Four-directional heterogeneous experimental model and method for determining displacement velocity of different reservoirs by using the same

Abstract

The present disclosure provides a four-way heterogeneous experimental model and a method for determining different reservoir displacement velocities by using the same. The model comprises a grid sand filling box, a sealing cover, a four-way control valve, four hollow tubes and five injection-production control valves. Each grid cavity is a core with different physical properties. The four hollow tubes are provided with five through holes at 90 degrees to each other around the tubes to simulate perforations and construct an oil-water seepage channel between the wellbore and the core. The four-way control valve is provided with a rotary table and an injection valve, and a single-factor different level multi-scheme physical experiment simulation is completed through the rotary table and the injection valve. By using the model, the reasonable injection-production intensity and the reasonable displacement velocity in the field are determined by the maximum liquid production method. The experimental model provided by the present disclosure can simulate different injection-production intensities of different reservoirs at one time, so as to obtain the reasonable displacement velocity under different reservoir conditions.

Description

Technical fields: This disclosure relates to a four-dimensional heterogeneous experimental model that can realize multiple schemes in one unit and an application of the experimental model to determine the reasonable displacement rate under different reservoir conditions. Background technology: Currently, commonly used research methods in oilfield development include physical simulation experiments, numerical simulation calculations, reservoir engineering methods, and production dynamic analysis. Among these, physical simulation experiments, based on similarity principles and criteria, use scaled-down physical models to simulate the production dynamics of a prototype reservoir, and are widely accepted by oilfield workers. However, current experimental models can only conduct research on one factor and one scheme. Experiments involving multiple schemes for single factors have long cycles and consume a lot of materials. Furthermore, when using these existing experimental models to determine the reasonable injection-production intensity and displacement rate of the reservoir, the lack of correlation and unified calibration values ​​between multiple schemes leads to unclear boundaries and low accuracy in the measured results. Summary of the Invention: To address the technical problems mentioned in the background section, this disclosure provides a four-dimensional heterogeneous experimental model and method applicable to the field of petroleum engineering, enabling integrated multi-scheme testing. Based on different levels of single-factor experimental design, the sand-filled box in this model can be used to configure experimental cores with four different physical properties. Then, saturated water and saturated oil are applied, and a multi-scheme physical simulation study is completed in the laboratory through a four-way control valve.

[0001] The technical solution provided in this disclosure is as follows: This disclosure first presents a four-dimensional heterogeneous experimental model that can realize multiple schemes in one unit: The model includes a grid-filled sand box 2, a sealing cover 8, a four-way control valve bottom 4, a four-way control valve top 11, four hollow tubes 6, and five injection and extraction control valves 10; The sealing cover 8 is connected to the grid sand-filled box 2 by bolts to form a sealed space; The sand-filled cavity 3 has a threaded connection hole at the position corresponding to the sealing cover for connecting the valve; A four-way control valve 11 is located at the center of the sealing cover; The grid sand-filling box is equipped with a cavity partition 5 to divide the box into 4 sand-filling cavities 3, which are used to simulate rock cores with different physical properties; A hollow tube 6 is installed inside the sand-filled cavity 3 to simulate a production well; a four-way control valve bottom 4 is installed at the center of the cavity partition 5. The four-way control valve bottom is used to cooperate with the injection control valve 17. The study of the experimental law of different physical properties of core samples is completed by opening and closing the injection control valve 17 and rotating the turntable 16. Hollow tube 6 has five hollow tube perforation channels 12 that are 90° apart around it to simulate perforation and construct oil and water seepage channels between the wellbore and the core. The injection control valve 10 is installed on the sand filling cavity 3.

[0002] Furthermore, rubber is provided at the bottom of the sealing cap, which can serve as a buffer and ensure a full seal during bolt sealing reinforcement.

