Determination method of oil-water relative permeability and dynamic characterization model in the process of oil displacement regulated by infiltration

Abstract

The present invention provides a method for determining the relative permeability of oil and water and a dynamic characterization model in the process of infiltration regulation and oil recovery. The method for determining the relative permeability of oil and water includes: constructing a capillary bundle geometric model; respectively determining the initial contact angle, final contact angle and oil-water interfacial tension of each capillary in the capillary bundle geometric model during the flow simulation process; constructing a contact angle constitutive model that reflects the change in rock wettability during the process of infiltration regulation and oil recovery, so as to constrain the size of each capillary contact angle in the capillary bundle geometric model during the flow simulation process; based on the initial contact angle, final contact angle, oil-water interfacial tension and contact angle constitutive model of each capillary in the capillary bundle geometric model during the flow simulation process, using the capillary bundle geometric model, step-by-step controlling the displacement pressure difference to perform multiple rounds of flow simulation, and obtaining the oil-water relative permeability curves at different stages in the process of infiltration regulation and oil recovery; wherein the flow simulation is a displacement flow simulation or a suction flow simulation.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development, and in particular to a method for determining oil-water relative permeability at different stages in an infiltration-controlled oil displacement process and a method for determining a dynamic characterization model thereof. Background Art

[0002] Tight oil, shale oil, and marine carbonate rock have the characteristics of low permeability, complex pore throat structure, strong heterogeneity, and rock tends to be oil-wet or mixed-wet. They face difficulties in production, rapid production decline, low recovery rate, and high mining costs, which need to be solved urgently. Since the pore throat scale of the reservoir is at the micro-nano level, it is difficult to establish an effective displacement system. The development of these types of reservoirs is still in a bottleneck period. Traditional enhanced recovery technologies (polymer flooding, ternary composite flooding, etc.) face technical difficulties such as poor reservoir adaptability and compatibility in promotion and application. Studies have shown that injecting nanofluids, surfactants, salts and other chemical agents into this type of reservoir for infiltration and regulation can gradually change the rock surface from oil-wet or mixed-wet to water-wet, which can greatly reduce the residual oil saturation and improve the efficiency of water flooding. During the infiltration and regulation flooding process, the oil displacement agent reacts with the reservoir rock, and there is a complex seepage-physical-chemical interaction in the porous medium. The rock wettability changes dynamically, which also determines the distribution state of the immiscible fluid.

[0003] The oil-water relative permeability curve is a constitutive equation that characterizes the flow capacity of wetting and non-wetting phase fluids in porous media. At present, the constitutive relationship of the core-scale oil-water relative permeability curve only reflects the influence of fluid saturation, and does not consider the dynamic changes of wettability at the pore scale. In general, rock wettability is considered to be constant, but in fact, rock wettability is a dynamically changing property, which is affected by factors such as rock surface chemical properties, fluid composition, reaction time with chemicals, reservoir temperature, and reservoir pressure. How to accurately characterize the dynamic changes of rock wettability at the pore scale and then accurately determine the core-scale oil-water relative permeability is particularly important for revealing the infiltration and seepage control mechanism of nanofluids, surfactants, ion-matched water and other systems, and guiding the optimization design of oilfield development plans. Summary of the invention

[0004] The object of the present invention is to provide a method for determining an oil-water relative permeability curve taking into account the influence of dynamic changes in microscopic wetting during oil displacement by infiltration control.

[0005] The object of the present invention is to provide a method for determining a dynamic oil-water relative permeability determination model taking into account the influence of dynamic changes in microscopic wetting during infiltration regulation and oil displacement.

[0006] In order to achieve the above objectives, the present invention provides the following two technical solutions.

[0007] In a first aspect, the present invention provides a method for determining the relative permeability of oil and water in an infiltration-controlled oil displacement process, wherein the method comprises:

[0008] Construct capillary bundle geometry model;

[0009] Determine the initial contact angle and final contact angle of each capillary in the capillary bundle geometric model during the flow simulation, and determine the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation;

[0010] A contact angle constitutive model is constructed to reflect the change of rock wettability during the process of infiltration-controlled oil displacement, which is used to constrain the size of the capillary contact angles in the capillary bundle geometric model during the flow simulation.

[0011] Based on the initial contact angle and final contact angle of each capillary in the capillary bundle geometric model during the flow simulation, the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation, and the contact angle constitutive model, the capillary bundle geometric model is used to perform multiple rounds of flow simulation by step-controlled displacement pressure difference to obtain oil-water relative permeability curves at different stages in the infiltration-controlled oil displacement process;

[0012] Wherein, the flow simulation is displacement flow simulation or suction flow simulation.

[0013] According to the method provided in the first aspect, preferably, constructing the capillary bundle geometric model includes:

[0014] Obtain the pore throat distribution characteristics of the target reservoir;

[0015] A capillary bundle model that can describe the pore throat distribution characteristics of the target reservoir is constructed; wherein the capillary radius distribution in the capillary bundle model is characterized by a truncated Weibull distribution function;

[0016] More preferably, the capillary bundle model is a triangular prism capillary bundle model;

[0017] More preferably, the capillary radius distribution in the capillary bundle model is characterized by the following truncated Weibull distribution function:

[0018] R=(R max -R min ){-δln[y(1-exp(-1 / δ))+exp(-1 / δ)]} 1 / γ +R min

[0019] In the formula, R max is the maximum pore throat radius of the target reservoir; R min is the minimum pore throat radius of the target reservoir; δ and γ are dimensionless parameters; y is a random number between 0 and 1; R is the radius of the capillary in the capillary bundle model.

[0020] According to the method provided in the first aspect, preferably, respectively determining the initial contact angle and the final contact angle of each capillary in the capillary bundle geometric model during the flow simulation process, and determining the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation process includes:

[0021] Determine the rock contact angle in the initial wetting state and the rock contact angle in the final wetting state during the target reservoir infiltration and oil displacement process; determine the oil-water interfacial tension during the target reservoir infiltration and oil displacement process;

[0022] Based on the rock contact angle in the initial wetting state during the oil displacement process of the target reservoir infiltration control, the initial contact angle of each capillary in the capillary bundle geometric model during the flow simulation process is determined;

[0023] The final contact angle of each capillary in the capillary bundle geometric model during the flow simulation is determined based on the rock contact angle in the final wetting state during the target reservoir infiltration and oil displacement process;

[0024] The oil-water interfacial tension in the capillary bundle geometric model during flow simulation is determined based on the target reservoir infiltration and oil-water interfacial tension regulation during oil displacement.

[0025] According to the method provided in the first aspect, preferably, the contact angle constitutive model is a calculation model of the contact angle with respect to the contact reaction time;

[0026] More preferably, the contact angle constitutive model reflecting the change of rock wettability during the process of wetting regulation and oil displacement is:

[0027]

[0028]

[0029]

[0030] In the formula, θ m (·) is the contact angle at each position of the mth capillary during the flow simulation; is the initial contact angle of the mth capillary; is the final contact angle of the mth capillary; is a dynamic parameter reflecting the degree of adsorption of the wetting control chemical on the rock pore wall, with a value of 0-1; C is a dimensionless parameter determined by the ratio of the adsorption and desorption rate constants during the wetting control oil displacement process, and is used to control the conversion speed from the initial wetting state to the final wetting state; χ m (t) is the normalized contact reaction time of the mth capillary at time t of flow simulation; V p,m is the pore throat volume of the mth capillary; A b,mis the cross-sectional area of ​​the mth capillary; ζ is the time for all capillaries to perform a round of flow simulation under the initial contact angle condition; is the interface position of the mth capillary at the time of flow simulation τ, ranging from 0 to L; t is the duration of flow simulation, ranging from 0 to T;

[0031] More preferably, the method further comprises the step of obtaining the time for all capillaries to perform a round of flow simulation under the initial contact angle condition:

[0032] Based on the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation, the contact angle of each capillary in the capillary bundle geometric model during the flow simulation is the initial contact angle, and the capillary bundle geometric model is used to step-control the displacement pressure difference to perform a round of flow simulation, and the time for all capillaries to perform a complete flow simulation is obtained, which is the time for all capillaries to perform a round of flow simulation under the condition of the initial contact angle.

[0033] According to the method provided in the first aspect, preferably, when the flow simulation is a displacement flow simulation, stepwise controlling the displacement pressure difference to perform a round of flow simulation includes:

[0034] ①Get the maximum threshold pressure

[0035] ② Obtain the displacement pressure difference ΔP between the water phase and the oil phase fluid, Where P l res , are the pressures of the water phase fluid at the inlet end and the oil phase fluid at the outlet end of the capillary bundle model, respectively;

[0036] ③In Under the condition, for each capillary in the capillary bundle geometric model, determine the capillary pressure P of the capillary m Is it less than the displacement pressure difference ΔP? If so, the displacement simulation is performed on the capillary until a stable state is reached and the contact reaction time of the capillary is determined. It is also determined whether the initial contact angle of the capillary is less than If so, determine the cross-sectional areas of the continuous phase fluid and the corner fluid;

[0037] ④ Determine the average saturation of the capillary bundle geometric model based on the cross-sectional areas of the continuous phase fluid and the corner fluid in the capillary determined in step ③, and determine the oil-water relative permeability corresponding to the average saturation;

[0038] ⑤Gradually increase the pressure P of the water phase fluid at the inlet l res Repeat steps ②-④ to update the displacement pressure difference ΔP and perform displacement simulation under the updated displacement pressure difference ΔP until If it does not hold, the displacement simulation is completed;

[0039] ⑥ Determine the average contact reaction time of each capillary during displacement flow simulation based on the contact reaction time of each capillary;

[0040] More preferably, during the multiple rounds of flow simulation, after each round of flow simulation is completed, for each initial contact angle less than The capillary tube is provided with a capillary tube, and the size of the contact angle in the capillary tube is determined and updated based on the contact angle constitutive model, and then the above steps ① to ⑥ are repeated to perform the next round of flow simulation.

