Positive and negative displacement experimental device and method for oilfield water drive development

Abstract

The invention belongs to the technical field of oil field water drive development, and discloses a positive and negative displacement experiment device and method for oil field water drive development. The device comprises a constant-flow constant-speed displacement pump, a displacement pump outlet valve, a water intermediate container, an oil intermediate container, a six-way valve a, an emptying system, a six-way valve b, a core holder, a confining pressure pump, a metering system, a constant-temperature box and a pressure sensor. The method comprises the steps of optimal steering opportunity research, reverse displacement parameter research and parallel core forward and reverse displacement experiment research. According to the method, a theoretical basis is provided for researching the influence of redistribution of the remaining oil on the core recovery degree after the displacement direction is changed, and the method plays an important role in making a development scheme of a water-drive oil field.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield water flooding development, and in particular relates to a forward and reverse displacement experimental device and method for oilfield water flooding development. Background Art

[0002] At present, the water drive reversal field test in Jilin Oilfield has entered the implementation stage, but the microscopic oil increase mechanism, reversal timing, and reverse displacement parameters are still unclear. It is necessary to combine core experiments to understand its mechanism, reversal timing and other parameters and the microscopic occurrence state of the remaining oil, and to clarify the changes in the degree of positive and reverse displacement under different reservoir types, different well network methods, and different water content conditions. Summary of the invention

[0003] In order to overcome the deficiencies of the prior art, the present invention provides a forward and reverse displacement experimental method for oil field water drive development. The method carries out forward displacement to reverse displacement, compares the change in the degree of recovery and the final degree of recovery, and optimizes the best turning time. Carry out reverse drive parameter optimization, such as injection rate, injection volume, periodicity, etc., compare and analyze the final degree of recovery, and clarify the optimal parameters for reverse drive displacement. At the same time, the experimental optimization of the influence of different stop injection times on the reverse drive effect is carried out, which provides a theoretical basis for studying the influence of the redistribution of residual oil on the core recovery degree after changing the displacement direction, and plays an important role in the formulation of development plans for water drive oil fields.

[0004] The above-mentioned purpose of the present invention is achieved through the following technical scheme: a forward and reverse displacement experimental device for oilfield water flooding development, comprising a constant flow and constant speed displacement pump, a displacement pump outlet valve, a water intermediate container, an oil intermediate container, a six-way valve a, an emptying system, a six-way valve b, a core clamp, a confining pressure pump, a metering system, a constant temperature box, and a pressure sensor; wherein the constant flow and constant speed displacement pump is connected to the six-way valve a pipeline and a displacement pump outlet valve is provided on the pipeline, the six-way valve a is further connected to a water intermediate container and an oil intermediate container, the other ends of the water intermediate container and the oil intermediate container are connected to the six-way valve b, the six-way valve b is also connected to the emptying system, the pressure sensor, and the core clamp in the constant temperature box, and the core clamp is also connected to the metering system in the constant temperature box and the confining pressure pump outside the constant temperature box.

[0005] A forward and reverse displacement experimental method for oilfield water flooding development, comprising the following steps:

[0006] 1. Open the forward and reverse displacement experimental device used for oilfield water flooding development to conduct displacement experiments;

[0007] 2. Study on the best diversion time: 18 core samples with different sedimentary types, different vertical layers and different well patterns were selected to carry out forward displacement and reverse displacement, and compare the changes in the recovery degree and the final recovery degree;

[0008] 3. Reverse displacement parameter study: Based on the determination of the best turning time, select one core each from the # and 2# layers of different sedimentary types for comparative analysis, conduct reverse displacement parameter study, compare and analyze the final recovery degree, and clarify the best parameters for reverse displacement;

[0009] 4. Experimental study on forward and reverse displacement of parallel cores: Three cores with different vertical layers are selected in parallel. First, forward displacement is carried out until the water content reaches 100%, and the recovery degree of each core is calculated respectively; then reverse displacement is carried out until the recovery degree no longer increases, and the recovery degree of each core is calculated respectively; finally, the overall recovery degree is calculated, and the relationship between the increase in the recovery degree of each core and the layer is analyzed.