[0003] Furthermore, the top 11 of the four-way control valve has three bolt holes 15, which are bolted to connect it to the bottom 4 of the four-way control valve; the central injection control valve 17 is used to control the injection of the injection well; the turntable 16 is marked with indicator marks indicating the positions of the circumferential rubber holes; the turntable 16 on the top of the four-way control valve is used to control the rotation of the circumferential rubber at the bottom 4 of the four-way control valve, and when the indicator arrows point in each direction, core physics simulation experiments can be carried out in that direction. The bottom 4 of the four-way control valve has several four-way control valve perforation channels 13 around its perimeter, used to simulate injection well perforation; the bottom 4 of the four-way control valve is composed of a cavity and a circumferential rubber with several internal circular holes on one side, the longitudinal position of the internal circular holes being consistent with the four-way control valve perforation channels; the top of the circumferential rubber has three four-way control valve bottom bolt holes 14, used to connect the turntable 16 of the top 11 of the four-way control valve and the injection control valve 17, and the rotation of the turntable 16 enables core experiments on different physical properties.

[0004] Another aspect of this disclosure provides a method for determining different reservoir displacement velocities in a laboratory, using the aforementioned four-dimensional heterogeneous experimental model, the method comprising the following steps: The first step is to prepare the amount of quartz sand and adhesive for the four sand-filling cavities according to a certain ratio, based on the required plan. The second step is to wrap the surfaces of the four hollow tubes 6 and the bottom 4 of the four-way control valve with gauze to prevent the subsequent sand and adhesive from clogging the inside of the hollow tubes 6. After wrapping, fill each sand filling cavity 3 with the prepared quartz sand and adhesive, and pressurize and compact it to form a rock core. The third step is to seal the prepared core in the grid sand-filled box 2 with a sealing cap 8, and at the same time connect the bottom 4 and top 11 of the four-way control valve, connect the injection and production pipeline, and conduct saturated water, saturated oil and aging tests in sequence. Fourth step, open injection control valve 17, rotate turntable 16 to any direction core, and simultaneously open injection-production control valve 10 of core in that direction. Use constant speed displacement, use measuring cylinder to measure the produced water and oil, and monitor changes in water cut and production level in real time. When the water cut reaches 98%, close injection control valve 17 and close injection-production control valve 10 in that direction. Fifth step, determine the displacement rate of different reservoirs according to formula (12). V 模型 ; (12) In the formula: V 模型 , V 矿场 —Model displacement velocity, water-drive leading edge advance velocity in the mine; L 模型井距 , L 矿场井距 —Model, well spacing of oil and water wells in the mining area; Water drive leading edge propulsion speed in mining V 矿场 Represented as equation (13): (13) In the formula, H represents the production thickness of the oil well. Q Lmax is the maximum liquid production rate; Step 6: Rotate turntable 16 clockwise or counterclockwise to the next core direction, and sequentially open injection control valve 17 and injection-production control valve 10 for the core in that direction. At the same time, start recording changes in the produced fluid, and calculate water cut and production degree. When the water cut reaches 98%, repeat step 5 until the experiment is completed for cores in all four directions.

[0005] Furthermore, in the fifth step, the maximum fluid production of the oil well in the mining area is determined according to formulas (1) to (11): (1) In the formula: Q L—Oil well production rate; η L —Production index; H —Oil well production thickness; △ P —Production pressure differential; The liquid production index is expressed as formula (2), which is controlled by the water content and the oil production index.

[0006] (2) (3) In the formula: η o —Oil production index during the waterless period; L ( f — Dimensionless liquid production index; o ( f — Dimensionless oil production index; f w —Water cut of oil wells; The water cut of an oil well is expressed by formula (4): (4) In the formula: q w —Water production from oil wells; q o —Oil production from oil wells; B w —The volume coefficient of water; B o —Oil volume coefficient; K ro —Relative permeability of the oil phase; K rw —Relative permeability of the aqueous phase; μ w —The viscosity of water; μ o —Crude oil viscosity; The relative permeability of the oil phase and water phase in the oil well water cut formula is expressed as formula (5)-formula (7). (5) (6) (7) In the formula: S or —Residual oil saturation; S wi —Bound water saturation; S w —Water saturation; S wd —Standardized water saturation; n w —Water phase index; n o —Oil phase index; Linear fitting was performed on the oil phase and water phase indices to obtain their specific values. Based on the field relative permeability data, the dimensionless oil production index was calculated according to formula (8), and the liquid production index was calculated according to formula (9). (8) (9) In the formula: oj , Lj ——No. j Point-dimensional oil and liquid production indices; f wj ——No. j Point moisture content; S wi , S wj —Bound water, the first j Point water saturation; K ro ( S wi ), K ro ( S wj — Corresponding to bound water saturation and the first j Oil phase permeability at point saturation; Plot the relationship curves between dimensionless oil production, liquid production index and water content, and fit the relationship formula between dimensionless oil production, liquid production index and water content, i.e., formula (3); after determining the variation law of oil production and liquid production index, the maximum liquid production depends on the production pressure difference, i.e., formula (10). (10) For reservoirs with different physical properties, the pressure conductivity depends on the reservoir permeability, as expressed by formula (11). The stronger the pressure conductivity, the weaker the pressure attenuation from the injection end to the middle of the oil-water well, and vice versa. (11) In the formula: —Coefficient of pressure conductivity; K —Reservoir permeability; C t —Comprehensive compression ratio; —Reservoir porosity; For several maximum production volumes existing in the same water-bearing stage, the top four production volumes are selected, and their average value is determined as the maximum production volume of the oil well in the mining area.

