Establishment of a steady-state foam transport model coupled with the drag force of CO2 bubble liquid film

Abstract

The present invention provides a method for establishing a foam steady-state transmission model coupled with a CO2 bubble liquid film drag force, comprising the following steps: collecting physical property parameters of oil, gas and water and physical property parameter data of a block to be developed and bringing them into STARS, establishing a foam transmission model and its numerical simulation plate and physical simulation plate, establishing and introducing a liquid film drag force model into the foam transmission model, obtaining a foam steady-state transmission model of the CO2 bubble liquid film drag force and its numerical simulation plate, comparing the numerical simulation plate of the foam steady-state transmission model coupled with the CO2 bubble liquid film drag force with the physical simulation plate of the foam transmission model, and using the accurately fitted numerical simulation plate of the foam steady-state transmission model in the formulation of a foam flooding scheme for the block to be developed; the foam steady-state transmission model coupled with the CO2 bubble liquid film drag force in the present invention can accurately quantify and analyze the stability and strength of the liquid film drag force on the bubble, so that the formulated flooding scheme is closer to reality, and the effect of foam flooding can be effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield development, and in particular to a method for establishing a foam steady-state transmission model coupled with the dragging force of a CO2 bubble liquid film. Background Art

[0002] The application of carbon capture, utilization and storage (CCUS) technology in the field of oil and gas extraction has become a hot technology today. The captured CO2 is injected into deep geological reservoirs to achieve the purpose of energy extraction and improve oil and gas recovery. The use of carbon dioxide for improving oil and gas recovery can greatly improve the recovery rate, but the viscosity and density of CO2 are lower than those of general gases, and the mobility in the formation is large, which is easy to form viscous fingering, gas crossflow, gravity overburden or invalid circulation, etc., which ultimately leads to low CO2 injection sweep efficiency and affects oil and gas recovery. In medium and high permeability formations, foam has low fluidity. By introducing foam as a gas-liquid medium, the CO2 mobility is reduced and the gas viscosity is significantly increased, thereby suppressing the three major CO2 gas drive defects and greatly improving the injection gas sweep coefficient, which is beneficial to low permeability layers and maximizes the recovery rate and storage effect of CO2 injection.

[0003] The widespread application of CCUS technology has promoted new demands for CO2 foam flooding technology in oil fields, and it is urgent to establish accurate and efficient mining plans. According to the reservoir environment and fluid physical parameters of the undeveloped blocks of the oil field, the existing foam simulator LE-IT model uses its comprehensive function formula and calculation method to quantify the foam flooding mining plan, such as gas-liquid two-phase injection flow rate, surfactant system ratio, foam quality, gas-liquid two-phase injection volume and other field data, rather than just referring to the mining experience of developed oil wells, providing new ideas and new outlets for the development of oil wells in undeveloped blocks.

[0004] The LE-IT foam model calculation method can characterize the flow behavior of foam in the reservoir environment, that is, the stability, strength and rheology of the foam. Based on the principle that the foam generation rate is equal to the foam collapse rate, the steady-state flow stage of foam flooding is captured, and the factors affecting the physical properties of steady-state flow foam are characterized, which include surfactant concentration, water saturation, oil saturation, salinity, capillary number, rheology and permeability, etc., but do not include foam water saturation, apparent viscosity and bubble liquid film drag factors.

[0005] Therefore, it is necessary to combine the LE-IT model calculation method and the principle of foam liquid film drag force in porous media, while ensuring the accuracy and versatility of the model, to establish a method for establishing a foam steady-state transmission model coupled with the CO2 bubble liquid film drag force, to more comprehensively evaluate the CO2 foam steady-state flow behavior mechanism, and to provide targeted guidance for oil field enhanced oil and gas recovery technology. Summary of the invention

[0006] In view of this, the present invention proposes a method for establishing a foam steady-state transmission model that couples the drag force of the CO2 bubble liquid film and a calculation method thereof, which can specifically formulate an injection plan corresponding to the reservoir physical properties in combination with the reservoir simulation stage, and effectively improve the injection effect of CO2 and foaming agent.