[0010] Furthermore, the timing of switching from forward displacement to reverse displacement in step 2 is at water content of 75%, 80%, 85%, 90%, 95% and 100% respectively.

[0011] Furthermore, the parameters in the reverse drive parameter study in step 3 include injection speed, injection volume, and periodicity.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: when various cores are forward driven to the moment when the water content is 100%, the higher the core permeability, the higher the forward oil recovery rate. The lower the permeability, the higher the recovery rate is compared with the forward drive reverse drive. The high and low core permeability has a good correlation with the recovery rate improvement by reverse drive; through the reverse drive parameter optimization experiment of the 1# and 2# reservoir cores, it can be known that the reasonable time for core reverse drive is 0.3PV~0.5PV; within the low permeability range, the final recovery degree of the core increases first and then decreases with the increase of the reverse drive speed, and there is a reasonable reverse drive speed; the reasonable reverse drive speed of the relatively low permeability core is lower than the reverse drive speed of the relatively high permeability core. The displacement speed is suitable at 0.05mL / min~0.1mL / min. In the low permeability range, the lower the core permeability, the longer the stop injection time, the better the reverse drive effect. When the permeability is relatively high, the longer the stop injection time, the smaller the reverse drive amplification effect. The existence of stop injection time can effectively improve the recovery degree. Methods From forward displacement to reverse displacement, the changes in the recovery degree and the final recovery degree are compared to select the best turning time. Reverse drive parameter optimization is carried out, such as injection rate, injection volume, periodicity, etc., the final recovery degree is compared and analyzed, and the optimal parameters of reverse drive displacement are clarified. At the same time, the experimental optimization of the influence of different stop injection times on the reverse drive effect is carried out, which provides a theoretical basis for studying the influence of the redistribution of residual oil on the core recovery degree after changing the displacement direction, and plays an important role in the development plan of water-driven oilfields. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0014] Figure 1 This is a structural diagram of the forward and reverse displacement experimental device of the present invention for oil field water flooding development;

[0015] Figure 2 is 0.5×10 -3 μm 2 Core forward and reverse flooding water content, recovery rate, and pressure change diagram;

[0016] Figure 3 is 10×10 -3 μm 2 Core forward and reverse flooding water content, recovery rate, and pressure change diagram;

[0017] Figure 4 It is the recovery factor increase diagram of different permeability layers;

[0018] Figure 5 is 0.5×10 -3 μm 2 Core recovery factor increase graph, reverse drive timing optimization experiment bar graph;

[0019] Figure 6 is 10×10 -3 μm 2 Core recovery factor increase graph, reverse drive timing optimization experiment bar graph;

[0020] Figure 7 is 0.5×10 -3 Line graph of reverse displacement velocity optimization experiment;

[0021] Figure 8 is 10×10 -3 Line graph of reverse displacement velocity optimization experiment;

[0022] Fig. 9 is 0.5×10 -3 Line chart of the injection stop time optimization experiment;

[0023] Fig.10 is 10×10 -3 Line chart of the injection stop time optimization experiment;

[0024] Fig.11 It is the parallel drive flow distribution curve.

[0025] In the figure, 1. constant flow and constant speed displacement pump; 2. displacement pump outlet valve; 3. water intermediate container; 4. oil intermediate container; 5. six-way valve a; 6. emptying system; 7. six-way valve b; 8. core clamp; 9. confining pressure pump; 10. metering system; 11. constant temperature box; 12. pressure sensor. DETAILED DESCRIPTION

[0026] The present invention is described in detail below by specific examples, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0027] Example 1

[0028] A forward and reverse displacement experimental device for oilfield water flooding development comprises a constant flow and constant speed displacement pump, a displacement pump outlet valve, a water intermediate container, an oil intermediate container, a six-way valve a, an emptying system, a six-way valve b, a core clamp, a confining pressure pump, a metering system, a thermostat, and a pressure sensor; wherein the constant flow and constant speed displacement pump is connected to the six-way valve a pipeline and a displacement pump outlet valve is arranged on the pipeline, the six-way valve a is further connected to a water intermediate container and an oil intermediate container, the other ends of the water intermediate container and the oil intermediate container are connected to the six-way valve b, the six-way valve b is also connected to the emptying system, the pressure sensor, and a core clamp in the thermostat, and the core clamp is also connected to the metering system in the thermostat and the confining pressure pump outside the thermostat.