[0007] The present invention has the following beneficial effects: The model structure provided by the present invention is simple and easy to operate, solving the problems of current experimental models that can only conduct research on one factor and one scheme, as well as the long experimental cycle, large material consumption, and indeterminate injection-production intensity limits of single-factor multi-scheme experiments. The sand-filled box in the model provided in this disclosure can be configured with experimental cores of four different physical properties, and then saturated with water and saturated with oil. A multi-scheme physical simulation study is completed in the laboratory through a four-way control valve. The numerical values ​​obtained after the simulation experiment have the same simulation basis, are correlated numerically, and have unified calibration values. After verification by experimental data, the reasonable displacement rate measured by this experimental model is basically the same as the actual maximum displacement rate. Attached image description: Figure 1 This is a schematic diagram of a grid-filled sand box structure.

[0008] Figure 2 This is a cross-sectional view of a grid-filled sand box.

[0009] Figure 3 This is a schematic diagram of the bottom structure of a four-way control valve.

[0010] Figure 4 This is a cross-sectional view of the bottom of a four-way control valve.

[0011] Figure 5 This is a schematic diagram of a hollow tube structure.

[0012] Figure 6 This is a schematic diagram of the sealing cap structure.

[0013] Figure 7 This is a schematic diagram of the top structure of a four-way control valve.

[0014] Figure 8 This is a schematic diagram of the injection and production control valve.

[0015] Figure 9 This is a schematic diagram of water phase index fitting under a specific embodiment of this disclosure.

[0016] Figure 10 This is a schematic diagram of oil phase index fitting under a specific embodiment of this disclosure.

[0017] Figure 11 This is a schematic diagram illustrating the relationship between dimensionless oil production index and water cut in a specific embodiment of this disclosure.

[0018] Figure 12 This is a schematic diagram of cumulative oil production at different displacement rates under a specific embodiment of this disclosure.

