A device and method for simulating water injection at the bottom of a fractured horizontal seam-ultra-low permeability oil reservoir

Abstract

The present invention relates to a fracturing horizontal seam-ultra-low permeability reservoir bottom water injection simulation device and method, comprising a cuboid core and an input end and an output end respectively connected to the cuboid core; further comprising a core holder, wherein 5 cuboid cores with different permeabilities are arranged side by side in the horizontal direction in the core holder; a horizontal seam is arranged on the cuboid core at the bottom of the core holder; the input end is connected to the formation water injection system and the formation oil injection system on the one hand, and is connected to the left end face of the cuboid core on the other hand; the output end is connected to the right end face of the cuboid core at the top of the core holder; the inner side of the core holder is provided with a plurality of rows of pressure detection points and resistivity detection points distributed alternately; the top of the core holder is connected to a confining pressure tracking pump, and the bottom is connected to a pressure relief valve. The dynamic seepage law test of bottom water injection in ultra-low permeability reservoirs with developed fracturing horizontal seams is realized, a theoretical basis is provided for the formulation of water injection schemes, and effective guidance is given to the efficient development of oilfield water injection.

Description

Technical Field

[0001] The present invention relates to a test device and method for optimizing water injection parameters in the field of oil field water injection development. Through this device, the dynamic seepage law test of water injection at the bottom of ultra-low permeability reservoirs with fracturing horizontal joint development can be realized, providing a theoretical basis for the formulation of water injection schemes and effectively guiding the efficient development of water injection in oil field water injection. Background Art

[0002] In conventional water injection development of fractured horizontal fracture-ultra-low permeability reservoirs, there are often many problems such as unidirectional advance of injected water along heterogeneous high permeability zones or rapid water channeling along fractures, resulting in small water drive affected area, rapid water rise, rapid flooding of oil wells, and low formation energy replenishment efficiency. Therefore, in order to solve the above problems of unsatisfactory conventional water injection development of fractured horizontal fracture-ultra-low permeability reservoirs, a new water injection method is proposed - bottom water injection (i.e. water injection at the bottom of the oil layer and oil production at the top). This water injection method is suitable for reservoirs with ultra-low formation permeability and in line with the positive rhythm of deposition, with developed horizontal fractures at the bottom of the oil layer, and with thick oil layers without interlayers. The main mechanism of this method is to use the vertical difference in injection and production positions and the gravity differentiation of oil and water to efficiently replenish formation energy, inhibit the rate of water rise, and improve water drive recovery. In order to provide effective guidance for the bottom water injection in the horizontal fracturing joint-ultra-low permeability reservoir mine test, we must not only master the real-time pressure distribution and oil-water saturation distribution changes at different locations of the oil layer during the bottom water injection and displacement process, but also analyze the rhythmicity of the formation (positive rhythm, anti-rhythm, composite rhythm) and the effect of the vertical spacing of the injection and production on the bottom water injection effect.

[0003] At present, there are very few researches on the bottom water injection simulation of the oil layer comprehensively considering the rhythm of the oil layer, the vertical spacing of the injection and production, and the fracturing horizontal fractures with real-time detection of pressure and oil-water saturation in the industry. Most water injection and flooding experimental studies are mainly conventional short core displacement experiments, long core displacement experiments and full-diameter core displacement experiments. Summary of the invention

[0004] In view of the above problems, the present invention proposes a device and method for simulating bottom water injection in a fractured horizontal fracture-ultra-low permeability oil reservoir, so as to realize accurate simulation of bottom water injection development in a fractured horizontal fracture-ultra-low permeability oil reservoir.

[0005] The technical solution of the present invention is:

[0006] The present invention proposes a water injection simulation device at the bottom of a fracturing horizontal crack-ultra-hypocenter reservoir, including a cuboid core, an input end and an output end connected to a cuboid core; wherein the input end is connected to a formation water injection system and a formation oil injection system, and the output end includes a production oil analysis system;

[0007] It also includes a core holder, in which five rectangular cores with different permeabilities are arranged side by side in a horizontal direction; wherein a horizontal seam is provided on the rectangular core at the bottom of the core holder;

[0008] On the one hand, the input end is connected to the formation water injection system and the formation oil injection system, and on the other hand, it is connected to the left end face of the cuboid core; the output end is connected to the right end face of the cuboid core located at the top of the core bouncing device;

[0009] The inner side of the core holder is provided with a number of pressure detection points and resistivity detection points distributed alternately;

[0010] The top of the core holder is connected to a confining pressure tracking pump, and the bottom is connected to a pressure relief valve.

