Physical simulation device for simulating flow characteristics of salt rock and application thereof

Abstract

The application provides a physical simulation device for simulating flow characteristics of salt rock and application thereof, and belongs to the field of oil and gas development. The physical simulation device for simulating flow characteristics of salt rock comprises, which are connected in sequence, a full-diameter shale core displacement simulation device, a parallel-plate crack flow simulation device and a vertical stainless steel wellbore. Observation windows are formed on the parallel-plate crack flow simulation device and the vertical stainless steel wellbore. A camera is arranged outside each observation window. The application realizes independent control of pressure and temperature of each flow link, so that the experimental conditions of each flow link are closer to actual production conditions. The combination of the camera and the observation window realizes real-time recording of flow images, which is beneficial to observation and recording of the salt rock crystallization process. The temperature of the vertical wellbore simulation device and the pressure of the inflow end and the outflow end are controllable, the temperature and the pressure at different depths of a real wellbore can be simulated, and thus the crystallization of salt rock at different depths of the real wellbore can be simulated.

Description

Technical Field

[0001] The present invention belongs to the field of oil and gas development, and specifically relates to a physical simulation device for simulating the flow characteristics of salt rock and its application, which is suitable for reservoir transformation operations such as oil, natural gas, and unconventional natural gas fracturing and unblocking to increase oil and gas production. Background Art

[0002] Currently, large-scale discoveries of inter-salt shale oil have been made in the Sinopec Jianghan Qianjiang Depression, with geological reserves exceeding 100 million tons in several key strata. The shale oil in this depression dates back 40 years. Initial attempts at water squeezing, acidizing, and fracturing revealed that fracturing provided the greatest oil production increase, but even this only yielded a little over 300 tons. Furthermore, the flow of salt rock became clogged during production, leading to a rapid decline in production. Despite measures like squeezing to dissolve salt, the effectiveness of this method is extremely limited. The small amount of water squeezed into the reservoir can only dissolve a limited amount of salt rock. Furthermore, within the 8-10 meter radius of the shale reservoir, there are multiple bands of salt rock (0.1-0.5 meter thick), and the salt rock in the top and bottom cap layers of the shale is even thicker, reaching tens of meters. Even if the salt rock is 0.1m thick, if calculated based on a radius of 200m, the volume of the salt rock is over 12,000 cubic meters, and the weight of the salt rock is approximately 30,000 tons. Therefore, if the salt rock continues to flow after compression, the water squeezing operation will be quite laborious. If there is also thick salt rock flowing between upper and lower layers, the flow or creep of the salt rock will cause significant production problems in the future.

[0003] Because salt rock flow and creep pose serious production challenges, it's necessary to simulate its creep and flow characteristics under underground pressure and temperature conditions. If flow persists, the fracturing process should strive to avoid cracking the salt rock. Conversely, the salt rock's influence can be disregarded, and even the use of water-based fracturing fluids presents no adverse effects. Whether or not salt rock flows significantly impacts both completion and fracturing methods.

[0004] Chinese patent publication CN2903987 discloses a salt rock fissure seepage-dissolution coupling test device, which involves seepage-dissolution of salt rock fissures. It is mainly used to study the dissolution process, permeability evolution and coupling relationship of salt rock fissures under the infiltration of aqueous solutions with different compositions and saturations. The test results can be applied to the fields of underground salt rock storage projects for oil and natural gas, underground disposal of nuclear waste and salt rock mining. Its characteristics are: it can make aqueous solutions with different compositions and different saturations flow through salt rock fissures. By analyzing the test data, the dissolution process, permeability evolution and coupling relationship of salt rock fissures under the seepage-dissolution coupling of aqueous solutions with different compositions and different saturations can be obtained. It uses aqueous solutions with different compositions and different saturations, and controls the flow rate of the aqueous solution to observe and test the ideal salt rock. The dissolution process, permeability evolution and coupling relationship of cracks are used to study the salt rock dissolution mechanism under the influence of the seepage-dissolution coupling effect of salt rock cracks. However, it does not consider the simulation of the precipitation and crystallization process of salt rock by factors such as pressure and temperature; Chinese patent publication CN2884197 discloses a seepage-dissolution coupling test device for rock salt cracks, which involves the seepage-dissolution coupling relationship of rock salt cracks. The device can make solutions of different components and different saturations flow through rock salt cracks, and provides a reference for studying the dissolution, permeability evolution and coupling relationship of rock salt cracks under the infiltration of solutions of different components and different saturations, and analyzing the dissolution mechanism of rock salt cracks under the influence of the seepage-dissolution coupling effect. The experimental results can be applied to underground salt cavern storage projects for oil and natural gas, underground salt cavern disposal of nuclear waste, and rock salt mine mining. The device is easy to install, the crack width can be easily adjusted, and the changes in the crack surface can be observed in real time. It can allow solutions of different compositions and saturations to flow through the rock salt cracks, providing an experimental basis for studying the dissolution, permeability evolution, and coupling relationship of rock salt cracks under the infiltration of solutions of different compositions and saturations, and analyzing the dissolution mechanism of rock salt cracks under the influence of the seepage-dissolution coupling effect. However, it does not consider the simulation of the precipitation and crystallization process of salt rock by factors such as pressure and temperature; Chinese patent publication CN105758731A Disclosed is a salt rock multi-field coupled long-term creep test system, comprising a cylinder, a heating layer, a lower pressure head, a test piece, and an upper pressure head, with a sodium chloride pressure chamber between the test piece and the heating layer. The system also includes an axial pressure piston, a confining pressure piston, and a CT imager. A chemical solution channel is provided on the test piece, the axial pressure piston, the confining pressure piston, and the bottom of the cylinder, allowing the chemical solution to be introduced into the test piece and the sodium chloride pressure chamber. The channel controls the temperature of sodium chloride powder through the heating layer, simulating the axial pressure and confining pressure on the test piece, thereby better simulating the salt cavern oil storage environment. Furthermore, sodium chloride powder is used as a pressure transmission medium, providing Cl- and Na+, which facilitates the analysis of recrystallization during salt rock creep.Furthermore, it can observe the evolution and growth of cracks within interbedded salt rock during long-term creep through CT scanning, providing basic parameters for defining the damage zone and establishing seepage models. It also provides a multi-field coupled long-term creep test system for salt rock, enabling simulation of deep salt cavern ground stress, geothermal conditions, and the corrosive effects of chemical storage media such as petroleum on salt layers, allowing for the study of the long-term creep damage characteristics of salt rock under these simulated conditions. However, it does not consider the effects of pressure and temperature on the precipitation and crystallization of salt rock.