[0019] In the diagram: 1-Bottom of the grid sand-filling box; 2-Grid sand-filling box; 3-Sand-filling cavity; 4-Bottom of the four-way control valve; 5-Cavity partition; 6-Hollow tube; 7-Bottom bolt hole of the grid sand-filling box; 8-Sealing cover; 9-Sealing cover bolt hole; 10-Injection control valve; 11-Top of the four-way control valve; 12-Hollow tube perforation channel; 13-Four-way control valve perforation channel; 14-Bottom bolt hole of the four-way control valve; 15-Top bolt hole of the four-way control valve; 16-Turntable; 17-Injection control valve. Specific implementation examples: The technical solution presented in this disclosure will be further explained below with reference to the accompanying drawings and specific examples of determining the injection-production intensity limits and displacement rates of different reservoirs: Depend on Figures 1 to 8 As shown, the experimental model consists of a grid-filled sand box 2, a sealing cover 8, a four-way control valve bottom 4 and a four-way control valve top 11, four hollow tubes 6, and five injection and extraction control valves 10. The sealing cover 8 is connected to the grid sand-filling box 2 by 8 bolts to form a sealed space; the rubber at the bottom of the sealing cover plays a role in buffering and fully sealing and fitting when the bolts are sealed and reinforced; there are 3 sealing cover bolt holes 9 on each side of the sealing cover, and 4 threaded connection holes are opened in the sand-filling cavity 3 at the position of the sealing cover for connecting valves; a four-way control valve top 11 is set in the center of the sealing cover. The grid-filled sand box 2 has three bolt holes 7 at the bottom of the grid-filled sand box on each of its four sides, which are used to connect to the sealing cover 8 by bolts; the internal cavity partition 5 divides the box into four cavities to simulate cores with different physical properties; the central internal cavity has four hollow tubes 6 pre-set to simulate the production well; the bottom of the four-way control valve 4 is connected to the center of the cavity partition 5, and the experimental law of cores with different physical properties is studied by injecting and controlling the opening and closing of the valve 17. The bottom 4 of the four-way control valve has five perforation channels 13 around each side, simulating injection well perforation; the bottom 4 of the four-way control valve is composed of a cavity and a circumferential rubber with five circular holes on one side (the longitudinal position of the circular holes is consistent with the external circular holes of the control valve); the top of the circumferential rubber has three bolt holes 14 for connecting the turntable 16 of the top 11 of the four-way control valve and the injection control valve 17, and the core experiments on different physical properties are realized by rotating the turntable 16; The top 11 of the four-way control valve has three bolt holes 15, which are used to connect it to the bottom 4 of the four-way control valve with bolts; the injection control valve 17 can realize injection control of the injection well; the turntable 16 is marked with indicator marks, which indicate the position of the circumferential rubber drilling; the turntable 16 on the top of the four-way control valve realizes the rotation control of the circumferential rubber of the bottom 4 of the four-way control valve, and when the indicator arrow points to each direction, the core physical simulation experiment can be carried out in that direction; Hollow tube 6 has five hollow tube perforation channels 12 that are 90° apart around it to simulate perforation and construct oil and water seepage channels between the wellbore and the core. The aforementioned model was used to determine the injection-production intensity limits and reasonable displacement rates for different reservoirs in the laboratory, including the following steps: The first step is to prepare four sand-filling cavities and the required amount of quartz sand and adhesive according to a certain ratio, based on the required plan. The second step is to wrap the surfaces of the four hollow tubes 6 and the bottom 4 of the four-way control valve with gauze to prevent the subsequent sand and adhesive from clogging the inside of the hollow tubes 6. After wrapping, fill each sand filling cavity 3 with the prepared quartz sand and adhesive, and then press and compact it. The third step is to seal the core prepared in the grid sand-filled box 2 with the sealing cap 8, and at the same time connect the bottom 4 and the top 11 of the four-way control valve, connect the injection and production pipeline, and carry out the saturated water, saturated oil, aging and other experimental steps in sequence. Fourth step: Open injection control valve 17, rotate turntable 16 to any core sample direction, and simultaneously open injection-production control valve 10 for that core sample direction. Use constant-speed displacement, measure the produced water and oil volume using a measuring cylinder, and monitor changes in water cut and recovery rate in real time. When the water cut reaches 98%, close injection control valve 17 and injection-production control valve 10 for that direction. The displacement rate determination steps are as follows: Taking a certain oilfield as an example, firstly, the water phase index and oil phase index are fitted, such as... Figure 9 , 10 As shown, the aqueous phase index can be obtained. n w =1.8007, oil phase index n o =1.7089, from which the permeability values ​​of the oil and water phases under different water saturation levels are calculated. The relationship between the dimensionless oil production index and water cut is fitted, and the relationship is obtained as formula (14). (14) Based on the thickness of the perforated oil layer and the maximum scalable production pressure differential, the oil recovery index during the waterless production period of oilfield wells is known as follows: Figure 11 As shown, in the low water content stage ( f w Taking the determination of reasonable injection-production intensity (<20%) as an example, with reservoir properties of 1000mD, the maximum pressure difference in the field can be amplified to 5MPa, and the oil layer perforation thickness of 110m, the calculated maximum production rate is shown in Table 1. The reasonable production rate in the low water-cut stage is located at 198.19m. 3 / d -379.64m 3 / d.

[0021] Table 1 Maximum Liquid Production of Oil Wells in the Low Water Cut Stage of the Mine

[0022] Based on formula (12), the displacement rate of the model was calculated as shown in Table 2. The experimental displacement rate was determined to be 0.48 mL / min-0.91 mL / min. Four displacement rates were selected for the experiment at the same displacement rate interval: 0.48 mL / min, 0.62 mL / min, 0.76 mL / min, and 0.91 mL / min.

