CN115901573A - Rock core imbibition device, simulated fracture fluid pressure imbibition experimental device and experimental method - Google Patents
Rock core imbibition device, simulated fracture fluid pressure imbibition experimental device and experimental method Download PDFInfo
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Abstract
The invention provides a core imbibition device, a simulated fracture fluid pressure imbibition experimental device and an experimental method, wherein the experimental device comprises the core imbibition device, an injection unit, a back pressure control unit, a confining pressure simulation unit, a reservoir temperature simulation unit and a parameter measurement unit; imbibition liquid in the liquid chamber can be discharged from the outflow channel through the rock core and can also be discharged from the return channel; the injection unit is connected with the injection channel and can inject the imbibition liquid into the liquid chamber; the backflow pressure control unit is connected with the backflow channel and can apply pressure reversely to control the backflow flow rate; the confining pressure simulation unit establishes confining pressure to prevent liquid from channeling; the reservoir temperature simulation unit can adjust the imbibition temperature of the rock core; the parameter metering unit is used for measuring pressure and flow parameters at each position. The device is simple and reliable, is easy to operate, and can well simulate the real conditions of the reservoir.
Description
Technical Field
The invention relates to the technical field of yield increase of oil and gas fields, in particular to a core imbibition device, a simulated fracture fluid pressure imbibition experimental device and an experimental method.
Background
The field of increasing the yield after the pressing is a popular topic in recent years, and the imbibition effect is an important mechanism of the increasing the yield after the pressing and has great significance for deeply understanding the mechanism. In the fracturing process, part of fracturing fluid enters the matrix under the action of the pressure difference between the fluid pressure of the artificial fracture and the fluid in the matrix to promote the occurrence of imbibition and displace crude oil. Therefore, the pressure of the fracture fluid is used as one of main driving forces of matrix imbibition, and the influence of the imbibition effect on quantitative representation has very important value on field construction guidance and yield increase benefit evaluation after pressing.
In recent years, the influence of the fracture fluid pressure on the matrix imbibition effect draws attention of many scholars at home and abroad. Guoguanchun et al (CN 110470585B) discloses an experimental test device and method for shale dynamic imbibition capacity. The device combines a reaction kettle with the injection end of the rock core holder, and simulates the influence of fluid pressure on the imbibition effect in the fluid flowing process in a fracture. However, the pressure resistance of the device is limited due to the addition of the stirring device in a sealed environment, and the seepage effect under the condition of high pressure difference cannot be simulated. Meanwhile, the further analysis and discussion are mainly directed at the characterization of the hydration and water absorption process of the shale oil reservoir, and the related invention has complex equipment and is difficult to operate.
The invention discloses a testing device and a testing method for determining reasonable well-closing time based on shale permeability, and discloses Zhao super energy (CN 111879674B), and establishes a permeability change characterization testing method in the shale water absorption process, and the influence of fracture fluid pressure on the permeability is considered in the testing process. Although the device establishes a fluid injection pressure environment, the device aims to obtain the influence of the shale water absorption process on the permeability of a reservoir under the condition of simulating a real reservoir, so that the soaking time is optimized. However, the influence of the fracture fluid pressure on the imbibition effect is mainly researched as one of the environmental conditions in the process of simulating the fracturing construction, and the influence of the fracture fluid pressure on the imbibition effect is not analyzed and discussed in detail.
Disclosure of Invention
The present invention aims to address at least one of the above-mentioned deficiencies of the prior art. For example, one of the objectives of the present invention is to provide a core imbibition device, a simulated fracture fluid pressure imbibition experimental apparatus and an experimental method, so as to simulate and evaluate the influence of fracture fluid pressure and soaking time on matrix imbibition effect under the condition close to the real reservoir condition.
In order to achieve the above object, the present invention provides a simulated fracture fluid pressure imbibition experimental apparatus, which includes a core imbibition device, an injection unit, a flow-back pressure control unit, a confining pressure simulation unit, a reservoir temperature simulation unit and a parameter measurement unit, wherein the core imbibition device includes a flow-back channel, and an injection channel, a liquid chamber, a core chamber and an outflow channel which are sequentially communicated, wherein the flow-back channel is further communicated with the liquid chamber, and the core chamber can be used for placing a core; the seepage liquid can enter the liquid chamber from the injection channel and be discharged from the outflow channel through the rock core, and can also enter the return channel from the liquid chamber and be discharged; the injection unit is connected with an injection channel of the core imbibition device through a pipeline and can inject imbibition liquid into the liquid chamber through the injection channel; the flow-back pressure control unit is connected with a flow-back channel of the core imbibition device through a pipeline and can apply pressure to the flow-back channel to control the flow rate of flow-back; the confining pressure simulation unit is connected with the rock core imbibition device through a pipeline and can apply pressure to a rock core chamber to prevent liquid from flowing by; the reservoir temperature simulation unit can adjust the imbibition temperature of the rock core; the parameter metering unit is connected on the pipeline of the experimental device to measure the pressure and flow parameters of all parts of the experimental device.
Optionally, the core imbibition device may further include a casing, a first plug, a second plug, an elastic sleeve and an inner sleeve, wherein the first and second plugs are symmetrically arranged with each other, and respectively extend into and are fixedly connected with the casing from two ends of the casing; the elastic sleeve penetrates through the shell and is sleeved outside the first plug and the second plug; the inner sleeve and the rock core are arranged in the elastic sleeve in a penetrating mode and are located between the first plug and the second plug, the injection channel and the backflow channel are arranged on the first plug, the outflow channel is arranged on the second plug, and the liquid chamber is formed in the inner sleeve.
Alternatively, the injection unit may include a first displacement pump and a first intermediate container, an outlet end of the first displacement pump is connected to one end of the first intermediate container through a pipeline, the other end of the first intermediate container is connected to the core imbiber through a pipeline, and the first displacement pump is capable of injecting the imbibing fluid in the first intermediate container into the injection channel through a pipeline.
Optionally, the back-discharge pressure control unit may include a second displacement pump, a second intermediate container, and a back-pressure valve, an outlet end of the second displacement pump is connected to one end of the second intermediate container through a pipeline, the other end of the second intermediate container is connected to a first end of the back-pressure valve through a pipeline, a second end of the back-pressure valve is connected to the core imbibition device through a pipeline, and the second displacement pump is capable of pressurizing the gas medium in the second intermediate container to the back-discharge passage through the back-pressure valve to control the back-discharge flow rate.
Optionally, a confining pressure cavity can be formed between the outer wall of the elastic sleeve and the inner wall of the shell, a liquid injection hole and a liquid discharge hole are formed in the side wall of the shell and are communicated with the confining pressure cavity, the confining pressure simulation unit comprises a pressure pump, the pressure pump is connected with the shell through a pipeline to inject a liquid medium into the confining pressure cavity through the liquid injection hole so as to prevent liquid channeling, and the liquid discharge hole can discharge the liquid in the confining pressure cavity.