[0041] According to the method provided in the first aspect, preferably, when the flow simulation is a sucking flow simulation, stepwise control of the displacement pressure difference to perform a round of flow simulation includes: ① obtaining the minimum threshold pressure

[0042] ② Obtain the displacement pressure difference ΔP between the water phase and the oil phase fluid, Where P l res , are the pressures of the water phase fluid at the inlet end and the oil phase fluid at the outlet end of the capillary bundle model, respectively;

[0043] ③In Under the condition, for each capillary in the capillary bundle geometric model, determine the capillary pressure P of the capillary m Is it greater than the displacement pressure difference ΔP? If so, the capillary is sucked and simulated until a stable state is reached and the contact reaction time of the capillary is determined. It is also determined whether the initial contact angle of the capillary is less than If so, determine the cross-sectional areas of the continuous phase fluid and the corner fluid;

[0044] ④ Determine the average saturation of the capillary bundle geometric model based on the cross-sectional areas of the continuous phase fluid and the corner fluid in the capillary determined in step ③, and determine the oil-water relative permeability corresponding to the average saturation;

[0045] ⑤Gradually reduce the pressure P of the water phase fluid at the inlet l res Repeat steps ②-④ to update the displacement pressure difference ΔP and perform the sucking simulation under the updated displacement pressure difference ΔP until Not established to complete the sucking simulation;

[0046] ⑥ Determine the average contact reaction time of each capillary during displacement flow simulation based on the contact reaction time of each capillary;

[0047] More preferably, during the multiple rounds of flow simulation, after each round of flow simulation is completed, for each initial contact angle less than The capillary tube is provided with a capillary tube, and the size of the contact angle in the capillary tube is determined and updated based on the contact angle constitutive model, and then the above steps ① to ⑥ are repeated to perform the next round of flow simulation.

[0048] According to the method provided in the first aspect, preferably, the maximum threshold pressure Not less than the maximum capillary pressure during flow simulation;

[0049] According to the method provided in the first aspect, preferably, the minimum threshold pressure is not greater than the minimum capillary pressure during the flow simulation process;

[0050] According to the method provided in the first aspect, preferably, the capillary pressure P m Determined by the following formula:

[0051]

[0052] Where P m is the capillary pressure, in Pa; σ is the oil-water interfacial tension, in mN / m; R m It is the cross-sectional radius between the corner fluid and the continuous phase fluid of the mth capillary, in μm.

[0053] According to the method provided in the first aspect, preferably, the contact angle is an oil phase contact angle.

[0054] According to the method provided in the first aspect, preferably, the oil-water relative permeability curves at different stages in the infiltration-controlled oil displacement process are oil-water relative permeability curves corresponding to different average contact reaction times in the infiltration-controlled oil displacement process.

[0055] According to the method provided in the first aspect, preferably, the method further comprises:

[0056] Determine the oil-water relative permeability curve in the initial wetting state and the oil-water relative permeability curve in the final wetting state during the target reservoir infiltration control oil recovery process.

[0057] The technical solution of the first aspect of the present invention creatively constrains the contact angle during the flow simulation of the displacement or suction process through a contact angle constitutive model that reflects the change in rock wettability during the infiltration and suction process, and obtains the oil-water relative permeability curves of each stage in the infiltration and suction process by using the flow simulation of the displacement or suction process. These oil-water relative permeability curves take into account the influence of the dynamic changes in microscopic wetting during the infiltration and suction process.

[0058] In a second aspect, the present invention provides a method for determining a dynamic oil-water relative permeability characterization model in an infiltration-controlled oil displacement process, wherein the method comprises:

[0059] Obtain oil-water relative permeability data at different stages of the target reservoir infiltration control oil recovery process;

[0060] Based on the oil-water relative permeability data of the target reservoir at different stages in the process of infiltration-controlled oil recovery, a dynamic oil-water relative permeability characterization model in the process of infiltration-controlled oil recovery was fitted.

[0061] According to the method provided in the second aspect, preferably, the dynamic oil-water relative permeability characterization model in the infiltration regulation oil displacement process is:

[0062]

[0063]

[0064]

[0065] In the formula, k rw is the relative permeability of the water phase; k rn is the relative permeability of the oil phase; is the uniform average contact reaction time, with a value of 0-1; S w is the water phase fluid saturation; is the dynamic correlation coefficient between the relative permeability of oil phase and water phase fluid; λ, a, b are dimensionless fitting coefficients.

[0066] According to the method provided in the second aspect, preferably, obtaining the oil-water relative permeability data at different stages in the target reservoir infiltration regulation oil displacement process includes:

[0067] Construct capillary bundle geometry model;

[0068] Determine the initial contact angle and final contact angle of each capillary in the capillary bundle geometric model during the flow simulation, and determine the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation;

[0069] A contact angle constitutive model is constructed to reflect the change of rock wettability during the process of infiltration-controlled oil displacement, which is used to constrain the size of the capillary contact angles in the capillary bundle geometric model during the flow simulation.

[0070] Based on the initial contact angle and final contact angle of each capillary in the capillary bundle geometric model during the flow simulation, the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation, and the contact angle constitutive model, the capillary bundle geometric model is used to perform multiple rounds of flow simulation by step-controlled displacement pressure difference to obtain oil-water relative permeability curves at different stages in the infiltration-controlled oil displacement process;

[0071] Wherein, the flow simulation is displacement flow simulation or suction flow simulation.

[0072] According to the method provided in the second aspect, preferably, constructing the capillary bundle geometric model includes:

[0073] Obtain the pore throat distribution characteristics of the target reservoir;

[0074] A capillary bundle model that can describe the pore throat distribution characteristics of the target reservoir is constructed; wherein the capillary radius distribution in the capillary bundle model is characterized by a truncated Weibull distribution function;

[0075] More preferably, the capillary bundle model is a triangular prism capillary bundle model;

[0076] More preferably, the capillary radius distribution in the capillary bundle model is characterized by the following truncated Weibull distribution function:

[0077] R=(R max -R min ){-δln[y(1-exp(-1 / δ))+exp(-1 / δ)]} 1 / γ +R min

[0078] In the formula, R max is the maximum pore throat radius of the target reservoir; R min is the minimum pore throat radius of the target reservoir; δ and γ are dimensionless parameters; y is a random number between 0 and 1; R is the radius of the capillary in the capillary bundle model.

[0079] According to the method provided in the second aspect, preferably, respectively determining the initial contact angle and the final contact angle of each capillary in the capillary bundle geometric model during the flow simulation process, and determining the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation process includes:

[0080] Determine the rock contact angle in the initial wetting state and the rock contact angle in the final wetting state during the target reservoir infiltration and oil displacement process; determine the oil-water interfacial tension during the target reservoir infiltration and oil displacement process;

[0081] Based on the rock contact angle in the initial wetting state during the oil displacement process of the target reservoir infiltration control, the initial contact angle of each capillary in the capillary bundle geometric model during the flow simulation process is determined;

[0082] The final contact angle of each capillary in the capillary bundle geometric model during the flow simulation is determined based on the rock contact angle in the final wetting state during the target reservoir infiltration control oil displacement process;

[0083] The oil-water interfacial tension in the capillary bundle geometric model during flow simulation is determined based on the target reservoir infiltration and oil-water interfacial tension regulation during oil displacement.

[0084] According to the method provided in the second aspect, preferably, the contact angle constitutive model is a calculation model of the contact angle with respect to the contact reaction time;

[0085] According to the method provided in the second aspect, preferably, the contact angle constitutive model reflecting the change of rock wettability during the process of wetting regulation and oil displacement is:

[0086]

[0087]

[0088]

[0089] In the formula, θ m (·) is the contact angle at each position of the mth capillary during the flow simulation; is the initial contact angle of the mth capillary; is the final contact angle of the mth capillary; is a dynamic parameter reflecting the degree of adsorption of the wetting control chemical on the rock pore wall, with a value of 0-1; C is a dimensionless parameter determined by the ratio of the adsorption and desorption rate constants during the wetting control oil displacement process, and is used to control the conversion speed from the initial wetting state to the final wetting state; χ m (t) is the normalized contact reaction time of the mth capillary at time t of flow simulation; V p,m is the pore throat volume of the mth capillary; A b,m is the cross-sectional area of ​​the mth capillary; ζ is the time for all capillaries to perform a round of flow simulation under the initial contact angle condition; is the interface position of the mth capillary at the time of flow simulation τ, ranging from 0 to L; t is the duration of flow simulation, ranging from 0 to T;

[0090] More preferably, the method further comprises the step of obtaining the time for all capillaries to perform a round of flow simulation under the initial contact angle condition:

[0091] Based on the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation, the contact angle of each capillary in the capillary bundle geometric model during the flow simulation is the initial contact angle, and the capillary bundle geometric model is used to step-control the displacement pressure difference to perform a round of flow simulation, and the time for all capillaries to perform a complete flow simulation is obtained, which is the time for all capillaries to perform a round of flow simulation under the condition of the initial contact angle.

