Oil reservoir oil displacement simulation experiment device and experiment method based on stratum complex structure

Abstract

The invention discloses an oil reservoir oil displacement simulation experiment device and method based on a stratum complex structure, and belongs to the technical field of oil reservoir development, the device comprises a stratum simulation box body, a compaction module is arranged at the top of the stratum simulation box body, a movable sand filling module is arranged between the stratum simulation box body and the compaction module, and a detachable simulation oil displacement shaft is arranged in the box body. The method comprises the following steps: preparing simulated stratum sand grains; selecting a producing well and surrounding water injection well positions and installing a shaft; sand grains are filled layer by layer through the sand filling module, and the retention time is adjusted according to the stratum thickness; selecting a sand layer as a simulated oil layer, injecting simulated oil, standing, continuously filling sand, and drilling and sealing at the corresponding height of the shaft; the sand filling module is removed, a compaction plate is installed, a corresponding check block of a shaft is taken down, and heating is conducted while hydraulic compaction is conducted; a producing well shaft is opened for sealed oil production, and the recovery ratio is calculated; opening a shaft of the water injection well to seal and inject water to displace remaining oil, and performing secondary extraction and analyzing the water flooding effect. The technical problem of seepage rule simulation distortion of an existing oil reservoir oil displacement simulation experiment device is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of oil reservoir development, and in particular relates to an oil reservoir oil displacement simulation experimental device based on a complex stratum structure, and also relates to an oil reservoir oil displacement simulation experimental method based on a complex stratum structure. Background Art

[0002] Reservoir development refers to the whole process of effectively extracting underground oil and gas resources to the surface through scientific planning and technical means, involving the comprehensive application of multiple disciplines such as geology, engineering, and economics. Its core goal is to maximize oil and gas recovery and achieve economic benefits. Reservoir geological exploration and reserve assessment are important factors in determining the benefits of reservoir exploitation. At present, the indoor simulation experimental device for reservoir geological research cannot accurately evaluate the reservoir exploitation status, especially the real-life simulation of reservoirs in the late stage of water flooding, which needs to be improved.

[0003] The following factors should be considered for water-driven oil production: 1. Water can be injected. Only after water is injected into the target formation can oil recovery be discussed. First of all, from the perspective of water source, it is best to adapt to the oil reservoir, and cause less damage to the oil reservoir after injection, or damage the surface layer, which is conducive to the recovery of the damaged formation. The mechanical impurities and iron content of the reinjection water are required to be low, and the injected water and formation fluid have good compatibility and will not cause damage to the formation; 2. For low-permeability reservoirs, the most troublesome thing is that after a period of water injection, there is insufficient injection or failure to inject water, which requires effective unblocking measures; 3. The heterogeneity of the oil strata in low-permeability oil fields is relatively serious, and it is very likely to be pointed out during water injection development. Therefore, it is necessary to take measures to block water or adjust the water absorption profile; 4. Water injection speed. The faster the speed, the more serious the non-uniform advancement of water drive. It is necessary to formulate a suitable water injection speed according to the specific conditions of the reservoir; 5. For low-permeability reservoirs, the effective period of water drive is relatively long. Therefore, it is recommended to improve the water injection well network, correspond to the relationship between oil and water wells, and increase the density of water injection wells and oil wells; 6. For simple water injection, after the water injection development enters the medium and high water content stage, there will be a sudden advance phenomenon inside the oil layer. It is recommended to adjust the drive to improve the oil recovery efficiency in the layer. It can be seen that the problems that need to be paid attention to in the process of water drive oil production are relatively complex. The indoor simulation experiment method can avoid or reflect the possible problems to a certain extent.

[0004] The Chinese invention patent with the patent publication number CN118148590A relates to a physical simulation experiment device and method for a water - drive oil reservoir. The physical simulation experiment device for a water - drive oil reservoir includes an injection system, a water - drive oil simulation system, a data acquisition system, and a discharge system. The production outlet of the rock sample is used to simulate a production well; the rock sample is filled with crude oil to saturation to simulate an oil reservoir; the cutting - section seam is used to simulate a channeling fracture; a pressure sensor is used to collect the pressure change of the crude oil in the cutting - section seam of the rock sample; and a resistivity probe is used to collect the change in formation water saturation during the process of driving the oil body in the cutting - section seam of the formation water rock sample. The physical simulation experiment method for a water - drive oil reservoir includes: inputting crude oil into the cutting - section seam to simulate the process of the crude oil reaching the saturated state in the formation and inputting formation water to simulate the process of water - drive oil, so as to realize the simulation of the process of the crude oil reaching the saturated state in the formation and the process of the water - drive oil reservoir under the development mode of channeling fractures. However, this device still cannot intuitively simulate the overall dynamic process before and after water - drive oil production. Summary of the Invention

[0005] The first object of the present invention is to provide an oil reservoir displacement simulation experiment device based on the complex structure of the formation, which solves the technical problems that the existing oil reservoir displacement simulation experiment device is difficult to achieve differential control of the thickness of sand body small layers and truly reproduce the formation undulation and heterogeneity, resulting in distorted simulation of seepage laws.

[0006] The second object of the present invention is to provide an oil reservoir displacement simulation experiment method based on the complex structure of the formation.

