Dynamic imbibition device and method for simulating temperature and pressure conditions of tight oil reservoir in whole process

Abstract

The invention relates to the technical field of tight sandstone reservoir development, in particular to a dynamic imbibition device and method for simulating the temperature and pressure conditions of a tight reservoir in the whole course, and the dynamic imbibition device comprises a rock core clamping cylinder, a sealing cover plate, a sealing ring and a to-be-tested matrix rock core. The prefabricated crack partition plate is positioned between the two matrix rock cores to be detected. The method comprises the following steps: S1, preparation work; s2, saturating crude oil in the matrix rock core; and S3, fracture water injection dynamic imbibition. According to the invention, heat preservation and pressure maintaining are carried out on the dynamic imbibition experiment of the tight sandstone reservoir in the whole process, and crack opening in the heat preservation and pressure maintaining process is realized, so that the imbibition mode of the tight sandstone reservoir is really simulated, the real stratum condition is highly restored, and the simulation experiment research of dynamic imbibition is greatly promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of tight sandstone reservoir development, and specifically to a dynamic imbibition device and method for fully simulating the temperature and pressure conditions of a tight oil reservoir. Background Art

[0002] In foreign literature, "tight oil" is not an exact term, and different researchers and research institutions have different definitions. However, it is generally emphasized that tight oil is an unconventional petroleum resource with light oil quality, and the production layer is siltstone, sandstone or carbonate rock with extremely low permeability. The tight reservoir is closely related to the organic-rich hydrocarbon source rock, and special production methods such as horizontal wells and volume fracturing are adopted. The definition of tight oil in China usually refers to the oil stored in tight sandstone, tight carbonate rock and other reservoirs with a matrix permeability under overburden pressure less than or equal to 0.1×10 -3 μm 2 (air permeability less than 1×10 -3 μm 2 ). Generally, a single well has no natural production capacity or the natural production capacity is lower than the lower limit of industrial oil flow, but industrial oil production can be obtained under certain economic conditions and technical measures. Usually, these measures include acid fracturing, multi-stage fracturing, horizontal wells, multi-branch wells, etc.

[0003] China is rich in tight oil reservoir resources. In recent years, important progress has been made in the development of tight oil reservoirs in the Upper Triassic Yanchang Formation of the Ordos Basin, the Qingshankou Formation of the Songliao Basin, the Shahejie Formation of the Qikou Sag in the Bohai Bay Basin, the Permian Fengcheng Formation and Lucaogou Formation in the Mahu and Jimusar sags of the Junggar Basin, the Xiagou Group in the Qiudong Sag of the Turpan-Hami Basin, and the Lower Youshashan Formation in the Fengxi area of the Qaidam Basin. The favorable area of tight oil has been initially determined to be about 16×10 4 km 2 ², and the geological reserves are about 200×10 8 t. In order to develop tight oil reservoirs efficiently and economically, China has made a large number of technical explorations. Such as the optimization of well patterns and well types, the field test of natural energy production, the early water injection in low-pressure reservoirs, the pilot test of energy supplementation in horizontal wells, polymer profile control, "tertiary oil recovery", etc. Although certain progress has been made, due to many congenital factors such as the complex pore structure of tight reservoirs, diverse and large-range variable seepage channels, and strong heterogeneity, a series of problems such as "difficult to inject, difficult to produce", easy water flooding, easy gas channeling, and poor economic effect of chemical agents are often encountered during the development process. Based on the above series of problems, the "pressure - injection - soaking - production" technology based on making full use of the capillary force (imbibition) effect is proposed in order to increase the cumulative oil production per well in the whole life cycle.

[0004] Imbibition phenomenon widely exists in many fields such as reservoir engineering, soil physics, water resources engineering, etc. In the early 20th century, the problems of imbibition statics and dynamics have attracted extensive attention from researchers. In petroleum engineering, the early research on imbibition oil displacement phenomenon mainly focused on fractured reservoirs. Due to the high conductivity of fractures in such reservoirs, the effect of water injection development is not ideal. By appropriately reducing the flow velocity of injected water in fractures, the capillary force imbibition oil displacement in the reservoir matrix is fully utilized, and good development results have been achieved. With the development of oil and gas from conventional to unconventional, more and more scholars have turned their attention to the study of imbibition displacement in tight reservoirs. The characteristics of small pore throat radius, large capillary force and hydrophilic wettability in the matrix of tight reservoirs provide good innate advantages for imbibition displacement. As a necessary means for the development of tight oil reservoirs, fracturing changes the seepage channels and seepage laws in the fracture-controlled area, and artificial fractures become the dominant seepage channels in tight reservoirs. Conducting dynamic imbibition research on "fracture-pore" based on full-size cores is of great significance and practical value for the efficient development of tight oil reservoirs.

