Experimental device and method for researching dynamic wave and volume of glutenite stratum

Abstract

The invention discloses an experimental device and method for researching dynamic waves and volume of glutenite stratum.The experimental device comprises a temperature control box and a rock core holder in the temperature control box, an experimental rock core is arranged in the rock core holder, and a plurality of sets of injection ends and extraction ends are arranged on the two sides of the rock core holder; the extraction end is connected with the liquid storage container through a pipeline, and the injection end is connected with an outlet of the displacement pump through a pipeline; the method comprises the following steps: fixing an experimental rock core for simulating glutenite in the rock core holder and putting the rock core holder in the temperature control box to simulate formation conditions; starting a displacement pump to inject an oil sample and simulated formation water into the experimental rock core in sequence, and simulating the influence of time on the dynamic evolution rule of swept volume in the oilfield development process according to the dynamic distribution of fluid between an injection end and an extraction end; and the water drive front edge position can be calculated. According to the method, a basis can be provided for oilfield water injection development, and the recovery efficiency of an oil layer can be conveniently improved by accurately regulating and controlling the water injection direction and speed in actual production.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield development, and in particular relates to an experimental device and method for studying the dynamic swept volume of a sandy conglomerate formation. Background Art

[0002] Water injection development is an important measure to stabilize oil production and improve oil recovery. Domestic oil reservoir development is mainly based on low permeability and tight oil reservoirs. Due to the heterogeneity of the reservoir itself (the heterogeneity of low permeability, ultra-low and even ultra-low permeability reservoirs is stronger), the advancement of the oil and water front is a non-piston-like advancement, so the determination of the advancement position of the front of the injected water in the process of water flooding oil brings great difficulties. During the development process, the injected water tends to flow along the pores with higher permeability, while the small pores are not fully washed, resulting in the contradiction of uneven water flooding on the plane and unbalanced water flooding on the section.

[0003] The sandstone reservoir has low permeability, complex pore structure, and serious microscopic heterogeneity, which leads to low water-to-oil efficiency during water injection. In addition, because of the extremely low porosity and permeability of abnormally high-pressure tight oil reservoirs and the large starting pressure gradient, the water absorption capacity of the water injection well is low, the starting pressure is large, and the pressure difference between the starting pressure and the fracture pressure is small, which increases the difficulty of water injection development.

[0004] In the actual production process, as the water injection time and water injection volume increase, the two-phase zone continues to expand, and the water drive front continues to move toward the oil well. However, the current existing technology cannot calculate the position of the water drive front, and cannot ensure the effective transmission of water drive pressure, resulting in an invalid cycle of water injection in the oil layer, resulting in water resource waste and formation pressure imbalance. Summary of the invention

[0005] The purpose of the present invention is to provide an experimental device and method for studying the dynamic swept volume of a sandy conglomerate formation, aiming to solve the technical problem that the existing device and method cannot calculate the water drive front position.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: An experimental device for studying the dynamic swept volume of a sandy conglomerate formation, the experimental device comprising a temperature control box and a core holder inside the box, an experimental core for simulating sandy conglomerate is arranged inside the core holder, a plurality of groups of injection ends and production ends are symmetrically arranged on both sides of the core holder, the production ends are connected to liquid storage containers through pipelines, and the number of the liquid storage containers is the same as that of the injection ends and the production ends; the injection end is connected to the outlet of a displacement pump through a pipeline, so as to simulate the fluid injection conditions in the actual formation.

[0007] Preferably, the material of the experimental core is epoxy resin.

[0008] Preferably, a mechanical property test is performed after the experimental core is produced.

[0009] Preferably, the liquid storage container is a glass tube, and a plurality of glass tubes are arranged in parallel on a tube rack.

[0010] Preferably, the lower end of the glass tube is threadedly engaged with the bottom of the tube rack.