[0005] In summary, current devices and their applications are unable to simulate the rheological and creep characteristics of salt rock during energy replenishment methods such as depletion mining, water flooding, carbon dioxide flooding, and alternating water and carbon dioxide flooding. Summary of the Invention

[0006] The purpose of the present invention is to solve the difficulties existing in the above-mentioned prior art and provide a physical simulation device for simulating the flow characteristics of salt rock and its application, which is used to simulate the flow characteristics of salt rock after inter-salt shale oil fracturing, simulate the rheological and creep characteristics of salt rock during energy replenishment methods such as depletion mining, water flooding, carbon dioxide flooding, and alternating water and carbon dioxide flooding through experimental methods, and study methods for controlling the rheological and creep of salt rock in the above-mentioned processes.

[0007] The present invention is achieved through the following technical solutions:

[0008] A first aspect of the present invention provides a physical simulation device for simulating the flow characteristics of salt rock, the physical simulation device for simulating the flow characteristics of salt rock comprising: a full-diameter shale core displacement simulation device, a parallel plate fracture flow simulation device, and a vertical stainless steel wellbore connected in sequence;

[0009] Observation windows are provided on the parallel plate fracture flow simulation device and the vertical stainless steel wellbore;

[0010] Cameras are installed outside each observation window.

[0011] A further improvement of the present invention is that the full-diameter shale core displacement simulation device comprises: a full-diameter core holder, a core pressure simulation component;

[0012] The core pressure simulation component includes: a first injection pump, a second injection pump, and an intermediate container;

[0013] The confining pressure interface of the full-diameter core holder is connected to the outflow end of the first injection pump through a pipeline, and a first manual valve is provided on the pipeline;

[0014] The inflow end of the full-diameter core holder is connected to the outflow end of the intermediate container through a pipeline, and a first temperature sensor, a first electronic flow meter, a first pressure sensor, and a third manual valve are arranged on the pipeline;

[0015] The inflow end of the intermediate container is connected to the outflow end of the second injection pump through a pipeline, and a second manual valve is arranged on the pipeline.

[0016] Preferably, the full-diameter core holder has a pressure resistance range of 0.1-10 MPa.

[0017] A further improvement of the present invention is that the outflow end of the full-diameter core holder is connected to the inflow end of the parallel plate fracture flow simulation device through a one-way pumping component;

[0018] The one-way pumping component includes: a first back-pressure valve, a second back-pressure valve, a first liquid storage barrel, a constant flow pump, a first manual pump, and a second manual pump;

[0019] The outflow end of the full-diameter core holder is connected to the inflow end of the first back pressure valve through a pipeline, and a second temperature sensor, a second pressure sensor, and a second electronic flow meter are provided in the pipeline;

[0020] The pressure control end of the first back pressure valve is connected to the second manual pump through a pipeline, and a seventh manual valve and a second pressure gauge are provided on the pipeline;

[0021] The outflow end of the first back-pressure valve is connected to the outflow end of the second back-pressure valve and the inflow end of the parallel plate crack simulation device through a three-way pipeline, and a fourth manual valve, a third pressure sensor, a third electronic flow meter, and a third temperature sensor are provided on the pipeline between the outflow end of the first back-pressure valve and the inflow end of the parallel plate crack simulation device;

[0022] The pressure control end of the second back pressure valve is connected to the outflow end of the first manual pump via a pipeline, and a sixth manual valve and a first pressure gauge are provided on the pipeline;

[0023] The inflow end of the second back pressure valve is connected to the outflow end of the constant flow pump through a pipeline, a fifth manual valve is provided on the pipeline, and the inflow end of the constant flow pump is connected to the first liquid storage tank through a pipeline.

[0024] Preferably, a plurality of holes are opened on the wall of the parallel plate crack simulation device, a first observation window is installed in each hole, and a camera and a lighting device are installed outside each first observation window.