Optionally, the reservoir temperature simulation unit may include a heating box, and the core imbibition device and the first intermediate container are disposed in the heating box, and the heating box may heat the core imbibition device and the first intermediate container to a preset temperature to adjust the imbibition temperature of the core.
Optionally, the parameter metering unit may comprise first, second and third pressure gauges and first and second meters, the first pressure gauge being connected to the line between the injection unit and the core sucker for measuring the injection pressure; the second pressure gauge is connected to a pipeline between the second intermediate container and the back pressure valve and used for measuring the pressure applied to the back discharge channel; the third pressure gauge is connected to a pipeline between the confining pressure simulation unit and the core imbibition device and is used for measuring confining pressure; the first meter is connected with the third end of the back pressure valve through a pipeline and is used for metering the crude oil imbibition displacement amount; and the second meter is connected with the core imbibition device through a pipeline and is used for measuring the volume of the crude oil flowing out of the outflow channel.
The invention provides a core imbibition device, which comprises a shell, a first plug, a second plug, an elastic sleeve and an inner sleeve, wherein the first plug and the second plug are symmetrically arranged and respectively extend into the shell from two ends of the shell and are fixedly connected with the shell; the elastic sleeve penetrates through the shell and is sleeved outside the first plug and the second plug; the inner sleeve is arranged in the elastic sleeve in a penetrating way, one end of the inner sleeve is abutted against the first plug, and a liquid chamber is formed in the inner sleeve; a core chamber is formed between the inner sleeve and the second plug, and a core can be placed in the core chamber; the injection channel and the back-flow channel are arranged on the first plug, the outflow channel is arranged on the second plug, the injection channel and the back-flow channel are communicated with the liquid chamber, the seepage and imbibition liquid can enter the liquid chamber from the injection channel and be discharged from the outflow channel through a rock core in the rock core chamber, and the liquid chamber can also be discharged from the back-flow channel.
Optionally, a confining pressure cavity can be formed between the outer wall of the elastic sleeve and the inner wall of the shell, a liquid injection hole and a liquid discharge hole are formed in the side wall of the shell, the liquid injection hole and the liquid discharge hole are communicated with the confining pressure cavity, a liquid medium can be injected into the confining pressure cavity through the liquid injection hole to prevent liquid channeling, and the liquid discharge hole can discharge liquid in the confining pressure cavity.
In another aspect, the invention provides a simulated fracture fluid pressure imbibition experimental method, which adopts the simulated fracture fluid pressure imbibition experimental device to perform imbibition experiments.
Optionally, the experimental method may include configuring simulated reservoir bottom water, configuring simulated oil, processing the core, assembling the experimental apparatus, simulating formation temperature by the reservoir temperature simulation unit, configuring imbibition liquid and filling the imbibition liquid into the injection unit, injecting the imbibition liquid in the injection unit into the core imbibition device, establishing confining pressure by the confining pressure simulation unit, controlling flowback flow rate by pressurization of the flowback pressure control unit, and measuring and recording pressure and flow parameters by the parameter measurement unit.
Compared with the prior art, the beneficial effects of the invention comprise at least one of the following:
(1) The experimental device has the advantages that the working temperature can reach 180 ℃ at most, the maximum pressure can reach 70MPa, the principle of equipment is simple and reliable, the operation is easy, the first meter and the second meter are respectively arranged at the outlets of the flow-back channel and the flow-out channel, and are combined to jointly measure the crude oil displacement, so that the experimental device has stronger universality, the evaluation on the imbibition performance of oil reservoirs with different properties can be realized under different lithological conditions, the crude oil displacement data can be accurately measured, the real imbibition process of the reservoir can be reduced as far as possible, and meanwhile, the experimental device has good feasibility for the influence of shale core imbibition displacement and soaking time.
(2) The experimental simulation of the influence of the fluid pressure of the crack on the matrix imbibition effect has obvious effect, the imbibition extraction degree is continuously increased along with the increase of the fluid pressure, and the imbibition capacity is gradually enhanced.
(3) The influence of the soaking time on the matrix imbibition effect is simulated in an experiment, and the result shows that the imbibition production degree is gradually increased along with the increase of the soaking time, the increase amplitude is sequentially reduced, and the optimal economic soaking time is indicated.
(4) The flow limiting device at the outlet end of the return pipeline achieves a good effect, can accurately predict the maximum imbibition time through the Poisea equation, and provides a good basis for experimental design.
(5) The precise metering device can realize oil-water separation and can maintain the oil column in the precise graduated tube in the whole imbibition process, thereby ensuring that the crude oil displacement can be accurately recorded in real time.
Drawings
The above and other objects and/or features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:
fig. 1 shows a schematic structural diagram of a simulated fracture fluid pressure imbibition experimental device according to an exemplary embodiment of the invention.
FIG. 2 shows a schematic diagram of the structure of a core imbibition device according to an exemplary embodiment of the invention.
Fig. 3 shows a schematic structural diagram of the first and second gauges in the simulated fracture fluid pressure imbibition experimental device according to the exemplary embodiment of the invention.
Description of reference numerals:
1-core imbibition device, 11-shell, 111-liquid injection hole, 112-liquid discharge hole, 113-confining pressure cavity, 12-first plug, 121-injection channel, 122-backflow channel, 13-second plug, 131-outflow channel, 14-elastic sleeve, 15-inner sleeve, 151-liquid chamber, 16-core chamber, 17-sealing element, 2-injection unit, 21-first displacement pump, 22-first intermediate container, 3-backflow pressure control unit, 31-second displacement pump, 32-second intermediate container, 33-back pressure valve, 4-confining pressure simulation unit, 41-pressure pump, 5-reservoir temperature simulation unit, 51-heating box, 6-parameter measurement unit, 61-first pressure gauge, 62-second pressure gauge, 63-third pressure gauge, 64-first pressure gauge, 641-precision graduated tube, 642-liquid filling bottle, 643-inlet end, 644-outlet end, 645-control valve, 65-second pressure gauge, 7-six-sixth pressure gauge.
Detailed Description
Hereinafter, a core imbibition device, a simulated fracture fluid pressure imbibition experimental device and an experimental method according to the present invention will be described in detail with reference to exemplary embodiments.
In the description of the present application, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a particular orientation, be constructed in a particular orientation, and be operated, and thus should not be construed as limiting the present application.
The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The field of increasing the yield after the pressing is a popular topic in recent years, and the imbibition effect is an important mechanism of the increasing the yield after the pressing and has great significance for deeply understanding the mechanism. In the fracturing process, part of fracturing fluid enters the matrix under the action of the pressure difference between the fluid pressure of the artificial fracture and the fluid in the matrix to promote the occurrence of imbibition and displace crude oil. In order to verify and evaluate the imbibition capacity of the matrix, related imbibition experimental devices are often adopted for carrying out imbibition experiments, however, most of the existing imbibition experimental devices have limited pressure resistance, cannot simulate the imbibition effect under the condition of high pressure difference, cannot analyze the influence of the pressure of the fracture fluid on the imbibition effect, and have complex structures and are difficult to operate.