[0011] An experimental method for studying the dynamic swept volume of a sandy conglomerate formation comprises the following steps: After the above experimental device is installed, it is placed in a temperature-controlled box for preheating to simulate the actual formation temperature; According to the experimental requirements, different oil displacement agents were injected into the experimental core to simulate water injection development. Oil samples were injected into the experimental core through a displacement pump, and the oil saturation was calculated after the experimental core was saturated with oil for 72 hours. After the oil displacement agent is switched to the prepared simulated formation water, the displacement pump is controlled to inject the simulated formation water at a constant displacement speed. The data recording time is set according to the displacement speed, and the changes in oil production in different areas are recorded. The dominant channel inside the core is determined according to the volume of oil samples collected by different glass tubes per unit time. After the liquid is discharged from the production end, the collected liquid volume is measured to calculate the water content and the degree of deviation of the water content:

[0012] In the formula: fw is the water content, %; Ls is the amount of water produced per unit time, ml; Ly is the amount of liquid produced per unit time, ml;

[0013] In the formula: s is the degree of deviation of water content, dimensionless; fw is the water content at a certain moment, %; fwi is the average water content of all outlet output fluids at a certain moment, %; fws is the standard deviation of the water content of all outlet output fluids at a certain moment, dimensionless; The dynamic evolution of the swept volume during the simulation of oil field development is affected by time: The swept volume coefficient at a certain moment:

[0014] v (t) is the swept volume coefficient at a certain moment, dimensionless; v (t, i) is the liquid production of a certain production end at a certain moment, ml / min; a is the injection end flow rate pumped in, ml / min, n is the number of production ends, pieces; b is the average flow rate at the production end outlet at that moment, ml / min; According to the v(t) experimental results, the dynamic sweep volume coefficient changes of conglomerate displacement at different times are obtained.

[0015] The position of the water drive front is analyzed by the change of water content at different positions. When the water content at a certain position is higher than that at other positions, it means that a dominant seepage channel appears at that position and the water drive front breaks through at this position.

[0016] Furthermore, before the experiment started, a displacement pump was used to inject saturated formation water into the experimental core and measure the wet weight of the core and the pore volume of the core. Then, the experimental core was dried to a constant weight and the dry weight of the core was measured.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The experimental device provided by the present invention simulates the temperature of the formation by fixing the experimental core of simulated sandstone in a core holder and placing it in a temperature control box; a plurality of injection ends and production ends are symmetrically arranged on both sides of the core holder, the production end is connected to the liquid storage container through a pipeline, and the injection end is connected to the outlet of the displacement pump through a pipeline, so as to simulate the fluid injection conditions in the actual formation. The displacement pump is used to inject oil samples and simulated formation water into the experimental core in sequence, and according to the dynamic distribution of the fluid between the injection end and the production end, the dynamic evolution law of the swept volume in the process of oil field development is simulated by time; the water drive front position can be calculated, and the water injection amount and pressure can be adjusted in time by monitoring the movement of the water injection front to ensure the stability and efficiency of the water injection process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0019] In the attached picture: Figure 1 A schematic diagram of the structure of an experimental device for studying the dynamic swept volume of a sandy conglomerate formation provided by an embodiment of the present invention; Figure 2 It is a curve diagram of the change of water content during the injection of nanoparticles with different concentrations; Figure 3 It is the variation curve of displacement front at different displacement time; Figure 4 It is a curve diagram of the front edge advance discrete index at different positions changing with time; Figure 5 It is a curve diagram showing the variation of the volume coefficient at different times; In the figure: 1- displacement pump; 2- injection end; 3- production end; 4- liquid storage container; 5- pipe rack; 6- core holder; 7- experimental core; 8- controller. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and Examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In the following detailed description of the present invention, some specific details are described in detail. However, for the parts not described in detail, those skilled in the art can also fully understand the present invention.

[0021] In addition, those skilled in the art should understand that the drawings are only provided to illustrate the purpose, features and advantages of the present invention, and the drawings are not actually drawn to scale.

[0022] At the same time, unless the context clearly requires otherwise, the words "include", "comprises" and similar words throughout the specification and claims should be interpreted as inclusive rather than exclusive or exhaustive; that is, the meaning is "including but not limited to".

[0023] like Figure 1 As shown, an experimental device for studying the dynamic swept volume of a sandy conglomerate formation is shown, the experimental device comprises a temperature control box (not shown) and a core holder 6 therein, the core holder 6 is provided with an experimental core 7 for simulating sandy conglomerate, a plurality of groups of injection ends 2 and production ends 3 are symmetrically provided on both sides of the core holder 6, the production ends 3 are connected to liquid storage containers 4 through pipelines, and the number of the liquid storage containers 4 is the same as that of the injection ends 2 and the production ends 3; the injection end 2 is connected to the outlet of the displacement pump 1 through a pipeline, so as to simulate the fluid injection conditions in the actual formation.