[0005] At present, most of the domestic research on imbibition focuses on static imbibition. Some scholars have completed relevant research on dynamic imbibition based on the modification or combination of mature experimental equipment. For example, the patent authorization announcement number CN109459556B discloses a dynamic imbibition device and an experimental method for dynamic imbibition experiments. The dynamic imbibition device includes: a base and a housing, and a pressurizing port for applying pressure to the inside of the housing is provided on the housing; a stirring module, arranged inside the housing, for stirring the experimental liquid in the housing to make the experimental liquid in the housing in a dynamic flow state; a fixing device, arranged inside the housing, for fixing the experimental sample; an imbibition bottle, arranged inside the housing, the imbibition bottle includes a cover body and a metering tube, the cover body is used to cover the experimental sample, and the oil droplets in the experimental sample float up to the metering tube under the action of capillary force and gravity differentiation; and a processing module, for controlling the stirring speed of the stirring module. This invention patent can shield the effect of displacement and only study the dynamic imbibition phenomenon. However, in fact, the device and method have the following problems: 1. In this experimental method, the core with a diameter of 2.5 cm to 4.0 cm is completely placed in the imbibition liquid, and it is defaulted that the end face and side face of the core are in full contact with the imbibition liquid (simulating that the matrix is in full contact with the fracture or the matrix is completely surrounded by the fracture). However, through actual field discovery, this condition assumption is too ideal and there is a large deviation from the actual situation (according to the actual coring of the artificial fracture detection well). At the same time, previous studies have shown that the size and mode of the contact area will directly affect the imbibition recovery rate, and the experimental data obtained by this method will be generally optimistic; 2. This device realizes the flow of the imbibition liquid around the core through a stirrer, making the core in a flowing dynamic environment. From actual field and laboratory experiments, it can be known that the so-called dynamic imbibition usually refers to the macroscopic reflection of the coupling effect of the seepage of the imbibition liquid in the fracture and the imbibition under the fracture-pore pressure difference and capillary force. One of the purposes of carrying out dynamic imbibition physical model experiments and research is to obtain the optimal water flooding front velocity and the corresponding pressure gradient under simulated reservoir conditions, and then convert them into the actual injection pressure or drainage rate in the field. However, this experimental device cannot achieve the above goals.

[0006] In addition, the following defects generally exist in other currently commonly used dynamic imbibition experimental devices: 1. The vacuum saturation oil method cannot completely ensure that all pores are saturated with crude oil in the experiment of tight sandstone reservoirs; 2. After the matrix core is saturated with oil, artificial fractures are created, and there are influencing factors such as stress release, which cause certain changes in the pore structure, and then lead to errors in the experimental data; 3. The standard experimental core sample size adopted by the current mainstream laboratories is relatively small (diameter 2.5 cm, maximum length 12 cm). When long core physical model experiments are required, multiple cores need to be spliced and used. Tight reservoirs have strong heterogeneity, and the selection of the physical properties and combination methods of the cores by this method has great randomness. There are certain errors compared with the experimental results obtained by using full-size cores. Summary of the Invention

[0007] In view of the above problems, the present invention provides a dynamic imbibition device and method for fully simulating the temperature and pressure conditions of a tight oil reservoir throughout the process.

[0008] The technical solution of the present invention is as follows: A dynamic imbibition device for fully simulating the temperature and pressure conditions of a tight oil reservoir includes a cylindrical core-holding cylinder with openings at both ends, a sealing cover plate located at the front end of the core-holding cylinder, an annular sealing ring located at the rear end of the core-holding cylinder, two semi-cylindrical core samples to be tested symmetrically arranged inside the core-holding cylinder, and a prefabricated fracture partition located between the two core samples to be tested; A sealing block is fixedly connected to the rear ends of the two core samples to be tested respectively in a butt joint manner, a sealing plate is fixedly connected to the rear end of the prefabricated fracture partition in a butt joint manner. The diameter of the rear end of the sealing block is 1.2 to 1.5 times that of the front end. The size of the rear end of the sealing plate matches the size of the rear end of the sealing block 4. The rear ends of the sealing block and the sealing plate are butt-jointed and spliced into a circle. A matrix core liquid guide pipe is provided at the end of each of the two sealing blocks. The front ends of the two matrix core liquid guide pipes penetrate through the sealing blocks and are respectively communicated with the rear ends of the two core samples to be tested. A plurality of fracture liquid guide pipes are provided at the end of the sealing plate. The front ends of the fracture liquid guide pipes penetrate through the sealing plate and are communicated with the prefabricated fracture partition; Two first liquid injection pipes are provided on both sides of the sealing cover plate. A plurality of second liquid injection pipes are provided at the center of the sealing cover plate corresponding to the prefabricated fracture partition. The two first liquid injection pipes respectively correspond to the two core samples to be tested. A rubber sleeve is provided between the outer surface of the core sample to be tested and the inner wall of the core-holding cylinder. The rubber sleeve also wraps the front ends of the sealing block and the sealing plate. A confining pressure pressurizing pipe is provided at the top of the core-holding cylinder, and a confining pressure pressure relief pipe is provided on one side of the core-holding cylinder; Grooves are symmetrically provided on both sides in the middle of the prefabricated fracture partition. The inside of the grooves is an artificial quartz sandstone plate with a guiding ability. A pull plate is slidably connected to each of the two corresponding grooves. After the rear end of the pull plate penetrates through the guide groove provided inside the sealing plate, it extends out of the inner diameter of the sealing ring, and the front end of the pull plate is flush with the front end of the prefabricated fracture partition.