Based on the above, the invention provides a core imbibition device, a simulated fracture fluid pressure imbibition experimental device and an experimental method, wherein the simulated fracture fluid pressure imbibition experimental device comprises the core imbibition device, an injection unit, a flow-back pressure control unit, a confining pressure simulation unit, a reservoir temperature simulation unit and a parameter measurement unit, wherein the core imbibition device comprises a flow-back channel, and an injection channel, a liquid chamber, a core chamber and an outflow channel which are sequentially communicated, wherein the flow-back channel is also communicated with the liquid chamber, and the core chamber can be used for placing a core; the seepage and suction liquid can enter the liquid chamber from the injection channel and is discharged from the outflow channel through the rock core, and can also enter the return channel from the liquid chamber and be discharged; the injection unit is connected with an injection channel of the core imbibition device through a pipeline and can inject imbibition liquid into the injection channel; the flow-back pressure control unit is connected with a flow-back channel of the core imbibition device through a pipeline and can apply pressure to the flow-back channel to control the flow rate of flow-back; the confining pressure simulation unit is connected with the core imbibition device through a pipeline and can apply pressure to the core imbibition device to prevent liquid from flowing; the reservoir temperature simulation unit can adjust the imbibition temperature of the rock core; the parameter metering unit is connected on the pipeline of the experimental device to measure the pressure and flow parameters of all parts of the experimental device.
The working temperature of the experimental device can reach 180 ℃ at most, the maximum pressure can reach 70MPa, the principle of the device is simple and reliable, the operation is easy, the first meter and the second meter are respectively arranged at the outlets of the flow-back channel and the flow-out channel, and the first meter and the second meter are combined to jointly measure the crude oil displacement, so that the experimental device has stronger universality, can realize the imbibition performance evaluation on oil reservoirs with different properties under different lithological conditions, accurately measure the crude oil displacement data, reduce the real imbibition process of the reservoir as far as possible, and simultaneously has good feasibility for the influence of shale core imbibition displacement and soaking time; the experimental simulation of the influence of the fracture fluid pressure on the matrix imbibition effect has obvious effect, the imbibition extraction degree is continuously increased along with the increase of the fluid pressure, and the imbibition capacity is gradually enhanced; the influence of the soaking time on the substrate imbibition effect is simulated in an experiment, and the result shows that the imbibition production degree is gradually increased along with the increase of the soaking time, the increase amplitude is sequentially reduced, and the optimal economic soaking time is indicated; the flow limiting device at the outlet end of the backflow pipeline achieves a good effect, the maximum imbibition time can be accurately predicted through the Poiseuille equation, and a good basis is provided for experimental design; the precise metering device can realize oil-water separation and can maintain the oil column in the precise graduated tube in the whole imbibition process, thereby ensuring that the crude oil displacement can be accurately recorded in real time.
The exemplary embodiment provides a simulated fracture fluid pressure imbibition experimental device.
FIG. 1 is a schematic diagram of a simulated fracture fluid pressure imbibition experimental device according to an exemplary embodiment of the invention; FIG. 2 shows a schematic diagram of a core breaker according to an exemplary embodiment of the present disclosure; fig. 3 is a schematic structural diagram illustrating first and second gauges in a simulated fracture fluid pressure imbibition experimental device according to an exemplary embodiment of the invention.
As shown in fig. 1 to 3, the simulated fracture fluid pressure imbibition experimental apparatus described in this exemplary embodiment may include a core imbibition device 1, an injection unit 2, a flow-back pressure control unit 3, a confining pressure simulation unit 4, a reservoir temperature simulation unit 5, a parameter measurement unit 6, and a six-way valve 7, where the core imbibition device 1 is provided with an injection channel 121, a flow-back channel 122, and a flow-out channel 131, a core is installed in a core chamber 16 of the core imbibition device 1, the core imbibition device 1 further includes a liquid chamber 151, the injection channel 121 and the flow-back channel 122 are respectively communicated with the liquid chamber 151, an outlet end of the injection unit 2 may be connected to the injection channel 121 on the core imbibition device 1 through a pipeline, the injection unit 2 may inject imbibition liquid stored therein into the injection channel 121 through a pipeline and enter the liquid chamber 151, the core chamber 16 is located between the liquid chamber 151 and the flow-out channel 131, and the imbibition liquid entering the liquid chamber 151 may enter the flow-out channel 131 through the core and may also directly flow out through the flow-back channel 122 according to different properties; the outlet end of the flow-back pressure control unit 3 can be connected to the flow-back channel 122 on the core imbibition device 1 through a pipeline, and the flow-back pressure control unit 3 can apply reverse pressure to the flow-back channel 122 through the pipeline to the gas medium stored in the flow-back pressure control unit 3, so as to control the flow rate of the liquid discharged from the flow-back channel 122; the outlet end of the confining pressure simulation unit 4 can be connected with the core imbibition device 1 through a pipeline, and a liquid medium stored in the confining pressure simulation unit can be injected into the core imbibition device 1 to establish confining pressure so as to avoid experiment failure caused by fluid channeling of imbibition liquid in the liquid chamber 151 under the action of fluid pressure; the reservoir temperature simulation unit 5 can heat part of assemblies in the core imbibition device 1 and the injection unit 2, and can simulate the real temperature in the stratum by adjusting the imbibition temperature of the core, so that the imbibition and the imbibition effects of the core are influenced; the parameter metering unit 6 is connected to pipelines at various positions in the simulated fracture fluid pressure imbibition experimental device and can measure various parameters such as pressure, flow and the like at different positions.
In this embodiment, the core infiltration suction device 1 may include an outer shell 11, a first plug 12, a second plug 13, an elastic sleeve 14 and an inner sleeve 15, wherein the outer shell 11 is a hollow cylindrical structure, the first plug 12 and the outer shell 11 are matched with each other, and can extend into the outer shell 11 from one end of the outer shell 11 and be fixedly connected with the outer shell 11 through screw fitting, the second plug 13 is the same as the first plug 12 in structure, and can also be matched with the outer shell 11, and can extend into the outer shell 11 from the other end of the outer shell 11 and be fixedly connected with the outer shell 11 through screw fitting, that is, when both the first plug 12 and the second plug 13 are installed in the outer shell 11, they are symmetrically arranged with each other, but the invention is not limited thereto, the connection manners of the first plug 12 and the second plug 13 with the outer shell 11 may also be other fixed connection manners such as welding, screw or bolt connection, and the structures of the first plug 12 and the second plug 13 may also be different, as long as both can be matched with the outer shell 11.