[0011] The inlet end of the core supporter is provided with a flow guide pad, and the flow guide pad includes five flow guide units arranged longitudinally, corresponding to five rectangular cores; each flow guide unit is composed of a flow guide channel and a flow guide hole, and a flow guide hole is provided on the flow guide channel along the water inlet direction, and an intersecting bracket is provided on the liquid outlet end of the flow guide channel, and a baffle corresponding to the position of the flow guide hole is provided on the support.

[0012] The core holder is located in a constant temperature box.

[0013] The production oil analysis system includes a production valve, a detection device and a backpressure device connected to the production valve respectively; the detection device includes an oil-water separation and metering device and an oil-water data acquisition and pressure-saturation analysis device connected in sequence;

[0014] The production valve is connected to the rectangular core located at the top of the core holder through a connecting pipeline, and a production pressure metering device is provided on the connecting pipeline;

[0015] A back pressure control valve and a back pressure metering device are provided on the connecting pipeline between the production valve and the back pressure device.

[0016] The input end includes 5 injection pipelines correspondingly connected to the 5 rectangular cores, and the injection pipelines are all provided with injection valves and injection pressure metering devices;

[0017] The formation water injection system includes a formation water piston container and five groups of formation water output pipelines respectively connected to the formation water piston containers, and the five groups of injection pipelines are respectively connected to the five groups of formation water output pipelines;

[0018] The formation oil injection system includes 5 groups of formation oil output pipelines, and the 5 groups of formation oil output pipelines are connected to the 5 groups of injection pipelines respectively; the formation oil output pipeline includes the formation oil piston container and the formation oil output valve connected in sequence.

[0019] It also includes a first displacement pump connected to the formation water piston container, and a second displacement pump connected to the formation oil piston containers respectively; and a first displacement control valve is provided on the connecting pipeline between the first displacement pump and the formation water piston container, and a second displacement control valve is provided on the connecting pipeline between the second displacement pump and 5 groups of formation oil piston containers; 5 groups of formation water output pipelines are all provided with formation water output valves, and 5 groups of formation oil output pipelines are all provided with formation oil output valves.

[0020] The present invention provides a method for simulating bottom water injection in a fractured horizontal fracture-ultra-low permeability oil reservoir, using the above-mentioned device for simulating bottom water injection in a fractured horizontal fracture-ultra-low permeability oil reservoir, the method is as follows:

[0021] Step 1: In the initial state, 5 rectangular cores are loaded into the core blessing device from bottom to top in the order of permeability from large to small / from small to large; horizontal joints are made on the rectangular core located at the bottom of the core blessing device; connecting pipelines to check the sealing properties;

[0022] Step 2: Turn on the confining pressure tracking pump, set the pressure of the confining pressure tracking pump to the overburden pressure of the formation, and keep the pressure constant for 24 hours; at the same time, turn on the thermostat to simulate the formation temperature environment;

[0023] Step 3: Open the formation water injection system and close the formation oil injection system; inject formation water to saturate the rectangular core for 24 hours;

[0024] Step 4: Turn off the formation water injection system and turn on the formation oil injection system; drive off the saturated formation water in the cuboid core, and when the water is no longer out of the output end, turn off the formation oil injection system; measure the amount of water that has been displaced;

[0025] Step 5: Start the bottom water injection experiment: only open the formation water injection system connected to the rectangular core with horizontal seams at the bottom of the core holder, that is, the formation water only enters through the rectangular core with horizontal seams to simulate the bottom water injection process; at the same time, open the back pressure device and the back pressure control valve to control the displacement pressure difference at both ends of the core holder to be constant; until the water production at the output end no longer changes, stop the bottom water injection experiment; get:

[0026] 1) When metering the formation water of different pore multiples, the oil production and water production at the output end are produced; at the same time, the injection pressure and production pressure data of the injection pressure metering device and the production pressure metering device are recorded; when obtaining formation water of different pore multiples, the relationship between the production degree and moisture content;

[0027] 2) During the bottom water injection process, record the data detected by each pressure detection point and resistivity detection point, and obtain the pressure distribution law and oil-water saturation distribution law when injecting formation water of different pore multiples.