[0092] According to the method provided in the second aspect, preferably, when the flow simulation is a displacement flow simulation, stepwise controlling the displacement pressure difference to perform a round of flow simulation includes:

[0093] ①Get the maximum threshold pressure

[0094] ② Obtain the displacement pressure difference ΔP between the water phase and the oil phase fluid, Where P l res , are the pressures of the water phase fluid at the inlet end and the oil phase fluid at the outlet end of the capillary bundle model, respectively;

[0095] ③In Under the condition, for each capillary in the capillary bundle geometric model, determine the capillary pressure P of the capillary m Is it less than the displacement pressure difference ΔP? If so, the displacement simulation is performed on the capillary until a stable state is reached and the contact reaction time of the capillary is determined. It is also determined whether the initial contact angle of the capillary is less than If so, determine the cross-sectional areas of the continuous phase fluid and the corner fluid;

[0096] ④ Determine the average saturation of the capillary bundle geometric model based on the cross-sectional areas of the continuous phase fluid and the corner fluid in the capillary determined in step ③, and determine the oil-water relative permeability corresponding to the average saturation;

[0097] ⑤Gradually increase the pressure P of the water phase fluid at the inlet l res Repeat steps ②-④ to update the displacement pressure difference ΔP and perform displacement simulation under the updated displacement pressure difference ΔP until If it does not hold, the displacement simulation is completed;

[0098] ⑥ Determine the average contact reaction time of each capillary during displacement flow simulation based on the contact reaction time of each capillary;

[0099] More preferably, during the multiple rounds of flow simulation, after each round of flow simulation is completed, for each initial contact angle less than The capillary tube is provided with a capillary tube, and the size of the contact angle in the capillary tube is determined and updated based on the contact angle constitutive model, and then the above steps ① to ⑥ are repeated to perform the next round of flow simulation.

[0100] According to the method provided in the second aspect, preferably, when the flow simulation is a suction flow simulation, stepwise controlling the displacement pressure difference to perform a round of flow simulation includes:

[0101] ① Obtain the minimum threshold pressure

[0102] ② Obtain the displacement pressure difference ΔP between the water phase and the oil phase fluid, Where P l res , are the pressures of the water phase fluid at the inlet end and the oil phase fluid at the outlet end of the capillary bundle model, respectively;

[0103] ③In Under the condition, for each capillary in the capillary bundle geometric model, determine the capillary pressure P of the capillary m Is it greater than the displacement pressure difference ΔP? If so, the capillary is sucked and simulated until a stable state is reached and the contact reaction time of the capillary is determined. It is also determined whether the initial contact angle of the capillary is less than If so, determine the cross-sectional areas of the continuous phase fluid and the corner fluid;

[0104] ④ Determine the average saturation of the capillary bundle geometric model based on the cross-sectional areas of the continuous phase fluid and the corner fluid in the capillary determined in step ③, and determine the oil-water relative permeability corresponding to the average saturation;

[0105] ⑤Gradually reduce the pressure P of the water phase fluid at the inlet l res Repeat steps ②-④ to update the displacement pressure difference ΔP and perform the sucking simulation under the updated displacement pressure difference ΔP until Not established to complete the sucking simulation;

[0106] ⑥ Determine the average contact reaction time of each capillary during displacement flow simulation based on the contact reaction time of each capillary;

[0107] More preferably, during the multiple rounds of flow simulation, after each round of flow simulation is completed, for each initial contact angle less than The capillary tube is provided with a capillary tube, and the size of the contact angle in the capillary tube is determined and updated based on the contact angle constitutive model, and then the above steps ① to ⑥ are repeated to perform the next round of flow simulation.

[0108] According to the method provided in the second aspect, preferably, the maximum threshold pressure Not less than the maximum capillary pressure during flow simulation;

[0109] According to the method provided in the second aspect, preferably, the minimum threshold pressure is not greater than the minimum capillary pressure during the flow simulation process;

[0110] According to the method provided in the second aspect, preferably, the capillary pressure P m Determined by the following formula:

[0111]

[0112] Where P m is the capillary pressure, in Pa; σ is the oil-water interfacial tension, in mN / m; R mIt is the cross-sectional radius between the corner fluid and the continuous phase fluid of the mth capillary, in μm.

[0113] According to the method provided in the second aspect, preferably, the contact angle is an oil phase contact angle.

[0114] According to the method provided in the second aspect, preferably, the oil-water relative permeability data at different stages in the infiltration-regulated oil displacement process is the oil-water relative permeability data corresponding to different average contact reaction times in the infiltration-regulated oil displacement process.

[0115] According to the method provided in the second aspect, preferably, the method further comprises:

[0116] Determine the oil-water relative permeability curve in the initial wetting state and the oil-water relative permeability curve in the final wetting state during the target reservoir infiltration control oil recovery process.

[0117] The technical solution of the second aspect of the present invention creatively obtains a dynamic oil-water relative permeability characterization model in the process of infiltration-regulated oil recovery based on the oil-water relative permeability data fitting at different stages in the process of infiltration-regulated oil recovery. The model takes into account the influence of dynamic changes in microscopic wetting in the process of infiltration-regulated oil recovery.

[0118] The technical solution provided by the present invention is applicable to low-permeability-tight oil, shale oil, and marine carbonate oil reservoirs. The method is easy to implement and the prediction results are highly accurate. It can provide a basis for the optimization design of infiltration control oil recovery schemes, development dynamic law analysis, and production optimization control for this type of complex oil reservoirs. The technical solution provided by this method solves the technical problem that the traditional phase permeability theoretical model cannot reflect the influence of dynamic wetting changes, resulting in low accuracy of numerical simulation results. In addition, the technical solution provided by the present invention is not limited to infiltration control oil recovery systems such as nanofluids, surfactants, and ion-matched water, but can also be applied to other new technologies for improving recovery that can cause wetting changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0119] Figure 1 A flow chart of a method for determining oil-water relative permeability during infiltration-controlled oil displacement provided by one embodiment of the present invention.

[0120] Figure 2 A flow chart of a method for determining a dynamic oil-water relative permeability characterization model in an infiltration-controlled oil displacement process provided by an embodiment of the present invention.

[0121] Figure 3 The microscopic distribution pattern of fluid in the triangular capillary bundle model.

[0122] Figure 4A It is a graph showing the relative permeability of the oil phase at different stages in the process of oil displacement by infiltration control in Example 1 of the present invention.

[0123] Figure 4B This is a graph showing the relative permeability of the water phase at different stages during the infiltration-controlled oil displacement process in Example 1 of the present invention.

[0124] Figure 5 This is a graph of capillary contact angles of various sizes at different stages during the infiltration and regulation oil displacement process in Example 1 of the present invention.

[0125] Fig. 6A This is a comparison diagram of the oil phase relative permeability curve obtained by using the dynamic relative permeability characterization model in Example 1 of the present invention and the oil phase relative permeability curve obtained by flow simulation.

[0126] Figure 6B This is a comparison diagram of the water phase relative permeability curve obtained by using the dynamic relative permeability characterization model in Example 1 of the present invention and the water phase relative permeability curve obtained by flow simulation. DETAILED DESCRIPTION

[0127] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0128] See also Figure 1 A specific embodiment of the present invention provides a method for determining the relative permeability of oil and water in the process of infiltration control oil displacement, wherein the method comprises:

[0129] Step S1: constructing a capillary bundle geometric model;

[0130] Step S2: respectively determining the initial contact angle and the final contact angle of each capillary in the capillary bundle geometric model during the flow simulation process, and determining the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation process;

[0131] Step S3: constructing a contact angle constitutive model that reflects the change in rock wettability during the infiltration-controlled oil displacement process, so as to constrain the size of each capillary contact angle in the capillary bundle geometric model during the flow simulation process;

[0132] Step S4: Based on the initial contact angle and final contact angle of each capillary in the capillary bundle geometric model during the flow simulation, the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation, and the contact angle constitutive model, the capillary bundle geometric model is used to perform multiple rounds of flow simulation by step-by-step controlling the displacement pressure difference to obtain the oil-water relative permeability curves at different stages in the infiltration control oil displacement process;

[0133] Wherein, the flow simulation is displacement flow simulation or suction flow simulation.

