Method for determining relative permeability curve of ternary composite oil displacement
By establishing a numerical simulation model and fitting the relative permeability curve using core experimental data, the problem of determining the relative permeability curve of ternary composite oil displacement was solved, enabling more accurate research and development scheme optimization and improving the recovery rate of tertiary oil recovery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DAQING OILFIELD CO LTD
- Filing Date
- 2024-10-09
- Publication Date
- 2026-04-10
AI Technical Summary
The lack of effective methods in the current technology to determine the relative permeability curve of ternary composite oil displacement has affected the accuracy of research results and production indicators. The corrected oil-water relative permeability curve is often used to replace the phase permeability characteristics of ternary composite oil displacement, which leads to large errors.
By establishing a numerical simulation model, using core experimental data to set the relative permeability curve as an uncertain parameter, fitting the core displacement data, and inverting the relative permeability curve of the ternary composite oil displacement, the model is applicable to the Darcy flow equation in numerical simulation software.
This improves the accuracy of research results, enabling a better understanding of the seepage characteristics during tertiary oil recovery, optimizing development strategies, and increasing oil recovery rates.
Smart Images
Figure CN121835103A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of tertiary oil recovery technology in oil development, specifically to a method for obtaining the relative permeability curve of ternary composite oil displacement. This method can be used to carry out research work such as calculation of engineering parameters, dynamic analysis, and numerical simulation of tertiary oil recovery reservoirs. Background Technology
[0002] The statements in this section provide only background information in connection with this disclosure and do not constitute prior art.
[0003] Relative permeability curves are important reservoir parameters, describing the seepage characteristics of subsurface multiphase fluids. They are indispensable basic data for oil and gas field development prediction indicators, development plan formulation, and reservoir numerical simulation technology research. Due to the complexity of the physicochemical mechanism of ternary composite flooding, there is currently no method to determine its relative permeability curves.
[0004] Currently, experimental methods for determining relative permeability curves are divided into steady-state and unsteady-state methods. It is difficult to establish a two-phase steady state using the steady-state method for determining the relative permeability curve of a ternary composite flooding process; therefore, the steady-state method is not suitable for determining the relative permeability curve of a ternary composite flooding process. Traditional unsteady-state relative permeability curve determination is based on the JBN method, calculating the relative permeability of each single phase using the Buckley-Leverett two-phase displacement theory based on the cumulative injection volume, cumulative oil production, and pressure difference recorded during the experiment. The unsteady-state method for determining the relative permeability curve of a ternary composite flooding process considers the shear characteristics of power-law fluids flowing through porous media, corrects the viscosity of the ternary solution during the displacement process, establishes the relationship between the viscosity of the ternary solution and other displacement data, and calculates the relative permeability. However, the relative permeability curve obtained by the power-law fluid method is not applicable to the Darcy flow equation in numerical simulation software; therefore, the unsteady-state method also lacks a method for calculating the relative permeability curve of a ternary composite flooding process.
[0005] The relative permeability curves currently used in ternary composite flooding still follow the water-driven phase permeation method. The seepage characteristics in the ternary composite flooding process are different from the conventional oil-water Darcy flow. At present, the modified oil-water relative permeability curve is often used to replace the relative permeability curve of ternary composite flooding, which seriously affects the accuracy of research results and production indicators. There is an urgent need to establish a method for obtaining the phase permeation curve that belongs to the characteristics of ternary composite flooding.
[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art. Summary of the Invention
[0007] In view of this, this disclosure provides a method for obtaining the relative permeability curve of ternary composite flooding through numerical simulation inversion, which solves the problem that the current method of using the modified oil-water relative permeability curve to replace the polymer flooding relative permeability curve is not yet available, and there is no method for determining the relative permeability curve of ternary composite flooding.