Further, the elastic sleeve 14 may be made of a rubber material, and the elastic sleeve 14 is simultaneously sleeved outside the first plug 12 and the second plug 13 and is inserted into the housing 11, that is, the elastic sleeve 14 is located between the first plug and the housing 11 along the radial direction of the housing 11; the inner sleeve 15 can be made of steel, can bear confining pressure applied to the inner sleeve by a medium in the confining pressure cavity 113, keeps rigidity and does not deform, and cannot be corroded by seepage and absorption liquid, the inner sleeve 15 penetrates through the elastic sleeve 14, the inner sleeve 15 is located between the first plug 12 and the second plug 13 along the axial direction of the outer shell 11, one end of the inner sleeve 15 can be abutted against the first plug 12, a core chamber 16 is formed between the other end of the inner sleeve 15 and the second plug 13, a core can be installed in the core chamber 16, after the core is installed in the core chamber 16, two ends of the core can be abutted against the inner sleeve 15 and the second plug 13 respectively, a sealing element 17 is installed at the joint between the elastic sleeve 14 and the first and second plugs, and a sealing element is also installed at the joint between the inner sleeve 15 and the first plug 12, but the invention is not limited to this, and the material of the elastic sleeve 14 can also be other elastic materials meeting the use requirements besides rubber; the material of the inner sleeve 15 can also be other materials meeting the rigidity requirement besides steel materials, such as other alloy materials or non-metallic carbon fiber materials; the first plug 12, the inner sleeve 15, the core in the core chamber 16 and the second plug 13 may be arranged at intervals, and as long as the elastic sleeve 14 is sealed with the first plug 12 and the second plug 13, the fluid in the inner sleeve 15 does not leak from the joint between the elastic sleeve 14 and the first plug 12 and the second plug 13.
Further, both the injection channel 121 and the return channel 122 may be opened on the first plug 12, and both the injection channel 121 and the return channel 122 axially penetrate through both ends of the first plug 12, and the injection channel 121 and the return channel 122 are radially spaced apart from each other and are not directly communicated with each other; the outflow channel 131 is formed on the second plug 13, and the outflow channel 131 also axially penetrates through two ends of the second plug 13; the inner sleeve 15 is a hollow cylindrical structure, a liquid chamber 151 capable of containing liquid is formed in the inner sleeve 15, and when the inner sleeve 15 is installed in the core infiltration apparatus 1, the liquid chamber 151 in the inner sleeve can be communicated with the injection channel 121 and the return channel 122 on the first plug 12, that is, liquid can enter the liquid chamber 151 from the injection channel 121, and can also be discharged from the liquid chamber 151 along the return channel 122; the core chamber 16 is formed between the inner casing 15 and the second plug 13, that is, when the core is installed in the core chamber 16, the core can separate the liquid chamber 151 from the outflow channel 131, and the liquid in the liquid chamber 151 can penetrate into and pass through the core and then be discharged from the outflow channel 131, but the present invention is not limited thereto, and the injection channel 121 and the return channel 122 can be opened on the second plug 13, while the outflow channel 131 is opened on the first plug 12, and the inner casing 15 and the core chamber 16 can be exchanged as long as the injection channel 121, the return channel 122 and the liquid chamber 151 are disposed on the same side of the core chamber 16, and the outflow channel 131 is disposed on the other side of the core chamber 16.
Furthermore, a confining pressure cavity 113 can be formed between the inner wall of the casing 11 and the outer wall of the elastic sleeve 14, a liquid injection hole 111 and a liquid discharge hole 112 are formed in the side wall of the casing 11, and both the liquid injection hole 111 and the liquid discharge hole 112 are communicated with the confining pressure cavity 113, that is, both the liquid injection hole 111 and the liquid discharge hole 112 can penetrate through the inner wall and the outer wall of the casing 11, so that liquid can be injected into the confining pressure cavity 113 through the liquid injection hole 111, and the liquid discharge hole 112 is closed at the same time, so that the pressure in the confining pressure cavity 113 is increased to establish confining pressure, and therefore seepage and suction liquid in the liquid chamber 151 is prevented from flowing along a gap between the core and the elastic sleeve 14 under the action of fluid pressure to cause experimental failure; when the pressure needs to be relieved after the experiment is finished, the liquid discharge hole 112 is opened, so that the liquid in the confining pressure cavity 113 can be discharged from the core imbibition device 1 along the liquid discharge hole 112, but the invention is not limited thereto, and the medium injected into the confining pressure cavity 113 can also be gas such as nitrogen, carbon dioxide, air and the like, as long as the function of establishing confining pressure to avoid channeling can be realized, the confining pressure cavity 113 is ensured to have sufficient sealing performance, and the filled medium can not corrode and damage the materials of the elastic sleeve 14 and the shell 11.
In the present embodiment, the injection unit 2 may include a first displacement pump 21 and a first intermediate container 22, wherein an outlet end of the first displacement pump 21 is connected to an inlet end of the first intermediate container 22 through a pipeline, an outlet end of the first intermediate container 22 is further connected to the first stopper 12 on the core imbiber 1 through a pipeline, the outlet end of the first intermediate container 22 is communicated with the injection channel 121, imbibition liquid is stored in the first intermediate container 22, and the imbibition liquid stored in the first intermediate container 22 may be input into the injection channel 121 from the outlet end of the first intermediate container 22 along a pipeline and a positive input pressure may be applied to the injection channel 121 under the driving of the first displacement pump 21, but the present invention is not limited thereto, and other types of driving members than the first displacement pump 21 may be included in the injection unit 2 as a driving source, and other types of storage containers than the first intermediate container 22 may be included to store and convey the imbibition liquid.
In the present embodiment, the back-flow pressure control unit 3 may include a second displacement pump 31, a second intermediate container 32, and a back-pressure valve 33, wherein an outlet end of the second displacement pump 31 is connected to an inlet end of the second intermediate container 32 through a pipeline, an outlet end of the second intermediate container 32 is connected to a first end of the back-pressure valve 33 through a pipeline, a second end of the back-pressure valve 33 is connected to the first stopper 12 on the core infiltrator 1 through a pipeline, so that the outlet end of the second intermediate container 32 is communicated with the back-flow passage 122 through the back-pressure valve 33, nitrogen gas is stored in the second intermediate container 32, and the back-flow rate of the infiltrant liquid in the liquid chamber 151 flowing out along the back-flow passage 122 may be controlled by driving the second displacement pump 31 to apply a back pressure from the outlet end of the second intermediate container 32 to the back-flow passage 122 through the back-pressure valve 33, so as to ensure that the experiment process is continued for a long time enough to better test the infiltrant performance of the core, but the invention is not limited thereto, the back-flow pressure control unit 3 may include other types of an inert medium storage medium such as a storage container, and may also include a helium gas storage medium storage container 31, and other types that the inert medium storage container 31 may be used as a storage medium storage container.