[0134] Further, in step S1, constructing the capillary bundle geometric model includes:

[0135] Step S11: obtaining the pore throat distribution characteristics of the target reservoir;

[0136] Among them, the pore throat distribution characteristics of the target reservoir can be determined by low-field nuclear magnetic resonance T2 spectrum analysis of actual rock samples of the target reservoir; in a specific implementation, actual rock samples at the target position of the target reservoir are drilled, the rock samples are deoiled and dried, and the dried rock samples are subjected to low-field nuclear magnetic resonance T2 spectrum testing, and the pore throat distribution characteristics including the minimum pore throat radius, the maximum pore throat radius and the pore throat radius distribution curve are determined based on the low-field nuclear magnetic resonance T2 spectrum obtained by the test;

[0137] Step S12: constructing a capillary bundle model that can describe the pore throat distribution characteristics of the target reservoir; wherein the capillary radius distribution in the capillary bundle model is characterized by a truncated Weibull distribution function;

[0138] Furthermore, the capillary bundle model is a triangular prism capillary bundle model;

[0139] Among them, when performing multi-round flow simulation based on the triangular prism capillary bundle model, the following can be considered: Figure 3 The six fluid distribution modes shown are: A represents the initial state; B and C represent the primary displacement process; D and E represent the sucking process; F represents the secondary and above displacement processes;

[0140] Furthermore, the capillary radius distribution in the capillary bundle model is characterized by the following truncated Weibull distribution function:

[0141] R=(R max -R min ){-δln[y(1-exp(-1 / δ))+exp(-1 / δ)]} 1 / γ +R min

[0142] In the formula, R max is the maximum pore throat radius of the target reservoir; R min is the minimum pore throat radius of the target reservoir; δ and γ are dimensionless parameters; y is a random number between 0 and 1; R is the radius of the capillary in the capillary bundle model;

[0143] Among them, δ, γ, and y can be determined by fitting the pore throat radius distribution interpreted by nuclear magnetic resonance.

[0144] Further, in step S2, the initial contact angle and the final contact angle of each capillary in the capillary bundle geometric model during the flow simulation are determined respectively, and the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation is determined, including:

[0145] Step S21: determining the rock contact angle in the initial wetting state and the rock contact angle in the final wetting state during the target reservoir infiltration and regulation oil displacement process; determining the oil-water interfacial tension during the target reservoir infiltration and regulation oil displacement process;

[0146] Among them, the rock contact angle in the initial wetting state and the rock contact angle in the final wetting state during the infiltration and regulation of oil displacement of the target reservoir can be determined by testing the rock surface contact angle before and after the infiltration and regulation of oil displacement for the target reservoir rock sample; in a specific implementation manner, the rock surface contact angle test is carried out before and after the infiltration and regulation of oil displacement for the target reservoir rock sample, and then the rock surface contact angles before and after the infiltration and regulation of oil displacement obtained by the test are used as the rock contact angle in the initial wetting state and the rock contact angle in the final wetting state during the infiltration and regulation of oil displacement of the target reservoir, respectively;

[0147] Among them, the oil-water interfacial tension during the oil displacement process of the target reservoir can be determined by conducting an oil-water interfacial tension test on the target reservoir rock sample; in a specific implementation, an oil-water interfacial tension test is conducted on the target reservoir rock sample, and the oil-water interfacial tension obtained by the test is used as the oil-water interfacial tension during the oil displacement process of the target reservoir;

[0148] Step S22: determining the initial contact angle of each capillary in the capillary bundle geometric model during the flow simulation process based on the rock contact angle in the initial wetting state during the target reservoir infiltration control oil displacement process;

[0149] Among them, the rock contact angle in the initial wetting state during the oil displacement process of the target reservoir infiltration control can be used as the initial contact angle of each capillary in the capillary bundle geometric model during the flow simulation process;

[0150] Step S23: determining the final contact angle of each capillary in the capillary bundle geometric model during the flow simulation process based on the rock contact angle in the final wetting state during the target reservoir infiltration control oil displacement process;

[0151] Among them, the rock contact angle in the final wetting state during the target reservoir infiltration and oil displacement process can be used as the final contact angle of each capillary in the capillary bundle geometric model during the flow simulation process;

[0152] Step S24: determining the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation process based on the oil-water interfacial tension in the target reservoir infiltration control oil displacement process;

[0153] Among them, the oil-water interfacial tension in the target reservoir infiltration control oil displacement process can be used as the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation process.

[0154] Further, in step S3, the contact angle constitutive model is a calculation model of the contact angle with respect to the contact reaction time;

[0155] Furthermore, the contact angle constitutive model reflecting the change of rock wettability during oil displacement is:

[0156]

[0157]

[0158]

[0159] In the formula, θ m (·) is the contact angle at each position of the mth capillary during the flow simulation (i.e., the contact angle at each position in the mth capillary when the flow simulation time is t); is the initial contact angle of the mth capillary; is the final contact angle of the mth capillary; is a dynamic parameter reflecting the degree of adsorption of the wetting control chemical agent on the rock pore wall, with a value of 0-1; C is a dimensionless parameter determined by the ratio of the adsorption rate constant to the desorption rate constant during the wetting control oil displacement process (in a specific embodiment, it is equal to the ratio of the adsorption rate constant to the desorption rate constant during the wetting control oil displacement process), and is used to control the conversion speed from the initial wetting state to the final wetting state; χ m (t) is the normalized contact reaction time of the mth capillary with a flow simulation time of t; V p,m is the pore throat volume of the mth capillary; A b,m is the cross-sectional area of ​​the mth capillary; ζ is the time for all capillaries to perform a round of flow simulation under the initial contact angle condition; is the interface position of the mth capillary with a flow simulation time of τ (i.e., the function of the interface position changing with the flow simulation time), ranging from 0 to L; t is the flow simulation time, ranging from 0 to T;

[0160] Among them, for capillaries with different radius distributions, the contact reaction time of flow simulation duration t is significantly different (in the above model, the normalized contact reaction time χ m To reflect), the wetting state of the capillary bundles with different radius distributions is non-uniform;

[0161] Furthermore, before performing step S4, the method further comprises the step of obtaining the time for all capillaries to perform a round of flow simulation under the condition that the contact angle of each capillary is the initial contact angle:

[0162] Based on the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation, the contact angle formula of each capillary in the capillary bundle geometric model during the flow simulation is the initial contact angle, and the capillary bundle geometric model is used to step-control the displacement pressure difference to perform a round of flow simulation, and the time for all capillaries to perform a complete flow simulation is obtained, that is, the time for all capillaries to perform a round of flow simulation under the condition that each capillary contact angle is the initial contact angle.

[0163] The contact angle constitutive model provided in the preferred technical method that reflects the change in rock wettability during the infiltration and regulation of oil recovery can effectively reflect the dynamic change mechanism of microscopic wetting during the infiltration and regulation of oil recovery by chemical agents such as nanofluids, surfactants, and ion-matched water.

[0164] Furthermore, when the flow simulation is a displacement flow simulation, the stepwise control of the displacement pressure difference to perform a round of flow simulation includes:

[0165] 1) Fluid displacement process simulation steps:

[0166] ①Get the maximum threshold pressure

[0167] ② Obtain the displacement pressure difference ΔP between the water phase and the oil phase fluid, Where P l res , are the pressures of the water phase fluid at the inlet end and the oil phase fluid at the outlet end of the capillary bundle model, respectively;

[0168] ③In Under the condition, for each capillary in the capillary bundle geometric model, determine the capillary pressure P of the capillary m Is it less than the displacement pressure difference ΔP? If so, the displacement simulation is performed on the capillary until a stable state is reached and the contact reaction time of the capillary is determined. It is also determined whether the initial contact angle of the capillary is less than If so, determine the cross-sectional areas of the continuous phase fluid and the corner fluid;

[0169] ④ Determine the average saturation of the capillary bundle geometric model based on the cross-sectional areas of the continuous phase fluid and the corner fluid in the capillary determined in step ③, and determine the oil-water relative permeability corresponding to the average saturation;

[0170] ⑤Gradually increase the pressure P of the water phase fluid at the inlet l res Repeat steps ②-④ to update the displacement pressure difference ΔP and perform displacement simulation under the updated displacement pressure difference ΔP until If it does not hold, the displacement simulation is completed;

[0171] ⑥ Determine the average contact reaction time of each capillary during displacement flow simulation based on the contact reaction time of each capillary;

[0172] More preferably, during the multiple rounds of flow simulation, after each round of flow simulation is completed, for each initial contact angle less than The capillary tube is provided with a capillary tube, and the contact angle in the capillary tube is determined based on the contact angle constitutive model and the contact angle in the capillary tube is updated, and then the above steps ① to ⑥ are repeated to perform the next round of flow simulation;

[0173] Among them, the initial contact angle is not less than There is only continuous phase fluid in the capillary and no corner fluid; the initial contact angle is not less than The capillary does not update the contact angle and always maintains the initial contact angle.