[0025] A further improvement of the present invention is that the outflow end of the parallel plate fracture simulation device is connected to the inflow end of the vertical stainless steel wellbore through a bottom hole pressure simulation component;

[0026] The bottom hole pressure simulation component includes: a third back pressure valve, a third manual pump;

[0027] The outflow end of the parallel-plate fracture simulation device is connected with the inflow end of the third back pressure valve through a pipeline, and a fourth temperature sensor, a fourth pressure sensor and a fourth electronic flowmeter are arranged on the pipeline;

[0028] The pressure control end of the third back pressure valve is connected with the third hand pump through a pipeline, and a ninth hand valve and a third pressure gauge are arranged on the pipeline;

[0029] The outflow end of the third back pressure valve is connected with the inlet end of the vertical stainless steel wellbore through a pipeline, and an eighth hand valve, a fifth pressure sensor, a fifth electronic flowmeter and a sixth temperature sensor are arranged on the pipeline.

[0030] The method is further improved in that a plurality of second observation windows are arranged on the vertical stainless steel wellbore and distributed along the axial direction of the vertical stainless steel wellbore.

[0031] A camera and a lighting device are installed outside each second observation window.

[0032] The method is further improved in that a wellbore pressure simulation assembly is connected with the outflow end of the vertical stainless steel wellbore.

[0033] The wellbore pressure simulation assembly comprises a fourth back pressure valve, a fourth hand pump and a second liquid storage barrel.

[0034] The outflow end of the vertical stainless steel wellbore is connected with the fourth back pressure valve through a pipeline, and a fifth temperature sensor, a sixth pressure sensor and a sixth electronic flowmeter are arranged on the pipeline.

[0035] The outflow end of the fourth back pressure valve is connected with the second liquid storage barrel through a pipeline, and a tenth hand valve is arranged on the pipeline.

[0036] The pressure control end of the fourth back pressure valve is connected with the fourth hand pump through a pipeline, and an eleventh hand valve and a fourth pressure gauge are arranged on the pipeline.

[0037] The method is further improved in that the full-diameter core holder and the intermediate container are placed in a heating oven.

[0038] The parallel-plate fracture simulation device and the first liquid storage barrel are wrapped in a large heating jacket.

[0039] The vertical stainless steel wellbore is wrapped in a large heating jacket.

[0040] In the second aspect, the application provides a method for simulating the flow characteristics of salt rock by using the physical simulation device for simulating the flow characteristics of salt rock.

[0041] A further improvement of the present invention is that the method comprises:

[0042] (1) Core preparation

[0043] (2) Calibration of pressure gauge and flow meter

[0044] (3) Setting the pressure and temperature of the flow link: Heat the full-diameter core holder and the parallel plate fracture simulator to the formation temperature, and set the pressure of the first back pressure valve, the second back pressure valve, the third back pressure valve, and the fourth back pressure valve;

[0045] (4) Simulating the flow process of salt rock:

[0046] Pour the injection fluid into the first storage tank and heat it to the formation temperature;

[0047] allowing the injected fluid to flow through the core and into the parallel plate fracture simulation device, while simultaneously utilizing a constant flow pump to increase the fluid flow rate within the parallel plate fracture flow simulation device;

[0048] Turn on all the corresponding lighting and camera devices outside the first observation window and the second observation window, and start recording the salt rock flow process;

[0049] The fluid flowing out of the outflow end of the vertical stainless steel wellbore is collected in a second liquid storage barrel;

[0050] (5) Cleaning and collecting salt rock crystals:

[0051] After the experiment is completed, the parallel plate fracture flow simulation device and the crystallized salt rock in the vertical stainless steel wellbore are cleaned with hot water, and the liquid cleaned with hot water is dry-distilled together with the fluid flowing out of the outflow end of the vertical stainless steel wellbore to obtain the quality of the salt rock.

[0052] A further improvement of the present invention is that the method further comprises:

[0053] (6) Critical flow rate test

[0054] Replace a parallel core;

[0055] First, adjust the flow rate of the constant flow pump to the set speed, then gradually reduce the flow rate of the constant flow pump, and repeat step (4) until salt rock crystallization is observed. The flow rate of the constant flow pump at this time is the critical flow rate for salt rock crystallization.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] 1. This invention uses a full-diameter core holder, enabling higher fluid velocity in shale with extremely low permeability, facilitating flow experiments. Because full-diameter cores are much larger than smaller cores, the salt content in full-diameter cores (10 cm diameter) is significantly higher than in smaller cores (typically 2.54 cm diameter), making crystallization processes easier to observe.

[0058] 2. The parallel plates in conventional parallel plate fracture simulators are glass or transparent plastic plates, lacking viewing windows and being very large. Their pressure resistance is generally lower than 0.5 MPa or virtually nonexistent, and they are even less able to withstand temperatures exceeding 100°C. The present invention, however, improves the pressure and temperature resistance of the parallel plate fracture simulator and vertical wellbore simulator by providing an observation window, making the experimental conditions closer to actual formation and wellbore conditions.

[0059] 3. The present invention utilizes a back pressure valve device and an independent heating device to achieve independent control of the pressure and temperature of each flow link, making the experimental conditions of each flow link closer to the actual production conditions;

[0060] 4. The combination of camera and observation window realizes real-time recording of flow images, which is conducive to the observation and recording of the salt rock crystallization process;

[0061] 5. The temperature of the vertical wellbore simulation device, as well as the pressure at the inflow and outflow ends are controllable, which can simulate the temperature and pressure at different depths of the real wellbore, thereby simulating the crystallization of salt rock at different depths of the real wellbore.