[0028] Preferably, when the permeability of the five rectangular cores in the core holder increases from top to bottom, the rectangular cores with the largest permeability and provided with horizontal seams are adjusted up one position in turn, and the remaining rectangular cores are arranged in a cycle; only the formation water is injected into the rectangular cores with horizontal seams, and steps 2 to 5 are repeated; to simulate water injection at the bottom of the horizontal seam-ultra-low permeability reservoir with different injection and production vertical spacings; the relationship between the degree of recovery and the water content, the pressure distribution law, and the oil-water saturation distribution law are obtained when the formation water with different injection porosity multiples is injected.

[0029] Alternatively, preferably, when the permeabilities of the five rectangular cores in the core holder no longer increase or decrease sequentially from top to bottom, the five rectangular cores in the core holder are divided into two parts, the permeabilities of the rectangular cores in each part maintain a law of increasing or decreasing sequentially, and a horizontal seam is created on the rectangular core at the bottom of the core holder; steps 2 to 5 are repeated to simulate the development of horizontal seams in a sedimentary composite rhythm - water injection at the bottom of an ultra-low permeability reservoir; and the relationship between the degree of recovery and the water content, the pressure distribution law, and the oil-water saturation distribution law when formation water with different injection porosity multiples is obtained.

[0030] More preferably, the method further comprises adjusting the horizontal seam to a high-angle seam or a vertical seam to simulate a high-angle seam / vertical seam-bottom water injection oil recovery experiment of an ultra-low permeability oil reservoir.

[0031] The technical effects of the present invention are:

[0032] The present invention can simulate the bottom water injection experiment of horizontal fracture-ultra-low permeability reservoirs with different injection and production vertical spacing, analyze the relationship between the degree of recovery and the water content when different injection porosity multiples of formation water are injected, as well as the pressure distribution law and the oil-water saturation distribution law. It can also simulate the bottom water injection and oil displacement experiment of horizontal fracture-ultra-low permeability reservoirs with positive rhythm, reverse rhythm and compound rhythm of deposition, and simulate the bottom water injection and oil displacement experiment of high-angle fracture and vertical fracture-ultra-low permeability reservoirs, and analyze the influence of deposition rhythm and fracture type on bottom water injection development. It provides a theoretical basis for exploring the bottom water injection and oil displacement mechanism of fractured horizontal fracture-ultra-low permeability reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The present invention is a structural diagram of a fracturing horizontal seam-ultra-low permeability oil reservoir bottom water injection simulation device.

[0034] Figure 2 This is a schematic diagram of the distribution of resistivity detection points and pressure detection points on the side of the core holder of the bottom water injection device for measuring horizontal fractures in ultra-low permeability oil reservoirs according to the present invention.

[0035] Figure 3 This is a schematic diagram of the distribution of resistivity detection points and pressure detection points on the side of the core holder of the bottom water injection device for measuring high-angle fractures and ultra-low permeability oil reservoirs in the present invention.

[0036] Figure 4 This is a schematic diagram of the distribution of resistivity detection points and pressure detection points on the side of the core holder of the bottom water injection device for measuring vertical seams in ultra-low permeability oil reservoirs according to the present invention.

[0037] Figure 5 It is a schematic diagram of the guide pad of the present invention.

[0038] Figure 6 This is a simulation diagram of oil saturation distribution in a horizontal fracture-ultra-low permeability reservoir with bottom water injection.

[0039] Figure 7 This is a simulation diagram of the formation pressure distribution during water injection at the bottom of a horizontal fracture-ultra-low permeability reservoir.

[0040] Reference marks: 1-first drive replacement pump, 2-first drive replacement control valve, 3-former water piston container, 8-former water output valve, 10-former oil output valve, 11-former oil piston container, 12-second drive replacement control valve, 15-second drive replacement pump, 21-injection valve, 30-injection pressure metering device, 31-driving pad, 32-clip-floor core, 33-pressure relief valve, 34-temperature box, 35-core buffer, 36-confining pressure Control valve, 37-boundary pressure tracking pump, 38-produced pressure metering device, 39-produced valve, 40-oil-water separation and metering device, 41-back pressure control valve, 42-back pressure metering device, 43-back pressure device, 44-oil and water data acquisition and pressure-saturation analysis device, 45-horizontal joint, 48-resistivity detection point, 49-pressure detection point, 50-driving channel, 51-driving hole, 52-high angle joint, 53-vertical joint. DETAILED DESCRIPTION

[0041] The invention will be further described below in conjunction with the accompanying drawings.

