A method for evaluating the oil displacement performance of an oil displacement system

Abstract

The application provides a method for evaluating the oil displacement performance of an oil displacement system, which comprises the following steps: determining matching parameters of the oil displacement system and the oil reservoir performance; determining the weight of the matching parameters and the qualified value range of the matching parameters; determining the oil displacement system that does not meet the qualified value range of the matching parameters as an unqualified system and determining the oil displacement system that meets the qualified value range of the matching parameters as a qualified system; separately scoring the value of each matching parameter in the qualified system and sub-combination scoring the sub-combinations between the matching parameters, and distributing the sub-combination scores to each matching parameter according to the weight coefficients in the sub-combinations to obtain the comprehensive scores of the matching parameters; and calculating the overall score of the qualified system according to the weight and the comprehensive score of the matching parameters to quantitatively characterize the oil displacement system. The method can evaluate the oil displacement system with single component or multiple components, and can screen the oil displacement system with high oil displacement rate through only indoor tests, and is simple and convenient.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil production, and particularly relates to a method for evaluating oil displacement performance of an oil displacement system. BACKGROUND

[0002] Chemical flooding is one of the dominant technologies for enhancing oil recovery in continental sedimentary oilfields. The second potential evaluation result shows that chemical flooding (polymer flooding and chemical composite flooding) can increase recoverable reserves, in which the potential of chemical composite flooding accounts for 52.3%. At present, the chemical composite flooding technology is generally in a critical period of transition from strong alkali to weak alkali and no alkali.

[0003] With the increasingly expanding of oil reservoir objects and the technical progress of chemical flooding, the object of chemical composite flooding is expanded from high-permeability oil reservoirs (class I) to low-permeability oil reservoirs (classes II and III), and from large-scale sandstone oil reservoirs to complex fault-block oil reservoirs, conglomerate oil reservoirs and fractured oil reservoirs. Harsh oil reservoir conditions and imperfect supporting technologies limit the application of chemical composite flooding technology.

[0004] The oil displacement experiment shows that the composite flooding production end produces continuous emulsion, and the emulsified oil displacement system can improve the oil displacement effect by 5-8% compared with the non-emulsified system. The monitoring of the Daqing field test shows that the oil recovery degree of the block with emulsification is increased by 5%-6% compared with the block without emulsification. The emulsification performance of the oil displacement system is crucial to ensure the effectiveness of the application. Surfactants can effectively improve the oil recovery. In the past, the performance of reducing the oil-water interfacial tension was basically taken as the evaluation key for screening surfactants. However, it is found in the research process that the oil displacement efficiency of the surfactant system with good interfacial performance is not necessarily high.

[0005] It is found that the strong emulsified system can better improve the oil displacement efficiency than the weak emulsified system, and the emulsion formed in the oil displacement process plays a very important role in improving the oil recovery. Especially with the development of the object to low-permeability, strong heterogeneity conglomerate, high-temperature and high-salt oil reservoirs, the polymer injection property and the improvement of sweep volume are difficult to be achieved at the same time, and the emulsification performance of the oil displacement system is crucial. The surfactant with strong emulsification capacity can form emulsion with crude oil. It is observed through the micro model that the emulsion droplets can produce a certain degree of plugging effect at the throat during the oil displacement process. The emulsification intensity regulation and its matching with the pore throat are the key oil displacement mechanisms of the binary composite flooding, and it is urgent to research the emulsification regulation and oil displacement system to greatly improve the oil displacement effect and orderly promote the field application of the binary composite flooding.

[0006] The current oil displacement evaluation mainly evaluates the macroscopic stability performance, and the static qualitative evaluation method (emulsification phase state, water shutoff rate and emulsification comprehensive index) cannot dynamically and systematically evaluate the emulsification performance. The stable mechanism of the emulsion cannot be obtained from the micro level, the quantitative research on the structure performance relationship is carried out, the individual oil displacement system is optimized, and the quantitative regulation of the emulsion grade of the oil displacement system is realized.