[0009] Further, the sealing cover plate and the sealing ring are detachably connected in a threaded seal with the internal threads provided at both ends of the outer surface of the core-holding cylinder. After the sealing cover plate is tightened, the first liquid injection pipe and the second liquid injection pipe are just located at the designated positions. The rear end of the sealing cover plate extends into the core-holding cylinder and is wrapped by the rubber sleeve.

[0010] Furthermore, a plurality of limit blocks are provided at equal intervals on the side wall of the sealing block, and the limit blocks are engaged with a plurality of limit slots provided at the rear end of the core clamping cylinder in a one-to-one correspondence. The diameter of the rear end of the sealing block is 1.2 times the diameter of the matrix core to be tested.

[0011] Note: The limiting card block and the limiting card slot are connected to ensure a tight fit between the sealing block and the matrix core to be tested.

[0012] Furthermore, three fracture liquid guide tubes are provided on each side of the pumping plate, and three second liquid injection tubes are provided. The two first liquid injection tubes are arranged with one high and one low on the left and right sides, and the two matrix core liquid guide tubes are arranged with one high and one low on the left and right sides. Moreover, the first liquid injection tubes and the matrix core liquid guide tubes on the same matrix core to be tested are arranged with one high and one low on the front and back sides.

[0013] Note: By adjusting the fluid inlet and outlet positions at different heights, the inside of the matrix core to be tested is ensured to be completely saturated with simulated formation water and simulated formation oil, thereby simulating the reservoir conditions more realistically.

[0014] Furthermore, a positioning groove is provided on the inner side wall of each of the two sealing blocks, and a spring positioning plate is provided inside the positioning groove. One side of the spring positioning plate abuts against the side wall of the sealing plate to assist in positioning the sealing plate.

[0015] Furthermore, the two pumping plates are driven to slide by an external servo motor push rod, and the output shaft of the servo motor push rod is fixedly connected to the end of the pumping plate.

[0016] The present invention also provides a dynamic imbibition method for fully simulating the temperature and pressure conditions of a tight oil reservoir, which is implemented based on any one of the above-mentioned dynamic imbibition devices for fully simulating the temperature and pressure conditions of a tight oil reservoir, and comprises the following steps: S1. Preparation: Process the full-diameter core sampled from the core to the specified size according to the experimental requirements, place it in the core oil washer to wash the oil, take it out and dry it in a 100℃ environment for 48 hours. Measure the porosity and permeability of the matrix core using a full-diameter core porosity-permeability tester. Use a high-speed wire cutting machine to cut the cylindrical core into two semi-cylindrical matrix cores, place the two semi-cylindrical matrix cores on the left and right sides of the core clamping cylinder, and then place the etched prefabricated fracture partition. Then place the sealing block and sealing plate to position the matrix core to be tested and the prefabricated fracture partition. Place the two pumping plates in the groove through the guide groove, install the servo motor push rod at the rear end of the pumping plate, and then install the sealing cover plate and sealing ring in sequence. Then seal the entire device internally, and squeeze the rubber sleeve through the confining pressure pipe to make the external confining pressure of the matrix core to be tested reach the confining pressure set by the experiment. The confining pressure range of this device is: 10~40MPa. Open the constant temperature box and adjust it to the simulated reservoir temperature. S2. Saturate the matrix core with crude oil: Slowly inject simulated formation water through two first liquid injection pipes to completely saturate two semi-cylindrical matrix cores with simulated formation water. Subsequently, slowly inject simulated formation oil to completely saturate the two matrix cores to be tested with simulated formation oil. Collect the discharged simulated formation water and simulated formation oil through two matrix core liquid guiding pipes respectively. When the liquid output reaches 3 - 5 PV, it is considered that the core is completely saturated. S3. Dynamic imbibition during fracture water injection: Turn on the servo motor push rod to pull the two extraction plates backward by a certain distance and ensure that the front end of the extraction plate is located in the guide groove. The extraction speed is 0.5 - 2 cm / 5 s, and the simulated fractures on the prefabricated fracture partition board are opened. Subsequently, inject tap water through the second liquid injection pipe at a speed of 5 - 100 ml / min to simulate the dynamic imbibition process, and collect the discharged simulated formation water and simulated formation oil through the fracture liquid guiding pipe.