[0029] A forward and reverse displacement experimental method for oilfield water flooding development, comprising the following steps:

[0030] 1. Open the forward and reverse displacement experimental device used for oilfield water flooding development to conduct displacement experiments;

[0031] 2. Study on the best diversion time: 18 core samples with different sedimentary types, different vertical layers and different well patterns were selected to carry out forward displacement and reverse displacement, and compare the changes in the recovery degree and the final recovery degree;

[0032] 3. Reverse displacement parameter study: Based on the determination of the best turning time, select one core each from the # and 2# layers of different sedimentary types for comparative analysis, conduct reverse displacement parameter study, compare and analyze the final recovery degree, and clarify the best parameters for reverse displacement;

[0033] 4. Experimental study on forward and reverse displacement of parallel cores: Three cores with different vertical layers are selected in parallel. First, forward displacement is carried out until the water content reaches 100%, and the recovery degree of each core is calculated respectively; then reverse displacement is carried out until the recovery degree no longer increases, and the recovery degree of each core is calculated respectively; finally, the overall recovery degree is calculated, and the relationship between the increase in the recovery degree of each core and the layer is analyzed.

[0034] The timing of switching from forward displacement to reverse displacement in step 2 is respectively at water content of 75%, 80%, 85%, 90%, 95% and 100%.

[0035] The parameters in the reverse drive parameter study in step 3 include injection speed, injection volume, and periodicity.

[0036] Example 2

[0037] Experiments were conducted using the apparatus and method in Example 1

[0038] 1. Core selection

[0039] A total of 18 groups of positive and negative displacement experiments were carried out, and 6 groups of cores with different typical strata and permeabilities were selected for analysis.

[0040] 2. Wash the core for oil, dry it for 36 hours, measure the gas permeability, and weigh the dry weight.

[0041] 3. Use a vacuum pump to draw suction from the core to create a vacuum inside the core for 24 hours. Use the vacuum pressure inside the core to make the core self-absorb saturated with water. Finally, use a displacement pump to perform a pressurization method to saturate the core with water. Calculate the pore volume and porosity of the core saturated with water based on the dry weight and wet weight of the core.

[0042] 4. Use simulated oil to displace formation water and establish irreducible water saturation.

[0043] 5. Use a displacement pump to displace at a constant speed of 0.1 ml / min until the water content reaches 100%, and then end the experiment by positive displacement. During the displacement process, record the oil production, water production and experimental pressure.

[0044] 6. After the forward flooding experiment, the core was subjected to a reverse flooding experiment. The reverse flooding was carried out at a constant speed of 0.1 ml / min, and the displacement was 1.00 PV. The experiment was ended. The experimental pressure of oil and water production was recorded during the flooding process.

[0045] 7. 18 core samples with different sedimentary types, different vertical layers and different well network conditions were selected, and forward displacement was carried out to 0.1PV, 0.2PV, 0.3PV, 0.5PV, 1.0PV and 2.0PV, and reverse displacement was carried out to compare the changes in the recovery degree and the final recovery degree, and to select the best turning time.

[0046] 8. Conversion between indoor stop injection time and on-site stop injection time. After the stop injection, the water in the large pores of the core enters the small pores through the infiltration and drives the retained oil in the small pores to the large pores, and the remaining oil in the core will be redistributed. Therefore, the length of the stop injection time is related to the infiltration behavior.

[0047] The imbibition behavior depends on: ① rock properties such as porosity, permeability and pore structure; ② fluid properties such as viscosity, surface tension and ③ physical parameters such as size, shape and sample boundary conditions.

[0048] Commonly used dimensionless time-scaled indoor infiltration data

[0049]

[0050]

[0051] Where: tD is dimensionless time; K is permeability; is the porosity; σ is the fluid interfacial tension; μ is the fluid viscosity; D is the core diameter; L is the core length; Lc is the characteristic length, which depends on the sample shape and boundary conditions.