[0062] In summary, the present invention can simulate the crystallization of salt rock in fractures and wellbores in a near-real-life situation, and can study the effects of temperature, pressure, and flow rate on the crystallization process of salt rock in fractures and wellbores. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 A schematic structural diagram of a physical simulation device for simulating the flow characteristics of rock salt according to the present invention. DETAILED DESCRIPTION

[0064] The present invention is further described in detail below with reference to the accompanying drawings:

[0065] like Figure 1 As shown, the physical simulation device for simulating the flow characteristics of salt rock provided by the present invention comprises: a full-diameter shale core displacement simulation device, a parallel plate fracture flow simulation device, and a vertical stainless steel wellbore, connected in sequence. Both the parallel plate fracture flow simulation device and the vertical stainless steel wellbore have observation windows, each equipped with a camera mounted outside the observation window, which can record the salt rock crystallization process in real time.

[0066] The full-diameter shale core displacement simulation device, the parallel plate crack simulation device and the vertical stainless steel wellbore can all use existing mature products, the physical simulation of the salt rock flow characteristics is realized by connecting the three through various components, and the sealing and pressure resistance of the connection between the three meet the requirements. The heating systems of the three can adopt oil bath or electromagnetic heating mode.

[0067] Specifically, the full-diameter shale core displacement simulation device uses a full-diameter core (a columnar core that is not cut and split and is used for analyzing and measuring parameters in a laboratory), and the salt rock strip is located in the radial direction of the cross section of the cylindrical core (the salt rock layer is horizontal in the formation, and the full-diameter core is generally vertical or has a certain angle of inclination, so that the salt rock layer is in the radial direction of the core cross section). The salt rock flows out of the full-diameter shale core displacement simulation device, flows into the parallel plate crack flow simulation device, and then flows out of the parallel plate crack flow simulation device and flows into the vertical stainless steel wellbore.

[0068] Preferably, the parallel plate crack flow simulation device is designed according to actual needs, for example, its width is designed to be 1:1 (i.e. the same as the width of the actual hydraulic fracture, generally 0.001-0.1 meters), the length to height ratio of the crack is 4 times (i.e. the length of the crack is 4 times the height), and the actual length to height ratio is also designed to be 1:1, i.e. 2 meters long and 0.5 meters high.

[0069] The parallel plate crack flow simulation device is made of stainless steel material, in order to observe the salt rock crystallization process in the parallel plate, 5-6 first observation windows are opened on the parallel plate crack flow simulation device along the length direction, and the diameter is generally 0.06 meters. Illumination devices and cameras are arranged outside the first observation windows. The outlet end of the parallel plate crack flow simulation device is connected with the vertical stainless steel wellbore.

[0070] The size of the vertical stainless steel wellbore is designed according to actual needs, and the diameter is generally 0.1-0.15 meters and the height is 0.5 meters. The traditional vertical stainless steel wellbore does not have observation windows, and in order to observe the salt rock crystallization process in the vertical wellbore, 3-4 second observation windows are opened on the wall of the vertical stainless steel wellbore along the axial direction, and the diameter is generally 0.06 meters. Monitoring cameras and illumination devices are additionally arranged outside each observation window on the parallel plate crack flow simulation device and the vertical stainless steel wellbore, for real-time recording of the salt rock crystallization process.

[0071] The connecting pipelines between the above-mentioned devices are made of stainless steel to ensure corrosion resistance. Pressure sensors, flow sensors, and temperature sensors are installed at each of the above-mentioned flow links, including the inflow and outflow of the full-diameter shale core displacement simulator, the inflow and outflow of the parallel plate fracture flow simulator, and the inflow and outflow of the vertical stainless steel wellbore. Each of these devices can independently control the loading temperature, generally designed for oil bath heating or electromagnetic heating up to 180°C.

[0072] The inflow and outflow ends of the parallel plate fracture flow simulation device, as well as the inflow and outflow ends of the vertical stainless steel wellbore, are respectively installed with back pressure valves to enable the two devices to independently control the internal flow pressure.

[0073] A one-way pumping assembly consisting of a back pressure valve and a constant flow pump is installed between the full-diameter shale core displacement simulation device and the parallel plate fracture flow simulation device to control the flow of formation fluid in the simulated fracture and simulated wellbore.

[0074] [Example 1]

[0075] like Figure 1As shown, the device of the present invention includes: a first injection pump 1, a second injection pump 2, a first manual valve 3, a second manual valve 4, a third manual valve 6, a fourth manual valve 16, a fifth manual valve 23, a sixth manual valve 24, a seventh manual valve 25, an eighth manual valve 38, a ninth manual valve 39, a tenth manual valve 44, and an eleventh manual valve 46, for controlling the flow of the pipeline; a first pressure sensor 7, a second pressure sensor 12, a third pressure sensor 17, a fourth pressure sensor 33, a fifth pressure sensor 36, and a sixth pressure sensor 49, for measuring the pressure of the fluid in the pipeline; a first electronic flowmeter 8, a second electronic flowmeter 13, a third electronic flowmeter 18, a fourth electronic flowmeter 34, a fifth electronic flowmeter 37, and a sixth electronic flowmeter 48, for measuring the flow rate of the fluid in the pipeline; a first temperature sensor 9, a second temperature sensor 11, a third temperature sensor 26, a fourth temperature sensor 32, a fifth temperature sensor 51, and a sixth temperature sensor 54, for measuring the temperature of the fluid in the pipeline; The full-diameter core holder 10 is used for fluid displacement; the first back-pressure valve 14, the second back-pressure valve 15, the third back-pressure valve 35, and the fourth back-pressure valve 47 are used to control the fluid pressure in each flow link; the camera 19 is used to observe and record the salt rock crystallization process in real time; the first observation window 20 and the second observation window 53 are used to observe the salt rock crystallization process; the parallel plate fracture flow simulation device 21 is used to simulate the flow of fluid in the fracture and the crystallization process of salt rock in the fracture; the first liquid storage tank 22 is used to store The apparatus is used to store and provide the fluid flowing in the pipeline; the first pressure gauge 27, the second pressure gauge 28, the third pressure gauge 40, and the fourth pressure gauge 45 are used to measure the back-pressure valve control pressure; the constant flow pump 29 is used to pump the fluid in the pipeline at a constant flow rate; the first manual pump 30, the second manual pump 31, the third manual pump 41, and the fourth manual pump 43 are used to apply the back-pressure valve control pressure; the second liquid storage barrel 42 is used to collect waste liquid; the vertical stainless steel wellbore 50 is used to simulate the flow of fluid in the wellbore and the crystallization process of salt rock in the wellbore.