[0024] The displacement pump 1 is controlled by the controller 8. Due to the strong heterogeneity and permeability differences of the experimental core simulating sandstone, pressure control becomes complicated, and the amount of injected fluid needs to be precisely controlled to ensure the repeatability and accuracy of the experimental conditions. The displacement pump adopts a constant pressure and constant speed displacement pump with high-precision pressure control and flow regulation functions. The controller precisely controls the injection pressure and injection speed, so that the injection end and the production end have high-precision flow control and metering functions respectively to simulate the fluid injection conditions in the actual formation.

[0025] During the specific production, the material of the experimental core 7 is epoxy resin, and the structure is as follows: Figure 1 The long plate-shaped artificial conglomerate core shown. Since the particle size distribution of conglomerate has an important influence on its pore structure and mechanical properties, it is necessary to accurately control the particle size ratio of quartz sand during the production process to simulate the pore structure of natural conglomerate. The preparation is based on the particle size of the conglomerate rock in the actual natural situation. For example: 20 mesh quartz sand and 100 mesh quartz sand are prepared in a ratio of 3:1.

[0026] After the experimental core is made, a mechanical property test is performed to evaluate whether its performance indicators such as compressive strength, tensile strength, elastic modulus, etc. meet the requirements.

[0027] In a specific embodiment of the present invention, Figure 1 As shown, the liquid storage container 4 is a glass tube, and several glass tubes are arranged in parallel on the tube rack 5. The lower end of the glass tube is threadedly matched with the bottom of the tube rack 5. Since the experimental liquid may have the characteristics of being difficult to clean, such as high-viscosity oil, emulsion, etc., in order to facilitate the removal of residual experimental liquid and impurities, an easy-to-clean glass tube is used. At the same time, the columnar glass tube and the tube rack base are designed to be detachably connected, which is convenient for disassembly and cleaning.

[0028] The present invention also provides an experimental method for studying the dynamic swept volume of a sandy conglomerate formation, comprising the following steps: Before the experiment begins, a displacement pump is used to inject saturated formation water into the experimental core and measure the wet weight of the core and the pore volume of the core. Then the experimental core is dried to a constant weight and the dry weight of the core is measured. Using conventional oil displacement methods, before the formal experiment begins, it is necessary to measure its dry weight and the wet weight after vacuum saturation with water. The difference in mass is the pore volume.

[0029] After the above experimental device is installed, it is placed in a temperature-controlled box for preheating to simulate the actual formation temperature and conduct displacement experiments at a constant temperature; According to the experimental requirements, different oil displacement agents were injected into the experimental core to simulate water injection development. The oil sample was injected into the experimental core through a displacement pump. The oil saturation was calculated after the experimental core was saturated with oil for 72 hours. The calculation of oil saturation is an existing technology and will not be repeated here.

[0030] After the oil displacement agent is switched to simulated formation water prepared on site, the displacement pump is controlled to inject simulated formation water at a constant displacement speed. The data recording time is set according to the displacement speed, and the changes in oil production in different areas are recorded. According to the volume of oil samples collected by different glass tubes per unit time, the dominant channel inside the core is determined. Since the flow rate at different outlet positions of the production end during the displacement process will be affected by the swept volume of the oil displacement agent, the liquid production at different outlet positions will be different, and it will not flow out at the same flow rate. Therefore, the location of the dominant channel can be determined according to the volume of oil samples collected by different glass tubes per unit time. If the degree of deviation of the water content at a certain moment is large, it means that the changes in the water content at different outlets at that moment are significantly different, and the sweep effect of the displacement is poor.

[0031] As the time of formation water injection increases, it becomes difficult to continue to use water for displacement. Oil displacement agents can be used to increase the oil and water production per unit time, and then calculate the water content and water content changes. For the changes and parameters of the water flooding front, the degree of dispersion is analyzed, and then the swept volume is quantitatively characterized. The specific contents are as follows: After the liquid is discharged from the production end, the volume of the collected liquid (oil sample containing water) is measured to calculate the water content and the degree of deviation of the water content:

[0032] In the formula: fw is the water content, %; Ls is the amount of water produced per unit time, ml; Ly is the amount of liquid produced per unit time, ml;

[0033] In the formula: s is the degree of deviation of water content, dimensionless; fw is the water content at a certain moment, %; fwi is the average water content of all outlet output fluids at a certain moment, %; fws is the standard deviation of the water content of all outlet output fluids at a certain moment, dimensionless.