[0007] Therefore, it is necessary to develop a new evaluation method of oil displacement system. SUMMARY

[0008] In view of the problems in the prior art, the present application provides a method for evaluating the oil displacement performance of an oil displacement system, which combines the advantages of macro-emulsification and in-situ emulsification in porous media, optimizes key evaluation conditions to eliminate system errors, establishes a multi-dimensional quantitative characterization method based on multiple parameters such as water separation rate, emulsion viscosity, stability factor, dynamic and static emulsification particle size, droplet coalescence, visual in-situ emulsification and microfluidic seepage, and realizes accurate definition of the emulsification strength of different oil displacement systems.

[0009] To achieve this purpose, the present application adopts the following technical solutions:

[0010] The present application provides a method for evaluating the oil displacement performance of an oil displacement system, which comprises:

[0011] Determining the matching parameters of the oil displacement system and the reservoir performance;

[0012] Determining the weight of the matching parameters and the qualified value range of the matching parameters;

[0013] Determining the oil displacement system that does not meet the qualified value range of the matching parameters as an unqualified system, and determining the oil displacement system that meets the qualified value range of the matching parameters as a qualified system;

[0014] Separately scoring the values of each matching parameter in the qualified system and sub-combination scoring the sub-combinations between the matching parameters, and distributing the sub-combination scores to each matching parameter according to the weight coefficients in the sub-combinations to obtain the comprehensive scores of the matching parameters;

[0015] According to the weight and comprehensive score of the matching parameters, the overall score of the qualified system is calculated, and the oil displacement system is quantitatively characterized.

[0016] Preferably, the matching parameters include any one or a combination of at least two of the water separation rate, emulsion viscosity, stability factor, dynamic and static emulsification particle size, extensional rheological property, droplet coalescence time, microscopic sweep efficiency or porous medium short core migration retention capacity, preferably a combination of the extensional rheological property, droplet coalescence time, microscopic sweep efficiency and porous medium short core migration retention capacity.

[0017] In the present application, the water separation rate Wr is the separation ratio of water in the lower phase of the oil-water emulsion, which is equal to the ratio of the separation volume of water to the original volume.

[0018] In the present application, the emulsion viscosity μ refers to the Brookfield viscosity after the oil displacement system is mixed with crude oil.

[0019] The stability factor TSI in the application is a measure of the emulsion stability, and the smaller the value, the more stable the emulsion formed by the oil-water system.

[0020] The dynamic and static emulsion particle size d in the application is also a quantitative representation of the emulsion performance, and the smaller the particle size, the smaller the dynamic change, and the better the stability of the emulsion.

[0021] The extensional rheological property Dr in the application is another quantitative representation of the emulsion performance, and the interfacial extensional modulus and phase angle are two important parameters in the representation of the extensional rheological property. Among them, the extensional modulus (ε) is defined as the change of the interfacial tension with the interfacial area, which is a direct representation of the strength of the oil-water interfacial film, and is composed of extensional elasticity and extensional viscosity. The phase angle (θ) is the phase difference between the interfacial tension and the interfacial area change curve, and is equal to the ratio of the viscous modulus to the elastic modulus in quantity. The larger the extensional modulus, the smaller the phase angle, which means that the adsorption film formed by the surfactant molecules on the oil-water interface is more stable, and the film strength is higher.

[0022] The droplet coalescence time t in the application is an important parameter for representing the droplet coalescence ability, and the longer the time, the weaker the droplet drainage ability, the greater the difficulty of coalescence, and the higher the film strength of the emulsion.

[0023] The micro-irrigation efficiency η in the application is an important parameter for representing the micro-fluid dynamic seepage capacity, and the higher the efficiency, the better the effect of improving oil recovery.

[0024] The porous medium short core migration retention capacity Rc in the application is the ratio of the oil-water two-phase seepage pressure difference before the emulsion is generated in situ in the short core to the oil-water two-phase seepage pressure difference after the emulsion is generated, which is combined with the oil displacement experiment result to guide the selection of the oil displacement system, and the larger the Rc, the weaker the emulsion retention capacity.

[0025] Preferably, the method limits the qualified value range of the water separation rate to 15-90%, which can be 15%, 24%, 32%, 40%, 49%, 57%, 65%, 74%, 82% or 90%, etc., but is not limited to the listed values, and other unlisted values within the range are also applicable.