[0008] The technical concept of the method for obtaining the relative permeability curve of ternary composite oil displacement by numerical simulation inversion of the present invention is as follows: a numerical simulation model is established using core experimental data, and the relative permeability curve is set as an uncertain parameter to fit the core displacement data, thereby inverting the relative permeability curve of ternary composite oil displacement.
[0009] Based on the technical concept of this invention, and to achieve the above-mentioned objective, the method for determining the relative permeability curve of the ternary composite oil displacement includes:
[0010] A ternary composite oil displacement numerical simulation model was established to simulate the ternary composite oil displacement process. The relative permeability curve was set as an uncertain parameter to fit the core displacement data, and the relative permeability curve of the ternary composite oil displacement was obtained by inversion.
[0011] In this disclosure and possible embodiments, the core displacement data are oil production and water cut indicators.
[0012] In this disclosure and possible embodiments, the method for establishing a ternary composite oil displacement numerical simulation model includes:
[0013] Using core experimental data, characteristic points of the relative permeability curve were determined, a numerical simulation model of single-phase ternary composite flooding was constructed, the single-phase flooding process was fitted, and sensitive parameters of ternary composite flooding were determined.
[0014] The ternary composite flooding numerical simulation model is constructed using the characteristic points of the relative permeability curve and the sensitive parameters of the ternary composite flooding.
[0015] In this disclosure and possible embodiments, the method for constructing a numerical simulation model of a single-phase ternary composite flooding system using core experimental data includes:
[0016] A static numerical simulation model was built based on core data;
[0017] Based on the static model, a numerical simulation dynamic model was built using core data of the ternary composite solution.
[0018] The dynamic model is the numerical simulation model of the single-phase ternary composite drive.
[0019] In this disclosure and possible embodiments, the method for constructing a static numerical simulation model based on core data includes:
[0020] A homogeneous numerical simulation model at the core scale was constructed. The model adopted laboratory units and was a one-dimensional model with a grid of 100*1*1. The pore volume, cross-sectional area, length, porosity, and permeability of the model were consistent with those of the core model. The temperature was 45℃, the initial water saturation was 1, and the initial pressure was atmospheric pressure. The ternary solution parameters were taken from the core experimental data to obtain the static model.
[0021] In this disclosure and possible embodiments, the method for constructing a numerical simulation dynamic model based on displacement process data includes:
[0022] Based on the static model, and following a constant production rate of 1 injection and 1 extraction, the dynamic model was obtained by simulating the process of a single-phase ternary solution passing through the core.
[0023] In this disclosure and possible embodiments, the flow rates of the constant-rate production are 0.1, 0.2, 0.4, 0.6, 1 and 2 ml / min, respectively.
[0024] In this disclosure and possible embodiments, the method for fitting a single-phase drive process to determine the sensitive parameters of a ternary composite drive includes:
[0025] A ternary composite oil displacement mechanism is added to the dynamic model, and the pressure difference data of the simulated single-phase ternary solution through the core process are used to generate an observation file;
[0026] The maximum adsorption capacity and accessible pore volume are defined as uncertain parameters. The production pressure difference index is fitted, and the values of the maximum adsorption capacity and accessible pore volume are determined as the ternary composite flooding sensing parameters.
[0027] In this disclosure and possible embodiments, the CMG’s auxiliary history fitting module CMOST is used to define the maximum adsorption amount and accessible pore volume. Based on the range of user-defined uncertain parameters and experimental algorithms, models with different parameter combinations are generated. The model approximates the objective function based on the optimization algorithm to achieve index fitting of production pressure difference.
[0028] In this disclosure and possible embodiments, the method for obtaining the core experimental data includes:
[0029] Prepare parallel cores and use one of the cores to conduct a single-phase ternary solution passing through the core to obtain the residual drag coefficient at different flow rates and the relationship between velocity and viscosity.
[0030] A ternary composite oil displacement experiment was conducted using saturated oil from parallel rock samples. The pore volume and bound water saturation were measured, and the cumulative oil production and pressure difference during the measurement process were recorded at the set displacement rate.