[0042] Example 1

[0043] A fracturing horizontal seam-ultra-low permeability reservoir bottom water injection simulation device, comprising a rectangular core 32 and an input end and an output end respectively connected to the rectangular core 32; wherein the input end is connected to a formation water injection system and a formation oil injection system, and the output end comprises a produced oil analysis system; further comprising a core holder 35, wherein five rectangular cores 32 with different permeabilities are arranged side by side in a horizontal direction in the core holder 35; wherein a horizontal seam 45 is provided on the rectangular core 32 located at the bottom of the core holder 35; the input end is connected to the formation water injection system and the formation oil injection system on the one hand, and is connected to the left end face of the rectangular core 32 on the other hand; the output end is connected to the right end face of the rectangular core 32 located at the top of the core holder 35; a plurality of rows of pressure detection points 49 and resistivity detection points 48 distributed alternately are provided on the inner side surface of the core holder 35; a confining pressure tracking pump 37 is connected to the top of the core holder 35, and a pressure relief valve 33 is connected to the bottom.

[0044] Example 2

[0045] On the basis of Example 1, it also includes: the inlet end of the core holder 35 is provided with a diversion pad 31, and the diversion pad 31 includes 5 diversion units arranged longitudinally, corresponding to 5 rectangular cores 32 respectively; each diversion unit is composed of a diversion channel 50 and a diversion hole 51, and the diversion channel 50 is provided with a through diversion hole 51 along the water inlet direction, and the diversion channel 50 is provided with a cross-type bracket on the liquid outlet end, and the bracket is provided with a baffle corresponding to the position of the diversion hole 51. The formation water input from the input end first enters the diversion hole 51, and then the formation water is evenly injected into the end face of the rectangular core 32 through the diversion channel 50, so as to improve the saturated formation water and water-to-oil efficiency. The core holder 35 is located in a constant temperature box 34.

[0046] The production oil analysis system includes a production valve 39, a detection device and a backpressure device 43 respectively connected to the production valve 39; the detection device includes an oil-water separation and metering device 40 connected in sequence and an oil-water data acquisition and pressure-saturation analysis device 44;

[0047] The production valve 39 is connected to the rectangular core 32 located at the top of the core holder 35 through a connecting pipeline, and a production pressure metering device 38 is provided on the connecting pipeline;

[0048] A back pressure control valve 41 and a back pressure metering device 42 are provided on the connecting pipeline between the production valve 39 and the back pressure device 43 .

[0049] The input end includes five injection pipelines corresponding to the five rectangular cores 32, and each of the injection pipelines is provided with an injection valve 21 and an injection pressure metering device 30;

[0050] The formation water injection system includes a formation water piston container 3 and five groups of formation water output pipelines respectively connected to the formation water piston container 3. The five groups of injection pipelines are respectively connected to the five groups of formation water output pipelines.

[0051] The formation oil injection system includes five groups of formation oil output pipelines, and the five groups of formation oil output pipelines are respectively connected to the five groups of injection pipelines. The formation oil output pipeline includes a formation oil piston container 11 and a formation oil output valve 10 connected in sequence.

[0052] It further includes a first displacement control valve 2 connected to the formation water piston container 3 and a second displacement pump 15 respectively connected to the formation oil piston container 11. And a first displacement control valve is provided on the connecting pipeline between the first displacement control valve 2 and the formation water piston container 3, and a second displacement control valve 12 is provided on the connecting pipeline between the second displacement pump 15 and the five groups of formation oil piston containers 11. Formation water output valves 8 are provided on all five groups of formation water output pipelines, and formation oil output valves 10 are provided on all five groups of formation oil output pipelines.

[0053] Example 3 - Positive rhythm

[0054] Based on Example 2, a simulation method for bottom water injection in a fractured horizontal well - ultra - low permeability oil reservoir is proposed. The method is as follows:

[0055] Step 1: The size of the core holder 35 is 50 cm * 10 cm * 30 cm and it is placed in the constant temperature box 34.

[0056] As Figure 1 shown: In the initial state, five cuboid cores 32 (permeability K1 < K2 < K3 < K4 < K5) are successively loaded into the core holder 35 in the order of decreasing permeability. Among them, a horizontal fracture 45 is provided on the cuboid core 32K5 with the largest permeability at the bottom of the core holder 35. The size of each cuboid core 32 is 40 cm * 6 cm * 5 cm, and a sedimentary positive - rhythm vertical - flat - type ultra - low permeability oil reservoir model with a horizontal fracture 45 is formed. Connect the pipelines and check the airtightness.