[0023] Table 2 Calculation of Experimental Displacement Rate

[0024] Fifth step: Rotate the four-way control valve turntable 16 clockwise or counterclockwise to the next core direction, and open the injection control valve 17 and the injection-production control valve 10 of the core in that direction in sequence. At the same time, start recording the changes in the produced fluid and calculate indicators such as water cut and production degree. When the water cut reaches 98%, repeat the fifth step until the experiment is completed for all four cores.

[0025] Experimental data and results analysis: Table 3 shows the experimental data for a displacement rate of 0.48 mL / min.

[0026] Table 4 shows the experimental data for a displacement rate of 0.62 mL / min.

[0027] Table 5 shows the experimental data for a displacement rate of 0.76 mL / min.

[0028] Table 7 shows the experimental data for a displacement rate of 0.91 mL / min.

[0029] Based on the experimental results, such as Figure 12 As shown, under different displacement rates, when the cumulative oil production displacement rate exceeds 0.62 mL / min, although the displacement rate increases, the cumulative oil production gain decreases. Therefore, 0.62 mL / min is the most reasonable displacement rate. This demonstrates the practicality of the experimental model and method presented in this disclosure.

Claims

1. A four-dimensional heterogeneous experimental model capable of realizing multiple schemes in one unit, the model comprising: The structure includes a grid-filled sand box (2), a sealing cap (8), a four-way control valve bottom (4), a four-way control valve top (11), four hollow tubes (6), and five injection and extraction control valves (10). The sealing cap (8) is connected to the grid sand-filled box (2) by bolts to form a sealed space; The sealing cover is provided with a four-way control valve at the top (11) in the center; rubber is provided at the bottom of the sealing cover, which can play a role in buffering and fully sealing and fitting when the bolt is sealed and reinforced. The grid sand-filling box is equipped with a cavity partition (5) to divide the box into 4 sand-filling cavities (3) to simulate rock cores with different physical properties; the sand-filling cavity (3) has a threaded connection hole at the corresponding sealing cover position for connecting valves; A hollow tube (6) is installed in the sand-filled cavity to simulate a production well; a four-way control valve bottom (4) is installed in the center of the cavity partition (5). The four-way control valve bottom is used to cooperate with the injection control valve (17). The study of the experimental law of different physical properties of core samples is completed by opening and closing the injection control valve (17) and rotating the turntable (16). Five hollow tube perforation channels (12) with 90° intervals are opened around the hollow tube (6) to simulate perforation and construct the oil and water seepage channel between the wellbore and the core; the injection and production control valve (10) is set on the sand filling cavity (3); Its features are: The top (11) of the four-way control valve has three bolt holes (15) for connecting to the bottom (4) of the four-way control valve with bolts; the injection control valve (17) is used to control the injection of the injection well; the turntable (16) is marked with an indicator mark indicating the position of the circumferential rubber hole; the turntable (16) on the top of the four-way control valve is used to control the rotation of the circumferential rubber at the bottom (4) of the four-way control valve. When the indicator arrow points to each direction, it can realize the core physical simulation experiment research in that direction; The bottom (4) of the four-way control valve has several four-way control valve perforation channels (13) around its perimeter, which are used to simulate injection well perforation. The bottom (4) of the four-way control valve is composed of a cavity and a ring of rubber with several internal circular holes on one side. The longitudinal position of the internal circular holes is consistent with the perforation channels of the four-way control valve. The top of the ring of rubber has three four-way control valve bottom bolt holes (14) drilled to connect the turntable (16) of the top (11) of the four-way control valve and the injection control valve (17). The rotation of the turntable (16) enables core experiments on different physical properties.