[0031] In this disclosure and possible embodiments, the method for determining characteristic points of the relative permeability curve using core experimental data includes:
[0032] The characteristic points of the relative permeability curve refer to the bound water saturation, residual oil saturation, and maximum relative permeability of the aqueous phase.
[0033] The remaining oil volume in the core is calculated based on the cumulative oil production, and the residual oil saturation is obtained by dividing the remaining oil volume by the pore volume.
[0034] The maximum relative permeability of the aqueous phase is calculated using the displacement velocity, the pressure difference, the core parameters, and the viscosity of the ternary solution.
[0035] In this disclosure and possible embodiments, the method for conducting single-phase ternary solutions through core experiments includes:
[0036] (5) Empty the core to remove saturated formation water and weigh it to calculate the pore volume;
[0037] (6) First, set the flow rate to 0.1 ml / min for water driving, and then change the flow rate to 0.2, 0.4, 0.6, 1.0 and 2.0 ml / min for water driving in sequence. After stabilization, read the pressure difference ΔP1 at each flow rate.
[0038] (7) Change the water drive process to a ternary composite drive process, set the flow rate to a constant displacement of 0.1 ml / min, and read the pressure ΔP2 when the pressure stabilizes after injecting 1 PV; change the flow rate to 0.2, 0.4, 0.6, 1.0 and 2.0 ml / min in sequence, and read the pressure when the pressure stabilizes respectively;
[0039] (8) Change the ternary composite flooding process to a water flooding process, measure the subsequent water flooding pressure ΔP3, the pressure at the initial flow rate of 0.1 ml / min, record the pressure change during the displacement process, and calculate the resistance coefficient, residual resistance coefficient and the relationship between flow rate and viscosity at different flow rates.
[0040] In this disclosure and possible embodiments, the method for conducting a ternary composite oil displacement experiment using parallel rock sample saturated oil includes:
[0041] (1) After the core was emptied of saturated formation water, oil was used to drive the water and the bound water saturation and pore volume were measured.
[0042] (2) Use a ternary solution to drive the oil at a rate of 0.1 mL / min, and record the cumulative oil production and pressure difference during the measurement process.
[0043] The beneficial effects of this invention are as follows:
[0044] The method for determining the relative permeability curve of ternary composite oil displacement disclosed herein utilizes core experimental data to establish a numerical simulation model. The relative permeability curve is set as an uncertain parameter to fit the core displacement data, thereby inverting the relative permeability curve of the ternary composite oil displacement. The relative permeability curve determined by this method is not limited by the type of ternary composite solution and is also applicable to the Darcy flow equation in numerical simulation software. Applying the relative permeability curve disclosed herein to conduct research on reservoir engineering parameter calculation, dynamic analysis, and numerical simulation can improve the accuracy of research results, help further elucidate the seepage characteristics in the tertiary oil recovery process, and provide important technical support for formulating reasonable working systems, optimizing development plans, and improving the recovery rate of tertiary oil recovery. Attached Figure Description
[0045] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the specification, serve to illustrate the technical solutions of this disclosure.
[0046] Figure 1 This is a flowchart of a method for obtaining the relative permeability curve of a ternary composite oil displacement through numerical simulation inversion according to an embodiment of this disclosure;
[0047] Figure 2 This is a fitting result of the oil production rate in the CMOST software-assisted oil displacement experiment according to an embodiment of this disclosure;
[0048] Figure 3 This is a fitting result of the water content in the CMOST software oil displacement experiment according to an embodiment of this disclosure;
[0049] Figure 4 The ternary composite oil displacement phase permeation curve is inverted from the embodiments of this disclosure. Detailed Implementation
[0050] The present disclosure is described below based on embodiments; however, it is worth noting that the present disclosure is not limited to these embodiments. In the detailed description of the present disclosure below, certain specific details are described in detail. However, those skilled in the art will fully understand the present disclosure for the parts not described in detail.