[0017] Furthermore, in S1, the materials of the upper and lower parts of the prefabricated fracture partition board are cemented carbide, so that the artificial quartz sandstone board inside the groove of the prefabricated fracture partition board forms a prefabricated simulated fracture with connected pores. The width of the prefabricated fracture partition board at the position where the artificial quartz sandstone board is located is 0.5 - 2 cm, and the width of the prefabricated fracture partition board at other positions is 1 - 3 cm.

[0018] Note: By making the artificial quartz sandstone board inside the groove of the prefabricated fracture partition board form a prefabricated simulated fracture with connected pores, and the permeability is adjustable.

[0019] Furthermore, in S2, the salinity of the simulated formation water is 5000 - 50000 mg / L, and the viscosity of the simulated formation oil is 1 - 5 mPa / s.

[0020] The beneficial effects of the present invention are as follows: (1) The dynamic imbibition device and method for fully simulating the temperature and pressure conditions of a tight oil reservoir in the present invention truly simulate the imbibition mode of a tight sandstone oil reservoir by maintaining the temperature and pressure during the dynamic imbibition experiment of the tight sandstone oil reservoir throughout the process and realizing the opening of fractures during the temperature and pressure maintenance process, highly restoring the real formation conditions, and playing an important role in promoting the simulation experimental research of dynamic imbibition.

[0021] (2) The dynamic imbibition device for fully simulating the temperature and pressure conditions of a tight oil reservoir in the present invention is provided with a prefabricated fracture partition board and an extraction plate that cooperate with each other. At the same time, the provided sealing block and sealing plate can realize the extraction of the extraction plate under the condition of complete sealing, temperature and pressure maintenance, so as to complete the formation of a simulated fracture between two matrix cores to be tested, making up for the problem that the artificial fractures in the current dynamic imbibition indoor experimental devices generally cause stress damage to the core and thus generate errors. The accuracy of the experimental data is greatly improved, which has certain guiding significance for the subsequent research on dynamic imbibition.

[0022] (3) The present invention provides a complete set of experimental methods based on the device of the present invention, which fully simulates the dynamic imbibition method of temperature and pressure conditions of tight oil reservoirs. It clearly defines key parameters such as "fracture-pore" conductivity, fluid characteristics, and water injection rate. This is an unprecedented attempt in previous studies and provides new ideas for indoor and field research on dynamic imbibition of tight oil reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of a dynamic imbibition device for fully simulating temperature and pressure conditions of a tight oil reservoir according to the present invention.

[0024] Figure 2 It is a schematic diagram of the front-end structure of a dynamic imbibition device for fully simulating temperature and pressure conditions of a tight oil reservoir according to the present invention.

[0025] Figure 3 This is a schematic diagram of the internal structure of the core support cylinder after the sealing cover plate and sealing ring are omitted, which is a dynamic imbibition device for fully simulating the temperature and pressure conditions of a tight oil reservoir according to the present invention.

[0026] Figure 4 This is a schematic diagram of the front end structure of the core support cylinder after the sealing cover plate and sealing ring are omitted, which is a dynamic imbibition device for fully simulating the temperature and pressure conditions of a tight oil reservoir according to the present invention.

[0027] Figure 5 This is a right side view of a dynamic imbibition device for fully simulating temperature and pressure conditions of a tight oil reservoir according to the present invention.

[0028] Figure 6 The present invention is a schematic diagram of a spring positioning plate structure of a dynamic imbibition device for fully simulating temperature and pressure conditions of a tight oil reservoir.

[0029] Figure 7 This is a schematic diagram of the internal structure of a dynamic imbibition device that fully simulates the temperature and pressure conditions of a tight oil reservoir, omitting the core support cylinder.

[0030] Figure 8 This is a top view of a dynamic imbibition device for fully simulating temperature and pressure conditions of a tight oil reservoir according to the present invention, after being connected to an external servo motor.

[0031] Figure 9 It is a left side view of a dynamic imbibition device for fully simulating temperature and pressure conditions of a tight oil reservoir according to the present invention.

[0032] Figure 10 This is an internal cross-sectional view of a dynamic imbibition device of the present invention that fully simulates the temperature and pressure conditions of a tight oil reservoir.

[0033] Figure 11 It is a side view of a sealing cover plate of a dynamic imbibition device for fully simulating temperature and pressure conditions of a tight oil reservoir according to the present invention.

[0034] Figure 12 It is a schematic diagram of the overall structure when a dynamic imbibition device for fully simulating the temperature and pressure conditions of a tight oil reservoir in the present invention is applied to the method of the present invention.