2. A method for determining displacement velocities of different reservoirs in a laboratory, using the four-dimensional heterogeneous experimental model as described in claim 1, characterized in that... The method includes the following steps: The first step is to prepare the amount of quartz sand and adhesive in four sand-filling cavities (3) according to the required scheme and in a certain proportion; The second step is to wrap the surface of the four hollow tubes (6) and the bottom (4) of the four-way control valve with gauze to prevent the subsequent sand and adhesive from clogging the inside of the hollow tubes (6). After wrapping, fill each sand filling cavity (3) with prepared quartz sand and adhesive, and pressurize and compact it to form a rock core. The third step is to seal the prepared core in the grid sand-filled box (2) with a sealing cap (8), and connect the bottom (4) and top (11) of the four-way control valve, and connect the injection and production pipeline to conduct saturated water, saturated oil and aging tests in sequence. Fourth step, open the injection control valve (17), rotate the turntable (16) to any direction of the core, and at the same time open the injection and production control valve (10) in that direction. Use constant speed displacement, use a measuring cylinder to measure the amount of water produced and the amount of oil produced, and monitor the changes in water cut and production degree in real time. When the water cut reaches 98%, close the injection control valve (17) and close the injection and production control valve (10) in that direction. Fifth step, determine the displacement rate of different reservoirs according to formula (12). V 模型 ; （12） In the formula: V 模型 , V 矿场 —Model displacement velocity, water-drive leading edge advance velocity in the mine; L 模型井距 , L 矿场井距 —Model, well spacing of oil and water wells in the mining area; Water drive leading edge propulsion speed in mining V 矿场 Represented as equation (13): （13） In the formula, H represents the production thickness of the oil well. Q Lmax is the maximum liquid production rate; Step 6: Rotate the turntable (16) clockwise or counterclockwise to the next core direction, and open the injection control valve (17) and the injection and production control valve (10) of the core in that direction in sequence. At the same time, start recording the changes in the produced fluid, calculate the water content and the degree of production. When the water content reaches 98%, repeat step 5 until the cores in all four directions have completed the experiment.

3. The method according to claim 2, characterized in that: In the fifth step, the maximum fluid production of the oil well in the mining area is determined according to formulas (1) to (11): （1） In the formula: Q L—Oil well production rate; η L —Production index; H —Oil well production thickness; △ P —Production pressure differential; Among them, the liquid production index is expressed by formula (2), which is controlled by water content and oil production index; （2） （3） In the formula: η o —Oil production index during the waterless period; L ( f — Dimensionless liquid production index; o ( f — Dimensionless oil production index; f w —Water cut of oil wells; The water cut of an oil well is expressed by formula (4): （4） In the formula: q w —Water production from oil wells; q o —Oil production from oil wells; B w —The volume coefficient of water; B o —Oil volume index; K ro —Relative permeability of the oil phase; K rw —Relative permeability of the aqueous phase; μ w —The viscosity of water; μ o —Crude oil viscosity; The relative permeability of the oil phase and water phase in the oil well water cut formula is expressed as formula (5)-formula (7). （5） （6） （7） In the formula: S or —Residual oil saturation; S wi —Bound water saturation; S w —Water saturation; S wd —Standardized water saturation; n w —Water phase index; n o —Oil phase index; Linear fitting was performed on the oil phase and water phase indices to obtain their specific values. Based on the field relative permeability data, the dimensionless oil production index was calculated according to formula (8), and the liquid production index was calculated according to formula (9). （8） （9） In the formula: oj , Lj ——No. j Point-dimensional oil and liquid production indices; f wj ——No. j Point moisture content; S wi , S wj —Bound water, the first j Point water saturation; K ro ( S wi ), K ro ( S wj — Corresponding to bound water saturation and the first j Oil phase permeability at point saturation; Plot the relationship curves between dimensionless oil production, liquid production index and water content, and fit the relationship formula between dimensionless oil production, liquid production index and water content, i.e., formula (3); after determining the variation law of oil production and liquid production index, the maximum liquid production depends on the production pressure difference, i.e., formula (10). （10） For reservoirs with different physical properties, the pressure conductivity depends on the reservoir permeability, as expressed by formula (11). The stronger the pressure conductivity, the weaker the pressure attenuation from the injection end to the middle of the oil-water well, and vice versa. （11） In the formula: —Coefficient of pressure conductivity; K —Reservoir permeability; C t —Comprehensive compression ratio; —Reservoir porosity; For several maximum production volumes existing in the same water-bearing stage, the top four production volumes are selected, and their average value is determined as the maximum production volume of the oil well in the mining area.

Images