[0051] Furthermore, unless the context explicitly requires it, the words "comprising," "including," and similar terms throughout the specification and claims should be interpreted as including rather than exclusive or exhaustive; that is, meaning "including but not limited to."
[0052] Currently, modified oil-water relative permeability curves are often used to replace polymer flooding relative permeability curves, which seriously affects the accuracy of research results and production indicators. To solve the above problems, this invention provides a method for obtaining the relative permeability curve of ternary composite flooding based on numerical simulation inversion. The technical idea of this method is as follows:
[0053] First, single-phase solutions were used in core experiments to measure the pressure difference during displacement at different velocities, obtaining pressure difference data for the displacement process. The purpose of the experiment was to measure the residual drag coefficient and the relationship between velocity and viscosity. Since the experimental process did not involve an oil phase, it was irrelevant to the morphology of the relative permeability curve. Second, parallel rock samples were used for oil displacement experiments to obtain the oil and water production during the displacement process. These data are crucial for reflecting the relative permeability curve.
[0054] Then, a single-phase numerical simulation model was established to simulate single-phase core experiments. The fitting index of the single-phase numerical simulation model was pressure difference, and the parameters were modified to non-experimentally obtained parameters such as adsorption and accessible pore volume. Since the relative permeability curve used in the single-phase numerical simulation model is only related to the right endpoint and is not related to the curve shape, the relative permeability curve was not modified during the fitting process of the single-phase numerical simulation model.
[0055] Finally, using the parameters determined after fitting the single-phase numerical simulation model, an oil displacement numerical simulation model was established to simulate the core oil displacement experiment. This oil displacement numerical simulation model fits the oil production and water production indicators by modifying the relative permeability curve. Since the production indicators are related to the relative permeability curve, the relative permeability curve can be obtained by inverting the results of fitting the oil displacement numerical simulation model.
[0056] Based on the above technical approach, the method for obtaining the relative permeability curve of a ternary composite flooding system based on numerical simulation inversion disclosed herein is implemented according to the following specific technical solution, the process of which is as follows: Figure 1 As shown, the specific steps of the proposed solution are as follows:
[0057] 1. Prepare two parallel core samples (with similar lithology, porosity, and permeability) for physical experiments.
[0058] (1) Single-phase fluid passing through core experiment
[0059] The pore volume was calculated by passing a single-phase fluid through a core sample, and the drag coefficient and residual drag coefficient were calculated at velocities of 0.1, 0.2, 0.4, 0.6, 1.0, and 2.0 ml / min.
[0060] (2) Ternary solution oil displacement experiment
[0061] Take another parallel rock sample, saturate it with oil, and measure the bound water saturation and pore volume. Drive oil with a ternary solution at a rate of 0.1 mL / min, record the oil production and pressure difference during the measurement process, and obtain all three characteristic points of the relative permeability curve (bound water saturation Swcr, residual oil saturation, and maximum relative permeability of the aqueous phase).
[0062] II. Establishing a numerical model of the reservoir to simulate core experiments and inverting relative permeability curves
[0063] (1) Constructing a single-phase ternary composite flooding numerical simulation model and determining the sensitive parameters of the ternary composite flooding: Using the STARS module of CMG software, a core-scale homogeneous numerical simulation model was constructed. Production was carried out at a constant rate of 1 injection and 1 production (flow rates of 0.1, 0.2, 0.4, 0.6, 1, and 2 ml / min) to simulate the process of single-phase fluid passing through the core. Using the CMG auxiliary history fitting module CMOST, non-measurable parameters other than the phase permeation curve were defined as sensitive parameters, and the production pressure differential index was fitted. Based on this step, the values of the model's maximum adsorption capacity and accessible pore volume can be determined for the next step of oil displacement experimental simulation.
[0064] (2) Establish a ternary composite flooding simulation model and invert the ternary composite flooding phase permeation curve.