[0026] Preferably, the qualified value range of the emulsion viscosity is 1.0-40.0 cp, which can be 1.0 cp, 1.4 cp, 1.7 cp, 2 cp, 2.4 cp, 2.7 cp, 3 cp, 3.4 cp, 3.7 cp, 4.0 cp, 10 cp, 15 cp, 20 cp, 25 cp, 30 cp, 35 cp or 40 cp, etc., but is not limited to the listed values, and other unlisted values within the range are also applicable.

[0027] Preferably, the qualified value of the stability factor ranges from 0.8 to 10, such as 0.8, 1.83, 2.85, 3.87, 4.89, 5.92, 6.94, 7.96, 8.98, or 10, etc., but is not limited to the listed values, and other values not listed in the range are also applicable.

[0028] Preferably, the qualified value of the dynamic-static emulsion particle size ranges from 60 to 180 μm, such as 60 μm, 75 μm, 80 μm, 100 μm, 110 μm, 120 μm, 140 μm, 150 μm, 160 μm, or 180 μm, etc., but is not limited to the listed values, and other values not listed in the range are also applicable.

[0029] Preferably, the qualified value of the dynamic-static emulsion particle size ranges from 60 to 180 μm, such as 60 μm, 75 μm, 80 μm, 100 μm, 110 μm, 120 μm, 140 μm, 150 μm, 160 μm, or 180 μm, etc., but is not limited to the listed values, and other values not listed in the range are also applicable.

[0030] Preferably, the qualified value of the droplet coalescence time ranges from 2 to 50 s, such as 2 s, 8 s, 13 s, 18 s, 24 s, 29 s, 34 s, 40 s, 45 s, or 50 s, etc., but is not limited to the listed values, and other values not listed in the range are also applicable.

[0031] Preferably, the qualified value of the micro-areal sweep efficiency ranges from 50 to 95%, such as 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, etc., but is not limited to the listed values, and other values not listed in the range are also applicable.

[0032] Preferably, the qualified value of the porous media short core retention capacity ranges from 0.6 to 2.5, such as 0.6, 0.7, 0.8, 0.9, 1.0, 1.2, 1.5, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, or 2.5, etc., but is not limited to the listed values, and other values not listed in the range are also applicable.

[0033] Preferably, the sub-combination includes a first sub-combination and a second sub-combination.

[0034] Preferably, the first sub-combination is droplet coalescence time and extensional rheology.

[0035] The present application further preferably combines the droplet coalescence time and the extensional rheology as a first sub-combination for the combined score, because the combination of the two reflects the strength of the adsorption film formed by the surfactant molecules on the oil-water interface, and strengthening the film strength of the adsorption film has an impact on oil displacement, making the final evaluation more accurate.

[0036] Preferably, the sub-weight of the droplet coalescence time in the first sub-combination is 0.5-0.6, for example, it can be 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.58 or 0.6, etc., and the sub-weight of the extensional rheology in the first sub-combination is 0.4-0.5, for example, it can be 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46 or 0.5, etc.

[0037] Preferably, the second sub-combination is the combination of the stability factor and the dynamic-static emulsion particle size.

[0038] The present application further preferably combines the stability factor and the dynamic-static emulsion particle size for the combined evaluation, because the two together reflect the stability of the emulsion formed by the oil-water system, and strengthening the stability of the emulsion has an impact on oil displacement, making the final evaluation more accurate.

[0039] Preferably, the sub-weight of the stability factor in the second sub-combination is 0.3-0.45, for example, it can be 0.3, 0.31, 0.32, 0.33, 0.35, 0.38, 0.40, 0.41, 0.42, 0.43, 0.44 or 0.45, etc., and the sub-weight of the dynamic-static emulsion particle size in the second sub-combination is 0.55-0.7, for example, it can be 0.55, 0.58, 0.59, 0.6, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67 or 0.7, etc.

[0040] Preferably, the individual scoring and the sub-combination scoring each independently adopts an expert scoring method.