[0007] The technical solution adopted by the present invention to solve the above problems is:

[0008] Step S1: Collecting data on oil, gas, water physical property parameters and reservoir physical property parameters of the block to be developed;

[0009] Step S2: Bring the collected oil, gas, water and reservoir physical property parameter data into STARS, and use the LE-IT model to establish a foam transmission model, i.e., a numerical simulation chart; and carry out steady-state flow experiments of relevant physical property parameters to obtain foam pressure gradients at different gas and liquid flow rates, and use the linear trigonometric interpolation method to fit the data calculated from the above parameters to obtain a physical simulation chart of the foam transmission model;

[0010] Step S3: Establishing the liquid film drag force model F drag The drag force model is introduced into the foam transport model established by the LE-IT model in step S2 to obtain the coupled CO2 bubble liquid film drag force F drag Foam Steady-State Transport Model FM new , input STARS to calculate FM new Numerical simulation plate of

[0011] Step S4: FM obtained in step S3 new The numerical simulation diagram of the foam transport model in step S2 is compared with the physical simulation diagram of the foam transport model in step S2 to introduce F drag FM with accurate post-model fitting and meeting the judgment conditions new The numerical simulation chart is used in the formulation of foam flooding scheme for the blocks to be developed.

[0012] The specific effects of the present invention are:

[0013] The present invention combines the LE-IT foam model calculation method, Darcy's law and Corey model, and proposes a method for establishing a foam steady-state transmission model of coupled CO2 bubble liquid film drag force and its calculation method. This model takes into account the drag force exerted on the coupled bubbles in the reservoir, and accurately quantifies and analyzes the effect of the liquid film drag force on the stability and strength of the bubbles in the capillary, so that the targeted foam flooding scheme formulated for the oil reservoirs in the development blocks is closer to the actual effect, and the effect of foam flooding can be effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below.

[0015] Figure 1 It is a physical simulation diagram of the foam transmission model in the present invention;

[0016] Figure 2 It is a numerical simulation plate of the foam transmission model in the present invention;

[0017] Figure 3 F in the present invention drag Model epdrag parameter change trend line chart;

[0018] Figure 4 F in the present invention drag Model fmdry parameter change trend line chart;

[0019] Figure 5 F in the present invention drag Diagram of the calculation method of the epdrag parameters of the model;

[0020] Figure 6 FM in the present invention new Numerical simulation diagram of . DETAILED DESCRIPTION

[0021] In order to facilitate those skilled in the art to better understand the present invention, the present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0022] Example:

[0023] The method for establishing a foam steady-state transmission model coupled with the drag force of a CO2 bubble liquid film comprises the following steps:

[0024] Step S1: Collecting data on oil, gas, water physical property parameters and reservoir physical property parameters of the block to be developed;

[0025] In this embodiment, the oil, gas and water physical property parameters include: liquid phase viscosity, gas phase viscosity, liquid phase factor, gas phase factor, bound water saturation, residual gas saturation, liquid phase relative permeability, gas phase relative permeability, gas-liquid two-phase surface tension; the reservoir physical property parameters include: absolute permeability. The physical property parameter data are shown in Table 1:

[0026] Table 1 Physical parameter data of sandstone core model

[0027]

[0028] Where, k is the absolute permeability of the core; is the CO2 gas phase viscosity; μ w is the liquid viscosity; σwg is the surface tension of gas-liquid two phases; k is the relative permeability of the gas phase in the gas-liquid two-phase flow process; rw (S w ) is the relative permeability of the liquid phase in the gas-liquid two-phase flow process; n g is the gas phase Corey factor; n w is the liquid phase Corey factor; S gr is the residual gas saturation; S wr is the bound water saturation.

[0029] Step S2: Bring the oil, gas, water and reservoir physical property parameter data collected in step S1 into STARS, and use the LE-IT algorithm to establish a foam transmission model, i.e., a numerical simulation chart; carry out steady-state flow experiments on relevant physical property parameters to obtain foam pressure gradients at different gas and liquid flow rates, and use the linear trigonometric interpolation method to fit the data calculated from the above parameters to obtain a physical simulation chart of the foam transmission model.

[0030] Among them, the foam transmission model is:

[0031]

[0032]

[0033]

[0034] At the same time, the relative permeability of the liquid phase at the limit water saturation The calculation formula is:

[0035]

[0036] Gas phase relative permeability at the ultimate water saturation The calculation formula is:

[0037]

[0038] Where FM is the gas relative permeability reduction factor, dimensionless; is the relative permeability of gas without foam, dimensionless; FM is the gas relative permeability reduction factor, dimensionless; fmmob is the foam strength, which controls the gas mobility reduction value, dimensionless; F n is the multiple physical property function of LE-IT foam model; U w is the liquid phase flow rate, μ w is the liquid viscosity, is the liquid relative permeability at the ultimate water saturation, K is the simulated permeability, is the pressure gradient, U g is the gas phase flow rate, is the relative permeability of the gas phase at the ultimate water saturation, μ g is the gas phase viscosity, fmmob * is the foam strength considering only the water saturation factor; is the relative permeability of gas in the presence of foam; is the relative permeability of the water phase endpoint; S wc is the residual water saturation; S g is the gas saturation;

[0039] The above is for multiple groups obtained The experimental data were numerically fitted using linear trigonometric interpolation to establish the following Figure 1 The physical simulation diagram shown.