[0007] The first technical solution adopted by the present invention is that an oil reservoir displacement simulation experiment device based on the complex structure of the formation includes a simulated formation box body. A compaction module is provided at the top of the simulated formation box body, and a movable sand - filling module is provided between the simulated formation box body and the compaction module; a plurality of detachable simulated oil - displacement wellbores are further provided inside the simulated formation box body.

[0008] The characteristics of the first technical solution of the present invention also lie in: The compaction module includes a plurality of hydraulic presses and a compaction plate located at the telescopic ends of the plurality of hydraulic presses. A plurality of openings for accommodating the simulated oil - displacement wellbores are provided inside the compaction plate, and stoppers are detachably provided inside the openings; The sand - filling module includes a relatively rotatable upper cylinder and a lower cylinder. A sand - inlet hose is connected to the top of the upper cylinder. A main sand - discharge channel is provided in the middle of the lower cylinder. A plurality of auxiliary sand - discharge channels are arranged around the main sand - discharge channel inside the lower cylinder. The upper cylinder remains fixed and its movement is controlled by a numerical control machine. The plane on which the sand - filling module moves is a plane parallel to the simulated formation box body, and the movement direction of the sand - filling module is at least two directions: longitudinal and transverse; There are multiple threaded seats provided at the bottom inside the simulated formation box, and threaded grooves are provided on the inner wall of the simulated oil displacement wellbore. The threaded seats and the threaded grooves are detachably connected by threads. The top of the simulated oil displacement wellbore is open, and a threaded sealing rod is threadedly connected inside the cavity of the simulated oil displacement wellbore. A simulated wellbore is provided on the side wall of the simulated oil displacement wellbore.

[0009] The numerical control machine tool is fixedly connected to the outer wall of the upper cylinder through a telescopic rod. A fixed ring is fixedly provided on the outer side wall at the bottom of the upper cylinder, and the inner wall at the bottom of the fixed ring is rotatably connected to the top side wall of the lower cylinder; A driving motor is provided on the outer wall of the fixed ring. A driving gear is provided at the bottom output end of the driving motor. A toothed ring is provided on the middle side wall of the lower cylinder. The driving gear is meshed and rotatably connected to the toothed ring.

[0010] A circle of limiting plates is provided on the top side wall of the lower cylinder, and a circle of limiting rings is provided on the inner wall of the fixed ring; the limiting plates and the limiting rings are slidably and vertically limited and connected.

[0011] The distribution mode of the threaded seats is matrix type, and the number distribution of the threaded seats is 5×5 to 9×9. The number and position of the openings on the compaction plate correspond one by one to the number and position of the threaded seats.

[0012] A clamping groove is provided at the bottom of the opening on the compaction plate. The block is inverted T-shaped. The block and the clamping groove are magnetically clamped and connected. And when the block and the clamping groove are magnetically clamped and connected, the bottom surface of the block is flush with the bottom surface of the compaction plate.

[0013] There are 4 hydraulic presses, which are respectively located at the 4 top corner positions on the top surface of the compaction plate. An electric heater is provided at the bottom of each outer wall surface of the simulated formation box.

[0014] The second technical solution adopted by the present invention is an oil reservoir oil displacement simulation experiment method based on the complex formation structure. Using the above-mentioned oil reservoir oil displacement simulation experiment device based on the complex formation structure, it includes the following steps: S1. Prepare simulated formation sand grains with a particle size < 0.05 mm; S2. Select 1 - 3 simulated production wells and 3 - 6 simulated injection well positions around them, and install simulated wellbores; S3. Fill the sand grains in layers through the numerical control sand filling module, and adjust the residence time at different positions according to the formation thickness parameters to realize the simulation of the small layer thickness structure of the sand body; S4. Select a sand layer as the simulated oil layer, inject simulated oil, let it stand still, and then continue to fill the sand. Drill holes at the corresponding height of the wellbore and seal them; S5. Remove the sand filling module, install the compaction plate, remove the blocks at the corresponding positions of the wellbore, and heat while hydraulically compacting for 24 - 48 h; S6. Open the seal of the production wellbore, produce oil under formation pressure, and calculate the recovery factor; S7. Open the wellbore seal of the water injection well, displace the remaining oil by water injection, and produce it for the second time from the production well and analyze the water flooding effect.

