Improved high-temperature and high-pressure three-dimensional large-scale model saturation testing method

Abstract

The invention discloses an improved high-temperature and high-pressure three-dimensional large-scale model saturation testing method. According to the method, a three-dimensional large-scale model experimental device is adopted for gas saturation testing; the experimental device comprises a three-dimensional large-scale model, an experimental fluid injection unit, a confining pressure pump and a gas-liquid separation metering device, a plurality of resistance wires which are crisscrossed and distributed in a #-shaped net-shaped structure are arranged in a cavity of the three-dimensional large-scale model, and according to physical property parameters and reservoir characteristic parameters of the target oil reservoir, quartz sand of a specific mesh number is selected to carry out layered sand filling on the cavity; and all the resistance wires are connected with the resistance tester through leads. According to the method, the three-dimensional large-scale model is filled with the net-shaped resistance wires to calibrate resistance values of different areas in the three-dimensional large-scale model under different gas saturation degrees. A chart curve is obtained by fitting data scatter points, so that the change condition of the gas saturation is calculated based on the resistance values of different areas in the three-dimensional large-scale model monitored in real time.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field exploration and development, and in particular to an experimental method for measuring gas saturation using an improved high-temperature and high-pressure three-dimensional large-scale model device. Background Art

[0002] With the adjustment of domestic energy strategy and the transformation of energy structure, more and more oil and gas fields have entered the mid-to-late development stage, and the difficulty of oil and gas resource development has increased day by day. The preparation and design of practical and effective oil and gas field development plans is an important way for oil and gas companies to improve the recovery rate of hydrocarbon resources and reduce production costs.

[0003] Reasonable water injection development methods can maximize the use of oil and gas resources, extend the production life of oil fields, and achieve sustainable development of oil fields. During the development process, the distribution and change characteristics of gas and water saturation can provide important theoretical support for the dynamic adjustment of development plans. Indoor physical simulation experiments are an important means to understand the changes in gas and water saturation during the actual development of underground reservoirs. At present, most studies are based on three-dimensional large-scale physical sand filling models.

[0004] For the determination of oil and water saturation in indoor three-dimensional large-scale physical models, the prior art CN104675394 A discloses a method for testing the distribution of oil and water saturation based on a three-dimensional physical simulation experimental device for heterogeneous bottom water oil and gas reservoirs. This method is based on resistivity electrode probes to monitor and collect the distribution of oil and water saturation in heterogeneous multi-layer flat plate edge bottom water models under different displacement multiples. However, during the measurement process, the electrode probe is easily surrounded by oil droplets or water droplets in the porous medium, resulting in large errors in the saturation measurement results; the electrode probe is easy to interfere with the seepage process of the displacement experiment, and the probe needs to be resistant to high pressure. In addition, the electrode probe required for such a device is expensive, and the required experimental cost is high. Summary of the invention

[0005] In view of the above-mentioned problems existing in the existing three-dimensional large-scale physical model saturation determination method using a resistivity probe, the present invention provides an improved high-temperature and high-pressure three-dimensional large-scale model saturation testing method, that is, testing the gas saturation by using an improved high-temperature and high-pressure three-dimensional large-scale model device.

[0006] The saturation test method of the present invention mainly calibrates the resistance values ​​of different areas in the three-dimensional large-scale model at different gas saturations during the development process by embedding mesh resistance wires in the three-dimensional large-scale model and connecting resistance testers to all resistance wires. Then, the corresponding plate curve is obtained by fitting the data scatter points, so that the change of gas saturation can be calculated based on the resistance values ​​of different areas in the three-dimensional large-scale model monitored in real time.

[0007] The saturation test method of the present invention is based on an improved three-dimensional large-scale model experimental device to perform gas saturation test.

[0008] The experimental device includes a three-dimensional large-scale model, an experimental fluid injection unit, a confining pressure pump and a gas-liquid separation metering device; the three-dimensional large-scale model includes a square shell, and a plurality of resistance wires are arranged in a cavity inside the shell in a criss-cross pattern to form a "well" mesh structure. According to the physical properties and reservoir characteristic parameters of the target oil reservoir, quartz sand of a specific mesh size is selected to fill the cavity in layers, and then the shell is sealed; all resistance wires are connected to the resistance tester through wires; a liquid inlet and a liquid outlet are respectively arranged at the left and right ends of the shell.