[0041] Preferably, the expert scoring method comprises: first determining the optimal range value of each matching parameter by an expert, and then dividing into 4 different grades according to the closeness to the optimal range value, the 4 different grades being excellent, good, medium and qualified, respectively.

[0042] Preferably, each of the grades corresponds to a different score.

[0043] Preferably, the weight of the water separation rate ranges from 0.05 to 0.1, for example, it can be 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1, etc., but is not limited to the listed values, and other unlisted values within this range are also applicable.

[0044] Preferably, the weight of the emulsion viscosity ranges from 0.05 to 0.1, for example, can be 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0045] Preferably, the weight of the stability factor ranges from 0.1 to 0.15, for example, can be 0.1, 0.11, 0.12, 0.13, 0.14 or 0.15, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0046] Preferably, the weight of the dynamic and static emulsion particle size ranges from 0.2 to 0.25, for example, can be 0.2, 0.21, 0.22, 0.23, 0.24 or 0.25, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0047] Preferably, the weight of the extensional rheological property ranges from 0.10 to 0.2, for example, can be 0.10, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19 or 0.2, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0048] Preferably, the weight of the droplet coalescence time ranges from 0.15 to 0.25, for example, can be 0.15, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24 or 0.25, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0049] Preferably, the weight of the micro-areal sweep efficiency ranges from 0.05 to 0.15, for example, can be 0.05, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14 or 0.15, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0050] Preferably, the weight of the porous media short core retention capacity ranges from 0.1 to 0.3, for example, can be 0.1, 0.13, 0.15, 0.17, 0.19, 0.22, 0.24, 0.26, 0.28 or 0.3, etc., but not limited to the listed values, other values not listed in the range are also applicable.

[0051] Preferably, the oil displacement system comprises a single component surfactant, a multi-component surfactant, or a combination of a surfactant and other components.

[0052] Compared with the prior art, the present application has at least the following beneficial effects:

[0053] (1) The method for evaluating the oil displacement performance of an oil displacement system provided by the present application is established based on multiple parameters such as water separation rate, emulsion viscosity, stability factor, dynamic and static emulsification particle size, extensional rheological performance, droplet coalescence, microfluidic visual in-situ emulsification and percolation, and porous medium short core retention capacity, so as to realize accurate definition of the emulsification strength of different oil displacement systems.

[0054] (2) The method for evaluating the oil displacement performance of an oil displacement system provided by the present application can reveal the interface and bulk phase molecular interaction mechanism of surfactants / polymer through the above evaluation mechanism, and deepen the synergistic effect law of the oil displacement system.

[0055] (3) The method for evaluating the oil displacement performance of an oil displacement system provided by the present application is based on the multiple parameter quantitative characterization of emulsification regulation of the oil displacement system, and can clearly determine the emulsification regulation and pore throat matching law of the system and the key role of the system in the large-scale recovery rate of the binary combination flooding, reveal the key technical indicators of emulsification regulation, deepen the understanding of the oil displacement mechanism of emulsification regulation, and clearly determine the potential of large-scale enhanced oil recovery and the main technical direction of different physical properties of oil reservoirs. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 is a flow chart of the method for evaluating the oil displacement performance of an oil displacement system provided by the present application. DETAILED DESCRIPTION

[0057] The technical solutions of the present application will be further described below by means of specific embodiments and in conjunction with the accompanying drawings.

[0058] The present application will be further described below. However, the following examples are only simple examples of the present application, and do not represent or limit the protection scope of the present application, and the protection scope of the present application is subject to the claims.

[0059] As a specific embodiment of the present application, a method for evaluating the oil displacement performance of an oil displacement system is provided, as shown in Figure 1 The method comprises the following steps:

[0060] Determine the matching parameters of the oil displacement system and the oil reservoir performance;

[0061] Determine the weight of the matching parameters and the qualified value range of the matching parameters;

[0062] Determine the oil displacement system that does not meet the qualified value range of the matching parameters as an unqualified system, and determine the oil displacement system that meets the qualified value range of the matching parameters as a qualified system;

[0063] Score each matching parameter in the qualified system individually and score the sub-combination between the matching parameters, and distribute the sub-combination score to each matching parameter according to the weight coefficient in the sub-combination to obtain the comprehensive score of the matching parameter;

[0064] The overall score of the qualified system is calculated according to the weight of the matching parameters and the comprehensive score, and the oil displacement system is quantitatively characterized.