[0174] Furthermore, when the flow simulation is a sucking flow simulation, the step-by-step control of the displacement pressure difference to perform a round of flow simulation includes:

[0175] ① Obtain the minimum threshold pressure

[0176] ② Obtain the displacement pressure difference ΔP between the water phase and the oil phase fluid, Where P l res , are the pressures of the water phase fluid at the inlet end and the oil phase fluid at the outlet end of the capillary bundle model, respectively;

[0177] ③In Under the condition, for each capillary in the capillary bundle geometric model, determine the capillary pressure P of the capillary m Is it greater than the displacement pressure difference ΔP? If so, the capillary is sucked and simulated until a stable state is reached and the contact reaction time of the capillary is determined. It is also determined whether the initial contact angle of the capillary is less than If so, determine the cross-sectional areas of the continuous phase fluid and the corner fluid;

[0178] ④ Determine the average saturation, average contact reaction time and oil-water relative permeability of the capillary bundle geometric model based on the cross-sectional areas of the continuous phase fluid and the corner fluid in the capillary determined in step ③;

[0179] ⑤Gradually reduce the pressure P of the water phase fluid at the inlet l res Repeat steps ②-④ to update the displacement pressure difference ΔP and perform the sucking simulation under the updated displacement pressure difference ΔP until Not established to complete the sucking simulation;

[0180] ⑥ Determine the average contact reaction time of each capillary during displacement flow simulation based on the contact reaction time of each capillary;

[0181] More preferably, during the multiple rounds of flow simulation, after each round of flow simulation is completed, for each initial contact angle less than The capillary tube is provided with a capillary tube, and the contact angle in the capillary tube is determined based on the contact angle constitutive model and the contact angle in the capillary tube is updated, and then the above steps ① to ⑥ are repeated to perform the next round of flow simulation;

[0182] Among them, the initial contact angle is not less than There is only continuous phase fluid in the capillary and no corner fluid; the initial contact angle is not less than The capillary does not update the contact angle and always maintains the initial contact angle.

[0183] Furthermore, the maximum threshold pressure Not less than the maximum capillary pressure during flow simulation;

[0184] Furthermore, the minimum threshold pressure is no greater than the minimum capillary pressure during the flow simulation;

[0185] Furthermore, the capillary pressure P m Determined by the following formula:

[0186]

[0187] Where P m is the capillary pressure, in Pa; σ is the oil-water interfacial tension, in mN / m; R m is the inner diameter of the mth capillary, in μm; θ m is the contact angle of the mth capillary, in degrees.

[0188] Furthermore, the contact angle is the oil phase contact angle.

[0189] Furthermore, the oil-water relative permeability curves at different stages in the infiltration-controlled oil displacement process are oil-water relative permeability curves corresponding to different average contact reaction times in the infiltration-controlled oil displacement process.

[0190] Furthermore, the method further comprises:

[0191] Determine the oil-water relative permeability curve in the initial wetting state and the oil-water relative permeability curve in the final wetting state during the infiltration and oil displacement process of the target reservoir;

[0192] Among them, the oil-water relative permeability curve in the initial wetting state and the oil-water relative permeability curve in the final wetting state of the target reservoir in the infiltration and regulation oil displacement process can be determined by performing non-steady-state core flooding experimental tests on the target reservoir rock sample before and after the infiltration and regulation oil displacement; in a specific implementation method, for the target reservoir rock sample, non-steady-state core flooding experimental tests are carried out before and after the infiltration and regulation oil displacement, and then the dynamic data such as pressure and flow rate of the core flooding experiment are interpreted by using the Johnson-Bossler-Naumann (JBN) method to determine the oil-water relative permeability curve before and after the infiltration and regulation oil displacement, and the determined oil-water relative permeability curves before and after the infiltration and regulation oil displacement are used as the oil-water relative permeability curve in the initial wetting state and the oil-water relative permeability curve in the final wetting state of the target reservoir in the infiltration and regulation oil displacement process.

[0193] The oil-water relative permeability curves at different stages in the process of infiltration-controlled oil displacement are obtained by performing multiple rounds of flow simulation based on step-by-step control of displacement pressure differences, and can be specifically performed using conventional methods in the art.

[0194] See also Figure 2 The embodiment of the present invention also provides a method for determining a dynamic oil-water relative permeability characterization model in an infiltration-controlled oil displacement process, wherein the method comprises:

[0195] Step A1: Obtaining oil-water relative permeability data at different stages of the target reservoir infiltration control oil displacement process;

[0196] Step A2: Based on the oil-water relative permeability data at different stages of the target reservoir infiltration-controlled oil recovery process, a dynamic oil-water relative permeability characterization model in the infiltration-controlled oil recovery process is fitted.

[0197] Furthermore, the dynamic oil-water relative permeability determination model in the infiltration control oil displacement process is:

[0198]

[0199]

[0200]

[0201] In the formula, k rw is the relative permeability of the water phase; k rn is the relative permeability of the oil phase; is the uniform average contact reaction time, with a value of 0-1; S w is the water phase fluid saturation; is the dynamic correlation coefficient between the relative permeability of oil phase and water phase fluid; λ, a, b are dimensionless fitting coefficients.

[0202] Furthermore, the oil-water relative permeability data at different stages of the target reservoir infiltration control oil recovery process are obtained, including:

[0203] Step A11: constructing a capillary bundle geometric model;

[0204] Step A12: respectively determining the initial contact angle and the final contact angle of each capillary in the capillary bundle geometric model during the flow simulation process, and determining the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation process;

[0205] Step A13: constructing a contact angle constitutive model for the change of rock wettability during the reaction-wetting regulation oil displacement process, so as to constrain the size of each capillary contact angle in the capillary bundle geometric model during the flow simulation process;

[0206] Step A14: Based on the initial contact angle and final contact angle of each capillary in the capillary bundle geometric model during the flow simulation, the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation, and the contact angle constitutive model, the capillary bundle geometric model is used to perform multiple rounds of flow simulation by step-by-step controlling the displacement pressure difference to obtain the oil-water relative permeability curves at different stages in the infiltration-controlled oil displacement process;

[0207] Wherein, the flow simulation is displacement flow simulation or suction flow simulation.

[0208] Furthermore, in step A11, constructing the capillary bundle geometric model includes:

[0209] Step A111: obtaining pore throat distribution characteristics of the target reservoir;

[0210] Step A112: constructing a capillary bundle model that can describe the pore throat distribution characteristics of the target reservoir; wherein the capillary radius distribution in the capillary bundle model is characterized by a truncated Weibull distribution function;

[0211] Furthermore, the capillary bundle model is a triangular prism capillary bundle model;

[0212] Among them, when performing multi-round flow simulation based on the triangular prism capillary bundle model, the following can be considered: Figure 3 The six fluid distribution modes shown are: A represents the initial state; B and C represent the primary displacement process; D and E represent the sucking process; F represents the secondary and above displacement processes;

[0213] Furthermore, the capillary radius distribution in the capillary bundle model is characterized by the following truncated Weibull distribution function:

[0214] R=(Rmax -R min ){-δln[y(1-exp(-1 / δ))+exp(-1 / δ)]} 1 / γ +R min

[0215] In the formula, R max is the maximum pore throat radius of the target reservoir; R min is the minimum pore throat radius of the target reservoir; δ and γ are dimensionless parameters; y is a random number between 0 and 1; R is the radius of the capillary in the capillary bundle model.

[0216] Furthermore, in step A12, the initial contact angle and the final contact angle of each capillary in the capillary bundle geometric model during the flow simulation are determined respectively, and the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation is determined, including:

[0217] Step A121: determining the rock contact angle in the initial wetting state and the rock contact angle in the final wetting state during the target reservoir infiltration and oil displacement process; determining the oil-water interfacial tension during the target reservoir infiltration and oil displacement process;

[0218] Step A122: determining the initial contact angle of each capillary in the capillary bundle geometric model during the flow simulation process based on the rock contact angle in the initial wetting state during the target reservoir infiltration control oil displacement process;

[0219] Step A123: determining the final contact angle of each capillary in the capillary bundle geometric model during the flow simulation process based on the rock contact angle in the final wetting state during the target reservoir infiltration control oil displacement process;

[0220] Step A124: Determine the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation based on the oil-water interfacial tension in the oil displacement process during the target reservoir infiltration control.

[0221] Furthermore, in step A13, the contact angle constitutive model is a calculation model of the contact angle with respect to the contact reaction time;

[0222] Furthermore, the contact angle constitutive model of rock wettability changes during oil displacement regulated by reactive infiltration is:

[0223]

[0224]

[0225]

[0226] In the formula, θ m (·) is the contact angle at each position of the mth capillary during the flow simulation; is the initial contact angle of the mth capillary; is the final contact angle of the mth capillary; is a dynamic parameter reflecting the degree of adsorption of the wetting control chemical on the rock pore wall, with a value of 0-1; C is a dimensionless parameter determined by the ratio of the adsorption and desorption rate constants during the wetting control oil displacement process, and is used to control the conversion speed from the initial wetting state to the final wetting state; χ m (t) is the normalized contact reaction time of the mth capillary at time t of flow simulation; V p,m is the pore throat volume of the mth capillary; A b,m is the cross-sectional area of ​​the mth capillary; ζ is the time for all capillaries to perform a round of flow simulation under the initial contact angle condition; is the interface position of the mth capillary at the time of flow simulation τ, ranging from 0 to L; t is the duration of flow simulation, ranging from 0 to T;

[0227] Furthermore, before performing step A14, the method further includes the step of obtaining the time for all capillaries to perform a round of flow simulation under the initial contact angle condition:

[0228] Based on the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation, the contact angle of each capillary in the capillary bundle geometric model during the flow simulation is the initial contact angle, and the capillary bundle geometric model is used to step-control the displacement pressure difference to perform a round of flow simulation, and the time for all capillaries to perform a complete flow simulation is obtained, which is the time for all capillaries to perform a round of flow simulation under the initial contact angle condition.