[0015] The features of the second technical solution of the present invention are further in that: S1 - S7 are specifically as follows: S1. Grind the sand grains to a particle size < 0.05 mm as the simulated formation sand grains; S2. Select the positions of 1 - 3 screw seats as the simulated production well well positions, and select the positions of 3 - 6 screw seats around the simulated production well well positions as the simulated water injection well well positions. Install the simulated oil displacement wellbore by screwing connection at the selected simulated production well well positions and simulated water injection well well positions. S3. Formation structure simulation: Add the simulated formation sand grains into the interior of the simulated formation box through the sand filling module, introduce the simulated formation sand grains into the interior of the upper cylinder through the sand inlet hose, and then enter the interior of the lower cylinder. Export the simulated formation sand grains through the main sand outlet channel and the auxiliary sand outlet channel. While exporting, the lower cylinder rotates to achieve uniform sand falling. Control the sand filling module to move longitudinally and transversely successively by the numerical control machine tool to complete the filling of a whole layer of simulated formation sand grains. According to the thickness parameter of the formation, the sand filling module stays for a longer time at the thicker position and for a shorter time at the thinner position, so as to form the thickness structure simulation of this layer of sand body sub - layer. After completing the filling of a sand body sub - layer, reset the sand filling module and fill the next sand body sub - layer in the same way again; S4. Oil layer structure simulation: When the filling of several sand body sub - layers is completed according to the method in S1, one of the sand body sub - layers needs to be used as the simulated oil layer, that is, pour the simulated formation oil onto the surface of this sand body sub - layer. After standing for 15 min - 20 min, the filling of the next sand body sub - layer can be carried out. At the same time, drill holes at the height corresponding to this simulated oil layer on the side wall of the simulated oil displacement wellbore. After completing the drilling to obtain the simulated wellbore, screw in the threaded sealing rod through the thread to seal the simulated oil displacement wellbore. After all the sand body sub - layers are filled, the complete formation structure simulation is formed; S5. Formation structure compaction: Move the sand filling module out of the upper part of the simulated formation box and put in the compaction plate. Remove the blocks at the positions corresponding to the simulated oil displacement wellbore so that the simulated oil displacement wellbore can pass through the openings. Blocks are clamped at other positions. Then, press down the compaction plate from the 4 top - corner positions by the hydraulic press to compact all the sand body sub - layers. At the same time, heat the simulated formation box and keep it for 24 h - 48 h; S6. Simulated oil production: Rotate and screw out the threaded sealing rod in the simulated oil displacement wellbore serving as the simulated production well well position to open the simulated wellbore of the simulated oil displacement wellbore serving as the simulated production well well position to communicate with the simulated oil layer. At this time, under the formation structure pressure, the simulated formation oil inside the simulated oil layer flows into the simulated oil displacement wellbore serving as the simulated production well well position, and calculate the recovery factor; S7. Simulated water injection: After completing S6 simulated oil production, a part of the simulated formation oil in the simulated oil reservoir remains unproduced. Therefore, the threaded sealing rod in the simulated displacement wellbore serving as the simulated water injection well position is unscrewed to open the simulated wellbore of the simulated displacement wellbore serving as the simulated water injection well position to communicate with the simulated oil reservoir, inject water into the interior of the simulated displacement wellbore serving as the simulated water injection well position, displace the remaining simulated formation oil in the simulated oil reservoir, and it is produced again by the simulated displacement wellbore serving as the simulated oil production well position. Calculate the recovery factor and analyze the water flooding effect.

[0016] In S3, the rotational speed of the lower cylinder is 50 rpm to 100 rpm, and in S5, the heating temperature is 80 °C to 90 °C.

[0017] Compared with the prior art, the beneficial effects of the present invention are: The reservoir displacement simulation experimental device based on the complex formation structure of the present invention can completely restore the real reservoir development state by constructing a box that truly simulates the formation undulation height. Through the sand filling module, uniform sand filling can be achieved to create small layers with different thicknesses of high and low undulations, maximizing the restoration of the real formation state. Finally, it can effectively reflect the ultimate impact of the water injection rate, water injection time, and injection well deployment on oilfield development, as well as the water flooding effect, which is of great significance for the current water flooding reservoir development. Description of the Drawings

[0018] Figure 1 is the overall structural schematic diagram of the reservoir displacement simulation experimental device based on the complex formation structure of the present invention; Figure 2 is the structural schematic diagram of the sand filling module of the reservoir displacement simulation experimental device based on the complex formation structure of the present invention; Figure 3 is the internal structural schematic diagram of the sand filling module of the reservoir displacement simulation experimental device based on the complex formation structure of the present invention; Figure 4 is the structural schematic diagram of the bottom of the lower cylinder of the reservoir displacement simulation experimental device based on the complex formation structure of the present invention; Figure 5 is the internal structural schematic diagram of the simulated formation box of the reservoir displacement simulation experimental device based on the complex formation structure of the present invention in the experimental state after completing formation structure compaction; Figure 6 is the cross-sectional view of the compaction plate of the reservoir displacement simulation experimental device based on the complex formation structure of the present invention; Figure 7 is the internal structural schematic diagram of the simulated displacement wellbore of the reservoir displacement simulation experimental device based on the complex formation structure of the present invention; Figure 8 is the internal cross-sectional view of the simulated formation box of the reservoir displacement simulation experimental device based on the complex formation structure of the present invention in the experimental state after completing formation structure compaction; Figure 9 It is the top view of the simulated formation box body after formation structure compaction under the experimental state of the reservoir oil displacement simulation experimental device based on the complex formation structure of the present invention.