[0009] The experimental fluid injection unit includes a constant speed and constant pressure double-cylinder pump, an intermediate container filled with formation water and an intermediate container filled with formation gas. The constant speed and constant pressure double-cylinder pump is connected to the intermediate container filled with formation water and the intermediate container filled with formation gas through a pipeline to inject the experimental fluid into the three-dimensional large-scale model. The liquid inlet of the three-dimensional large-scale model is simultaneously connected to the intermediate container filled with formation water and the intermediate container filled with formation gas, and the liquid outlet is connected to the back pressure valve and the gas-liquid separation metering device, and the gas-liquid separation metering device records the gas and water production in real time. The three-dimensional large-scale model is installed in a clamp, and the confining pressure pump is connected to the clamp to apply confining pressure to the three-dimensional large-scale model. The back pressure valve is connected to the constant speed and constant pressure single-cylinder back pressure pump to provide back pressure for the displacement experiment.

[0010] It is further preferred that the experimental device also includes a computer control terminal, the resistance tester receives the electrical signal in real time, calculates the resistance value, and stores the result to the computer control terminal; and the computer control terminal can control the power supply of the resistance wire connected to the resistance tester in real time according to the experimental plan, so as to achieve the purpose of measuring the resistance values ​​in different areas and directions of the three-dimensional large-scale model.

[0011] The method for testing gas saturation based on the above experimental device is as follows:

[0012] S1. Install the experimental device.

[0013] S2. Simulate the original state of the gas reservoir: put the three-dimensional large-scale model into the holder, evacuate it, and then establish confining pressure; inject V1 volume of formation water into the three-dimensional large-scale model through a constant speed and constant pressure double-cylinder pump, so that the water saturation S in the model w Reach 100%; then inject the formation gas into the three-dimensional large-scale model through a constant speed and constant pressure double-cylinder pump until the gas-liquid separation metering device shows that the water production at the holder outlet is 0ml, then the injection is terminated and the injected gas volume V is recorded o1 and the output gas volume V o2

[0014] S3. Determine the resistance value R0 of the three-dimensional large-scale model under bound water saturation.

[0015] S4. Physical simulation of water flooding development of indoor gas reservoirs: Formation water is injected into the three-dimensional large-scale model through a constant speed and constant pressure double-cylinder pump. When the volume of formation water is 1, the resistance value R1 is measured, and the gas saturation S in the three-dimensional large-scale model is calculated. g1 , where V3 = V o1 -V o2 , n≥5;

[0016] S5. Repeat step S4 multiple times and record different gas saturations S gi The resistance value R of the three-dimensional large-scale model under i ;

[0017] S6, gas saturation S gi is the horizontal axis, the resistance value R i A scatter plot is drawn in a Cartesian coordinate system with the vertical coordinate as the ordinate, and a function is fitted to obtain a curve relationship chart between gas saturation and resistance value; based on this chart and the experimental device, when conducting further physical simulation experiments on indoor gas reservoir development, the gas and water saturations in the three-dimensional large-scale model at different times are calculated according to the real-time monitored resistance value, and their distribution patterns and change characteristics are analyzed.

[0018] In the above method, in step S3, different resistance wires can be connected to positive and negative electrodes to form a combination of schemes to determine the overall gas saturation of the model in the plane or vertical direction, as well as the gas saturation between different layers and between different pairs of resistance wires, and the measurement area is flexible and changeable.

[0019] Compared with the prior art, the present invention is beneficial in that:

[0020] (1) The resistance wires used in the present invention are distributed in a "well"-shaped grid pattern, dividing the sand-filled model into multiple blocks. By energizing the resistance wires in different directions, the resistivity in different directions of different regions can be obtained, thereby converting the horizontal and vertical gas and water saturations in different regions of the sand-filled model. This improvement can more comprehensively and flexibly monitor the gas and water saturation of the model during the experiment.

