 2022-12-08 基于异步周期的采油装置、方法及系统 WO2024060415A1 (zh)

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