[0034] The degree of deviation of water content can characterize the change law of oil and liquid production under the same displacement conditions due to the influence of porous media structure. As the oil field development deepens, a variety of production-increasing measures are involved in the entire process of oil field development, resulting in dynamic changes in the displacement swept volume. Therefore, it is necessary to simulate the dynamic evolution of the swept volume during oil field development under the influence of time: The swept volume coefficient at a certain moment:

[0035] v (t) is the swept volume coefficient at a certain moment, dimensionless; v (t, i) is the liquid production of a certain production end at a certain moment, ml / min; a is the injection end flow rate (total injection end flow rate) pumped in, ml / min, n is the number of production ends, pieces; b is the average flow rate at the production end outlet at that moment, ml / min; According to the v(t) experimental results, the dynamic sweep volume coefficient changes of conglomerate displacement at different times are obtained.

[0036] The position of the water drive front is analyzed by the change of water content at different positions. When the water content at a certain position is higher than that at other positions, it means that a dominant seepage channel appears at that position and the water drive front breaks through at this position.

[0037] the following Figure 2-Figure 4 These are several curves calculated from experimental data, showing the dynamic changes of the displacement front during the displacement process. Figure 2As shown in the figure, the change curve of water content during the injection of oil displacement agents containing different concentrations of nanoparticles can characterize the oil displacement efficiency and recovery rate. Through the water content curve, the recovery rate under the injection of different concentrations of nanoparticles can be indirectly evaluated. The experimental process is to first inject formation water to simulate the fluid migration of the formation, then inject oil samples to simulate the migration and storage process of the oil phase in the formation, and finally inject oil displacement agents to simulate the development process. It can be seen that at a specific concentration, the appropriate nanoparticle concentration can more effectively reduce the oil-water interfacial tension and improve the fluidity of crude oil, thereby achieving a higher recovery rate at the same injection rate. The faster increase in water content may mean that the nanoparticles have a better displacement effect on crude oil at this concentration.

[0038] like Figure 3 As shown in the figure, the change rate of the front water saturation can indirectly reflect the displacement speed, and the relationship curve between the front water saturation and the outlet position can also reflect the displacement efficiency. Among them, water saturation = 1-oil saturation. If the curve shows that the front water saturation can reach a higher level in a shorter time, and the water phase output at the outlet position increases significantly, then it means that the displacement efficiency is high. If the front water saturation remains at a low level for a long time, and the water phase output at the outlet position increases slowly, it may mean that the recovery factor is low.

[0039] like Figure 4 As shown in the figure, the degree of frontal advance dispersion reflects the difference in fluid flow velocity in different regions of the reservoir. If the degree of dispersion is large, it means that there is obvious heterogeneous flow in the reservoir, that is, the fluid flow velocity in different regions is significantly different. This heterogeneity is often related to the permeability distribution of the reservoir. The fluid flow velocity in the high permeability area is fast, while the fluid flow in the low permeability area is slow, resulting in an increase in the degree of frontal advance dispersion. If the degree of dispersion is small and the displacement front advances steadily, it means that the displacement efficiency is high. Similarly, the change in the slope of the curve can reflect the change in the displacement velocity. A larger slope indicates a faster displacement velocity.

[0040] like Figure 5 As shown in Figure 2, the swept volume coefficient reflects the change in the swept volume of the oil displacement agent at different locations in the reservoir. The larger the swept volume coefficient, the smaller the swept volume of the oil displacement agent. Figure 5 It can be seen that as the experiment progresses, the swept volume coefficient of the oil displacement agent is low at the initial moment, and the sweep effect is good. However, when the displacement time reaches 25-45 minutes, the swept volume coefficient increases significantly, indicating that the sweep effect of the oil displacement agent becomes worse.