[0229] Furthermore, when the flow simulation is a displacement flow simulation, the stepwise control of the displacement pressure difference to perform a round of flow simulation includes:

[0230] 1) Fluid displacement process simulation steps:

[0231] ①Get the maximum threshold pressure

[0232] ② Obtain the displacement pressure difference ΔP between the water phase and the oil phase fluid, Where P l res , are the pressures of the water phase fluid at the inlet end and the oil phase fluid at the outlet end of the capillary bundle model, respectively;

[0233] ③In Under the condition, for each capillary in the capillary bundle geometric model, determine the capillary pressure P of the capillary m Is it less than the displacement pressure difference ΔP? If so, the displacement simulation is performed on the capillary until a stable state is reached and the contact reaction time of the capillary is determined. It is also determined whether the initial contact angle of the capillary is less than If so, determine the cross-sectional areas of the continuous phase fluid and the corner fluid;

[0234] ④ Determine the average saturation of the capillary bundle geometric model based on the cross-sectional areas of the continuous phase fluid and the corner fluid in the capillary determined in step ③, and determine the oil-water relative permeability corresponding to the average saturation;

[0235] ⑤Gradually increase the pressure P of the water phase fluid at the inlet l res Repeat steps ②-④ to update the displacement pressure difference ΔP and perform displacement simulation under the updated displacement pressure difference ΔP until If it does not hold, the displacement simulation is completed;

[0236] ⑥ Determine the average contact reaction time of each capillary during displacement flow simulation based on the contact reaction time of each capillary;

[0237] More preferably, during the multiple rounds of flow simulation, after each round of flow simulation is completed, for each initial contact angle less than The capillary tube is provided with a capillary tube, and the contact angle in the capillary tube is determined based on the contact angle constitutive model and the contact angle in the capillary tube is updated, and then the above steps ① to ⑥ are repeated to perform the next round of flow simulation;

[0238] Among them, the initial contact angle is not less than There is only continuous phase fluid in the capillary and no corner fluid; the initial contact angle is not less than The capillary does not update the contact angle and always maintains the initial contact angle.

[0239] Furthermore, when the flow simulation is a sucking flow simulation, the step-by-step control of the displacement pressure difference to perform a round of flow simulation includes:

[0240] ① Obtain the minimum threshold pressure

[0241] ② Obtain the displacement pressure difference ΔP between the water phase and the oil phase fluid, Where P l res , are the pressures of the water phase fluid at the inlet end and the oil phase fluid at the outlet end of the capillary bundle model, respectively;

[0242] ③In Under the condition, for each capillary in the capillary bundle geometric model, determine the capillary pressure P of the capillary m Is it greater than the displacement pressure difference ΔP? If so, the capillary is sucked and simulated until a stable state is reached and the contact reaction time of the capillary is determined. It is also determined whether the initial contact angle of the capillary is less than If so, determine the cross-sectional areas of the continuous phase fluid and the corner fluid;

[0243] ④ Determine the average saturation, average contact reaction time and oil-water relative permeability of the capillary bundle geometric model based on the cross-sectional areas of the continuous phase fluid and the corner fluid in the capillary determined in step ③;

[0244] ⑤Gradually reduce the pressure P of the water phase fluid at the inlet l res Repeat steps ②-④ to update the displacement pressure difference ΔP and perform the sucking simulation under the updated displacement pressure difference ΔP until Not established to complete the sucking simulation;

[0245] ⑥ Determine the average contact reaction time of each capillary during displacement flow simulation based on the contact reaction time of each capillary;

[0246] More preferably, during the multiple rounds of flow simulation, after each round of flow simulation is completed, for each initial contact angle less than The capillary tube is provided with a capillary tube, and the contact angle in the capillary tube is determined based on the contact angle constitutive model and the contact angle in the capillary tube is updated, and then the above steps ① to ⑥ are repeated to perform the next round of flow simulation;

[0247] Among them, the initial contact angle is not less than There is only continuous phase fluid in the capillary and no corner fluid; the initial contact angle is not less than The capillary does not update the contact angle and always maintains the initial contact angle.

[0248] Going further, the maximum threshold pressure Not less than the maximum capillary pressure during flow simulation;

[0249] Furthermore, the minimum threshold pressure is no greater than the minimum capillary pressure during the flow simulation;

[0250] Furthermore, the capillary pressure P m Determined by the following formula:

[0251]

[0252] Where P m is the capillary pressure, in Pa; σ is the oil-water interfacial tension, in mN / m; R m It is the cross-sectional radius between the corner fluid and the continuous phase fluid of the mth capillary, in μm.

[0253] Furthermore, the contact angle is the oil phase contact angle.

[0254] Furthermore, each oil-water relative permeability curve during the infiltration-controlled oil displacement process is an oil-water relative permeability curve corresponding to different average contact reaction times during the infiltration-controlled oil displacement process.

[0255] Furthermore, the method further comprises:

[0256] Determine the oil-water relative permeability curve in the initial wetting state and the oil-water relative permeability curve in the final wetting state during the target reservoir infiltration control oil recovery process.

[0257] The dynamic oil-water relative permeability characterization model determined by the above-mentioned method for determining the dynamic oil-water relative permeability characterization model during the infiltration-controlled oil recovery process can be used to determine the dynamic oil-water relative permeability curve during the infiltration-controlled oil recovery process.

[0258] The oil-water relative permeability curves at different stages in the process of infiltration-controlled oil displacement are obtained by performing multiple rounds of flow simulation based on step-by-step control of displacement pressure differences, and can be specifically performed using conventional methods in the art.

[0259] Example 1

[0260] Taking the low permeability rock sample of a multimodal carbonate reservoir in a certain area as an example, the method for determining the oil-water relative permeability and the dynamic characterization model in the process of infiltration control oil recovery described in the present invention is described; specifically, the following steps are followed:

[0261] 1. Determine the pore throat distribution characteristics of the target reservoir, construct a capillary bundle model that can describe the pore throat distribution characteristics of the target reservoir, and characterize the capillary radius distribution in the capillary bundle model by using the truncated Weibull distribution function;

[0262] Specifically, actual rock samples at the target position of the target reservoir are drilled, the rock samples are deoiled and dried, low-field nuclear magnetic resonance T2 spectrum test is performed on the dried rock samples, and the pore throat distribution characteristics including the minimum pore throat radius (see Table 1), the maximum pore throat radius (see Table 1) and the pore throat radius distribution curve are determined based on the low-field nuclear magnetic resonance T2 spectrum obtained in the test;

[0263] Then, a triangular prism capillary bundle model that can describe the pore throat distribution characteristics of the target reservoir is constructed, and the capillary radius distribution in the capillary bundle model is characterized by the truncated Weibull distribution function as shown below:

[0264] R=(R max -R min ){-δln[y(1-exp(-1 / δ))+exp(-1 / δ)]} 1 / γ +R min

[0265] In the formula, R maxis the maximum pore throat radius of the target reservoir; R min is the minimum pore throat radius of the target reservoir; δ and γ are dimensionless parameters (the values ​​in this embodiment are shown in Table 1); y is a random number between 0 and 1; R is the radius of the capillary in the capillary bundle model;

[0266] Among them, the number of capillaries and the length of capillaries in the capillary bundle model are shown in Table 1;

[0267] Among them, when performing multi-round flow simulation based on the triangular prism capillary bundle model, the following are considered: Figure 3 There are four fluid distribution modes A, C, E and F shown, A represents the initial state, C represents the primary displacement process, E represents the sucking process, and F represents the secondary and above displacement processes.

[0268] 2. Determine the pore throat distribution characteristics of the target reservoir, the rock oil phase contact angle in the initial wetting state and the rock oil phase contact angle in the final wetting state during the infiltration and regulation of oil displacement, the oil-water phase permeability curve in the initial wetting state and the oil-water phase permeability curve in the final wetting state during the infiltration and regulation of oil displacement, and the oil-water interfacial tension; determine the initial oil phase contact angle of each capillary in the capillary bundle geometric model during the displacement flow simulation based on the rock oil phase contact angle in the initial wetting state during the infiltration and regulation of oil displacement of the target reservoir (see Table 1); determine the final oil phase contact angle of each capillary in the capillary bundle geometric model during the displacement flow simulation based on the rock contact angle in the final wetting state during the infiltration and regulation of oil displacement of the target reservoir (see Table 1); determine the oil-water interfacial tension in the capillary bundle geometric model during the displacement flow simulation based on the oil-water interfacial tension during the infiltration and regulation of oil displacement of the target reservoir (see Table 1);

[0269] Specifically: for the target reservoir rock samples, the rock surface contact angle test is carried out before and after the infiltration and regulation oil displacement, and then the rock surface contact angles before and after the infiltration and regulation oil displacement obtained by the test are used as the rock contact angle in the initial wetting state and the rock contact angle in the final wetting state during the infiltration and regulation oil displacement process of the target reservoir, respectively; the rock contact angle in the initial wetting state during the infiltration and regulation oil displacement process of the target reservoir is used as the initial contact angle of each capillary in the capillary bundle geometric model during the displacement flow simulation; the rock contact angle in the final wetting state during the infiltration and regulation oil displacement process of the target reservoir is used as the final contact angle of each capillary in the capillary bundle geometric model during the displacement flow simulation;

[0270] For the target reservoir rock samples, the oil-water interface tension test is carried out, and the oil-water interface tension obtained by the test is used as the oil-water interface tension in the process of oil displacement by infiltration and regulation of the target reservoir; the oil-water interface tension in the process of oil displacement by infiltration and regulation of the target reservoir is used as the oil-water interface tension in the capillary bundle geometric model during displacement flow simulation;

[0271] For the target reservoir rock samples, non-steady-state core flooding experiments were carried out before and after the infiltration and regulation flooding, and then the Johnson-Bossler-Naumann (JBN) method was used to interpret the dynamic data such as pressure and flow of the core flooding experiment to determine the oil-water relative permeability curves before and after the infiltration and regulation flooding. The determined oil-water relative permeability curves before and after the infiltration and regulation flooding were used as the oil-water relative permeability curves of the target reservoir in the initial wetting state during the infiltration and regulation flooding process (see Figure 4A , Figure 4B ) and the oil-water relative permeability curve in the final wetting state (see Figure 4A , Figure 4B ).