[0021] (2) Since the traditional electrode probe does not penetrate the sand filling model, the measured resistivity is easily affected by the model heterogeneity, and the gas and water saturation errors obtained are large. The resistance wire used in the present invention is small in size, has weak interference with fluid seepage, is less affected by the model heterogeneity, and has a more accurate measurement result.

[0022] (3) Traditional electrode probes are expensive, while resistance wires are cheaper. After the experiment, the contaminated resistance wires can be directly replaced, which reduces the test cost and improves the test efficiency.

[0023] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall planar structure of the three-dimensional large-scale model experimental device of the present invention.

[0025] Figure 2 Schematic diagram of the structure of the three-dimensional large-scale model.

[0026] Figure 3 Schematic diagram of the distribution of resistance wires inside the three-dimensional large-scale model.

[0027] Figure 4 It is a structural schematic diagram of the gas-liquid separation metering device.

[0028] Figure 5 This is a diagram showing the relationship between the resistance value and gas saturation curve measured and fitted at the top and between layers of the three-dimensional large-scale model in this embodiment.

[0029] Numbers in the figure: 1-constant speed and constant pressure double-cylinder pump; 2-valve; 3-intermediate container filled with formation water; 4-intermediate container filled with formation gas; 5-constant speed and constant pressure single-cylinder confining pressure pump; 6-clamp; 7-three-dimensional large-scale model; 8-conductor; 9-gas output metering component; 10-back pressure valve; 11-gas-liquid separation metering device; 12-constant speed and constant pressure single-cylinder back pressure pump; 13-resistance wire placement point; 14-computer control terminal; 15-resistance tester; 16-resistance wire; 17-gas-liquid separator; 91-metering tube; 92-liquid storage tank; 93-vacuum pump. DETAILED DESCRIPTION

[0030] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0031] like Figure 1-4As shown, the improved three-dimensional large-scale model experimental device used in the present invention includes a constant speed and constant pressure double-cylinder pump 1, and the constant speed and constant pressure double-cylinder pump 1 is connected to an intermediate container 3 filled with formation water and an intermediate container 4 filled with formation gas through two valves 2 respectively; it is used to inject experimental fluid into the three-dimensional large-scale model 7. The three-dimensional large-scale model 7 is installed in a clamp 6, and the intermediate container 3 and the intermediate container 4 are connected to the liquid inlet of the three-dimensional large-scale model 7 through a pipeline passing through the clamp 6. The confining pressure pump 5 is connected to the clamp 6 to apply confining pressure to the three-dimensional large-scale model 7. The confining pressure pump 5 is preferably a constant speed and constant pressure single-cylinder confining pressure pump. The liquid outlet of the three-dimensional large-scale model 7 is connected to a back pressure valve 10 and a gas-liquid separation metering device 11. The gas-liquid separation metering device 11 includes a gas-liquid separator 17 and an air outlet metering component 9. The gas-liquid separator 7 is used to separate the gas-liquid fluid discharged from the outlet of the three-dimensional large-scale model. The liquid is directly collected and measured by the gas-liquid separator 17, and the gas flows to the air outlet metering component 9, and the gas volume is collected and measured by the air outlet metering component. The structure of the air outlet metering component 9 includes a metering tube 91, a liquid storage tank 92 and a vacuum pump 93. A scale is set on the tube wall of the metering tube 91. One end of the metering tube 91 is connected to the air outlet of the gas-liquid separator 17. The liquid is contained in the liquid storage tank 92. The bottom end of the metering tube 91 is inserted below the liquid level in the liquid storage tank 92. The vacuum pump 93 is connected to the top of the metering tube 91 to suck the air in the metering tube 91. The working principle of the gas output metering component 9 is as follows: first, turn on the vacuum pump 92 to discharge the air in the metering tube 91, so that the liquid in the liquid storage tank 92 is adsorbed into the metering tube 91 and the scale where the liquid level is controlled to be 0; then, through the method of gas-water drainage, the gas discharged from the outlet of the three-dimensional large-scale model during the experiment enters the metering tube 91, which will drive the liquid in the metering tube to be discharged and flow into the liquid storage tank 92; finally, the gas discharge amount can be known according to the scale line. The gas-liquid separation metering device can accurately measure the gas and liquid produced in the experiment, and record the gas and water output in real time. The back pressure valve 10 is connected to the constant speed and constant pressure single-cylinder back pressure pump 12 to provide back pressure for the displacement experiment.