[0035] Among them, 1 is a core clamping cylinder body, 11 is a sealing cover plate, 12 is a sealing ring, 131 is a first liquid injection pipe, 132 is a second liquid injection pipe, 14 is a rubber sleeve, 15 is a confining pressure pressurizing pipe, 16 is a confining pressure pressure relief pipe, 17 is a limit card slot, 2 is a matrix core to be measured, 3 is a prefabricated fracture partition plate, 31 is a groove, 4 is a sealing block, 41 is a matrix core liquid guiding pipe, 42 is a limit card block, 43 is a positioning groove, 44 is a spring positioning plate, 5 is a sealing plate, 51 is a fracture liquid guiding pipe, 52 is a guiding groove, 6 is a draw plate, and 7 is a servo motor push rod. Specific embodiments

[0036] Example 1 As Figure 1 、 Figure 7 and Figure 11 shown, a dynamic imbibition device for fully simulating the temperature and pressure conditions of a tight oil reservoir includes a cylindrical core clamping cylinder body 1 with openings at both ends, a sealing cover plate 11 at the front end of the core clamping cylinder body 1, an annular sealing ring 12 at the rear end of the core clamping cylinder body 1. The sealing cover plate 11 and the sealing ring 12 are detachably connected in a threaded seal with the internal threads provided at both ends of the outer surface of the core clamping cylinder body 1. Two semi-cylindrical matrix cores 2 to be measured are symmetrically arranged inside the core clamping cylinder body 1, and a prefabricated fracture partition plate 3 is arranged between the two matrix cores 2 to be measured; As Figures 2 to 7 shown, a sealing block 4 is fixedly butt-connected to the rear ends of the two matrix cores 2 to be measured respectively, and a sealing plate 5 is fixedly butt-connected to the rear end of the prefabricated fracture partition plate 3. The surface area of the rear end of the sealing block 4 is increased. Six limit card blocks 42 are equidistantly arranged on the side wall of the sealing block 4, and the six limit card blocks 42 are respectively clamped with the six limit card slots 17 provided at the rear end of the core clamping cylinder body 1. The surface area of the rear end of the sealing plate 5 is increased. The area of the rear end of the sealing block 4 is 1.2 times the area of the matrix core 2 to be measured. The rear ends of the sealing block 4 and the sealing plate 5 are butt-connected and spliced into a circle. A matrix core liquid guiding pipe 41 is respectively provided at the ends of the two sealing blocks 4. The front ends of the two matrix core liquid guiding pipes 41 penetrate through the sealing block 4 and are respectively communicated with the rear ends of the two matrix cores 2 to be measured. Six fracture liquid guiding pipes 51 are provided at the end of the sealing plate 5, with three fracture liquid guiding pipes 51 on each side of the draw plate 6. The front ends of the fracture liquid guiding pipes 51 penetrate through the sealing plate 5 and are communicated with the prefabricated fracture partition plate 3. A positioning groove 43 is provided on the inner side wall of each of the two sealing blocks 4, and a spring positioning plate 44 is arranged inside the positioning groove 43. One side of the spring positioning plate 44 abuts against the side wall of the sealing plate 5 for auxiliary positioning of the sealing plate 5; As Figures 2 to 7As shown, two first injection pipes 131 are provided on both sides of the sealing cover plate 11, and three second injection pipes 132 are provided in the center of the sealing cover plate 11 corresponding to the prefabricated fracture partition 3. The two first injection pipes 131 correspond to the two matrix cores 2 to be tested. After the sealing cover plate 11 is tightened, the first injection pipe 131 and the second injection pipe 132 are just located at the designated positions. The rear end of the sealing cover plate 11 extends to the inside of the core clamping cylinder 1 and is wrapped by the rubber sleeve 14. The two first injection pipes 131 are divided into left and right. High-low setting: the two matrix core liquid guide tubes 41 are divided into a left and right high and low setting, and the first liquid injection tube 131 and the matrix core liquid guide tube 41 on the same matrix core 2 to be tested are divided into a front and back high and low setting. A rubber sleeve 14 is provided between the outside of the matrix core 2 to be tested and the inner wall of the core clamping cylinder 1. The rubber sleeve 14 also wraps the front end of the sealing block 4 and the sealing plate 5. A confining pressure pressurization pipe 15 is provided on the top of the core clamping cylinder 1, and a confining pressure relief pipe 16 is provided on one side of the core clamping cylinder 1. like Figure 7 and Figure 10 As shown, grooves 31 are symmetrically provided on both sides of the middle of the prefabricated crack partition 3. The interior of the groove 31 is an artificial quartz sandstone plate with flow conduction capability. A pull-out plate 6 is provided for sliding connection at each of the two grooves 31. The rear end of the pull-out plate 6 passes through the guide groove 52 provided inside the sealing plate 5 and extends out of the inner diameter of the sealing ring 12. The front end of the pull-out plate 6 is flush with the front end of the prefabricated crack partition 3. like Figure 8 As shown, the two pumping plates 6 are driven to slide by an external servo motor push rod 7 , and the output shaft of the servo motor push rod 7 is fixedly connected to the end of the pumping plate 6 .