[0065] A ternary composite displacement model was established using the STARS module of CMG software. Sensitive parameters determined by the single-phase displacement model were used, and the mixture was injected at a rate of 0.1 ml / min. A power function was selected to characterize the morphology of the relative permeability curve. The CMG auxiliary history fitting module CMOST was used, with the relative permeability curve set as an uncertain parameter. The oil production rate and water cut were used as inversion parameters to obtain the ternary composite displacement relative permeability curve.
[0066] The following are preferred embodiments of this disclosure:
[0067] 1. Prepare two parallel core samples with similar lithology, porosity, and permeability for physical experiments:
[0068] (1) Single-phase fluid passing through core experiment
[0069] ① The core was emptied of saturated formation water and weighed to calculate the pore volume;
[0070] ② First, set the flow rate to 0.1 ml / min for water driving, and then change the flow rate to 0.2, 0.4, 0.6, 1.0, and 2.0 ml / min for water driving in sequence. After stabilization, read the pressure difference ΔP1 at each flow rate.
[0071] ③ Change the process to polymer flooding, set the flow rate to a constant displacement of 0.1 ml / min, and read the pressure ΔP2 when the pressure stabilizes after injecting 1 PV; change the flow rate to 0.2, 0.4, 0.6, 1.0, and 2.0 ml / min in sequence, and read the pressure when the pressure stabilizes.
[0072] ④ Change the process to a water-drive process and measure the subsequent water-drive pressure ΔP3 (the initial pressure is the pressure at a flow rate of 0.1 ml / min in the previous step, and record the pressure change during the displacement process, with the time interval being small at first and then large).
[0073] ⑤ Taking Table 1 as an example, calculate the drag coefficient and residual drag coefficient at different flow velocities according to the following formulas 1 and 2.
[0074] Drag coefficient:
[0075] Residual drag coefficient:
[0076] Table 1. Values of drag coefficient and residual drag coefficient of ternary solution at different flow rates
[0077]
[0078] ⑥ Calculate the relationship between velocity and viscosity of a ternary solution.
[0079] In the numerical model, viscosity is defined according to velocity. For now, velocity is understood as Darcy velocity. It is calculated using formula (3). The polymer viscosity corresponding to each velocity is calculated using formula (4).
[0080] Darcy speed:
[0081] Non-Newtonian viscosity:
[0082] Among them: Q W(asp) Let A be the injection velocity, and μ be the core cross-sectional area. w The viscosity of water can be obtained from Table 2.
[0083] Table 2 Relationship between velocity and viscosity at different injection fluid velocities
[0084] Injection speed (ml / min) Speed (cm / min) Viscosity (cp) 0.1 0.020 0.900 0.2 0.041 1.125 0.4 0.081 2.213 0.6 0.122 3.075 1.0 0.204 3.750 2.0 0.407 4.200
[0085] (2) Three-way composite oil displacement experiment:
[0086] ① Take another parallel rock sample, evacuate the core to remove saturated formation water, and then use oil to drive the water. At this time, there is bound water in the core. Measure the bound water saturation Swcr and pore volume.
[0087] ② The oil was driven by a ternary solution at a rate of 0.1 mL / min. The cumulative oil production and pressure difference during the measurement process were recorded, as shown in Table 3.
[0088] Table 3 Experimental data of ternary composite oil displacement
[0089]
[0090] ③ Obtain the residual oil saturation and maximum relative permeability of the aqueous phase in the model.
[0091] The remaining oil volume in the core can be calculated based on the cumulative oil production from the experiment. Dividing this by the pore volume yields the residual oil saturation. The maximum relative permeability of the aqueous phase is calculated using Formula 5. Thus, all three characteristic points of the relative permeability curve are obtained: bound water saturation (Swcr), residual oil saturation, and maximum relative permeability of the aqueous phase.
[0092] Maximum relative permeability of aqueous phase:
[0093]
[0094] Where: Q - flow velocity, μ o - Oil viscosity, L - Core length, A - Core cross-sectional area -Pressure difference.