[0065] Embodiment 1

[0066] The embodiment provides a method for evaluating the oil displacement performance of an oil displacement system, which tests four different unknown single-component surfactants, namely anionic-nonionic surfactant A, anionic surfactant B, linear betaine C and branched betaine D. The evaluation method comprises the following steps:

[0067] (1) Determining the matching parameters of the oil displacement system and the reservoir performance

[0068] The selected matching parameters include water separation rate, emulsion viscosity, stability factor, dynamic and static emulsification particle size, extensional rheological property, droplet coalescence time, microscopic sweep efficiency and porous medium short core retention capacity.

[0069] The test method of each matching parameter is as follows:

[0070] The water separation rate Wr is the separation ratio of water in the lower phase of the oil-water emulsion, which is equal to the ratio of the separation volume of water to the original volume.

[0071] The emulsion viscosity μ is tested by measuring the Brookfield viscosity of the oil displacement system and the crude oil mixed at a volume ratio of 1:1 at a rotation speed of 6 r / min. 1 ml of stable crude oil emulsion is placed in the center of the cone plate of the viscosity instrument to ensure the uniformity of the sample. The viscosity value is the steady-state value that does not change within 30 s.

[0072] The stability factor TSI is measured by an optical method. The fully emulsified crude oil emulsion (the volume ratio of the oil displacement system to the crude oil is 1:1, the same below) is first placed in the sample cell, and optical scanning is performed every 30 s within 2 h. The sum of the difference in light intensity before and after each scanning is the stability factor.

[0073] The dynamic and static emulsification particle size d is measured by a Malvern particle size analyzer. 1 ml of crude oil emulsion at different times is diluted 500 times by simulated formation water and then placed in a quartz tank. The distribution peak value of the test curve is considered as the particle size of the current emulsion.

[0074] Dilation rheological property Dr, 8 μL of oil droplets was immersed in a quartz tank filled with surfactant solution by bending needle, dA / A = 10% sinusoidal perturbation was applied to the oil droplets by the oscillator, the first step was the process of oscillation with constant frequency, the frequency was fixed at 0.1 Hz. After the dilation modulus no longer changed, the second step was the process of changing the frequency, the oscillation frequency was sequentially reduced in the order of 0.1, 0.055, 0.03, 0.017, 0.009, 0.005 Hz, the interface dilation modulus and phase angle were tested, and the dilation rheological property Dr was calculated.

[0075] Drop coalescence time t, two oil droplets with similar sizes were formed by a steel needle during the test process, and were immersed in a quartz tank filled with surfactant solution, the upper needle was kept stationary and connected to a micro-force balance, the lower needle slowly rose along the needle direction until the two oil droplets contacted, extruded and finally coalesced into a complete large oil droplet, the process from the beginning of contact to the completion of coalescence was the coalescence time t.

[0076] Microscopic sweep efficiency η, during the test process, the surfactant was injected into the heterogeneous glass model saturated with oil at a rate of 0.1 μL / min, the seepage and sweep situation in the model was monitored and recorded in real time by a body microscope, when the volume of oil in the model no longer changed, the photograph was taken and the gray scale was processed, the gray scale change of the oil phase was the microscopic sweep efficiency.

[0077] Porous medium short core retention capacity Rc, an oil reservoir natural core or short Berea core with a length of 5.0 cm and a diameter of 2.5 cm and a target permeability was taken, saturated with brine after vacuumizing, placed in a constant temperature and dryness box, and kept at a constant temperature of 45℃ for more than 3h to make the water fully wet the core, and the whole core reached the experimental temperature; the core was injected with 1.5 PV of crude oil and brine at a volume ratio of 1:1 through separate pipelines at a rate of 0.3 mL / min, and the pressure value during the injection process was recorded every 5 min. The average pressure value during the injection of 1-1.5 PV was taken as p wo ; the core was injected with 10 PV of crude oil and chemical flooding oil system solution at a volume ratio of 1:1 through separate pipelines at a rate of 0.3 mL / min; the core was injected with 3 PV of crude oil and brine at a volume ratio of 1:1 through separate pipelines at a rate of 0.3 mL / min, and the pressure value during the injection process was recorded every 5 min. The average pressure value during the injection of 2-3 PV was taken as p ewo ; Rc was calculated, the calculation formula of Rc was

[0078] The test results of the above matching parameters are shown in Table 1.