[0272] Table 1

[0273] parameter Value unit parameter Value unit Oil-water interfacial tension 7.2 mN / m Number of capillaries 500 indivual Minimum pore throat radius 1.0 μm Maximum pore throat radius 100.0 μm Final oil phase contact angle 180 Spend Initial oil phase contact angle 0.0 Spend Oil phase viscosity 1.5 mPa·s Water phase viscosity 1.5 mPa·s Capillary length 0.001 m Dimensionless parameter γ 0.5 Dimensionless Dimensionless parameter δ 1.5 Dimensionless

[0274] 3. Construct a contact angle constitutive model that reflects the change in rock wettability during the process of infiltration-controlled oil displacement, which is used to constrain the size of the capillary contact angles in the capillary bundle geometric model during displacement flow simulation;

[0275] Specifically: Construct the following contact angle constitutive model to reflect the change of rock wettability during the process of oil displacement regulated by infiltration:

[0276]

[0277]

[0278]

[0279] In the formula, θ m (·) is the contact angle at each position of the mth capillary during displacement flow simulation; is the initial contact angle of the mth capillary; is the final contact angle of the mth capillary; is a dynamic parameter reflecting the degree of adsorption of the wetting control chemical on the rock pore wall, with a value of 0-1; C is a dimensionless parameter, which is equal to the ratio of the adsorption and desorption rate constants during the wetting control oil displacement process, and is used to control the conversion speed from the initial wetting state to the final wetting state. In this embodiment, the value is 3×10 -3 ; m (t) is the normalized contact reaction time of the mth capillary at time t in displacement flow simulation; V p,m is the pore throat volume of the mth capillary; A b,m is the cross-sectional area of ​​the mth capillary; ζ is the time for all capillaries to perform a round of displacement flow simulation under the initial contact angle condition; is the interface position of the mth capillary at the time of displacement flow simulation τ, ranging from 0 to L; t is the duration of displacement flow simulation, ranging from 0 to T;

[0280] Among them, the capillary contact angle is the time for all capillaries to perform a round of displacement flow simulation under the initial contact angle condition and is determined by the following method:

[0281] Based on the oil-water interfacial tension in the capillary bundle geometric model during the displacement flow simulation, the contact angle of each capillary in the capillary bundle geometric model during the displacement flow simulation is the initial contact angle, and the capillary bundle geometric model of this embodiment is used to step-control the displacement pressure difference to perform a round of displacement flow simulation, and the time for all capillaries to perform a complete displacement flow simulation is obtained, which is the time for all capillaries to perform a round of displacement flow simulation under the condition of the initial contact angle.

[0282] 4. Based on the initial contact angle and final contact angle of each capillary in the capillary bundle geometric model during the displacement flow simulation, and the constitutive model of oil-water interfacial tension and contact angle in the capillary bundle geometric model during the displacement flow simulation, the capillary bundle geometric model is used to step-by-step control the displacement pressure difference to perform multiple rounds of displacement flow simulation, and the oil-water relative permeability data at different stages in the infiltration regulation oil displacement process are obtained, and the oil-water relative permeability curves at different stages in the infiltration regulation oil displacement process are obtained;

[0283] Among them, the step-by-step control of displacement pressure difference for multiple rounds of displacement flow simulation includes:

[0284] ①Get the maximum threshold pressure

[0285] ② Obtain the displacement pressure difference ΔP between the water phase and the oil phase fluid, Where P l res , are the pressures of the water phase fluid at the inlet end and the oil phase fluid at the outlet end of the capillary bundle model, respectively;

[0286] ③In Under the condition, for each capillary in the capillary bundle geometric model, determine the capillary pressure P of the capillary m Is it less than the displacement pressure difference ΔP? If so, the displacement simulation is performed on the capillary until a stable state is reached and the contact reaction time of the capillary is determined. It is also determined whether the initial contact angle of the capillary is less than If so, determine the cross-sectional areas of the continuous phase fluid and the corner fluid;

[0287] ④ Determine the average saturation of the capillary bundle geometric model based on the cross-sectional areas of the continuous phase fluid and the corner fluid in the capillary determined in step ③, and determine the oil-water relative permeability corresponding to the average saturation;

[0288] ⑤Gradually increase the pressure P of the water phase fluid at the inlet l res Repeat steps ②-④ to update the displacement pressure difference ΔP and perform displacement simulation under the updated displacement pressure difference ΔP until If it is not established, the displacement simulation is completed;

[0289] ⑥ Determine the average contact reaction time of each capillary during displacement flow simulation based on the contact reaction time of each capillary;

[0290] ⑦ For each initial contact angle in the capillary bundle geometry model, The capillary tube is provided with a capillary tube, and the contact angle in the capillary tube is determined based on the contact angle constitutive model and the contact angle in the capillary tube is updated, and then the above steps ① to ⑥ are repeated to perform the next round of flow simulation;

[0291] Among them, the initial contact angle is not less than There is only continuous phase fluid in the capillary and no corner fluid; the initial contact angle is not less than The capillary does not update the contact angle and always maintains the initial contact angle;

[0292] Among them, the maximum threshold pressure is the maximum capillary pressure in displacement flow simulation; the minimum threshold pressure is the minimum capillary pressure during displacement flow simulation;

[0293] Where, capillary pressure P m Determined by the following formula:

[0294]

[0295] Where P m is the capillary pressure, in Pa; σ is the oil-water interfacial tension, in mN / m; R m is the cross-sectional radius between the corner fluid and the continuous phase fluid of the mth capillary, in μm;

[0296] The oil-water relative permeability curves at different stages of the infiltration-controlled oil displacement process are determined as follows: Figure 4A , Figure 4B As shown in the figure, it can be seen that the contact reaction time with the chemical agent has a significant effect on the relative permeability curves of the oil and water phases. With the increase of the contact reaction time, the relative permeability of the oil phase fluid gradually increases, while the relative permeability of the water phase fluid gradually decreases. The dynamic changes of the contact angle during the infiltration control oil displacement process are shown in Figure 5 As shown, it can be seen that the dynamic contact angle has a good correlation with the contact reaction time, indicating that in addition to the wetting phase fluid saturation, the length of the contact reaction time with the chemical agent will also significantly affect the relative permeability and curve shape.

[0297] 5. Based on the oil-water relative permeability data at different stages of the target reservoir infiltration control oil displacement process, a dynamic oil-water relative permeability determination model in the infiltration control oil displacement process is fitted;

[0298] The dynamic capillary pressure calculation model finally fitted is:

[0299]

[0300]

[0301]

[0302] In the formula, k rw is the relative permeability of the water phase; k rn is the relative permeability of the oil phase; is the uniform average contact reaction time, with a value of 0-1; S w is the water phase fluid saturation; is the dynamic correlation coefficient between the relative permeability of oil phase and water phase fluid; λ, a, b are dimensionless fitting coefficients;

[0303] In order to verify the accuracy of the dynamic oil-water relative permeability determination model, the dynamic relative permeability characterization model was used to determine the oil-water relative permeability curve during the infiltration regulation oil displacement process. The oil-water relative permeability curve during the infiltration regulation oil displacement process determined by the dynamic characterization model was compared with the oil-water relative permeability curve obtained by displacement flow simulation in step 4 (e.g. Fig. 6A , Figure 6B As shown), it can be seen that the dynamic oil-water relative permeability determination model established in the embodiment of the present invention can well match the displacement flow simulation results.