[0057] Step 2: Open the confining pressure tracking pump 37 at the top of the core holder 35 and set the confining pressure to 5 MPa. Open the pressure relief valve 33 at the bottom of the core holder 35. Open the confining pressure control valve 36 to discharge the residual air in the core holder 35. After discharging the residual air, close the pressure relief valve 33, and then reset the pressure of the confining pressure tracking pump 37 to the overburden pressure of the formation of the cuboid core 32, which is 10 MPa, and keep the set pressure constant for 24 hours. Open the constant temperature box 34 and set a constant temperature to simulate the formation temperature environment.

[0058] Step 3: Open the formation water injection system and close the formation oil injection system; open the first displacement control valve 2 and inject formation water to saturate the rectangular core for 3224 hours;

[0059] Step 4: Turn on the second displacement pump 15, start the displacement with the second displacement control valve 12, open all the formation oil output valves 10 and the production valve 39, close all the formation water output valves 8 to stop injecting formation water; inject the prepared formation oil into the core holder 35 at a constant rate to displace the saturated formation water in the rectangular core 32; when the production valve 39 no longer discharges water, stop injecting formation oil; use the oil-water separation-metering device to measure the amount of water displaced in the core holder 35, and the irreducible water saturation of the rectangular core 32 is established.

[0060] Step 5: Start the bottom water injection experiment: open the first displacement control valve 2 to set the displacement pressure, and stop injecting formation oil; only open the formation water injection system connected to the rectangular core 32 with a horizontal slit 45 at the bottom of the core holder 35, that is, the formation water only enters through the rectangular core 32 with a horizontal slit 45, simulating the bottom water injection process; at the same time, open the back pressure device 43 and the back pressure control valve 41 to control the displacement pressure difference at both ends of the core holder to be constant; until the water production at the output end no longer changes, stop the bottom water injection experiment; get:

[0061] 1) Measuring the oil production and water production at the output end when injecting formation water with different porosity multiples of 0.5, 1, 1.5, 3, 5, and 10 PV; recording the injection pressure and production pressure data of the injection pressure metering device 30 and the production pressure metering device 38 at the same time; obtaining the relationship between the production degree and the water content when injecting formation water with different porosity multiples;

[0062] 2) During the bottom water injection process, the data detected at each pressure detection point 49 and resistivity detection point 48 are recorded to obtain the pressure distribution law and oil-water saturation distribution law when injecting formation water with different porosity multiples.

[0063] Example 4 - Anti-rhythm

[0064] Based on Example 2, a method for simulating bottom water injection in a fractured horizontal seam-ultra-low permeability reservoir is proposed. The method is as follows: Step 1: The core holder 35 with a size of 50cm*10cm*30cm is placed in a constant temperature box 34.

[0065] In the initial state, five cuboid cores 32 (with permeabilities K1 < K2 < K3 < K4 < K5) are successively loaded into the core holder 35 in ascending order of permeability; among them, a horizontal fracture 45 is provided on the cuboid core 32K1 with the largest permeability at the bottom of the core holder 35; the size of each cuboid core 32 is 40 cm * 6 cm * 5 cm, forming a sedimentary inverse rhythm vertical - flat - type ultra - low - permeability reservoir model with a horizontal fracture 45; connect the pipelines and check the tightness;

[0066] The remaining steps are the same as those in Example 3.

[0067] Obtain the relationship between the recovery degree and water cut, the pressure distribution law, and the oil - water saturation distribution law of the formation water at different injection pore multiples in this case.

[0068] Example 5 - Simulating bottom water injection in a horizontal - fracture ultra - low - permeability reservoir with different injection - production vertical spacings. On the basis of Example 2, a simulation method for bottom water injection in a fractured horizontal - fracture ultra - low - permeability reservoir is proposed. The method is as follows: when the permeabilities of the five cuboid cores 32 in the core holder 35 increase successively from top to bottom, the cuboid core 32K5 with the largest permeability and provided with a horizontal fracture 45 is successively adjusted upward by one position, and the remaining cuboid cores 32 are cyclically arranged; only the formation water is injected into the cuboid core 32 provided with a horizontal fracture 45.

[0069] The remaining steps are the same as those in Example 3.