[0079] Table 1

[0080]

[0081] (2) Determine the weight of the matching parameters, and determine the qualified value range of the matching parameters, as shown in Table 2.

[0082] Table 2

[0083]

[0084] (3) Determine the oil displacement system that does not meet the qualified value range of the matching parameters as an unqualified system, and determine the oil displacement system that meets the qualified value range of the matching parameters as a qualified system; wherein anionic surfactant B does not meet the range of droplet coalescence time t, and is determined as an unqualified system.

[0085] (4) Score each matching parameter value in the qualified system separately and score the sub-combinations between the matching parameters, and distribute the sub-combination scores to each matching parameter according to the weight coefficients in the sub-combinations to obtain the comprehensive score of the matching parameters.

[0086] Select five experts to determine the optimal range value of each matching parameter, and take the average of the upper and lower limits to obtain the optimal range value, then divide it into four different levels according to the closeness to the optimal range value, the four different levels are excellent, good, medium and qualified, the corresponding scores are 1, 0.8, 0.6 and 0.4, wherein excellent and good need to fall within the optimal range value, medium and qualified are not within the range, the average results of the five experts are shown in Table 3, the units are referred to the units in Table 2.

[0087] Table 3

[0088]

[0089] The first sub-combination is droplet coalescence time and extensional rheological property, the sub-weight of droplet coalescence time in the first sub-combination is 0.5, and the sub-weight of extensional rheological property in the first sub-combination is 0.5.

[0090] The second sub-combination is the combination of stability factor and dynamic-static emulsion particle size, the sub-weight of stability factor in the second sub-combination is 0.35, and the sub-weight of dynamic-static emulsion particle size in the second sub-combination is 0.65. Redistribute it to the corresponding matching parameters to obtain the scores of each matching parameter as shown in Table 4.

[0091] Table 4

[0092]

[0093]

[0094] (5) According to the weight of the matching parameters and the comprehensive score, the overall score of the qualified system is calculated, and the oil displacement system is quantitatively characterized, and the calculation result is shown in Table 5.

[0095] Table 5

[0096] Anionic surfactant A Linear betaine C Branched betaine D Overall score 0.9075 0.7655 0.6035

[0097] As can be seen from Table 5, the anionic-nonionic surfactant A should have the best oil displacement effect, followed by the straight-chain betaine C, followed by the branched-chain betaine D, and the last is the anionic surfactant B which is determined to be unqualified.

[0098] In order to verify the above conclusion, the oil displacement experiment is carried out by using the above different oil displacement systems, and various indexes in the oil displacement process are measured, including EOR oil recovery rate, and the results are shown in Table 6.

[0099] The test method of EOR is as follows: a 30*4.5*4.5cm core is vacuum saturated with water, and the pore volume is measured. The core is placed in a 45℃ constant temperature box for heating for 15 hours. The core is saturated with crude oil, and after saturation, the core is placed in a 45℃ constant temperature box for heating for 20 hours. The water displacement is ended when the water content at the outlet reaches 98%, and the water displacement recovery rate is calculated. 0.3PV corresponding system + 0.2PV polymer protection slug 30mPa·s is injected, and the subsequent water displacement is ended when the water content at the outlet reaches 98%, and the recovery rate is calculated.

[0100] Table 6

[0101]

[0102] As can be seen from the above Table 6, the method for evaluating the oil displacement performance of the oil displacement system provided by the application can better evaluate the oil displacement system with excellent oil displacement effect, and the oil displacement system with high oil displacement effect can be better screened through indoor test, and the single-component and multi-component systems can be evaluated from multiple angles, and the screening cost of the oil displacement agent is reduced and the evaluation is more accurate.