[0019] In the figure: 1. Simulated formation box body, 11. Threaded seat, 2. Sand filling module, 21. Upper cylinder, 22. Lower cylinder, 221. Main sand outlet channel, 222. Auxiliary sand outlet channel, 223. Limiting plate, 23. Sand inlet hose, 24. Fixed ring, 241. Limiting ring, 25. Driving motor, 26. Driving gear, 27. Tooth ring, 3. Compaction module, 31. Hydraulic press, 32. Compaction plate, 321. Opening, 322. Card slot, 33. Block, 4. Simulated oil displacement wellbore, 41. Threaded groove, 42. Threaded sealing rod, 43. Simulated wellbore, 5. Numerical control machine tool, 51. Telescopic rod, 6. Electric heater. Specific embodiments

[0020] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0021] Embodiment 1 As Figure 1 and Figure 9 shown, the reservoir oil displacement simulation experimental device based on the complex formation structure disclosed in this embodiment includes a simulated formation box body 1, a compaction module 3 is provided at the top of the simulated formation box body 1, and a movable sand filling module 2 is provided between the simulated formation box body 1 and the compaction module 3; a plurality of detachable simulated oil displacement wellbores 4 are further provided inside the simulated formation box body 1.

[0022] The reservoir oil displacement simulation experimental device based on the complex formation structure disclosed in this embodiment includes a simulated formation box body 1, a compaction module 3 is provided at its top, and a movable sand filling module 2 is provided therebetween; the sand filling module 2 can fill the inside of the simulated formation box body 1 with simulated formation sand grains and achieve layered spreading of the sand grains through movement to construct simulated formation structures with different thickness characteristics; a plurality of detachable simulated oil displacement wellbores 4 are provided inside the simulated formation box body 1, which can be installed at different positions inside the box according to experimental requirements to simulate the well position layout of production wells or injection wells, and cooperate with the layered formation formed by the sand filling module 2 and the compaction effect of the compaction module 3 to construct a complete physical model of reservoir oil displacement simulation, providing an experimental platform for studying the formation structure and oil displacement effect.

[0023] Embodiment 2 As Figures 2 - 8As shown in the figure, on the basis of Embodiment 1, the compaction module 3 includes a plurality of hydraulic presses 31, and a compaction plate 32 located at the telescopic ends of the plurality of hydraulic presses 31. A plurality of openings 321 for accommodating the simulated oil displacement wellbore 4 are provided inside the compaction plate 32, and a stopper 33 is detachably provided inside the opening 321; In this embodiment, the compaction module 3 drives the compaction plate 32 to press vertically through a plurality of hydraulic presses 31, applying a uniform compaction force to the sand body in the simulated formation box 1; the opening 321 of the compaction plate 32 can accommodate the simulated oil displacement wellbore 4 to pass through, and the stopper 33 at the corresponding well position is detachable, and the stopper 33 at the non-well position is clamped in the opening 321 to prevent sand grains from entering, ensuring accurate wellbore positioning during compaction and uniform compression of the sand body in the non-well area.

[0024] The sand filling module 2 includes a separably relatively rotating upper cylinder 21 and a lower cylinder 22. A sand inlet hose 23 is connected to the top of the upper cylinder 21. A main sand outlet channel 221 is provided in the middle of the lower cylinder 22. A plurality of auxiliary sand outlet channels 222 are arranged around the main sand outlet channel 221 inside the lower cylinder 22. The upper cylinder 21 remains fixed and is controlled to move by a numerical control machine tool 5. The plane where the sand filling module 2 moves is a plane parallel to the simulated formation box 1, and the moving direction of the sand filling module 2 is at least two directions of longitudinal and transverse; In this embodiment, the upper cylinder 21 of the sand filling module 2 is fixed and controlled by a numerical control machine tool 5 to translate longitudinally and transversely (the moving plane is parallel to the simulated formation box 1), and the lower cylinder 22 rotates relative to the upper cylinder 21. After the sand grains flow into the upper cylinder 21 through the sand inlet hose 23, they are discharged through the combination of the main sand outlet channel 221 (central discharging) and the auxiliary sand outlet channels 222 (peripheral dispersed discharging) of the rotating lower cylinder 22, realizing uniform sand dropping while the sand grains are moving; by setting the residence time of the sand filling module 2 in different areas through a numerical control program, the thickness difference of the single-layer sand body can be controlled to simulate the heterogeneity of the formation.

[0025] A plurality of threaded seats 11 are provided at the inner bottom of the simulated formation box 1. Threaded grooves 41 are provided on the inner wall of the simulated oil displacement wellbore 4. The threaded seats 11 and the threaded grooves 41 are detachably threadedly connected. The top of the simulated oil displacement wellbore 4 is open, and a threaded sealing rod 42 is threadedly connected to the inner cavity of the simulated oil displacement wellbore 4. A simulated wellbore 43 is provided on the side wall of the simulated oil displacement wellbore 4.

[0026] In this embodiment, the simulated oil displacement wellbore 4 is detachably connected to the threaded seat 11 at the bottom of the box through the threaded groove 41 on the inner wall, and can be flexibly arranged as a production well or an injection well; the inner cavity of the simulated oil displacement wellbore 4 with an open top is blocked by the threaded sealing rod 42. When it is necessary to connect to the oil layer, the sealing rod is screwed out to expose the simulated wellbore 43 at the corresponding height on the side wall of the simulated oil displacement wellbore 4, realizing controllable switching between fluid conduction and sealing, and cooperating with the layered filling of the sand filling module 2 and the stress loading of the compaction module 3 to construct a physical model that can simulate the seepage process of the real formation.