[0037] Example 2 This embodiment differs from embodiment 1 in that: Four second liquid injection pipes 132 are provided at the center of the sealing cover plate 11 corresponding to the prefabricated crack partition plate 3, and eight crack liquid guide pipes 51 are provided at the end of the sealing plate 5. Four crack liquid guide pipes 51 are provided on each side of the pumping plate 6.

[0038] Example 3 This embodiment differs from embodiment 1 in that: Five second liquid injection pipes 132 are provided at the center of the sealing cover plate 11 corresponding to the prefabricated crack partition plate 3, and ten crack liquid guide pipes 51 are provided at the end of the sealing plate 5. Five crack liquid guide pipes 51 are provided on each side of the pumping plate 6.

[0039] Example 4 This embodiment provides a dynamic imbibition method for fully simulating temperature and pressure conditions of a tight oil reservoir, based on a dynamic imbibition device for fully simulating temperature and pressure conditions of a tight oil reservoir in Example 1. Figure 12 As shown, the following steps are included: S1. Preparation: Process the full-diameter core with complete sampling to the specified size according to the experimental requirements, place it in a core oil-washing instrument to wash the oil, and after taking it out, dry it in an environment of 100 °C for 48 hours. Measure the porosity and permeability of the matrix core through a full-diameter core pore-permeability measuring instrument. Use a high-speed wire cutting machine to cut the cylindrical core into two semi-cylindrical matrix cores 2. Place the two semi-cylindrical matrix cores 2 to be measured on the left and right sides inside the core clamping cylinder 1 respectively, and then place the pre-etched prefabricated fracture separator 3. The upper and lower parts of the prefabricated fracture separator 3 are made of cemented carbide, so that the artificial quartz sandstone plate in the groove 31 of the prefabricated fracture separator 3 forms a prefabricated simulated fracture with connected pores. The width of the prefabricated fracture separator 3 at the position where the artificial quartz sandstone plate is located is 1 cm, and the width of the prefabricated fracture separator 3 at other positions is 2 cm. Then place the sealing block 4 and the sealing plate 5 to position the matrix core 2 to be measured and the prefabricated fracture separator 3. Place the two extraction plates 6 in the groove 31 through the guide groove 52, install the servo motor push rod 7 at the rear end of the extraction plate 6, and then install the sealing cover plate 11 and the sealing ring 12 in sequence. Then the inside of the whole device is sealed, and water is injected through the confining pressure pressurizing pipe 15 to squeeze the rubber sleeve 14 so that the external confining pressure of the matrix core 2 to be measured reaches 15 MPa; S2. Saturating the matrix core with crude oil: Slowly inject simulated formation water through the two first liquid injection pipes 131. The salinity of the simulated formation water is 20,000 mg / L, and the viscosity of the simulated formation oil is 5 mPa / s, so that the two matrix cores 2 to be measured are completely saturated with the simulated formation water. Then slowly inject the simulated formation oil so that the two matrix cores 2 to be measured are completely saturated with the simulated formation oil. Collect the discharged simulated formation water and simulated formation oil through the two matrix core liquid guide pipes 41 respectively. When the liquid production volume reaches 3 - 5 PV, it is considered that the core is completely saturated; S3. Fracture water injection dynamic imbibition: Start the servo motor push rod 7 to pull the two extraction plates 6 backward by a certain distance and ensure that the front end of the extraction plate 6 is located in the guide groove 52. The extraction speed is 1 cm / 5 s, and the simulated fracture on the prefabricated fracture separator 3 is opened. Then inject tap water through the second liquid injection pipe 132 at a water injection speed of 60 ml / min to simulate the dynamic imbibition process, and collect the discharged simulated formation water and simulated formation oil through the fracture liquid guide pipe 51.

[0040] Example 5 The difference between this example and Example 4 is that: The width of the prefabricated fracture separator 3 at the position where the artificial quartz sandstone plate is located is 0.5 cm, and the width of the prefabricated fracture separator 3 at other positions is 1 cm. Water is injected through the confining pressure pressurizing pipe 15 to squeeze the rubber sleeve 14 so that the external confining pressure of the matrix core 2 to be measured reaches 10 MPa.

[0041] Example 6 The difference between this example and Example 4 is that: The width of the prefabricated fracture partition plate 3 at the location of the artificial quartz sandstone plate is 2 cm, and the width of the prefabricated fracture partition plate 3 at other locations is 3 cm. Water is injected through the confining pressure pipe 15 to squeeze the rubber sleeve 14 so that the external confining pressure of the matrix core 2 to be measured reaches 40 MPa.

[0042] Example 7 The difference between this example and Example 4 is that: The salinity of the simulated formation water is 5000 mg / L, and the viscosity of the simulated formation oil is 2 mPa / s.

[0043] Example 8 The difference between this example and Example 4 is that: The salinity of the simulated formation water is 50000 mg / L, and the viscosity of the simulated formation oil is 1 mPa / s.