[0041] In summary, the present invention has a simple structure and is easy to operate. It can accurately simulate the process of water injection development and determine the position of the water drive front. The formation conditions are simulated by fixing the experimental core simulating sandstone in a core holder and placing it in a temperature-controlled box; the oil sample and simulated formation water are injected into the experimental core by a displacement pump in sequence, and the dynamic evolution law of the swept volume in the oil field development process is simulated according to the dynamic distribution of the fluid between the injection end and the production end. The influence of time; the position of the water drive front is calculated by monitoring the movement of the water injection front. The present invention can provide experimental data for oil field water injection development, which is convenient in actual production. By accurately controlling the direction and speed of water injection, the effective transmission of water drive pressure is ensured, thereby improving the recovery rate of the oil layer, while avoiding the formation of invalid circulation of water injection in the oil layer, resulting in waste of water resources and imbalance of formation pressure.

[0042] Accurately control the direction and speed of water injection to ensure the effective transmission of water drive pressure, thereby improving the recovery rate of the oil layer, while avoiding the formation of invalid circulation of water injection in the oil layer, resulting in waste of water resources and imbalance of formation pressure.

[0043] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of protection of the claims of the present invention.

Claims

1. An experimental device for studying the dynamic swept volume of a sandy conglomerate formation, characterized in that: The experimental device includes a temperature control box and a core holder inside the box. An experimental core for simulating sandstone is arranged inside the core holder. A plurality of injection ends and production ends are symmetrically arranged on both sides of the core holder. The production ends are connected to liquid storage containers through pipelines. The number of the liquid storage containers is the same as that of the injection ends and the production ends. The injection end is connected to the outlet of a displacement pump through a pipeline to simulate the fluid injection conditions in an actual formation.

2. The experimental device for studying the dynamic sweep volume of sandstone strata according to claim 1, characterized in that: The material of the experimental core is epoxy resin.

3. The experimental device for studying the dynamic sweep volume of sandstone strata according to claim 2, characterized in that: After the experimental core is made, a mechanical property test is performed.

4. The experimental device for studying the dynamic sweep volume of sandstone strata according to claim 1, characterized in that: The liquid storage container is a glass tube, and a plurality of glass tubes are arranged in parallel on a tube rack.

5. The experimental device for studying the dynamic sweep volume of sandstone strata according to claim 4, characterized in that: The lower end of the glass tube is threadedly matched with the bottom of the tube rack.

6. An experimental method for studying the dynamic swept volume of a sandy conglomerate formation, characterized in that: The following steps are involved: The experimental device as described in any one of claims 1 to 5 is installed and placed in a temperature-controlled box for preheating to simulate the actual formation temperature; According to the experimental requirements, different oil displacement agents were injected into the experimental core to simulate water injection development. Oil samples were injected into the experimental core through a displacement pump, and the oil saturation was calculated after the experimental core was saturated with oil for 72 hours. After the oil displacement agent is switched to the prepared simulated formation water, the displacement pump is controlled to inject the simulated formation water at a constant displacement speed. The data recording time is set according to the displacement speed, and the changes in oil production in different areas are recorded. The dominant channel inside the core is determined according to the volume of oil samples collected by different glass tubes per unit time. After the liquid is discharged from the production end, the collected liquid volume is measured to calculate the water content and the degree of deviation of the water content: ； In the formula: fw is the water content, %; Ls is the amount of water produced per unit time, ml; Ly is the amount of liquid produced per unit time, ml; ； In the formula: s is the degree of deviation of water content, dimensionless; fw is the water content at a certain moment, %; fwi is the average water content of all outlet output fluids at a certain moment, %; fws is the standard deviation of the water content of all outlet output fluids at a certain moment, dimensionless; The dynamic evolution of the swept volume during the simulation of oil field development is affected by time: The swept volume coefficient at a certain moment: ； v (t) is the swept volume coefficient at a certain moment, dimensionless; v (t, i) is the liquid production of a certain production end at a certain moment, ml / min; a is the injection end flow rate pumped in, ml / min, n is the number of production ends, pieces; b is the average flow rate at the production end outlet at that moment, ml / min; According to the v(t) experimental results, the dynamic sweep volume coefficient changes of the conglomerate displacement at different times are obtained; The position of the water drive front is analyzed by the change of water content at different positions. When the water content at a certain position is higher than that at other positions, it means that a dominant seepage channel appears at that position and the water drive front breaks through at this position.

7. The experimental method for studying the dynamic swept volume of a sandy conglomerate stratum according to claim 6, characterized in that: Before the experiment, a displacement pump was used to inject saturated formation water into the experimental core, measure the wet weight of the core, and measure the pore volume of the core. Then, the experimental core was dried to a constant weight and the dry weight of the core was measured.

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