[0032] The three-dimensional large-scale model 7 includes a square shell, and a plurality of resistance wires 16 are arranged in the cavity of the shell in a criss-cross pattern in a "well" mesh structure. According to the physical parameters of the target oil reservoir and the reservoir characteristic parameters, quartz sand of a specific mesh size is selected to fill the cavity in layers, and then the shell is sealed. At the resistance wire placement point 13, all resistance wires 16 are connected to the resistance tester 15 through the wire 8; the resistance tester 15 is connected to the computer control terminal 14. The resistance tester receives the electrical signal in real time, calculates the resistance value, and stores the result to the computer control terminal; and the computer control terminal can control the power supply of the resistance wire connected to the resistance tester in real time according to the experimental plan, so as to achieve the purpose of measuring the resistance value in different areas and directions of the three-dimensional large-scale model.

[0033] The specific steps of saturation test using the above experimental device are as follows:

[0034] Step S1: construct and install the experimental device; place the resistance wire in a "well" mesh structure in the model, and select quartz sand of a specific mesh size to fill the three-dimensional large-scale model in layers according to the physical properties and reservoir characteristic parameters of the target gas reservoir; and connect and install the various components of the experimental device.

[0035] Step S2: Simulate the original state of the gas reservoir: First, place the three-dimensional large-scale model in the holder, evacuate the vacuum, and then close the inlet and outlet valves of the holder; open the constant speed and constant pressure single-cylinder confining pressure pump to establish confining pressure; then open the inlet valve of the holder, and inject V1 volume of formation water sample into the three-dimensional large-scale model through the constant speed and constant pressure double-cylinder pump, so that the water saturation S in the model is w When the gas-liquid separation metering device shows that the water output at the holder outlet is 0 ml, the injection is terminated and the injected gas volume V is recorded. o1 and the output gas volume V o2 .

[0036] Step S3: Determination of the resistance value of the three-dimensional large-scale model under irreducible water saturation. In this embodiment, the plane resistance value measurement is taken as an example, the mesh resistance wire of the top layer of the three-dimensional large-scale model is adjusted to the positive electrode, and the mesh resistance wire of the bottom layer is adjusted to the negative electrode, and the resistance value R0 between the top and bottom layers of the three-dimensional large-scale model under irreducible water saturation is measured.

[0037] Step S4: Physical simulation of water flooding development of indoor gas reservoirs: Inject formation water into the three-dimensional large-scale model through a constant speed and constant pressure double-cylinder pump. When the volume of formation water is measured, the resistance value R1 between the top and bottom layers of the three-dimensional large-scale model is measured once, and the gas saturation S in the three-dimensional large-scale model is calculated at this time. g1 ; Where V3 = V o1 -V o2 , n≥5.

[0038] Step S5: Repeat step S4 multiple times and record different gas saturations S gi The resistance value R between the top and bottom layers of the three-dimensional large-scale model i .

[0039] Step S6: using gas saturation S gi is the horizontal axis, the resistance value R i As the ordinate, a scatter plot is drawn in the Cartesian coordinate system, and a function fitting is performed to obtain a curve relationship chart between gas saturation and resistance value, such as Figure 5Based on this plate and the experimental device, when conducting further physical simulation experiments of indoor gas reservoir development, the gas and water saturations in the three-dimensional large-scale model at different times are calculated based on the real-time monitored resistance values ​​between the top and bottom layers, and their distribution patterns and change characteristics are analyzed.

[0040] In summary, this method proposes a method for determining gas saturation indoors through an improved high-temperature and high-pressure three-dimensional large-scale model device, which can avoid the surrounding and influence of water droplets on traditional resistivity electrode probes, as well as the interference of electrode probes on the displacement seepage process, so as to more conveniently and accurately understand the gas and water saturation distribution and change characteristics inside the simulated reservoir (three-dimensional large-scale model) during the experiment of the physical simulation development program of the gas reservoir.