[0044] Example 9 The difference between this example and Example 4 is that: S3. Dynamic imbibition of fracture water injection: Turn on the servo motor push rod 7 to pull the two extraction plates 6 backward by a certain distance and ensure that the front end of the extraction plate 6 is located in the guide groove 52. The extraction speed is 0.5 cm / 5 s, and the simulated fractures on the prefabricated fracture partition plate 3 are opened. Then, tap water is injected through the second liquid injection pipe 132 at a speed of 5 ml / min to simulate the dynamic imbibition process, and the discharged simulated formation water and simulated formation oil are collected through the fracture liquid guide pipe 51.

[0045] Example 10 The difference between this example and Example 4 is that: S3. Dynamic imbibition of fracture water injection: Turn on the servo motor push rod 7 to pull the two extraction plates 6 backward by a certain distance and ensure that the front end of the extraction plate 6 is located in the guide groove 52. The extraction speed is 2 cm / 5 s, and the simulated fractures on the prefabricated fracture partition plate 3 are opened. Then, tap water is injected through the second liquid injection pipe 132 at a speed of 100 ml / min to simulate the dynamic imbibition process, and the discharged simulated formation water and simulated formation oil are collected through the fracture liquid guide pipe 51.

Claims

1. A dynamic imbibition device that fully simulates the temperature and pressure conditions of a tight oil reservoir, characterized in that, It includes a cylindrical core clamping cylinder body (1) with both ends open, a sealing cover plate (11) located at the front end of the core clamping cylinder body (1), an annular sealing ring (12) located at the rear end of the core clamping cylinder body (1), two semi-cylindrical matrix cores to be measured (2) symmetrically arranged inside the core clamping cylinder body (1), and a prefabricated fracture partition plate (3) located between the two matrix cores to be measured (2); At the rear ends of the two matrix cores to be measured (2), a sealing block (4) is fixedly butted respectively. At the rear end of the prefabricated fracture partition plate (3), a sealing plate (5) is fixedly butted. The diameter of the rear end of the sealing block (4) is 1.2 to 1.5 times that of the front end. The size of the rear end of the sealing plate (5) matches the size of the rear end of the sealing block 4. The rear ends of the sealing block (4) and the sealing plate (5) are butted against each other and spliced into a circle. At the ends of the two sealing blocks (4), a matrix core liquid guide pipe (41) is provided respectively. The front ends of the two matrix core liquid guide pipes (41) penetrate through the sealing block (4) and are respectively communicated with the rear ends of the two matrix cores to be measured (2). At the end of the sealing plate (5), a plurality of fracture liquid guide pipes (51) are provided. The front ends of the fracture liquid guide pipes (51) penetrate through the sealing plate (5) and are communicated with the prefabricated fracture partition plate (3); On both sides of the sealing cover plate (11), two first liquid injection pipes (131) are provided. At the center of the sealing cover plate (11) corresponding to the prefabricated fracture partition plate (3), a plurality of second liquid injection pipes (132) are provided. The two first liquid injection pipes (131) respectively correspond to the two matrix cores to be measured (2). A rubber sleeve (14) is provided between the outer part of the matrix core to be measured (2) and the inner wall of the core clamping cylinder body (1). The rubber sleeve (14) simultaneously wraps the front ends of the sealing block (4) and the sealing plate (5). A confining pressure pressurizing pipe (15) is provided at the top of the core clamping cylinder body (1). A confining pressure pressure relief pipe (16) is provided on one side of the core clamping cylinder body (1); On both sides of the middle part of the prefabricated fracture partition plate (3), grooves (31) are symmetrically provided. The inside of the grooves (31) is an artificial quartz sandstone plate with a guiding ability. Corresponding to the two grooves (31), a draw plate (6) is slidably connected to each. After the rear end of the draw plate (6) penetrates through a guide groove (52) provided inside the sealing plate (5), it extends out of the inner diameter of the sealing ring (12). The front end of the draw plate (6) is flush with the front end of the prefabricated fracture partition plate (3).

2. The dynamic imbibition device for fully simulating the temperature and pressure conditions of a tight oil reservoir according to claim 1, wherein The sealing cover plate (11) and the sealing ring (12) are thread-sealed and detachably connected to the inner threads provided at both ends of the outer surface of the core clamping cylinder body (1). After the sealing cover plate (11) is tightened, the first liquid injection pipe (131) and the second liquid injection pipe (132) are just located at the designated positions. The rear end of the sealing cover plate (11) extends into the core clamping cylinder body (1) and is wrapped by the rubber sleeve (14).

3. The dynamic imbibition device for fully simulating the temperature and pressure conditions of a tight oil reservoir according to claim 1, wherein On the side wall of the sealing block (4), a number of limiting blocks (42) are equidistantly arranged. The limiting blocks (42) are respectively and correspondingly clamped with a number of limiting slots (17) provided at the rear end of the core clamping cylinder (1). The diameter of the rear end of the sealing block (4) is 1.2 times the diameter of the to-be-tested matrix core (2).