[0070] It is used to simulate bottom water injection in a horizontal - fracture ultra - low - permeability reservoir with different injection - production vertical spacings; obtain the relationship between the recovery degree and water cut, the pressure distribution law, and the oil - water saturation distribution law of the formation water at different injection pore multiples in this case.

[0071] When the cuboid core 32K5 with the largest permeability and provided with a horizontal fracture 45 is located at different positions, the following are obtained:

[0072] 1) Measure the oil production and water production output at the output end when injecting formation water with different pore multiples of 0.5, 1, 1.5, 3, 5, 10 PV; at the same time, record the injection pressure and production pressure data of the injection pressure measuring device 30 and the production pressure measuring device 38; obtain the relationship between the recovery degree and water cut of the formation water at different injection pore multiples;

[0073] 2) During the bottom water injection process, record the data detected by each pressure detection point 49 and resistivity detection point 48, and obtain the pressure distribution law and the oil - water saturation distribution law when injecting formation water with different pore multiples, as Figure 6 and Figure 7 shown.

[0074] Among them, the Archie formula is used to calculate the oil - water saturation

[0075]

[0076]

[0077] wherein, S o —oil saturation of the cuboid core 32; S w —water saturation of the cuboid core 32; R t —resistivity when the cuboid core 32 contains oil, obtained through the resistivity detection point 48 of the vertical-flat type core holder 35; R w —formation water resistivity; φ—porosity of the cuboid core 32; a—lithology coefficient, with a variation range of 0.5 - 1.5; b—lithology coefficient, where b is close to 1, n—saturation coefficient, generally taken as 2; m—cementation index; where the range of m is 1.5 - 3.

[0078] Example 6 - Composite rhythm

[0079] Based on Example 2, a simulation method for bottom water injection in a fractured horizontal well - ultra - low permeability oil reservoir is proposed. The method is as follows: When the permeabilities of the 5 cuboid cores 32 in the core holder no longer increase or decrease sequentially from top to bottom, the 5 cuboid cores 32 in the core holder are divided into 2 parts, and the permeabilities of the cuboid cores 32 within each part keep increasing or decreasing sequentially. A horizontal fracture 45 is created on the cuboid core 32 at the bottommost of the core holder; for example, when the permeabilities are K1 < K2 < K3 < K4 < K5, the cuboid cores 32 K2, K1, K3, K4, and K5 are sequentially loaded into the core holder 35; K2 is at the bottom layer and a horizontal fracture 45 is created on K2, and K5 is at the top layer; that is, K5, K4, and K3 maintain an inverse rhythm, and K1 and K2 maintain a positive rhythm, which is the composite rhythm;

[0080] The remaining steps are the same as those in Example 3.

[0081] Under this condition, the relationship between the recovery degree and water cut of the produced formation water at different injection pore multiples, as well as the pressure distribution law and the oil - water saturation distribution law, are obtained.

[0082] Example 7

[0083] Based on Example 3, a simulation method for bottom water injection in a fractured horizontal well - ultra - low permeability oil reservoir is proposed. The method is as follows: Based on the Figure 2 , Figure 3 , Figure 4 schematic diagram of the distribution of the resistivity detection point 48 and the pressure detection point 49, high - angle fractures 52 / vertical fractures 53 are provided, and then the 5 cuboid cores 32 are sequentially loaded into the core holder 35, the pipelines are connected, and the airtightness is checked; the remaining steps are the same as those in Example 3.

[0084] Used to simulate high angle fracture 52 / vertical fracture 53-bottom water injection of ultra-low permeability reservoir.

[0085] like Figure 2 As shown, the inner side of the core holder 35 of the bottom water injection simulation device for measuring the horizontal seam 45-ultra-low permeability reservoir is provided with pressure detection points 49 and resistivity detection points 48 distributed alternately in rows; wherein the resistivity detection points 48 and pressure detection points 49 at the horizontal seam 45 are densely distributed and arranged between columns, with 32 resistivity detection points 48 and 10 pressure detection points 49, while the resistivity detection points 48 at the matrix are dispersedly distributed, with 6 in each row and 6 in each column, with 36 resistivity detection points 48, while the pressure detection points 49 are arranged in 5 in each row and 3 in each column, with 15 pressure detection points 49, so as to realize real-time and accurate determination of the oil-water saturation and pressure change law at the horizontal seam 45.