[0103] The above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto, and those skilled in the art should understand that any changes or replacements within the technical scope disclosed by the application can be easily thought of by those skilled in the art, and all fall within the protection scope and disclosure scope of the application.

Claims

1. A method for evaluating the oil displacement performance of an oil displacement system, characterized by, The method comprises: determining matching parameters of the oil displacement system and the reservoir performance; determining the weight of the matching parameters and determining the qualified value range of the matching parameters; determining the oil displacement system not meeting the qualified value range of the matching parameters as an unqualified system and determining the oil displacement system meeting the qualified value range of the matching parameters as a qualified system; individually scoring the values of each matching parameter in the qualified system and subcombination scoring the subcombination between the matching parameters, and distributing the subcombination score to each matching parameter according to the weight coefficient in the subcombination to obtain the comprehensive score of the matching parameter; calculating the overall score of the qualified system according to the weight and the comprehensive score of the matching parameter, and quantitatively characterizing the oil displacement system; the matching parameters include at least two of the combination of water separation rate, emulsion viscosity, stability factor, dynamic and static emulsification particle size, extensional rheological property, droplet coalescence time, microscopic sweep efficiency or porous medium short core migration retention capacity; the oil displacement system is chemical complex flooding.

2. The method of claim 1, wherein, The method limits the qualified value range of the water separation rate to 15-90%.

3. The method of claim 1, wherein, The qualified value range of the emulsion viscosity is 1.0-40.0 cp.

4. The method of claim 1, wherein, The qualified value range of the stability factor is 0.8-10.

5. The method of claim 1, wherein, The qualified value range of the dynamic and static emulsification particle size is 60-180 μm.

6. The method of claim 1, wherein, The qualified value range of the extensional rheological property is 20-60 mN / m.

7. The method of claim 1, wherein, The qualified value range of the droplet coalescence time is 2-50 s.

8. The method of claim 1, wherein, The qualified value range of the microscopic sweep efficiency is 50-95%.

9. The method of claim 1, wherein, The range of the porous medium short core migration retention capacity is 0.6-2.

5.

10. The method of claim 1, wherein, The subcombination includes a first subcombination and a second subcombination.

11. The method of claim 10, wherein, The first subcombination is the combination of the droplet coalescence time and the extensional rheological property.

12. The method of claim 11, wherein, The subweight of the droplet coalescence time in the first subcombination is 0.5-0.6, and the subweight of the extensional rheological property in the first subcombination is 0.4-0.

5.

13. The method of claim 10, wherein, The second subcombination is the combination of the stability factor and the dynamic and static emulsification particle size.

14. The method of claim 13, wherein, The subweight of the stability factor in the second subcombination is 0.3-0.45, and the subweight of the dynamic and static emulsification particle size in the second subcombination is 0.55-0.

7.

15. The method of claim 1, wherein, The individual scoring and subcombination scoring each independently adopt an expert scoring method.

16. The method of claim 15, wherein, The expert scoring method comprises: first determining the optimal range value of each matching parameter by an expert, and then dividing into 4 different grades according to the closeness to the optimal range value, the 4 different grades being excellent, good, medium and qualified.

17. The method of claim 16, wherein, Each of the grades corresponds to different scores.

18. The method of claim 1, wherein, The weight range of the water separation rate is 0.05-0.

1.

19. The method of claim 1, wherein, The weight range of the emulsion viscosity is 0.05-0.

1.

20. The method of claim 1, wherein, The weight range of the stability factor is 0.1-0.

15.

21. The method of claim 1, wherein, The weight range of the dynamic and static emulsification particle size is 0.2-0.

25.

22. The method of claim 1, wherein, The weight range of the extensional rheological property is 0.10-0.

2.

23. The method of claim 1, wherein, The weight range of the droplet coalescence time is 0.15-0.

25.

24. The method of claim 1, wherein, The weight range of the microscopic sweep efficiency is 0.05-0.

15.

25. The method of claim 1, wherein, The weight range of the porous medium short core migration retention capacity is 0.1-0.3.

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