[0027] Example 3 On the basis of Example 2, the CNC machine tool 5 is fixedly connected to the outer wall of the upper cylinder 21 through a telescopic rod 51, and a fixing ring 24 is fixedly provided on the outer side wall of the bottom of the upper cylinder 21, and the bottom inner wall of the fixing ring 24 is rotatably connected to the top side wall of the lower cylinder 22; A driving motor 25 is disposed on the outer wall of the fixing ring 24 , a driving gear 26 is disposed at the bottom output end of the driving motor 25 , a gear ring 27 is disposed on the middle side wall of the lower cylinder 22 , and the driving gear 26 is meshed and rotatably connected with the gear ring 27 .

[0028] This embodiment further optimizes the driving control structure of the sand filling module 2 on the basis of the embodiment 2: the control end of the numerical control machine 5 is fixedly connected to the outer wall of the upper cylinder 21 through the telescopic rod 51, so that the upper cylinder 21 can be translated longitudinally and transversely (such as XY axis plane movement) under the program instruction of the numerical control machine 5; the telescopic rod 51 can adjust the distance between the sand filling module 2 and the top surface of the simulated formation box 1 to meet the filling requirements of the formation models in different regions. The bottom of the upper cylinder 21 is rotatably connected to the top of the lower cylinder 22 through the fixed ring 24, and the driving motor 25 on the outer wall of the fixed ring 24 is meshed with the gear ring 27 in the middle of the lower cylinder 22 through the driving gear 26 at the output end to form a gear transmission system. When the driving motor 25 is powered on, the driving gear 26 drives the gear ring 27 to rotate, so that the lower cylinder 22 rotates relative to the upper cylinder 21. Translation controls the plane distribution range of the sand layer, and rotation controls the uniformity of sand falling (for example, by rotating the auxiliary sand outlet channel 222 to periodically cover different areas to avoid central accumulation). Combined with the setting of the residence time parameter, the thickness variation and plane heterogeneity of the formation sand body can be accurately simulated (for example, the single layer thickness error ≤±0.2cm).

[0029] Example 4 On the basis of Example 3, a circle of limiting plates 223 is provided on the top side wall of the lower cylinder 22, and a circle of limiting rings 241 is provided on the inner wall of the fixing ring 24; the limiting plates 223 slide with the limiting rings 241 and are connected in upper and lower limiting manner.

[0030] This embodiment adds a mechanical limiting structure on the basis of embodiment 3 to improve the movement stability of the sand filling module 2: the annular limiting plate 223 on the top side wall of the lower cylinder 22 forms a sliding limiting pair with the annular limiting ring 241 on the inner wall of the fixed ring 24. Specifically, the limiting plate 223 is embedded in the annular groove of the limiting ring 241, and the radial clearance between the two is ≤0.5mm, allowing the lower cylinder 22 to rotate freely in the circumferential direction (sliding connection), but limiting its axial up and down movement (upper and lower limits). This design solves the problem of axial movement that may occur during gear transmission, ensuring that when the lower cylinder 22 rotates, the vertical height of the main sand outlet channel 221 and the auxiliary sand outlet channel 222 remains constant (error ≤±0.1mm), avoiding fluctuations in the position of the sand drop point due to the up and down deviation of the cylinder, which affects the uniformity of sand filling.

[0031] Example 5 Based on Example 2, a clamping groove 322 is provided at the bottom of the opening 321 on the compaction plate 32. The stopper 33 is inverted T-shaped, and the stopper 33 is magnetically clamped with the clamping groove 322. When the stopper 33 is magnetically clamped with the clamping groove 322, the bottom surface of the stopper 33 is flush with the bottom surface of the compaction plate 32.

[0032] In this embodiment, the connection structure between the compaction plate 32 and the stopper 33 is optimized based on Example 2, and the specific functional principle is as follows: A circular clamping groove 322 is provided at the bottom of the opening 321 of the compaction plate 32, and a permanent magnet (such as a neodymium iron boron magnet) is embedded. When the horizontal shoulder of the inverted T-shaped stopper 33 is inserted into the clamping groove 322, an adsorption force is generated between its iron bottom surface and the magnet, realizing rapid clamping and positioning. This design does not require mechanical fasteners such as bolts, and the stopper 33 can be disassembled and assembled by hand. When the stopper 33 is inserted into the clamping groove 322, its bottom surface is completely flush with the bottom surface of the compaction plate 32, avoiding sand grains entering the gap of the clamping groove during the compaction process to form protrusions, resulting in uneven compaction.

[0033] Example 6 Based on Example 2, the distribution mode of the threaded seats 11 is matrix type, and the number distribution of the threaded seats 11 is 5×5 to 9×9. The number and position of the openings 321 on the compaction plate 32 correspond one by one to the number and position of the threaded seats 11.

[0034] In this embodiment, the threaded seats 11 are uniformly distributed at the bottom of the simulated formation box body 1 with a matrix density of 5×5 to 9×9 to form a standardized well position array; the number and position of the openings 321 on the compaction plate 32 correspond exactly one by one to the threaded seats 11, ensuring that after the simulated oil displacement wellbore 4 is installed, the openings 321 on the compaction plate 32 can accurately avoid the wellbore, and the openings 321 at non-well positions are closed by the stopper 33 (such as the magnetic adsorption structure in Example 5).