[0095] 2. Establish a numerical model of the reservoir to simulate core experiments and invert the relative permeability curves.
[0096] (1) Construct a numerical simulation model of single-phase ternary composite drive and determine the sensitive parameters of ternary composite drive.
[0097] ①Build a static numerical simulation model based on core data
[0098] A core-scale homogeneous numerical simulation model was constructed using the STARS module of CMG software. The model was a laboratory unit with a 100*1*1 grid, ensuring that the pore volume, cross-sectional area, length, porosity, and permeability of the numerical model were consistent with those of the core model. The temperature was 45℃, the initial water saturation was 1, the initial pressure was atmospheric pressure, and the ternary solution parameters were consistent with those of the laboratory experiment.
[0099] ②Build a numerical simulation dynamic model based on displacement process data.
[0100] Production was carried out at a constant rate of 1 injection and 1 extraction (flow rates of 0.1, 0.2, 0.4, 0.6, 1, and 2 ml / min) to simulate the process of single-phase fluid passing through the core.
[0101] ③ Add a ternary composite oil displacement mechanism to the numerical model
[0102] By adding data parameters to the model, the effects of composition on viscosity, polymer, alkali and surfactant adsorption, permeability reduction, inaccessible pore volume, phase permeability difference and shear were described. At the same time, the data in Table 2 were added to the model as the actual viscosity.
[0103] ④ Experimental pressure difference generates observation data
[0104] The process pressure difference data of the ternary solution through the core experiment were used to generate observation files using CMG software for subsequent index fitting.
[0105] ⑤ Fitting the single-phase drive process using CMOST software
[0106] Using CMG's auxiliary history fitting module CMOST, uncertain parameters of the maximum polymer adsorption capacity and accessible pore volume are defined. Based on the range of user-defined uncertain parameters and experimental algorithms, models with different parameter combinations are generated. The model approximates the objective function based on the optimization algorithm, thereby achieving index fitting of the production pressure difference.
[0107] The specific steps for fitting a single-phase drive process are as follows: a. Import the basic model; b. Import the observation data; c. Set the uncertainty parameters; d. Set the objective function; e. Generate the experimental model; f. Perform simulation calculations; g. Analyze the fitting results.
[0108] Based on this step, the maximum adsorption capacity and accessible pore volume of the model can be determined, which will be used for the next step of oil displacement experiment simulation.
[0109] (2) Establish a ternary composite oil displacement simulation model and invert the ternary composite oil displacement phase permeation curve:
[0110] ① Construct a ternary composite oil displacement numerical simulation model
[0111] A numerical simulation model was established using the STARS module of CMG software. The construction method of the ternary composite flooding static model was the same as that of the single-phase flooding model. The initial water saturation was bound water, and the characteristic points of the phase permeability curve used were the characteristic points obtained from previous experiments. The morphology could be any water-driven phase permeability. The sensitive parameters determined by the single-phase flooding model were used, and the solution was injected at a rate of 0.1 ml / min. The oil production and water production data of the ternary solution displacement experiment were used to establish the observation file of the ternary composite flooding.
[0112] ②Establish a mathematical representation model for the relative permeability curve.
[0113] Choose a power function to characterize the shape of the interpenetration curve:
[0114] y = x a Formula (6) represents the function;
[0115] If the uncertain parameters co and cw are set as exponents of a power function, then
[0116] Relative permeability of the displaced phase: k ro =(1-s w ) co Formula (7);
[0117] Relative permeability of the displaced phase: k rasp =s w cw (Normalized) Formula (8);
[0118] ③ Set the relative permeability curve as an uncertain parameter.
[0119] Using CMG's auxiliary history fitting module CMOST, the relative permeability value corresponding to each Swi (water saturation) in the relative permeability curve table is associated with the uncertain parameter through the data-function-curve correlation method, and the relative permeability curve is designed as an uncertain parameter.