4. The dynamic imbibition device for fully simulating the temperature and pressure conditions of a tight oil reservoir according to claim 1, wherein, On each side of the extraction plate (6), three crack liquid guiding pipes (51) are provided. There are three second liquid injection pipes (132). The two first liquid injection pipes (131) are arranged in a left-right and high-low manner. The two matrix core liquid guiding pipes (41) are arranged in a left-right and high-low manner. And on the same to-be-tested matrix core (2), the first liquid injection pipe (131) and the matrix core liquid guiding pipe (41) are arranged in a front-back and high-low manner.

5. The dynamic imbibition device for fully simulating the temperature and pressure conditions of a tight oil reservoir according to claim 1, wherein On the inner side walls of the two sealing blocks (4), a positioning groove (43) is respectively provided. Inside the positioning groove (43), a spring positioning plate (44) is provided. One side of the spring positioning plate (44) abuts against the side wall of the sealing plate (5) for assisting in positioning the sealing plate (5).

6. The dynamic imbibition device for fully simulating the temperature and pressure conditions of a tight oil reservoir according to claim 1, wherein The two extraction plates (6) are driven to slide by an external servo motor push rod (7). The output shaft of the servo motor push rod (7) is fixedly connected to the end of the extraction plate (6).

7. A dynamic imbibition method for fully simulating the temperature and pressure conditions of a tight oil reservoir, based on the dynamic imbibition device for fully simulating the temperature and pressure conditions of a tight oil reservoir according to any one of claims 1 to 6, characterized in that, Including the following steps: S1. Preparation work: Process the full-diameter core with complete sampling to the specified size according to the experimental requirements, put it into a core oil washing instrument for oil washing, and take it out and dry it in an environment of 100 °C for 48 hours. Measure the porosity and permeability of the matrix core through a full-diameter core pore-permeability measuring instrument. Use a high-speed wire cutting machine to cut the cylindrical core into two semi-cylindrical matrix cores (2), put the two semi-cylindrical matrix cores (2) into the left and right sides inside the core clamping cylinder (1) respectively, then put in the pre-etched prefabricated fracture partition plate (3), and then put in the sealing block (4) and the sealing plate (5) to position the to-be-tested matrix core (2) and the prefabricated fracture partition plate (3). Place the two extraction plates (6) in the groove (31) through the guide groove (52), install the servo motor push rod (7) at the rear end of the extraction plate (6), then install the sealing cover plate (11) and the sealing ring (12) in sequence. Then the inside of the whole device is sealed. Inject water through the confining pressure pipe (15) to squeeze the rubber sleeve (14) so that the external confining pressure of the to-be-tested matrix core (2) reaches the confining pressure set in the experiment. Open the constant temperature box and adjust it to the simulated reservoir temperature; S2. Saturating the matrix core with crude oil: Slowly inject simulated formation water through the two first liquid injection pipes (131) to completely saturate the two semi-cylindrical matrix cores (2) with simulated formation water, and then slowly inject simulated formation oil to completely saturate the two to-be-tested matrix cores (2) with simulated formation oil. Collect the discharged simulated formation water and simulated formation oil through the two matrix core liquid guiding pipes (41) respectively; S3. Dynamic imbibition of fractured water injection: Turn on the servo motor push rod (7) to pull the two extraction plates (6) backward by a certain distance and ensure that the front ends of the extraction plates (6) are located in the guide grooves (52). The extraction speed is 0.5 - 2 cm / 5 s. The simulated fractures on the prefabricated fracture partition plate (3) are opened. Subsequently, tap water is injected through the second liquid injection pipe (132) at a speed of 5 - 100 ml / min to simulate the dynamic imbibition process. The discharged simulated formation water and simulated formation oil are collected through the fracture liquid guide pipe (51).

8. A dynamic imbibition method for fully simulating the temperature and pressure conditions of a tight oil reservoir according to claim 7, characterized in that, In the above S1, the materials of the upper and lower parts of the prefabricated fracture partition plate (3) are cemented carbide, so that the artificial quartz sandstone plate inside the groove (31) of the prefabricated fracture partition plate (3) forms a prefabricated simulated fracture with connected pores. The width of the prefabricated fracture partition plate (3) at the position where the artificial quartz sandstone plate is located is 0.5 - 2 cm, and the width of the prefabricated fracture partition plate (3) at other positions is 1 - 3 cm.

9. A dynamic imbibition method for fully simulating the temperature and pressure conditions of a tight oil reservoir according to claim 7, characterized in that In the above S2, the salinity of the simulated formation water is 5000 - 50000 mg / L, and the viscosity of the simulated formation oil is 1 - 5 mPa / s.

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