[0035] Furthermore, there are 4 hydraulic presses 31, which are respectively located at the four top corners of the top surface of the compaction plate 32, and an electric heater 6 is provided at the bottom of each outer wall surface of the simulated formation box body 1.

[0036] In this embodiment, the 4 hydraulic presses 31 are respectively located at the four corners of the rectangle on the top surface of the compaction plate 32, and an equal thrust is provided through a synchronous hydraulic control system (such as servo valve linkage), so that the compaction plate 32 is in balanced stress during vertical downward pressing, avoiding the inclination that may occur in traditional single-point or double-point driving.

[0037] The present invention also discloses a reservoir oil displacement simulation experiment method based on the complex formation structure, which uses the reservoir oil displacement simulation experiment device based on the complex formation structure as described in any one of Examples 1-6, and includes the following steps: S1. Prepare simulated formation sand grains with a particle size < 0.05 mm; Specifically, grind the sand grains to a particle size < 0.05 mm to serve as simulated formation sand grains; S2. Select 1 - 3 simulated oil production wells and 3 - 6 simulated water injection well positions around them, and install simulated wellbores; Specifically, select the positions of 1 - 3 threaded seats 11 as the simulated oil production well positions, and select the positions of 3 - 6 threaded seats 11 around the simulated oil production well positions as the simulated water injection well positions. Install the simulated oil displacement wellbore 4 by threaded connection at the selected simulated oil production well positions and simulated water injection well positions; S3. Fill the sand grains layer by layer through the numerical control sand filling module, and adjust the residence time at different positions according to the formation thickness parameter to achieve the simulation of the thickness structure of the sand body small layer; Specifically, for the formation structure simulation: Add simulated formation sand grains into the interior of the simulated formation box body 1 through the sand filling module 2, introduce the simulated formation sand grains into the interior of the upper cylinder body 21 through the sand inlet hose 23, and then enter the interior of the lower cylinder body 22. Export the simulated formation sand grains through the main sand outlet channel 221 and the auxiliary sand outlet channel 222. While exporting, the lower cylinder body 22 rotates to achieve uniform sand dropping. Control the sand filling module 2 to move longitudinally and transversely successively through the numerical control machine tool 5 to complete the filling of a whole layer of simulated formation sand grains. According to the thickness parameter of the formation, the sand filling module 2 stays for a longer time at the thicker position and for a shorter time at the thinner position, so as to form the simulation of the thickness structure of this layer of sand body small layer. After completing the filling of a sand body small layer, reset the sand filling module 2 and fill the next sand body small layer in the same way again; The rotation speed of the lower cylinder body 22 is 50 rpm - 100 rpm, and the heating temperature in S5 is 80 °C - 90 °C.

[0038] S4. Select a sand layer as the simulated oil layer, inject simulated oil, let it stand, and then continue to fill the sand. Drill a hole at the corresponding height of the wellbore and seal it; Specifically, for the oil layer structure simulation: When filling several sand body small layers according to the method in S1, it is necessary to select a certain sand body small layer as the simulated oil layer, that is, pour simulated formation oil onto the surface of this sand body small layer. After standing for 15 min - 20 min, the filling of the next sand body small layer can be carried out. At the same time, drill a hole at the height corresponding to this simulated oil layer on the side wall of the simulated oil displacement wellbore 4. After obtaining the simulated wellbore 43 by drilling, screw in the threaded sealing rod 42 through the thread to seal the simulated oil displacement wellbore 4. After all the sand body small layers are filled, the complete formation structure simulation is formed; S5. Remove the sand filling module, install the compaction plate, remove the block at the corresponding position of the wellbore, and compact it hydraulically while heating for 24 - 48 h; Specifically, for formation structure compaction: Remove the sand filling module 2 from above the simulated formation box 1, and place the compaction plate 32. Remove the block 33 at the position corresponding to the simulated oil displacement wellbore 4 so that the simulated oil displacement wellbore 4 can pass through the opening 321. The block 33 is clamped at other positions. Then, lower the compaction plate 32 from the four corner positions by the hydraulic press 31 to compact all the sand body layers. At the same time, heat the simulated formation box 1 and maintain it for 24 h to 48 h; S6. Open the seal of the production wellbore, produce oil under formation pressure, and calculate the recovery factor; Specifically, for simulated oil production: Rotate and screw out the threaded sealing rod 42 in the simulated oil displacement wellbore 4 serving as the simulated production well position to open the simulated wellbore 43 of the simulated oil displacement wellbore 4 serving as the simulated production well position to communicate with the simulated oil reservoir. At this time, the simulated formation oil inside the simulated oil reservoir flows into the simulated oil displacement wellbore 4 serving as the simulated production well position under the formation structure pressure, and calculate the recovery factor; S7. Open the seal of the injection wellbore, inject water to displace the remaining oil, and produce it again from the production well and analyze the water flooding effect.