[0052] Based on the dimensionless time theory of Mattax and Kyte, the dimensionless time under indoor conditions is equal to the dimensionless time under oil field conditions.

[0053]

[0054] Assuming that the porosity, permeability, interfacial tension and viscosity of indoor conditions and oil field conditions are the same, it is simplified to:

[0055]

[0056] Figure 2 and Figure 3 The following is a graph showing the change of water content, recovery rate, and pressure in the forward and reverse flooding of a single core. The injection pressure increased rapidly at the beginning of the experiment, and then tended to be gentle, with a relatively gentle overall change trend. During the reverse water injection flooding stage of the core, the total injection pressure of the core initially showed an upward trend, and then gradually fell back. For cores with low permeability, due to the large difference in pores, during the forward flooding process, the wettability of the natural core is water-wet. Under the action of capillary force, the water in the large and small parallel pores preferentially reaches the outlet along the small pores, and a large number of residual oil droplets may mainly remain in the large pores; after the reverse flooding, the Jiamin effect becomes relatively weak, and part of the oil droplets in the large pores can synthesize a continuous oil phase through the pore throats. There is oil phase flow in the entire core interval, and the recovery rate is greatly increased. For cores with higher permeability, the recovery rate of the forward flooding is already high, there is less residual oil in the pores, and the increase in the reverse flooding recovery rate is also low.

[0057] Figure 4 The figure is a recovery factor increase diagram for different permeability layers. By comparing and analyzing the recovery factor enhancement status of core reverse displacement in different layers of different wells, it can be seen that the core permeability has a good correlation with the recovery factor enhancement amplitude of reverse displacement.

[0058] Figure 5 and Figure 6 For the optimization experiment of reverse flooding timing for different permeability layer recovery rate enhancement diagram, the core reverse flooding timing can obtain a higher recovery rate when the forward flooding water injection multiple is between 0.3PV-0.5PV. The main reasons are as follows:

[0059] If the water injection multiple of the forward displacement is too low during the reverse displacement of the core, the injected water will not be able to fully reach the core, thereby reducing the recovery rate during the forward displacement process and increasing the retention of residual oil during the reverse displacement process.

[0060] If the water injection multiple of the forward displacement is too high during the reverse displacement of the core, water channeling channels will form and expand rapidly inside the core, which increases the complexity of the distribution of remaining oil in the core; during reverse displacement, the injected water will advance rapidly along the formed water channeling channels and cannot play an effective displacement role.

[0061] Figure 7 and Figure 8 It is the result of the reverse displacement speed optimization experiment. After the forward displacement of the low permeability core is completed, the reverse displacement speed and the injection stop time have a significant impact on the utilization of the remaining oil. On the basis of the optimization of the reverse drive timing, according to the on-site injection water advancement rate (2.3~14.0m / d), two cores were selected for the forward and reverse displacement injection speed optimization experiment.

[0062] When the permeability is relatively low, the injection rate is between 0.01 and 0.1 mL / min, and the water content of the core reverse drive decreases. When the reverse drive rate is 0.5 mL / min, the water content of the core reverse drive does not decrease immediately. Due to the large amount of injected water, the dominant water flow channel inside the core is quickly formed and expanded. A large amount of water does not play an effective role in displacement, but is directly produced from the production end, reducing water drive and increasing the degree of recovery.

[0063] Fig. 9 and Fig.10 This is the result of the stop injection time experiment. When the low permeability core is displaced to a certain extent, the injection is stopped. At this time, part of the remaining oil in the core will be redistributed under the action of capillary force, especially in the core with low permeability. This phenomenon will be more obvious. In order to study the effect of the redistribution of the remaining oil on the core recovery degree after changing the displacement direction, an experiment on the effect of different stop injection times on the reverse displacement effect was carried out.

[0064] Fig.11 It is a parallel drive flow rate curve. Through parallel core forward and reverse drive experiments, according to the actual geological characteristics of the formation, three cores are selected in parallel vertically. First, forward drive is carried out until the water content is 100%, and the recovery degree of each core is calculated respectively; then reverse drive is carried out until the recovery degree no longer increases, and the recovery degree of each core is calculated respectively; finally, the overall recovery degree is calculated, and the relationship between the increase in the recovery degree of each core and the stratum is analyzed.