In the present embodiment, the confining pressure simulation unit 4 may include a pressurizing pump 41, the pressurizing pump 41 is connected to the liquid injection hole 111 on the housing 11 through a pipeline, that is, the pressurizing pump 41 may perform pressurized liquid injection into the confining pressure chamber 113 through the liquid injection hole 111; further, the pressure pump 41 is a hand pump, that is, the pressure pump 41 can be operated to pressurize and inject liquid into the confining pressure cavity 113 in a manual operation manner, in the process of pressurizing and injecting liquid, the liquid discharge hole 112 is firstly opened, after the confining pressure cavity 113 is filled with liquid, the liquid discharge hole 112 is closed, the pressure is continuously applied to the confining pressure cavity 113, the operation of pressurizing and injecting liquid can be stopped until the pressure in the confining pressure cavity 113 is equal to the pressure in the liquid chamber 151, and at this time, the confining pressure is completely established. However, the present invention is not limited thereto, and the confining pressure simulation unit 4 may further include other types of pressurizing means besides the pressurizing pump 41 as long as the function of inputting the medium into the confining pressure chamber 113 to prevent the liquid from flowing by can be realized, and the pressurizing pump 41 may also be other types of pumps besides a hand pump, such as an electric pump, etc., as long as the pressure in the confining pressure chamber 113 can be controlled.
In this embodiment, the reservoir temperature simulation unit 5 may include a heating box 51, the heating box 51 may be an oven, the core imbiber 1 and the first intermediate container 22 may be placed in the heating box 51, and the core imbibition device 1, the first intermediate container 22 and the imbibition liquid in the core imbiber 1 and the first intermediate container 22 may be heated by controlling the heating temperature of the heating box 51 to simulate the actual temperature in the formation, so that the measured various parameters are closer to the conditions in the actual fracturing operation, and the influence of the temperature in the actual fracturing operation on the performance of the imbibition liquid and the imbibition performance of the core may be better analyzed, but the present invention is not limited thereto, and the reservoir temperature simulation unit 5 may also include other types of heating devices besides the heating box 51 as long as the temperature therein can be controlled to reach the preset temperature required by the experiment, and the heating box 51 may also be other types of devices besides the oven capable of realizing heating.
In this embodiment, the parameter metering unit 6 may include a first pressure gauge 61, a second pressure gauge 62, a third pressure gauge 63, a first meter 64 and a second meter 65, wherein the first pressure gauge 61 is installed on the six-way valve 7 of the line between the first intermediate container 22 and the first stopper 12, and may be used to measure the pressure of the imbibition liquid injected from the first intermediate container 22 into the injection channel 121; a second pressure gauge 62 is installed on the six-way valve 7 of the line between the second intermediate container 32 and the back pressure valve 33, and is operable to measure the back pressure applied to the back flow channel 122 by the nitrogen gas output from the second intermediate container 32; a third pressure gauge 63 is arranged on the six-way valve 7 of the pipeline between the pressure pump 41 and the shell 11 of the core infiltration suction device 1 and is used for measuring the confining pressure generated by the pressure pump 41 injecting a medium into the confining pressure cavity 113 through the injection hole 111; the first meter 64 is connected with the third end of the back pressure valve 33 through a pipeline and is used for metering the crude oil amount in the imbibition liquid which is back-discharged from the back-discharge channel 122 in the experimental process, namely the crude oil imbibition displacement amount; the second meter 65 is connected with the second plug 13 on the core infiltration suction device 1 through a pipeline, the crude oil flowing out of the outflow channel 131 can enter the second meter 65, and the second meter 65 can be used for metering the volume of the crude oil flowing out of the outflow channel 131. However, the present invention is not limited thereto, and the six-way valve 7 may be eliminated, and the first pressure gauge 61, the second pressure gauge 62, and the third pressure gauge 63 may be directly installed on the pipeline, as long as the pressure parameters at various positions can be accurately measured.
Further, the first meter 64 may be a precision meter, which includes a precision graduated tube 641, a liquid bottle 642, an inlet 643, an outlet 644 and a control valve 645, wherein the precision graduated tube 641 is integrally connected to the liquid bottle 642, the inlet 643 and the outlet 644 are respectively disposed at two sides of the liquid bottle 642, the outlet 644 is located at a position lower than the inlet 643, the control valve 645 is installed on a pipeline outside the outlet 644, liquid (typically a mixture of simulated formation water and simulated oil) may enter the liquid bottle 642 through the inlet 643, as the volume of the liquid in the liquid bottle 642 increases, the whole displaced crude oil column may rise into the precision graduated tube 641, oil-water separation may be achieved under the action of gravity during measurement, the whole crude oil column may be maintained within a measurable range in the precision graduated tube 641 through the control of the outlet 644, the volume parameter of crude oil may be read through the precision graduated tube, when the liquid discharge operation is completed, the control valve 645 is opened, the liquid in the liquid bottle 642 may flow out of the liquid bottle 642 through the outlet 642, thereby completing the liquid discharge operation, but the present invention is not limited to this, and the control valve may be installed at the position of the inlet 643, and the inlet and the outlet may be installed as long as the inlet 642 is not lower than the inlet 643, the inlet of the inlet 642, the inlet 645, the outlet is directly.
Further, the second meter 65 is the same as the first meter 64, and is not described in detail here.
Usually, when the imbibition experiment is started, clear water is filled in the liquid bottles of the first meter 64 and the second meter 65, so that the liquid level of the clear water reaches the lowest scale of the precision graduated tube, along with the performance of the imbibition experiment, oil-water mixed liquid flowing in from the inlet end can enter the liquid bottles and be mixed with the clear water added at first, and an oil-water layer is generated, the crude oil on the upper layer can enter the precision graduated tube, at the moment, the volume of the crude oil can be calculated according to the reading on the graduated tube, along with the increase of the water inflow, the oil-water interface can rise along with the increase of the water inflow, in order to avoid the situation that the crude oil on the upper layer in the precision graduated tube rises continuously and is pushed out of the metering range of the graduated tube, the position condition of the oil-water interface needs to be concerned at any time, the outlet end is opened to discharge the clear water in the liquid bottles to ensure that the crude oil is always in the metering range of the precision graduated tube, so as to ensure that the volume of the crude oil is accurately measured.
In the process of carrying out an imbibition experiment by using the simulated fracture fluid pressure imbibition experimental device described in this embodiment, if the core is a low permeability sandstone or a conventional sandstone, the imbibition liquid in the liquid chamber 151 can better displace the crude oil in the core, more crude oil will flow into the second meter 65 along the outflow channel 131, and at this time, the crude oil displacement amount is mainly measured by the second meter 65; if the core is shale or tight rock, the in situ fluid pressure is unable to displace the imbibition fluid through the core under the applied confining pressure, i.e. the crude oil in the core is unable to enter the outflow channel 131 and to drain into the second meter 65, and more crude oil enters the fluid chamber 151 and flows along the return channel 122 into the first meter 64, in which case the crude oil displacement will be measured primarily by means of the first meter 64.
Therefore, in the experimental device for simulating fracture fluid pressure imbibition, the first meter and the second meter are respectively arranged at the outlets of the flow-back channel and the flow-out channel, and the first meter and the second meter are combined to jointly measure the crude oil displacement, so that the experimental device has stronger universality, can meet the requirements of realizing the imbibition performance evaluation on oil reservoirs with different properties under different lithological conditions, accurately measure the crude oil displacement data, and reduce the real imbibition process of a reservoir layer as much as possible.
The present exemplary embodiment provides a core imbibition device.