[0039] Specifically, for simulated water injection: After completing S6 simulated oil production, a part of the simulated formation oil in the simulated oil reservoir remains unproduced. Therefore, screw out the threaded sealing rod 42 in the simulated oil displacement wellbore 4 serving as the simulated injection well position to open the simulated wellbore 43 of the simulated oil displacement wellbore 4 serving as the simulated injection well position to communicate with the simulated oil reservoir, inject water into the simulated oil displacement wellbore 4 serving as the simulated injection well position, displace the remaining simulated formation oil in the simulated oil reservoir, and produce it again from the simulated oil displacement wellbore 4 serving as the simulated production well position, calculate the recovery factor, and analyze the water flooding effect.

[0040] Note: When actually conducting the experiment, perform S4 oil reservoir structure simulation according to the oil equivalent converted from the reserves of the real oil reservoir to determine the amount of simulated formation oil to be poured. At the same time, reasonably adjust the water injection rate and water injection time as needed. The water injection rate can be selected as the result of proportional reduction of the real water injection rate and water injection time.

[0041] Finally, it should also be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising said element.

[0042] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. For the same or similar parts among the various embodiments, reference may be made to each other.

[0043] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An oil reservoir displacement simulation experimental device based on complex formation structures, characterized in that, It includes a simulated formation box body (1), a compaction module (3) is arranged at the top of the simulated formation box body (1), and a movable sand filling module (2) is arranged between the simulated formation box body (1) and the compaction module (3); a plurality of detachable simulated oil displacement wellbores (4) are also arranged inside the simulated formation box body (1).

2. The reservoir oil displacement simulation experiment device based on the complex formation structure according to claim 1, characterized in that: The compaction module (3) includes a plurality of hydraulic presses (31) and a compaction plate (32) located at the telescopic ends of the plurality of hydraulic presses (31). A plurality of openings (321) for accommodating the simulated oil displacement wellbores (4) are arranged inside the compaction plate (32), and a stopper (33) is detachably arranged inside the openings (321); The sand filling module (2) includes a split upper cylinder body (21) and a lower cylinder body (22) that rotate relative to each other. A sand inlet hose (23) is connected to the top of the upper cylinder body (21). A main sand outlet channel (221) is arranged in the middle of the lower cylinder body (22). A plurality of auxiliary sand outlet channels (222) are arranged in a surrounding manner inside the lower cylinder body (22) around the main sand outlet channel (221). The upper cylinder body (21) is kept fixed and controlled to move by a numerical control machine tool (5). The plane where the sand filling module (2) moves is a plane parallel to the simulated formation box body (1), and the moving direction of the sand filling module (2) is at least two directions of longitudinal and transverse; A plurality of threaded seats (11) are arranged at the inner bottom of the simulated formation box body (1). Threaded grooves (41) are arranged on the inner wall of the simulated oil displacement wellbore (4). The threaded seats (11) are threadedly and detachably connected to the threaded grooves (41). The top of the simulated oil displacement wellbore (4) is open, and a threaded sealing rod (42) is threadedly connected to the inner cavity of the simulated oil displacement wellbore (4). A simulated wellbore (43) is arranged on the side wall of the simulated oil displacement wellbore (4).

3. The reservoir oil displacement simulation experiment device based on the complex formation structure according to claim 2, characterized in that: The numerical control machine tool (5) is fixedly connected to the outer wall of the upper cylinder body (21) through a telescopic rod (51). A fixed ring (24) is fixedly arranged on the outer side wall of the bottom of the upper cylinder body (21). The inner wall of the bottom of the fixed ring (24) is rotatably connected to the top side wall of the lower cylinder body (22); A driving motor (25) is arranged on the outer wall of the fixed ring (24). A driving gear (26) is arranged at the bottom output end of the driving motor (25). A toothed ring (27) is arranged on the middle side wall of the lower cylinder body (22). The driving gear (26) is meshed and rotatably connected to the toothed ring (27).

4. The reservoir oil displacement simulation experiment device based on the complex formation structure according to claim 3, characterized in that: A circle of limiting plates (223) is arranged on the top side wall of the lower cylinder body (22), and a circle of limiting rings (241) is arranged on the inner wall of the fixed ring (24); the limiting plates (223) are slidably and vertically limitedly connected to the limiting rings (241).

5. The reservoir oil displacement simulation experiment device based on the complex formation structure according to claim 2, characterized in that: The distribution mode of the threaded seats (11) is matrix type, and the number of the threaded seats (11) is distributed in 5×5 to 9×9 pieces. The number and positions of the openings (321) on the compaction plate (32) correspond to the number and positions of the threaded seats (11) one by one.

6. The reservoir oil displacement simulation experiment device based on complex formation structure according to claim 2, wherein: A clamping groove (322) is arranged at the bottom of the opening (321) on the compaction plate (32). The blocking block (33) is in an inverted T shape. The blocking block (33) is magnetically clamped with the clamping groove (322), and when the blocking block (33) is magnetically clamped with the clamping groove (322), the bottom surface of the blocking block (33) is flush with the bottom surface of the compaction plate (32).

7. The reservoir oil displacement simulation experiment device based on complex formation structure according to claim 2, wherein: There are 4 hydraulic presses (31), which are respectively located at the 4 vertex positions on the top surface of the compaction plate (32). An electric heater (6) is arranged at the bottom of each outer wall surface of the simulated formation box body (1).