[0076] Specifically, the full-diameter shale core displacement simulation device includes a full-diameter core holder 10 and a core pressure simulation component. The core pressure simulation component includes a first injection pump 1 connected to the confining pressure interface of the full-diameter core holder 10; a second injection pump 2; and an intermediate container 5. The second injection pump 2, the intermediate container 5, and the inlet of the full-diameter core holder 10 are sequentially connected. The first and second injection pumps 1 and 2 are used to provide confining pressure and flow pore pressure to the full-diameter core holder 10. The intermediate container 5 can be an existing piston-type intermediate container for displacing fluid.

[0077] The full-diameter core holder's pressure range is 0.1-70 MPa to simulate the flow characteristics of shale reservoirs under formation conditions. Due to the presence of the observation window, the maximum pressure resistance of the parallel plate fracture flow simulator and the vertical stainless steel wellbore is much lower than that of the full-diameter core holder 10. Therefore, the full-diameter core holder 10 only needs to have a pressure range of 0.1-10 MPa to simulate the fluid flow conditions in real fractures and wellbores.

[0078] The specific connection structure is as follows: the inflow end of the full-diameter core clamp 10 is connected to the outflow end of the intermediate container 5 through a pipeline, and a first temperature sensor 9, a first electronic flow meter 8, a first pressure sensor 7, and a third manual valve 6 are arranged in sequence on the pipeline from the full-diameter core clamp 10 to the intermediate container 5.

[0079] The inflow end of the intermediate container 5 is connected to the outflow end of the second injection pump 2 via a pipeline, and a second manual valve 4 is provided on the pipeline.

[0080] The confining pressure interface of the full-diameter core holder 10 is connected to the outflow end of the first injection pump 1 through a pipeline, and a first manual valve 3 is provided on the pipeline.

[0081] The outflow end of the full-diameter core holder 10 is connected to the inflow end of the parallel plate fracture flow simulation device 21 via a one-way pumping component. The one-way pumping component includes: a first back-pressure valve 14, a second back-pressure valve 15, a first liquid storage tank 22, a constant flow pump 29, a first manual pump 30, and a second manual pump 31.

[0082] Specifically, the outflow end of the full-diameter core holder 10 is connected to the inflow end of the first back pressure valve 14 through a pipeline, and a second temperature sensor 11, a second pressure sensor 12, and a second electronic flow meter 13 are sequentially arranged on the pipeline from the full-diameter core holder 10 to the first back pressure valve 14.

[0083] The pressure control end of the first back pressure valve 14 is connected to the second manual pump 31 through a pipeline. A seventh manual valve 25 and a second pressure gauge 28 are sequentially provided on the pipeline from the first back pressure valve 14 to the second manual pump 31 .

[0084] The outflow end of the first back pressure valve 14 is connected to the outflow end of the second back pressure valve 15 and the inflow end of the parallel plate crack simulation device 21 through a three-way pipeline. On the pipeline between the outflow end of the first back pressure valve 14 and the inflow end of the parallel plate crack simulation device 21, a fourth manual valve 16, a third pressure sensor 17, a third electronic flow meter 18, and a third temperature sensor 26 are sequentially arranged from the first back pressure valve 14 to the parallel plate crack simulation device 21.

[0085] The pressure control end of the second back pressure valve 15 is connected to the outflow end of the first manual pump 30 through a pipeline. A sixth manual valve 24 and a first pressure gauge 27 are sequentially provided on the pipeline from the second back pressure valve 15 to the first manual pump 30 .

[0086] The inflow end of the second back pressure valve 15 is connected to the outflow end of the constant flow pump 29 through a pipeline. A fifth manual valve 23 is provided on the pipeline. The inflow end of the constant flow pump 29 is connected to the first liquid storage tank 22 through a pipeline.

[0087] A plurality of first observation windows 20 are provided on the parallel plate crack simulation device 21, and a camera 19 is installed outside each first observation window 20, that is, a hole is opened on the wall of the parallel plate crack simulation device 21, an observation window is installed in the hole, and a camera is installed outside each window.

[0088] The outflow end of the parallel plate fracture simulation device 21 is connected to the inflow end of the vertical stainless steel wellbore 50 via a bottomhole pressure simulation assembly. Specifically, the bottomhole pressure simulation assembly includes a third back-pressure valve 35 and a third manual pump 41. Specifically, the outflow end of the parallel plate fracture simulation device 21 is connected to the inflow end of the third back-pressure valve 35 via a pipeline. A fourth temperature sensor 32, a fourth pressure sensor 33, and a fourth electronic flowmeter 34 are sequentially arranged on the pipeline from the parallel plate fracture simulation device 21 toward the third back-pressure valve 35.