As shown in fig. 2, the core infiltration suction device 1 may include an outer shell 11, a first plug 12, a second plug 13, an elastic sleeve 14 and an inner sleeve 15, wherein the outer shell 11 is a hollow cylindrical structure, the first plug 12 and the outer shell 11 are matched with each other, and can extend into the outer shell 11 from one end of the outer shell 11 and be fixedly connected with the outer shell 11 through screw-fitting, the second plug 13 is the same as the first plug 12 in structure, and can also be matched with the outer shell 11 and can extend into the outer shell 11 from the other end of the outer shell 11 and be fixedly connected with the outer shell 11 through screw-fitting, that is, when both the first plug 12 and the second plug 13 are installed in the outer shell 11, they are symmetrically arranged with each other, but the present invention is not limited thereto, the connection modes of the first plug 12 and the second plug 13 with the outer shell 11 may also be other fixed connection modes such as welding, screw or bolt connection, and the structures of the first plug 12 and the second plug 13 may also be different as long as they can be matched with the outer shell 11.
Further, the elastic sleeve 14 may be made of a rubber material, and the elastic sleeve 14 is simultaneously sleeved outside the first plug 12 and the second plug 13 and is inserted into the outer shell 11, that is, the elastic sleeve 14 is located between the first plug and the outer shell 11 along the radial direction of the outer shell 11; the inner sleeve 15 can be made of steel, can bear confining pressure applied to the inner sleeve by a medium in the confining pressure cavity 113, keeps rigidity and does not deform, and cannot be corroded by seepage and absorption liquid, the inner sleeve 15 penetrates through the elastic sleeve 14, the inner sleeve 15 is located between the first plug 12 and the second plug 13 along the axial direction of the outer shell 11, one end of the inner sleeve 15 can be abutted against the first plug 12, a core chamber 16 is formed between the other end of the inner sleeve 15 and the second plug 13, a core can be installed in the core chamber 16, after the core is installed in the core chamber 16, two ends of the core can be abutted against the inner sleeve 15 and the second plug 13 respectively, a sealing element 17 is installed at the joint between the elastic sleeve 14 and the first and second plugs, and a sealing element is also installed at the joint between the inner sleeve 15 and the first plug 12, but the invention is not limited to this, and the material of the elastic sleeve 14 can also be other elastic materials meeting the use requirements besides rubber; the inner sleeve 15 can also be made of other materials, such as other alloy materials or non-metallic carbon fiber materials, which can meet the rigidity requirement and resist corrosion, besides steel; the first plug 12, the inner sleeve 15, the core in the core chamber 16 and the second plug 13 may be arranged at intervals, and as long as the elastic sleeve 14 is sealed with the first plug 12 and the second plug 13, the fluid in the inner sleeve 15 does not leak from the joint between the elastic sleeve 14 and the first plug 12 and the second plug 13.
Further, both the injection channel 121 and the return channel 122 may be opened on the first plug 12, and both the injection channel 121 and the return channel 122 axially penetrate through both ends of the first plug 12, and the injection channel 121 and the return channel 122 are radially spaced apart from each other and are not directly communicated with each other; the outflow channel 131 is formed on the second plug 13, and the outflow channel 131 also axially penetrates through two ends of the second plug 13; the inner sleeve 15 is a hollow cylindrical structure, a liquid chamber 151 capable of containing liquid is formed inside the inner sleeve 15, when the inner sleeve 15 is installed in the core sucker 1, the liquid chamber 151 inside the inner sleeve can be communicated with the injection channel 121 and the return channel 122 on the first plug 12, that is, liquid can enter the liquid chamber 151 from the injection channel 121, and can also be discharged from the liquid chamber 151 along the return channel 122; the core chamber 16 is formed between the inner casing 15 and the second plug 13, that is, when the core is installed in the core chamber 16, the core can separate the liquid chamber 151 from the outflow channel 131, and the liquid in the liquid chamber 151 can penetrate into and pass through the core and then be discharged from the outflow channel 131, but the present invention is not limited thereto, and the injection channel 121 and the return channel 122 can be opened on the second plug 13, while the outflow channel 131 is opened on the first plug 12, and the inner casing 15 and the core chamber 16 can be exchanged as long as the injection channel 121, the return channel 122 and the liquid chamber 151 are disposed on the same side of the core chamber 16, and the outflow channel 131 is disposed on the other side of the core chamber 16.
Furthermore, a confining pressure cavity 113 can be formed between the inner wall of the casing 11 and the outer wall of the elastic sleeve 14, a liquid injection hole 111 and a liquid discharge hole 112 are formed in the side wall of the casing 11, and both the liquid injection hole 111 and the liquid discharge hole 112 are communicated with the confining pressure cavity 113, that is, both the liquid injection hole 111 and the liquid discharge hole 112 can penetrate through the inner wall and the outer wall of the casing 11, so that liquid can be injected into the confining pressure cavity 113 through the liquid injection hole 111, and the liquid discharge hole 112 is closed at the same time, so that the pressure in the confining pressure cavity 113 is increased to establish confining pressure, and therefore seepage and suction liquid in the liquid chamber 151 is prevented from flowing along a gap between the core and the elastic sleeve 14 under the action of fluid pressure to cause experimental failure; when the pressure needs to be relieved after the experiment is finished, the liquid discharge hole 112 is opened, and the liquid in the confining pressure cavity 113 can be discharged from the core sucker 1 along the liquid discharge hole 112, but the invention is not limited to this, and the medium injected into the confining pressure cavity 113 can also be gas such as nitrogen, carbon dioxide, air and the like, as long as the function of establishing confining pressure to avoid channeling can be realized, the confining pressure cavity 113 is ensured to have sufficient sealing performance, and the filled medium can not corrode and damage the materials of the elastic sleeve 14 and the shell 11.
The present exemplary embodiment provides a simulated fracture fluid pressure imbibition experimental method that performs imbibition experiments using the simulated fracture fluid pressure imbibition experimental apparatus as described in exemplary embodiment 1 or the core imbibition device as described in exemplary embodiment 2.
As shown in fig. 1 to 3, the method for simulating a fracture fluid pressure imbibition experiment according to the present exemplary embodiment includes the following steps:
1. processing natural core into standard core (such as 5cm long and 2.5cm diameter), cleaning, placing into heating box 51, setting heating temperature of heating box 51 (such as 100 deg.C), drying core to constant weight, and recording dry weight m of core 1 (e.g., m) 1 =70.26 g), measure core length L using vernier caliper 1 And diameter D 1 (e.g. L) 1 ＝5.065cm，D 1 ＝2.534cm)。
2. Preparing standard salt water to simulate reservoir formation water, and measuring the water density rho of the formation according to the crude oil and liquid petroleum product laboratory density measuring and weighing type digital display hydrodensitometer method (NB/SH/T0874-2013) of the industry standard w (e.g.,. Rho.) w ＝0.9981g/cm 3 ) The method comprises saturating formation water with core by vacuum pumping method, and recording wet weight m of core 2 (e.g. m) 2 =74.06 g), the formula phi = ((m) is calculated by the pore size 2 -m 1 )/ρ w ) The porosity phi =15.5% was obtained per core volume, water core permeability K (e.g., K =1.36 mD).