[0041] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. An improved high temperature and high pressure three-dimensional large-scale model saturation test method, characterized in that: A three-dimensional large-scale model experimental device is used to test gas saturation; the experimental device includes a three-dimensional large-scale model, an experimental fluid injection unit, a confining pressure pump and a gas-liquid separation metering device; the three-dimensional large-scale model includes a square shell, a cavity inside the shell is provided with a plurality of resistance wires distributed in a criss-cross "well" mesh structure, and according to the physical parameters of the target oil reservoir and the reservoir characteristic parameters, quartz sand of a specific mesh size is selected to fill the cavity in layers, and then the shell is sealed; all the resistance wires are connected to the resistance tester through a wire; a liquid inlet and a liquid outlet are respectively provided at the left and right ends of the shell.

2. The improved high temperature and high pressure three-dimensional large-scale model saturation test method according to claim 1, characterized in that: The experimental fluid injection unit includes a constant speed and constant pressure double-cylinder pump, an intermediate container filled with formation water and an intermediate container filled with formation gas. The constant speed and constant pressure double-cylinder pump is connected to the intermediate container filled with formation water and the intermediate container filled with formation gas through a pipeline to inject experimental fluid into the three-dimensional large-scale model.

3. The improved high temperature and high pressure three-dimensional large-scale model saturation test method according to claim 2, characterized in that: The liquid inlet of the three-dimensional large-scale model is connected to an intermediate container filled with formation water and an intermediate container filled with formation gas at the same time, and the liquid outlet is connected to a back pressure valve and a gas-liquid separation metering device; the three-dimensional large-scale model is installed in a clamp; the confining pressure pump is connected to the clamp to apply confining pressure to the three-dimensional large-scale model.

4. The improved high temperature and high pressure three-dimensional large-scale model saturation test method according to claim 3, characterized in that: The back pressure valve is connected to a constant speed and constant pressure single cylinder back pressure pump to provide back pressure for displacement experiments.

5. The improved high temperature and high pressure three-dimensional large-scale model saturation test method according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Install the experimental device; S2, simulate the original state of the gas reservoir; S3, determining the resistance value R0 of the three-dimensional large-scale model under bound water saturation; S4. Physical simulation of water flooding development of indoor gas reservoirs: Formation water is injected into the three-dimensional large-scale model through a constant speed and constant pressure double-cylinder pump. When the volume of formation water is 1, the resistance value R1 is measured, and the gas saturation S in the three-dimensional large-scale model is calculated. g1 , where V3 = V o1 -V o2 , n≥5; S5. Repeat step S4 multiple times and record different gas saturations S gi The resistance value R of the three-dimensional large-scale model under i ; S6, gas saturation S gi is the horizontal axis, the resistance value R i A scatter plot is drawn in a Cartesian coordinate system with the vertical coordinate as the ordinate, and a function is fitted to obtain a curve relationship chart between gas saturation and resistance value; based on this chart and the experimental device, when conducting further physical simulation experiments on indoor gas reservoir development, the gas and water saturations in the three-dimensional large-scale model at different times are calculated according to the real-time monitored resistance value, and their distribution patterns and change characteristics are analyzed.

6. The improved high temperature and high pressure three-dimensional large-scale model saturation test method according to claim 5, characterized in that: The specific method of step S2 is as follows: The three-dimensional large-scale model is placed in the holder, vacuumed, and then the confining pressure is established; a constant speed and constant pressure double-cylinder pump is used to inject V1 volume of formation water into the three-dimensional large-scale model, so that the water saturation S w Reach 100%; then inject the formation gas into the three-dimensional large-scale model through a constant speed and constant pressure double-cylinder pump until the gas-liquid separation metering device shows that the water production at the holder outlet is 0ml, then the injection is terminated and the injected gas volume V is recorded o1 and the output gas volume V o2 .

7. The improved high temperature and high pressure three-dimensional large-scale model saturation test method according to claim 5, characterized in that: In step S3, by connecting different resistance wires to positive and negative electrodes, the overall gas saturation of the model in the plane or in the longitudinal direction, as well as the gas saturation between different layers and between different pairs of resistance wires are determined.

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