[0120] Relative permeability of ternary solutions:
[0121] k raspi =POWER((s wi -swcr) / (1-s orw -s wcr ),cw)*K rwmax Formula (9);
[0122] Relative permeability of oil phase:
[0123] k roi =POWER(1-(s) wi -s wcr ) / (1-s orw -s wcr Formula (10) ,co)
[0124] In the formula: S wi —The value of the i-th water saturation; s wcr —Bound water saturation; s orw —Residual oil saturation; K rwmax — Maximum relative penetration rate of ternary phase.
[0125] ④ Use CMOST software to fit the ternary composite oil displacement process
[0126] Using the CMG auxiliary history fitting module CMOST, in order to invert the relative permeability curve, this fitting only sets the relative permeability curve as an uncertain parameter. The Latin hypercube algorithm is selected to design the experimental scheme, and the oil production rate and water cut index are defined as objective functions for fitting.
[0127] By using the automatic history fitting function of CMOST, the model with the minimum objective function error can be obtained. Figure 2 and Figure 3 Thus, the values of co and cw in the model are determined to be 1.75 and 1.58, respectively. Using formulas 9-10, the phase permeation curve representing the ternary composite displacement characteristics is obtained. Figure 4 ).
[0128] Relative penetration rate of the displaced phase: K ro =(1-(Sw-0.2667) / 0.5316) 1.75 ;
[0129] Relative permeability of the displaced phase: K rasp =0.3225*((S) w -0.2667) / 0.5316) 1.58 .
[0130] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, and are not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical applications, or technical improvements to the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.
Claims
1. A method for determining the relative permeability curve of a ternary composite oil displacement system, characterized in that, include: A ternary composite oil displacement numerical simulation model was established to simulate the ternary composite oil displacement process. The relative permeability curve was set as an uncertain parameter to fit the core displacement data, and the relative permeability curve of the ternary composite oil displacement was obtained by inversion.
2. The method for determining the relative permeability curve of ternary composite oil displacement according to claim 1, characterized in that: The core displacement data are oil production and water content indicators.
3. The method for determining the relative permeability curve of ternary composite oil displacement according to claim 1 or 2, characterized in that, The method for establishing a ternary composite oil displacement numerical simulation model includes: Using core experimental data, characteristic points of the relative permeability curve were determined, a numerical simulation model of single-phase ternary composite flooding was constructed, the single-phase flooding process was fitted, and sensitive parameters of ternary composite flooding were determined. The ternary composite flooding numerical simulation model is constructed using the characteristic points of the relative permeability curve and the sensitive parameters of the ternary composite flooding.
4. The method for determining the relative permeability curve of ternary composite oil displacement according to claim 3, characterized in that, The method for constructing a numerical simulation model of a single-phase ternary composite flooding system using core experimental data includes: A static numerical simulation model was built based on core data; Based on the static model, a numerical simulation dynamic model was built using core data of the ternary composite solution. The dynamic model is the numerical simulation model of the single-phase ternary composite drive.
5. The method for determining the relative permeability curve of ternary composite oil displacement according to claim 4, characterized in that, The method for constructing a static numerical simulation model based on core data includes: A homogeneous numerical simulation model at the core scale was constructed. The model adopted laboratory units and was a one-dimensional model with a grid of 100*1*1. The pore volume, cross-sectional area, length, porosity, and permeability of the model were consistent with those of the core model. The temperature was 45℃, the initial water saturation was 1, and the initial pressure was atmospheric pressure. The ternary solution parameters were taken from the core experimental data to obtain the static model.
6. The method for determining the relative permeability curve of ternary composite oil displacement according to claim 5, characterized in that, The method for constructing a numerical simulation dynamic model based on displacement process data includes: Based on the static model, and following a constant production rate of 1 injection and 1 extraction, the dynamic model was obtained by simulating the process of a single-phase ternary solution passing through the core.