[0065] As the parallel displacement experiment proceeds, during the forward and reverse flooding processes, most of the injected water flows along the high permeability channel, and the high permeability liquid production ratio is high.

[0066] The above-described embodiments are only preferred embodiments of the present invention, but not all feasible embodiments of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.

Claims

1. A forward and reverse displacement experimental device for oilfield water flooding development, It is characterized in that The invention comprises a constant flow and constant speed displacement pump (1), a displacement pump outlet valve (2), a water intermediate container (3), an oil intermediate container (4), a six-way valve a (5), an exhaust system (6), a six-way valve b (7), a core holder (8), a confining pressure pump (9), a metering system (10), a thermostat (11), and a pressure sensor (12); wherein the constant flow and constant speed displacement pump (1) is connected to the six-way valve a (5) through a pipeline, and a displacement pump outlet valve (2) is provided on the pipeline. The six-way valve a (5) is also connected to a water intermediate container (3) and an oil intermediate container (4); the other ends of the water intermediate container (3) and the oil intermediate container (4) are connected to a six-way valve b (7); the six-way valve b (7) is also connected to an exhaust system (6), a pressure sensor (12), and a core holder (8) in a thermostatic box (11); the core holder (8) is also connected to a metering system (10) in the thermostatic box (11) and a confining pressure pump (9) outside the thermostatic box (11).

2. A forward and reverse displacement experimental method for oilfield water flooding development, It is characterized in that the steps include: S1. Open the forward and reverse displacement experimental device for oilfield water flooding development as claimed in claim 1 to conduct a displacement experiment; S2. Study on the best diversion time: 18 core samples with different sedimentary types, different vertical layers and different well patterns were selected to carry out forward displacement and reverse displacement, and compare the changes in the recovery degree and the final recovery degree; S3. Reverse displacement parameter study: Based on the determination of the best diversion time, select one core from each of the # and 2# layers of different sedimentary types for comparative analysis, conduct reverse displacement parameter study, compare and analyze the final recovery degree, and clarify the best parameters for reverse displacement; S4. Experimental study on forward and reverse displacement of parallel cores: Three cores with different vertical layers are selected in parallel. First, forward displacement is carried out until the water content reaches 100%, and the recovery degree of each core is calculated respectively; then reverse displacement is carried out until the recovery degree no longer increases, and the recovery degree of each core is calculated respectively; finally, the overall recovery degree is calculated, and the relationship between the increase in the recovery degree of each core and the layer is analyzed.

3. The forward and reverse displacement experimental method for oilfield water flooding development according to claim 2, It is characterized in that The step S2 specifically includes: selecting 18 core samples with different sedimentary types, different vertical layers, and different well pattern conditions, carrying out forward displacement and reverse displacement, and comparing the changes in the recovery degree and the final recovery degree.

4. The forward and reverse displacement experimental method for oilfield water flooding development according to claim 2, It is characterized in that The step S3 is specifically as follows: based on the determination of the best turning time, one core each of the # and 2# layers of different sedimentary types that can be compared and analyzed is selected to carry out a reverse drive parameter study, compare and analyze the final recovery degree, and clarify the best reverse drive displacement parameters.

5. The forward and reverse displacement experimental method for oilfield water flooding development according to claim 2, It is characterized in that The step S4 is specifically as follows: three cores are selected in parallel to form different vertical layers, and firstly forward displacement is carried out until the water content reaches 100%, and the recovery degree of each core is measured respectively; then reverse displacement is carried out until the recovery degree no longer increases, and the recovery degree of each core is measured respectively; finally, the overall recovery degree is calculated, and the relationship between the increase in the recovery degree of each core and the layer is analyzed.

6. The forward and reverse displacement experimental method for oilfield water flooding development according to claim 3, It is characterized in that The timing of switching from forward displacement to reverse displacement in step S2 is respectively at water content of 75%, 80%, 85%, 90%, 95% and 100%.

7. The forward and reverse displacement experimental method for oilfield water flooding development according to claim 4, It is characterized in that The parameters in the reverse drive parameter study in step S3 include injection speed, injection volume, and periodicity.

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