[0086] like Figure 3 As shown, the inner side of the core holder 35 of the bottom water injection simulation device for measuring high-angle fractures 52-ultra-low permeability reservoirs is provided with pressure detection points 49 and resistivity detection points 48 distributed alternately in rows; among them, the resistivity detection points 48 and pressure detection points 49 at the high-angle fractures 52 are densely distributed and arranged in rows, with 18 resistivity detection points 48 and 18 pressure detection points 49, while the resistivity detection points 48 at the matrix are dispersedly distributed, with 40 resistivity detection points 48, and the pressure detection points 49 have 16 pressure detection points 49, so as to realize real-time and accurate determination of the oil-water saturation and pressure change law at the high-angle fractures 52.

[0087] like Figure 4 As shown, the inner side of the core holder 35 of the bottom water injection simulation device for measuring vertical seams 53-ultra-low permeability reservoirs is provided with pressure detection points 49 and resistivity detection points 48 distributed alternately in rows; wherein the resistivity detection points 48 and pressure detection points 49 at the vertical seams 53 are densely distributed and arranged between columns, with 14 resistivity detection points 48 and 10 pressure detection points 49, while the resistivity detection points 48 at the matrix are dispersedly distributed, with 6 in each row and 8 in each column, with 48 resistivity detection points 48, while the pressure detection points 49 are arranged 4 in each row and 4 in each column, with 16 pressure detection points 49, so as to realize real-time and accurate determination of the oil-water saturation and pressure change law at the vertical seams 53.

Claims

1. A fracturing horizontal seam-ultra-low permeability reservoir bottom water injection simulation device, comprising a rectangular parallelepiped core (32) and an input end and an output end respectively connected to the rectangular parallelepiped core (32); wherein: The input end is connected to the formation water injection system and the formation oil injection system, and the output end includes a produced oil analysis system; the characteristics are: It also includes a core holder (35), wherein five rectangular cores (32) with different permeabilities are arranged side by side in a horizontal direction in the core holder (35); wherein a horizontal seam (45) is provided on the rectangular core (32) located at the bottom of the core holder (35); The input end is connected to the formation water injection system and the formation oil injection system on one hand, and is connected to the left end face of the rectangular core (32) on the other hand; the output end is connected to the right end face of the rectangular core (32) located at the top of the core holder (35); The inner side surface of the core holder (35) is provided with a plurality of rows of pressure detection points (49) and resistivity detection points (48) distributed alternately; The top of the core holder (35) is connected to a confining pressure tracking pump (37), and the bottom is connected to a pressure relief valve (33); The inlet end of the core holder (35) is provided with a flow guide pad (31), and the flow guide pad (31) includes five flow guide units arranged longitudinally, corresponding to five rectangular parallelepiped cores (32) respectively; each flow guide unit is composed of a flow guide channel (50) and a flow guide hole (51); the flow guide channel (50) is provided with a through flow guide hole (51) along the water inlet direction; a cross-shaped bracket is provided on the liquid outlet end of the flow guide channel (50), and a baffle corresponding to the position of the flow guide hole (51) is provided on the bracket; The produced oil analysis system comprises a production valve (39) and a detection device and a back pressure device (43) respectively connected to the production valve (39); the detection device comprises an oil-water separation and metering device (40) and an oil-water data acquisition and pressure-saturation analysis device (44) respectively connected to the production valve (39); The extraction valve (39) is connected to the rectangular core (32) located at the top of the core holder (35) through a connecting pipeline, and the connecting pipeline is provided with an extraction pressure metering device (38); A back pressure control valve (41) and a back pressure metering device (42) are provided on the connecting pipeline between the production valve (39) and the back pressure device (43); The input end comprises five injection pipelines correspondingly connected to the five rectangular cores (32), and each of the injection pipelines is provided with an injection valve (21) and an injection pressure metering device (30); The formation water injection system comprises a formation water piston container (3) and five groups of formation water output pipelines respectively connected to the formation water piston container (3), and the five groups of injection pipelines are respectively connected to the five groups of formation water output pipelines; The formation oil injection system comprises five groups of formation oil output pipelines, which are respectively connected to the five groups of injection pipelines; the formation oil output pipelines comprise a formation oil piston container (11) and a formation oil output valve (10) which are connected in sequence; The invention also comprises a first displacement pump (1) connected to the formation water piston container (3), and a second displacement pump (15) respectively connected to the formation oil piston containers (11); a first displacement control valve (2) is provided on the connecting pipeline between the first displacement pump (1) and the formation water piston container (3), and a second displacement control valve (12) is provided on the connecting pipeline between the second displacement pump (15) and the five groups of formation oil piston containers (11); the five groups of formation water output pipelines are all provided with a formation water output valve (8), and the five groups of formation oil output pipelines are all provided with a formation oil output valve (10).