[0089] The pressure control end of the third back-pressure valve 35 is connected to the third manual pump 41 through a pipeline. A ninth manual valve 39 and a third pressure gauge 40 are sequentially provided on the pipeline from the third back-pressure valve 35 to the third manual pump 42 .

[0090] The outflow end of the third back-pressure valve 35 is connected to the inlet end of the vertical stainless steel wellbore 50 through a pipeline. On the pipeline, an eighth manual valve 38, a fifth pressure sensor 36, a fifth electronic flowmeter 37, and a sixth temperature sensor 54 are sequentially arranged in the direction from the third back-pressure valve 35 to the vertical stainless steel wellbore 50.

[0091] A plurality of second observation windows 53 distributed along the axial direction of the vertical stainless steel shaft 50 are provided, and a camera 52 is installed outside each second observation window 53 .

[0092] Furthermore, a wellbore pressure simulation assembly is connected to the outflow end of the vertical stainless steel wellbore 50. The wellbore pressure simulation assembly includes a fourth back-pressure valve 47, a fourth manual pump 43, and a second liquid storage tank 42. Specifically, the outflow end of the vertical stainless steel wellbore 50 is connected to the fourth back-pressure valve 47 via a pipeline. A fifth temperature sensor 51, a sixth pressure sensor 49, and a sixth electronic flowmeter 48 are sequentially arranged on the pipeline from the vertical stainless steel wellbore 50 toward the fourth back-pressure valve 47.

[0093] The outflow end of the fourth back pressure valve 47 is connected with the second liquid storage barrel 42 through a pipeline, and the tenth manual valve 44 is arranged on the pipeline.

[0094] The pressure control end of the fourth back pressure valve 47 is connected with the fourth manual pump 43 through a pipeline, and the eleventh manual valve 46 and the fourth pressure gauge 45 are arranged in sequence on the pipeline from the fourth back pressure valve 47 to the fourth manual pump 43.

[0095] Figure 1 The three dashed areas in the inner part are heating areas. Among them, the full-diameter core holder 10 and the intermediate container 5 can be heated by using the same oven, the parallel plate fracture simulation device 21 can be heated by using a large heating sleeve, and the vertical stainless steel shaft 50 can be heated by using a large heating sleeve. Specifically, the full-diameter core holder 10 and the intermediate container 5 are placed in the heating oven, the parallel plate fracture simulation device 21 and the first liquid storage barrel 22 are wrapped in a large heating sleeve, and the vertical stainless steel shaft 50 is wrapped in a large heating sleeve to achieve heating.

[0096] The experimental device can independently control the fluid pressure and temperature of the full-diameter core holder, the parallel plate fracture simulation device and the vertical stainless steel shaft, and simulate the salt rock crystallization process under the flow conditions of the real formation, the fracture and the shaft. Through the present application, the rheological and peristaltic properties of salt rock in the processes of energy supplementing modes such as depletion production, water drive, carbon dioxide drive and alternating water and carbon dioxide displacement can be simulated by experimental methods, and the method for controlling the rheological and peristaltic properties of salt rock in the above processes can be studied.

[0097]

Example Two

[0098] Taking the simulation of the salt rock crystallization process in the depletion production process as an example, the experimental method using the above device includes the following steps:

[0099] (1) Core preparation

[0100] The full-diameter core of the target layer of the pilot well is used, and the core with a length of 10 cm is selected from the layer with obvious salt rock development. Then, the core is saturated with oil sample (i.e. the core is soaked in the oil sample for pressure saturation, which is not described here in the prior art). The core is placed in the full-diameter core holder, and the overburden pressure and the pore pressure are applied to achieve the original formation overburden pressure and the pore pressure. The confining pressure is realized by the confining pressure interface on the holder, and the pore pressure is realized by the combination of the first displacement pump 1, the second displacement pump 2 and the intermediate container 5, i.e. the displacement pressure is set.

[0101] (2) Calibration of pressure gauge and flow meter

[0102] At the beginning of the test injection, observe Figure 1 Check the readings and sensitivity of the pressure gauges and flow meters connected to the inlet and outflow ends of all devices, and calibrate the flow meters according to the volume of the outflow end. If there is a problem (for example, the readings of the pressure gauges or flow meters at the inlet and outflow ends of each component are too different), replace them in time.

[0103] (3) Pressure and temperature setting of flow link

[0104] The temperature field and bottomhole pressure can be simulated in detail using currently mature fracturing design software such as FracProPT, Stimplan, and Gofher. The full-diameter core holder is heated to the formation temperature, the first back-pressure valve 14 is set to simulate the bottomhole pressure corresponding to the actual maximum wellhead pressure used, and the second back-pressure valve 15 is set to be slightly higher than the first back-pressure valve 14 by 0.1 MPa to ensure that the constant flow pump 29 can pump fluid into the inlet of the parallel plate fracture simulation device 21 in a unidirectional manner. Specifically, after the liquid is pumped out of the first liquid storage barrel 22 by the constant flow pump 29, it passes through the fifth manual valve 23 along the pipeline and enters the inlet of the second back-pressure valve 15. From the outlet of the second back-pressure valve 15, it enters the three-way pipeline and flows through the fourth manual valve 16 together with the outflow liquid from the outlet of the first back-pressure valve 14 before entering the parallel plate fracture simulation device.