7. The method for determining the relative permeability curve of ternary composite oil displacement according to claim 6, characterized in that: The flow rates for constant-speed production are 0.1, 0.2, 0.4, 0.6, 1 and 2 ml / min, respectively.
8. The method for determining the relative permeability curve of ternary composite oil displacement according to claim 7, characterized in that, The method for determining the sensitive parameters of the ternary composite drive by fitting the single-phase drive process includes: A ternary composite oil displacement mechanism is added to the dynamic model, and the pressure difference data of the simulated single-phase ternary solution through the core process are used to generate an observation file; The maximum adsorption capacity and accessible pore volume are defined as uncertain parameters. The production pressure difference index is fitted, and the values of the maximum adsorption capacity and accessible pore volume are determined as the ternary composite flooding sensing parameters.
9. The method for determining the relative permeability curve of ternary composite oil displacement according to claim 8, characterized in that: Using CMG's auxiliary history fitting module CMOST, the maximum adsorption capacity and accessible pore volume are defined. Based on the range of user-defined uncertain parameters and experimental algorithms, models with different parameter combinations are generated. The model approximates the objective function based on the optimization algorithm, thus achieving index fitting of the production pressure difference.
10. The method for determining the relative permeability curve of ternary composite oil displacement according to any one of claims 4-9, characterized in that, The method for obtaining the core experimental data includes: Prepare parallel cores and use one of the cores to conduct a single-phase ternary solution passing through the core to obtain the residual drag coefficient at different flow rates and the relationship between velocity and viscosity. A ternary composite oil displacement experiment was conducted using saturated oil from parallel rock samples. The pore volume and bound water saturation were measured, and the cumulative oil production and pressure difference during the measurement process were recorded at the set displacement rate.
11. The method for determining the relative permeability curve of ternary composite oil displacement according to claim 10, characterized in that, The method for determining characteristic points of the relative permeability curve using core experimental data includes: The characteristic points of the relative permeability curve refer to the bound water saturation, residual oil saturation, and maximum relative permeability of the aqueous phase. The remaining oil volume in the core is calculated based on the cumulative oil production, and the residual oil saturation is obtained by dividing the remaining oil volume by the pore volume. The maximum relative permeability of the aqueous phase is calculated using the displacement velocity, the pressure difference, the core parameters, and the viscosity of the ternary solution.
12. The method for determining the relative permeability curve of ternary composite oil displacement according to claim 11, characterized in that, The method for conducting single-phase ternary solutions through core experiments includes: The core was emptied of saturated formation water, and the pore volume was calculated by weighing. First, set the flow rate to 0.1 ml / min for water driving, and then change the flow rate to 0.2, 0.4, 0.6, 1.0 and 2.0 ml / min for water driving in sequence. After stabilization, read the pressure difference ΔP1 at each flow rate. The water-driven process was changed to a ternary composite process. A constant displacement rate of 0.1 ml / min was set. After injecting 1 PV, the pressure ΔP2 was read when the pressure stabilized. The flow rate was changed to 0.2, 0.4, 0.6, 1.0, and 2.0 ml / min in sequence, and the pressure was read when the pressure stabilized. The ternary composite flooding process was changed to a water flooding process. The subsequent water flooding pressure ΔP3 was measured. The pressure was measured at the initial flow rate of 0.1 ml / min. The pressure change was recorded during the displacement process. The drag coefficient, residual drag coefficient and flow rate-viscosity relationship at different flow rates were calculated.
13. The method for determining the relative permeability curve of ternary composite oil displacement according to claim 12, characterized in that, The method for conducting ternary composite oil displacement experiments using parallel rock sample saturated oil includes: (1) After the core was emptied of saturated formation water, oil was used to drive the water and the bound water saturation and pore volume were measured. (2) Use a ternary solution to drive the oil at a rate of 0.1 mL / min, and record the cumulative oil production and pressure difference during the measurement process.