[0304] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining the relative permeability of oil and water in the process of oil displacement by infiltration control, wherein: The method includes: Construct capillary bundle geometry model; Determine the initial contact angle and final contact angle of each capillary in the capillary bundle geometric model during the flow simulation, and determine the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation; A contact angle constitutive model is constructed to reflect the change of rock wettability during the process of infiltration-controlled oil displacement, which is used to constrain the size of the capillary contact angles in the capillary bundle geometric model during the flow simulation. Based on the initial contact angle and final contact angle of each capillary in the capillary bundle geometric model during the flow simulation, the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation, and the contact angle constitutive model, the capillary bundle geometric model is used to perform multiple rounds of flow simulation by step-controlled displacement pressure difference to obtain oil-water relative permeability curves at different stages in the infiltration-controlled oil displacement process, that is, oil-water relative permeability curves corresponding to different average contact reaction times in the infiltration-controlled oil displacement process; Wherein, the flow simulation is a displacement flow simulation or a suction flow simulation; Among them, constructing the capillary bundle geometric model includes: Obtain the pore throat distribution characteristics of the target reservoir; A capillary bundle model capable of describing the pore throat distribution characteristics of the target reservoir is constructed; wherein the capillary radius distribution in the capillary bundle model is characterized by a truncated Weibull distribution function; wherein the capillary bundle model is a triangular prism capillary bundle model; wherein the capillary radius distribution in the capillary bundle model is characterized by the following truncated Weibull distribution function: R=(R max -R min ){-δln[y(1-exp(-1 / δ))+exp(-1 / δ)]} 1 / γ +R min In the formula, R max is the maximum pore throat radius of the target reservoir; R min is the minimum pore throat radius of the target reservoir; δ and γ are dimensionless parameters; y is a random number between 0 and 1; R is the radius of the capillary in the capillary bundle model; Among them, the contact angle constitutive model reflecting the change of rock wettability during the process of infiltration regulation and oil displacement is: In the formula, θ m (·) is the contact angle at each position of the mth capillary during the flow simulation; is the initial contact angle of the mth capillary; is the final contact angle of the mth capillary; is a dynamic parameter reflecting the degree of adsorption of the wetting control chemical on the rock pore wall, with a value of 0-1; C is a dimensionless parameter determined by the ratio of the adsorption and desorption rate constants during the wetting control oil displacement process, and is used to control the conversion speed from the initial wetting state to the final wetting state; χ m (t) is the flow simulation time t, the normalized contact reaction time of the mth capillary; V p,m is the pore throat volume of the mth capillary; A b,m is the cross-sectional area of ​​the mth capillary; ζ is the time for all capillaries to perform a round of flow simulation under the initial contact angle condition; is the flow simulation time τ, the interface position of the mth capillary, between 0-L; t is the flow simulation duration, between 0-T.

2. The method according to claim 1, wherein: Determine the initial contact angle and final contact angle of each capillary in the capillary bundle geometric model during the flow simulation, and determine the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation, including: Determine the rock contact angle in the initial wetting state and the rock contact angle in the final wetting state during the target reservoir infiltration and oil displacement process; determine the oil-water interfacial tension during the target reservoir infiltration and oil displacement process; Based on the rock contact angle in the initial wetting state during the oil displacement process of the target reservoir infiltration control, the initial contact angle of each capillary in the capillary bundle geometric model during the flow simulation process is determined; The final contact angle of each capillary in the capillary bundle geometric model during the flow simulation is determined based on the rock contact angle in the final wetting state during the target reservoir infiltration control oil displacement process; The oil-water interfacial tension in the capillary bundle geometric model during flow simulation is determined based on the target reservoir infiltration and oil-water interfacial tension regulation during oil displacement.

3. The method according to claim 1, wherein: The method further includes the step of obtaining the time for all capillaries to perform a round of flow simulation under the initial contact angle condition: Based on the oil-water interfacial tension in the capillary bundle geometric model during the flow simulation, the contact angle of each capillary in the capillary bundle geometric model during the flow simulation is the initial contact angle, and the capillary bundle geometric model is used to step-control the displacement pressure difference to perform a round of flow simulation, and the time for all capillaries to perform a complete flow simulation is obtained, which is the time for all capillaries to perform a round of flow simulation under the condition of the initial contact angle.

4. The method according to claim 1 or 3, wherein: When the flow simulation is a displacement flow simulation, the step-by-step control of the displacement pressure difference to perform a round of flow simulation includes: ①Get the maximum threshold pressure ② Obtain the displacement pressure difference ΔP between the water phase and the oil phase fluid, in are the pressures of the water phase fluid at the inlet end and the oil phase fluid at the outlet end of the capillary bundle model, respectively; ③In Under the condition, for each capillary in the capillary bundle geometric model, determine the capillary pressure P of the capillary m Is it less than the displacement pressure difference ΔP? If so, the displacement simulation is performed on the capillary until a stable state is reached and the contact reaction time of the capillary is determined. It is also determined whether the initial contact angle of the capillary is less than If so, determine the cross-sectional areas of the continuous phase fluid and the corner fluid; ④ Determine the average saturation of the capillary bundle geometric model based on the cross-sectional areas of the continuous phase fluid and the corner fluid in the capillary determined in step ③, and determine the oil-water relative permeability corresponding to the average saturation; ⑤Gradually increase the pressure of the water phase fluid at the inlet Repeat steps ②-④ to update the displacement pressure difference ΔP and perform displacement simulation under the updated displacement pressure difference ΔP until If it is not established, the displacement simulation is completed; ⑥ Based on the contact reaction time of each capillary, determine the average contact reaction time of each capillary during the displacement flow simulation process.

5. The method according to claim 4, wherein: When the flow simulation is a displacement flow simulation, during multiple rounds of flow simulation, after each round of flow simulation is completed, for each initial contact angle less than The capillary tube is provided with a capillary tube, and the size of the contact angle in the capillary tube is determined and updated based on the contact angle constitutive model, and then the above steps ① to ⑥ are repeated to perform the next round of flow simulation.

6. The method according to claim 4, wherein: Maximum threshold pressure Not less than the maximum capillary pressure during the flow simulation.

7. The method according to claim 4, wherein: Capillary pressure P m Determined by the following formula: Where P m is the capillary pressure, in Pa; σ is the oil-water interfacial tension, in mN / m; R m It is the cross-sectional radius between the corner fluid and the continuous phase fluid of the mth capillary, in μm.

8. The method according to claim 1 or 3, wherein: When the flow simulation is a sucking flow simulation, the step-by-step control of the displacement pressure difference is performed to perform a round of flow simulation including: ① Obtain the minimum threshold pressure ② Obtain the displacement pressure difference ΔP between the water phase and the oil phase fluid, in are the pressures of the water phase fluid at the inlet end and the oil phase fluid at the outlet end of the capillary bundle model, respectively; ③In Under the condition, for each capillary in the capillary bundle geometric model, determine the capillary pressure P of the capillary m Is it greater than the displacement pressure difference ΔP? If so, the capillary is sucked and simulated until a stable state is reached and the contact reaction time of the capillary is determined. It is also determined whether the initial contact angle of the capillary is less than If so, determine the cross-sectional areas of the continuous phase fluid and the corner fluid; ④ Determine the average saturation of the capillary bundle geometric model based on the cross-sectional areas of the continuous phase fluid and the corner fluid in the capillary determined in step ③, and determine the oil-water relative permeability corresponding to the average saturation; ⑤Gradually reduce the pressure of the water phase fluid at the inlet Repeat steps ②-④ to update the displacement pressure difference ΔP and perform the sucking simulation under the updated displacement pressure difference ΔP until Not established to complete the sucking simulation; ⑥ Based on the contact reaction time of each capillary, determine the average contact reaction time of each capillary during the displacement flow simulation process.

9. The method according to claim 8, wherein: When the flow simulation is a sucking flow simulation, during multiple rounds of flow simulation, after each round of flow simulation is completed, for each initial contact angle less than The capillary tube is provided with a capillary tube, and the size of the contact angle in the capillary tube is determined and updated based on the contact angle constitutive model, and then the above steps ① to ⑥ are repeated to perform the next round of flow simulation.

10. The method according to claim 8, wherein: The minimum threshold pressure is not greater than the minimum capillary pressure during the flow simulation.

11. The method according to claim 8, wherein: Capillary pressure P m Determined by the following formula: Where P m is the capillary pressure, in Pa; σ is the oil-water interfacial tension, in mN / m; R m It is the cross-sectional radius between the corner fluid and the continuous phase fluid of the mth capillary, in μm.

12. A method for determining a dynamic oil-water relative permeability characterization model during infiltration-controlled oil displacement, wherein: The method includes: The method for determining the oil-water relative permeability during the infiltration control displacement process according to any one of claims 1 to 11 is used to obtain the oil-water relative permeability curves at different stages during the infiltration control displacement process, i.e., the oil-water relative permeability curves corresponding to different average contact reaction times during the infiltration control displacement process, thereby obtaining the oil-water relative permeability data at different stages during the infiltration control displacement process of the target reservoir, i.e., the oil-water relative permeability data corresponding to different average contact reaction times during the infiltration control displacement process; Based on the oil-water relative permeability data at different stages of the target reservoir infiltration-controlled oil displacement process, a dynamic oil-water relative permeability characterization model in the infiltration-controlled oil displacement process is fitted; Among them, the dynamic oil-water relative permeability characterization model in the infiltration regulation oil displacement process is: In the formula, k rw is the relative permeability of the water phase fluid; k rn is the relative permeability of the oil phase fluid; is the uniform average contact reaction time, with a value of 0-1; S w is the water phase fluid saturation; is the dynamic correlation coefficient between the relative permeability of oil phase and water phase fluid; λ, a, b are dimensionless fitting coefficients.

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