[0105] The parallel plate fracture simulator is heated to formation temperature. The third back-pressure valve 35 is set to bottomhole pressure to ensure that the fluid pressure in the parallel plate fracture simulator is at bottomhole pressure. The fourth back-pressure valve 47 is set to the wellbore pressure. This pressure range can be determined using simulation software based on the desired wellbore depth.

[0106] (4) Simulating the flow process of salt rock

[0107] An injection fluid (e.g., injection oil) is poured into the first liquid storage tank 22 and heated for a period of time to reach the formation temperature. The fourth manual valve 16 is opened, allowing the injection fluid to flow through the core and into the parallel plate fracture simulation device. (Specifically, the injection oil is pumped by the combination of the intermediate container 5 and the injection pump 2, passes through the pressure sensor 7, enters the inlet end of the full-diameter core holder 10, flows through the core, and then flows out of the outflow end of the full-diameter core holder 10. After flowing through the first back-pressure valve 14 and the second back-pressure valve 15, it flows into the inlet end of the parallel plate fracture simulation device.) Because the fluid flow rate within the fracture is actually much greater than the flow rate provided by the full-diameter core, the present invention utilizes a constant flow pump 29 to increase the fluid flow rate within the parallel plate fracture flow simulation device (i.e., a portion of the injection fluid flows from the core holder, while another portion of the injection fluid flows from the constant flow pump 29 into the parallel plate fracture flow simulation device). This flow rate can be determined using simulation software based on the actual wellhead flow rate of production. (The flow rate of the constant flow pump is determined according to Darcy's law, which can be determined specifically through reservoir numerical simulation, a well-established method that will not be elaborated on here.) All the first observation windows and the corresponding lighting and camera devices outside the second observation windows are turned on to start recording the salt rock flow process. The fluid flowing out of the outflow end of the vertical stainless steel wellbore 50 is collected in the second liquid storage barrel 42.

[0108] (5) Cleaning and collecting salt rock crystals

[0109] After the designed injection volume is achieved (meaning the wellhead flow rate determined by the software simulation or the total injection volume set by the experimental design), the experiment is terminated. The crystallized salt rock in the parallel plate fracture flow simulator and the vertical stainless steel wellbore is cleaned with hot water and retorted together with the fluid from the previous outflow to determine the mass of the salt rock. If there is no salt rock content, it indicates that there is no salt rock flow.

[0110] (6) Critical flow rate test

[0111] Furthermore, the device of the present invention can also be used to measure the critical flow rate. The reduction in the wellhead liquid production will cause the liquid flow rate in the wellbore to decrease accordingly. The reduction in the liquid flow rate can lead to the crystallization of salt rock. This test can simulate the critical flow rate for the crystallization of salt rock. Replace a parallel sample core (from the same batch of cores in the same reservoir). First, adjust the constant flow pump 29 to a higher speed (set according to actual needs), then gradually reduce the set fluid flow rate of the constant flow pump 29, and repeat step (4) until salt rock crystallization is observed. The flow rate of the constant flow pump 29 at this time is the critical flow rate for salt rock crystallization.

[0112] [Example 3]

[0113] For the method of simulating the rheological and creep characteristics of rock salt during energy replenishment methods such as water flooding, carbon dioxide flooding, and alternating water and carbon dioxide flooding, the injected fluid can be replaced with the water or carbon dioxide to be tested and the above steps (1) to (6) can be carried out.

[0114] Finally, it should be noted that the above technical solution is only one embodiment of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the application methods and principles disclosed in the present invention, and it is not limited to the method described in the above specific embodiment of the present invention. Therefore, the method described above is only preferred and does not have a restrictive meaning.

Claims

1. A physical simulation device for simulating the flow characteristics of salt rock, characterized by: The physical simulation device for simulating the flow characteristics of salt rock comprises: a full-diameter shale core displacement simulation device, a parallel plate fracture flow simulation device and a vertical stainless steel wellbore connected in sequence; Observation windows are provided on the parallel plate fracture flow simulation device and the vertical stainless steel wellbore; Cameras are installed outside each observation window; The full-diameter shale core displacement simulation device includes: a full-diameter core holder and a core pressure simulation component; The outflow end of the full-diameter core holder is connected to the inflow end of the parallel plate fracture flow simulation device through a one-way pumping component; the one-way pumping component includes: a first back pressure valve, a second back pressure valve, a first liquid storage tank, a constant flow pump, a first manual pump, and a second manual pump; The outflow end of the full-diameter core holder is connected to the inflow end of the first back pressure valve through a pipeline, and a second temperature sensor, a second pressure sensor, and a second electronic flow meter are provided in the pipeline; The pressure control end of the first back pressure valve is connected to the second manual pump through a pipeline, and a seventh manual valve and a second pressure gauge are provided on the pipeline; The outflow end of the first back-pressure valve is connected to the outflow end of the second back-pressure valve and the inflow end of the parallel plate crack simulation device through a three-way pipeline, and a fourth manual valve, a third pressure sensor, a third electronic flow meter, and a third temperature sensor are provided on the pipeline between the outflow end of the first back-pressure valve and the inflow end of the parallel plate crack simulation device; The pressure control end of the second back pressure valve is connected to the outflow end of the first manual pump via a pipeline, and a sixth manual valve and a first pressure gauge are provided on the pipeline; The inflow end of the second back-pressure valve is connected to the outflow end of the constant flow pump through a pipeline, a fifth manual valve is provided on the pipeline, and the inflow end of the constant flow pump is connected to the first liquid storage tank through a pipeline; The outflow end of the parallel plate fracture simulation device is connected to the inflow end of the vertical stainless steel wellbore through a bottom hole pressure simulation component.