3. Preparing simulation oil, saturating the simulation oil for the rock core by adopting axial loading until the flow speed of the simulation oil at the outlet end of the rock core is stable, and recording the volume V of the saturated simulation oil 1 (e.g. V) 1 =2.01 ml), oil saturation So (e.g. So = 53%).
4. The method comprises the steps of completely wiping floating oil on the surface of a rock core, filling the floating oil into a rock core imbibition device 1, completing assembly of the rock core imbibition device 1, connecting pipelines, completing installation of a simulated fracture fluid pressure imbibition experimental device, placing the rock core imbibition device 1 and a first intermediate container 22 into a heating box 51, starting the heating box 51, adjusting the heating temperature of the heating box 51 (for example, adjusting the heating temperature to 80 ℃) to simulate the formation temperature, and keeping the temperature for a sufficient time (for example, 24 hours) to age the rock core.
5. The imbibition solution is prepared and filled into the first intermediate container 22 (e.g., the first intermediate container 22 has a volume of 500 ml), and the imbibition viscosity μ (e.g., μ =3.26mPa · s) is measured at a formation temperature of 80 ℃ using a six-speed rotational viscometer.
6. Setting the pressure of the back pressure valve 33 to 0, opening the first displacement pump 21, pumping the imbibition liquid in the first intermediate container 22 into the liquid chamber 151 through the injection channel 121, keeping the backflow channel 122 higher than the injection channel 121 at the moment to ensure that air in the liquid chamber 151 is exhausted and filled with imbibition liquid, establishing core confining pressure through the pressurizing pump 41, enabling the core confining pressure to be 4-5 MPa higher than the imbibition liquid pressure injected into the liquid chamber 151, and ensuring that the imbibition liquid cannot flow out from a joint between the core and the elastic sleeve 14 so as to generate cross flow.
7. The second displacement pump 31 is started, and the nitrogen in the second intermediate tank 32 is fed into the back-pressure valve 33, which is subjected to a pressure P 1 Then the first displacement pump 21 is started, and the pumping pressure P of the first displacement pump 21 is set according to the experimental requirements 2 (e.g. P) 2 =4 MPa) while maintaining the differential pressure P 2 -P 1 =1MPa, using a certain specification of the return line (for example 40cm long with 1.5mm internal diameter), whereby according to poiseuille equation:
in the formula: q, flow rate of the flow-back channel, cm 3 S; r, the inner diameter of the return pipeline, cm; Δ P, the pressure difference between the injection passage and the return passage, pa; mu, flow ofBulk viscosity, pas; l, length of the return line, cm.
The flow rate of the backflow channel Q =8.23 ml/day can be calculated by the parameter values listed above, so that the 500ml imbibition liquid can maintain the imbibition time up to 55 days at most, and the occurrence of the whole imbibition process can be ensured.
8. The liquid bottles of the first meter 64 and the second meter 65 are filled with water, the liquid level is maintained to reach the lowest readable scale of the precise graduated tube, the topmost end of the liquid bottle is kept lower than the core imbibition device 1, the precise meters are used for measuring the volume of crude oil imbibed and displaced by the back flow channel 122 and the outflow channel 131 in the whole imbibition process and analyzing the change rule of the crude oil, and the influence of the fracture fluid pressure and the soaking time on the imbibition effect is evaluated by adjusting experimental parameters. In addition, in the whole experiment process, the position condition of an oil-water interface in the metering device needs to be paid attention to at any time, the outlet end of the metering device is opened in time to discharge liquid, clear water in the liquid filling bottle is discharged to avoid that crude oil on the upper layer in the precise graduated tube is continuously lifted up to push out the metering range of the graduated tube, the crude oil is guaranteed to be always in the metering range of the precise graduated tube, and the volume of the crude oil is guaranteed to be accurately measured.
9. After imbibition, the first and second displacement pumps are turned off and the confining pressure is removed, and the imbibition time is determined as 30 days according to the experimental data listed above, the final imbibition extraction degree is 26.2% when the fluid pressure is 3MPa, 31.5% when the fluid pressure is 4MPa, 36.7% when the fluid pressure is 5MPa, and 42.3% when the fluid pressure is 6 MPa; when the fluid pressure was set to 4MPa, the final imbibition degree was 24.5% when the imbibition time was 10 days, 28.7% when the imbibition time was 20 days, 31.5% when the imbibition time was 30 days, and 33.6% when the imbibition time was 40 days.
The experimental result shows that the imbibition displacement rate is gradually increased along with the increase of the fluid pressure; and along with the increase of the soaking time, the seepage replacement rate is gradually stabilized after being continuously increased, so that the fluid pressure of the fracture in the fracturing construction process can promote the seepage action, and the optimal soaking time exists under the economic condition.
The experimental data exemplified in the above experimental methods are only data measured in a certain experiment in this embodiment, and if experimental data different from that in this embodiment is measured in other repeated experiments, the present invention is still included in the protection scope.
In conclusion, the working temperature of the experimental device can reach 180 ℃ at most, the maximum pressure can reach 70MPa, the principle of the device is simple and reliable, the operation is easy, the first meter and the second meter are respectively arranged at the outlets of the flow-back channel and the flow-out channel, and the first meter and the second meter are combined to jointly measure the crude oil displacement, so that the experimental device has stronger universality, can meet the requirements of realizing the imbibition performance evaluation on oil reservoirs with different properties under different lithological conditions, accurately measure the crude oil displacement data, reduce the real imbibition process of the reservoir as much as possible, and has good feasibility for the influence of shale core imbibition displacement and soaking time; the experimental simulation of the influence of the fracture fluid pressure on the matrix imbibition effect has obvious effect, the imbibition extraction degree is continuously increased along with the increase of the fluid pressure, and the imbibition capacity is gradually enhanced; the influence of the soaking time on the substrate imbibition effect is simulated in an experiment, and the result shows that the imbibition production degree is gradually increased along with the increase of the soaking time, the increase amplitude is sequentially reduced, and the optimal economic soaking time is indicated; the flow limiting device at the outlet end of the backflow pipeline achieves a good effect, the maximum imbibition time can be accurately predicted through the Poiseuille equation, and a good basis is provided for experimental design; the precise metering device can realize oil-water separation and can maintain the oil column in the precise graduated tube in the whole imbibition process, thereby ensuring that the crude oil displacement can be accurately recorded in real time. The core imbibition device, the simulated fracture fluid pressure imbibition experimental device and the experimental method provided by the invention can quantitatively evaluate the influence of the fluid pressure on the matrix imbibition effect in the fracturing process under the condition close to a reservoir stratum, and have important guiding significance for further understanding the imbibition displacement mechanism in the fracturing process.
Although the present invention has been described above in connection with the exemplary embodiments and the accompanying drawings, it will be apparent to those of ordinary skill in the art that various modifications may be made to the above-described embodiments without departing from the spirit and scope of the claims.