8. A reservoir oil displacement simulation experiment method based on complex formation structures, using the reservoir oil displacement simulation experiment device based on complex formation structures as described in any one of claims 1-7, characterized in that, It includes the following steps: S1. Prepare simulated formation sand grains with a particle size <0.05 mm; S2. Select 1 - 3 simulated oil production wells and 3 - 6 simulated water injection well positions around them, and install simulated wellbores; S3. Fill the sand grains in layers through the numerical control sand filling module, and adjust the residence time at different positions according to the formation thickness parameters to realize the simulation of the small layer thickness structure of the sand body; S4. Select a sand layer as the simulated oil layer, inject simulated oil and let it stand still, then continue to fill the sand, drill holes at the corresponding heights of the wellbores and seal them; S5. Remove the sand filling module, install the compaction plate and remove the blocking blocks at the corresponding positions of the wellbores, and perform hydraulic compaction while heating for 24 - 48 h; S6. Open the seal of the oil production wellbore, produce oil under formation pressure and calculate the oil recovery rate; S7. Open the seal of the water injection wellbore, inject water to displace the remaining oil, and produce it for the second time from the oil production well and analyze the water flooding effect.

9. The reservoir oil displacement simulation experiment method based on complex formation structures according to claim 8, characterized in that, S1 - S7 are specifically as follows: S1. Grind the sand grains to a particle size <0.05 mm as the simulated formation sand grains; S2. Select the positions of 1 - 3 of the threaded seats (11) as the simulated oil production well positions, and select the positions of 3 - 6 of the threaded seats (11) around the simulated oil production well positions as the simulated water injection well positions, and thread - connect and install the simulated oil displacement wellbores (4) at the selected simulated oil production well positions and simulated water injection well positions. S3. Formation structure simulation: Add the simulated formation sand grains into the interior of the simulated formation box body (1) through the sand filling module (2), introduce the simulated formation sand grains into the interior of the upper cylinder body (21) through the sand inlet flexible hose (23), and then enter the interior of the lower cylinder body (22). Export the simulated formation sand grains through the main sand outlet channel (221) and the auxiliary sand outlet channel (222). While exporting, the lower cylinder body (22) rotates to achieve uniform sand falling. Control the sand filling module (2) to move longitudinally and transversely successively through the numerical control machine tool (5) to complete the filling of one whole layer of the simulated formation sand grains. And according to the thickness parameter of the formation, the sand filling module (2) stays for a longer time at the thicker position and for a shorter time at the thinner position, so as to form the thickness structure simulation of this layer of sand body sub-layer. After completing the filling of one sand body sub-layer, reset the sand filling module (2) and fill the next sand body sub-layer in the same way again; S4. Oil reservoir structure simulation: After completing the filling of several sand body sub-layers according to the method in S1, one of the sand body sub-layers needs to be used as the simulated oil reservoir, that is, pour the simulated formation oil onto the surface of this sand body sub-layer. After standing for 15 min to 20 min, the filling of the next sand body sub-layer can be carried out. At the same time, drill holes at the height corresponding to this simulated oil reservoir on the side wall of the simulated oil displacement wellbore (4). After completing the drilling to obtain the simulated wellbore (43), screw the threaded sealing rod (42) into the simulated oil displacement wellbore (4) through the thread to seal the simulated oil displacement wellbore (4). After all the sand body sub-layers are filled, the complete formation structure simulation is formed; S5. Formation structure compaction: Move the sand filling module (2) out of the upper part of the simulated formation box body (1) and place the compaction plate (32). Remove the block (33) at the position corresponding to the simulated oil displacement wellbore (4) so that the simulated oil displacement wellbore (4) can pass through the opening (321). The block (33) is clamped at other positions. Then, press down the compaction plate (32) by the hydraulic press (31) from the four vertex positions to compact all the sand body sub-layers. At the same time, heat the simulated formation box body (1) and keep it for 24 h to 48 h; S6. Simulated oil production: Rotate and screw out the threaded sealing rod (42) in the simulated oil displacement wellbore (4) serving as the simulated oil production well position to open the simulated wellbore (43) of the simulated oil displacement wellbore (4) serving as the simulated oil production well position to communicate with the simulated oil reservoir. At this time, under the formation structure pressure, the simulated formation oil inside the simulated oil reservoir flows into the simulated oil displacement wellbore (4) serving as the simulated oil production well position, and calculate the recovery factor; S7. Simulation water injection: After the simulation of oil production in S6 is completed, a part of the simulated formation oil in the simulated oil reservoir remains unproduced. Therefore, the threaded sealing rod (42) in the simulated displacement wellbore (4) serving as the simulated water injection well location is screwed out to open the simulated wellbore (43) of the simulated displacement wellbore (4) serving as the simulated water injection well location to communicate with the simulated oil reservoir, inject water into the interior of the simulated displacement wellbore (4) serving as the simulated water injection well location, displace the remaining simulated formation oil in the simulated oil reservoir, and recover it again by the simulated displacement wellbore (4) serving as the simulated oil production well location, calculate the recovery factor, and analyze the water flooding effect.

10. The reservoir displacement simulation experiment method based on the complex formation structure according to claim 9, wherein: In S3, the rotational speed of the lower cylinder (22) is 50 rpm to 100 rpm, and in S5, the heating temperature is 80 °C to 90 °C.

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