2. The physical simulation device for simulating the flow characteristics of salt rock according to claim 1, characterized in that: The core pressure simulation component includes: a first injection pump, a second injection pump, and an intermediate container; The confining pressure interface of the full-diameter core holder is connected to the outflow end of the first injection pump through a pipeline, and a first manual valve is provided on the pipeline; The inflow end of the full-diameter core holder is connected to the outflow end of the intermediate container through a pipeline, and a first temperature sensor, a first electronic flow meter, a first pressure sensor, and a third manual valve are arranged on the pipeline; The inflow end of the intermediate container is connected to the outflow end of the second injection pump through a pipeline, and a second manual valve is arranged on the pipeline.

3. The physical simulation device for simulating the flow characteristics of salt rock according to claim 1, characterized in that: The full-diameter core holder has a pressure resistance range of 0.1-10 MPa.

4. The physical simulation device for simulating the flow characteristics of salt rock according to claim 1, characterized in that: A plurality of holes are opened on the wall of the parallel plate crack simulation device, a first observation window is installed in each hole, and a camera and a lighting device are respectively installed outside each first observation window.

5. The physical simulation device for simulating the flow characteristics of salt rock according to claim 1, characterized in that: The bottom hole pressure simulation component includes: a third back pressure valve, a third manual pump; The outflow end of the parallel plate crack simulation device is connected to the inflow end of the third back pressure valve through a pipeline, and a fourth temperature sensor, a fourth pressure sensor, and a fourth electronic flow meter are arranged on the pipeline; The pressure control end of the third back pressure valve is connected to the third manual pump through a pipeline, and a ninth manual valve and a third pressure gauge are provided on the pipeline; The outflow end of the third back pressure valve is connected to the inlet end of the vertical stainless steel wellbore through a pipeline, and an eighth manual valve, a fifth pressure sensor, a fifth electronic flow meter, and a sixth temperature sensor are arranged on the pipeline.

6. The physical simulation device for simulating the flow characteristics of salt rock according to claim 1, characterized in that: The vertical stainless steel shaft is provided with a plurality of second observation windows distributed along its axial direction; A camera and a lighting device are installed outside each second observation window.

7. The physical simulation device for simulating the flow characteristics of salt rock according to claim 1, characterized in that: A wellbore pressure simulation component is connected to the outflow end of the vertical stainless steel wellbore; The wellbore pressure simulation component includes: a fourth back pressure valve, a fourth manual pump and a second liquid storage barrel; The outflow end of the vertical stainless steel wellbore is connected to the fourth back pressure valve through a pipeline, and a fifth temperature sensor, a sixth pressure sensor, and a sixth electronic flow meter are arranged on the pipeline; The outflow end of the fourth back-pressure valve is connected to the second liquid storage tank through a pipeline, and a tenth manual valve is provided on the pipeline; The pressure control end of the fourth back-pressure valve is connected to the fourth manual pump through a pipeline, and an eleventh manual valve and a fourth pressure gauge are arranged on the pipeline.

8. The physical simulation device for simulating the flow characteristics of salt rock according to claim 2, characterized in that: The full-diameter core holder and the intermediate container are placed in a heating oven; The parallel plate crack simulation device and the first liquid storage barrel are wrapped in a large heating jacket; The vertical stainless steel shaft is encased in a large heating jacket.

9. A method for using the physical simulation device for simulating the flow characteristics of salt rock according to any one of claims 1 to 8, characterized in that: The method uses the physical simulation device for simulating the flow characteristics of salt rock as described in any one of claims 1 to 8 to simulate the rheological and creeping characteristics of salt rock during depletion mining, water flooding, carbon dioxide flooding, and alternating water and carbon dioxide flooding.

10. The method according to claim 9, characterized in that: The method comprises: (1) Core preparation (2) Calibration of pressure gauge and flow meter (3) Setting the pressure and temperature of the flow link: Heat the full-diameter core holder and the parallel plate fracture simulator to the formation temperature, and set the pressure of the first back pressure valve, the second back pressure valve, the third back pressure valve, and the fourth back pressure valve; (4) Simulating the flow process of salt rock: Pour the injection fluid into the first storage tank and heat it to the formation temperature; allowing the injected fluid to flow through the core and into the parallel plate fracture simulation device, while simultaneously utilizing a constant flow pump to increase the fluid flow rate within the parallel plate fracture flow simulation device; Turn on all the corresponding lighting and camera devices outside the first observation window and the second observation window, and start recording the salt rock flow process; The fluid flowing out of the outflow end of the vertical stainless steel wellbore is collected in a second liquid storage barrel; (5) Cleaning and collecting salt rock crystals: After the experiment is completed, the parallel plate fracture flow simulation device and the crystallized salt rock in the vertical stainless steel wellbore are cleaned with hot water, and the liquid cleaned with hot water is dry-distilled together with the fluid flowing out of the outflow end of the vertical stainless steel wellbore to obtain the quality of the salt rock.

11. The method according to claim 10, characterized in that: The method further comprises: (6) Critical flow rate test Replace a parallel core; First, adjust the flow rate of the constant flow pump to the set speed, then gradually reduce the flow rate of the constant flow pump, and repeat step (4) until salt rock crystallization is observed. The flow rate of the constant flow pump at this time is the critical flow rate for salt rock crystallization.

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