Claims (11)
1. The experimental device for simulating the fluid pressure imbibition of the fracture is characterized by comprising a rock core imbibition device, an injection unit, a flow-back pressure control unit, a confining pressure simulation unit, a reservoir temperature simulation unit and a parameter measurement unit,
the core imbibition device comprises a return channel, an injection channel, a liquid chamber, a core chamber and an outflow channel which are sequentially communicated, wherein the return channel is also communicated with the liquid chamber, and the core chamber can be used for holding a core; the seepage liquid can enter the liquid chamber from the injection channel and be discharged from the outflow channel through the rock core, and can also enter the return channel from the liquid chamber and be discharged;
the injection unit is connected with an injection channel of the core imbibition device through a pipeline and can inject imbibition liquid into the liquid chamber through the injection channel;
the flow-back pressure control unit is connected with a flow-back channel of the core imbibition device through a pipeline and can apply pressure to the flow-back channel to control the flow rate of flow-back;
the confining pressure simulation unit is connected with the rock core imbibition device through a pipeline and can apply pressure to a rock core chamber to prevent liquid from flowing by;
the reservoir temperature simulation unit can adjust the imbibition temperature of the rock core;
the parameter metering unit is connected on a pipeline of the experimental device to measure pressure and flow parameters of all parts of the experimental device.
2. The simulated fracture fluid pressure imbibition experimental device of claim 1, wherein the core imbibition device further comprises a shell, a first plug, a second plug, an elastic sleeve and an inner sleeve, wherein the first plug and the second plug are symmetrically arranged, extend into the shell from two ends of the shell respectively and are fixedly connected with the shell; the elastic sleeve penetrates through the shell and is sleeved outside the first plug and the second plug; the inner sleeve and the rock core are arranged in the elastic sleeve in a penetrating mode and are located between the first plug and the second plug, the injection channel and the backflow channel are arranged on the first plug, the outflow channel is arranged on the second plug, and the liquid chamber is formed in the inner sleeve.
3. The simulated fracture fluid pressure imbibition experimental device of claim 1, wherein the injection unit comprises a first displacement pump and a first intermediate container, an outlet end of the first displacement pump is connected with one end of the first intermediate container through a pipeline, the other end of the first intermediate container is connected with the core imbibition device through a pipeline, and the first displacement pump can inject imbibition liquid in the first intermediate container into the injection channel through a pipeline.
4. The simulated fracture fluid pressure imbibition experimental device of claim 1, wherein the flow-back pressure control unit comprises a second displacement pump, a second intermediate container and a back-pressure valve, an outlet end of the second displacement pump is connected with one end of the second intermediate container through a pipeline, the other end of the second intermediate container is connected with a first end of the back-pressure valve through a pipeline, a second end of the back-pressure valve is connected with the core imbibition device through a pipeline, and the second displacement pump can apply pressure to the flow-back channel through the back-pressure valve to control the flow rate of flow-back.
5. The experimental device for simulating fluid pressure imbibition of cracks as claimed in claim 2, wherein a confining pressure cavity is formed between the outer wall of the elastic sleeve and the inner wall of the housing, a liquid injection hole and a liquid discharge hole are formed in the side wall of the housing, the liquid injection hole and the liquid discharge hole are both communicated with the confining pressure cavity, the confining pressure simulation unit comprises a pressure pump, the pressure pump is connected with the housing through a pipeline so as to inject a liquid medium into the confining pressure cavity through the liquid injection hole to prevent liquid channeling, and the liquid discharge hole can discharge the liquid in the confining pressure cavity.
6. The simulated fracture fluid pressure imbibition experimental device of claim 3, wherein the reservoir temperature simulation unit comprises a heating box, the core imbibition device and the first intermediate container are arranged in the heating box, and the heating box can heat the core imbibition device and the first intermediate container to a preset temperature so as to adjust the imbibition temperature of the core.
7. The simulated fracture fluid pressure imbibition experimental device of claim 4, wherein the parameter metering unit comprises a first pressure gauge, a second pressure gauge, a third pressure gauge, a first meter and a second meter, wherein the first pressure gauge is connected to a pipeline between the injection unit and the core imbibition device and used for measuring the injection pressure; the second pressure gauge is connected to a pipeline between the second intermediate container and the back pressure valve and used for measuring the pressure applied to the back discharge channel; the third pressure gauge is connected to a pipeline between the confining pressure simulation unit and the core infiltration suction device and is used for measuring confining pressure; the first meter is connected with the third end of the back pressure valve through a pipeline and is used for metering the crude oil imbibition displacement amount; and the second meter is connected with the core imbibition device through a pipeline and is used for measuring the volume of the crude oil flowing out of the outflow channel.
8. A core infiltration and suction device is characterized by comprising a shell, a first plug, a second plug, an elastic sleeve and an inner sleeve, wherein the first plug and the second plug are symmetrically arranged and respectively extend into the shell from two ends of the shell and are fixedly connected with the shell; the elastic sleeve penetrates through the shell and is sleeved outside the first plug and the second plug; the inner sleeve is arranged in the elastic sleeve in a penetrating way, one end of the inner sleeve is abutted against the first plug, and a liquid chamber is formed in the inner sleeve; a core chamber is formed between the inner sleeve and the second plug, and a core can be placed in the core chamber; the injection channel and the back-flow channel are arranged on the first plug, the outflow channel is arranged on the second plug, the injection channel and the back-flow channel are communicated with the liquid chamber, the seepage and imbibition liquid can enter the liquid chamber from the injection channel and be discharged from the outflow channel through a rock core in the rock core chamber, and the liquid chamber can also be discharged from the back-flow channel.
9. The core imbibition device as recited in claim 8, wherein a confining pressure chamber is formed between the outer wall of the elastic sleeve and the inner wall of the casing, a liquid injection hole and a liquid discharge hole are formed in the side wall of the casing, the liquid injection hole and the liquid discharge hole are both communicated with the confining pressure chamber, a liquid medium can be injected into the confining pressure chamber through the liquid injection hole to prevent liquid channeling, and the liquid discharge hole can discharge the liquid in the confining pressure chamber.
10. A simulated fracture fluid pressure imbibition test method, which is characterized in that the test method adopts the simulated fracture fluid pressure imbibition test device as claimed in claims 1-7 to carry out imbibition tests.
11. The simulated fracture fluid pressure imbibition experimental method of claim 10, wherein the experimental method comprises configuring simulated reservoir bottom water, configuring simulated oil, processing the core, assembling the experimental apparatus, simulating formation temperature through the reservoir temperature simulation unit, configuring imbibition liquid and filling the imbibition liquid into the injection unit, injecting the imbibition liquid in the injection unit into the core imbibition device, establishing confining pressure through the confining pressure simulation unit, controlling flow velocity through pressure application of a flow-back pressure control unit, and metering and recording pressure and flow parameters through the parameter metering unit.
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| CN202211606418.8A CN115901573A (en) | 2022-12-14 | 2022-12-14 | Rock core imbibition device, simulated fracture fluid pressure imbibition experimental device and experimental method |
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