2. The device for simulating water injection at the bottom of a horizontal fracture-ultra-low permeability oil reservoir according to claim 1, characterized in that: The core holder (35) is located in a constant temperature box (34).

3. A method for simulating bottom water injection in a horizontal fracture-ultra-low permeability oil reservoir, characterized in that: Using the fracturing horizontal seam-ultra-low permeability reservoir bottom water injection simulation device as described in claim 2 above, the method is as follows: Step 1: In the initial state, five rectangular cores (32) are sequentially loaded from bottom to top in the core holder (35) in the order of permeability from large to small / from small to large; a horizontal seam (45) is made on the rectangular core (32) at the bottom of the core holder (35); pipelines are connected and the tightness is checked; Step 2: Turn on the confining pressure tracking pump (37), set the pressure of the confining pressure tracking pump (37) to the overburden pressure of the formation, and keep the pressure constant for 24 hours; at the same time, turn on the thermostat (34) to simulate the formation temperature environment; Step 3: Open the formation water injection system and close the formation oil injection system; inject formation water to saturate the rectangular core (32) for 24 hours; Step 4: close the formation water injection system and open the formation oil injection system; displace the saturated formation water in the rectangular core (32); when no more water is discharged from the output end, close the formation oil injection system; and measure the amount of water displaced; Step 5: Start the bottom water injection experiment: only open the formation water injection system connected to the rectangular core (32) with a horizontal slit (45) at the bottom of the core holder (35), that is, the formation water only enters through the rectangular core (32) with a horizontal slit (45), simulating the bottom water injection process; at the same time, open the back pressure device (43) and the back pressure control valve (41) to control the displacement pressure difference at both ends of the core holder to be constant; until the water production at the output end no longer changes, stop the bottom water injection experiment; get: 1) Measuring the oil production and water production at the output end when injecting formation water with different porosity multiples; simultaneously recording the injection pressure and production pressure data of the injection pressure metering device (30) and the production pressure metering device (38); obtaining the relationship between the production degree and the water content when injecting formation water with different porosity multiples; 2) During the bottom water injection process, the data detected at each pressure detection point (49) and resistivity detection point (48) are recorded to obtain the pressure distribution law and oil-water saturation distribution law when injecting formation water with different porosity multiples.

4. The method for simulating bottom water injection of a horizontal fracture-ultra-low permeability oil reservoir according to claim 3, characterized in that: When the permeability of the five rectangular cores (32) in the core holder (35) increases from top to bottom, the rectangular cores (32) with the largest permeability and provided with horizontal seams (45) are adjusted up one position in turn, and the remaining rectangular cores (32) are arranged in a circular manner; only the formation water is injected into the rectangular cores (32) provided with horizontal seams (45), and steps 2 to 5 are repeated; so as to simulate water injection at the bottom of an ultra-low permeability reservoir with horizontal seams (45) at different injection and production vertical intervals; and the relationship between the degree of production and the water content, the pressure distribution law, and the oil-water saturation distribution law are obtained when the formation water is injected with different porosity multiples.

5. The method for simulating bottom water injection of a horizontal fracture-ultra-low permeability oil reservoir according to claim 4, characterized in that: When the permeability of the five rectangular cores (32) in the core holder no longer increases or decreases from top to bottom, the five rectangular cores (32) in the core holder are divided into two parts, the permeability of the rectangular cores (32) in each part keeps increasing or decreasing in sequence, and a horizontal seam (45) is created on the rectangular core (32) at the bottom of the core holder; steps 2 to 5 are repeated to simulate the development of horizontal seams (45) in a sedimentary composite rhythm - water injection at the bottom of an ultra-low permeability oil reservoir; and the relationship between the recovery degree and the water content, the pressure distribution law, and the oil-water saturation distribution law when the formation water is injected with different porosity multiples are obtained.

6. The method for simulating bottom water injection of a horizontal fracture-ultra-low permeability reservoir according to claim 3, 4 or 5, characterized in that: The method also includes adjusting the horizontal seam (45) to a high-angle seam (52) or a vertical seam (53) to simulate a high-angle seam (52) / vertical seam (53)-bottom water injection oil recovery experiment in an ultra-low permeability oil reservoir.

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