[0040] STARS was used to iterate the physical simulation plates obtained above to obtain different S w The corresponding gas-liquid flow rate under Figure 2 The numerical simulation diagram of the foam transfer model is shown in the figure. However, the numerical simulation diagram obtained by relying solely on the STARS model cannot accurately fit the physical simulation diagram, indicating that the existing STARS model already has limitations, that is, it is impossible to obtain accurate numerical simulation diagrams, and the model needs to be further upgraded and improved.

[0041] Step S3: Establishing the liquid film drag force model F drag The drag force model is introduced into the foam transport model established by the LE-IT model in step S2 to obtain the foam steady-state transport model FM coupled with the CO2 bubble liquid film drag force new , FM is calculated using STRAS new Numerical simulation plate of

[0042] In porous media, the viscous force on CO2 foam with high liquid content is the sum of the tensile yield stress and the viscosity caused by the liquid film drag force. However, the foam drag force F is ignored in the above STARS model study. drag The relevant influence of the model results in the numerical simulation chart cannot accurately fit the actual results of the model in the physical simulation chart. Therefore, the foam film drag force F drag The influence of is added into the foam transport model derived from STARS, and the foam steady-state transport model FM coupled with the drag force of CO2 bubble liquid film is obtained. new .

[0043] Among them, the foam liquid film drag force model F drag for:

[0044]

[0045] In the formula, S wis the water saturation of the foam, epdrag is the drag force factor in the capillary, and fmdry is the critical water saturation;

[0046] Assuming that the superficial velocity of the gas phase remains constant, let F drag As a function describing the drag force of the bubble liquid film. When the water saturation of the foam increases, the pressure gradient decreases more, and the low dryness mechanism The greater the upward slope of the contour line, the greater the water saturation and F drag The specific meaning can be expressed as follows: when fmdry is a constant in a porous medium, the smaller epdrag is, the greater the foam film drag force F is. drag The smaller the value, the closer it is to 0, indicating that the foam strength fmmob is small; when epdrag is a constant in the porous medium, as the foam water saturation increases, the liquid film drag force F drag The smaller it is, the value tends to 0, indicating that the foam strength fmmob is smaller. Figure 3 , Figure 4 shown.

[0047] Therefore, the establishment of F drag The model is used to characterize the foam steady-state flow condition (S w >fmdry) The behavior of foam water saturation and liquid film drag force is affected, and the model is introduced into the FM function to update the FM function to characterize the factors affecting foam properties. The specific algorithm operation is as follows Figure 5 As shown: Draw a horizontal line on the model board ( Figure 5 Left figure), take multiple points where the pressure gradient contour line intersects, perform linear fitting on the logarithmic liquid phase flow rate values ​​and corresponding pressure gradient values ​​at multiple points, obtain the linear slope k, and further calculate the epdrag value (in Figure 5 epdrag = -4.3146). Substitute the epdrag value into F drag Function, obtain F at different liquid flow rates drag value, F drag Introducing the foam transmission model, we obtain FM new .

[0048] FM, a steady-state foam transport model coupled with the drag force of CO2 bubbles and liquid films new for:

[0049]

[0050] Among them, fmmob is the foam strength, and its calculation formula is:

[0051]

[0052] Where, fmmob *is the foam strength considering only the water saturation factor, fmcap is the capillary number under a certain pressure gradient; N ca is the reference capillary number; epcap is the shear behavior factor.

[0053] The epcap parameter satisfies the following formula:

[0054]

[0055] The slope σ is obtained by taking a certain value U w , use this point in the low dryness isoline region as a vertical line to the horizontal axis, perform double logarithmic numerical processing on the obtained set of gas phase flow rate and corresponding pressure gradient, and linearly fit the logarithmic data to obtain the slope σ;

[0056] Step S4: FM obtained in step S3 new The numerical simulation map of the foam transport model in step S2 is compared with the physical simulation map of the foam transport model in step S2, and the FM that meets the comparison conditions is selected. new The numerical simulation chart is used in the formulation of foam flooding plans for blocks to be developed.

[0057] Specific as Figure 6 FM shown new The numerical simulation chart of is obtained by STARS model calculation, which is compared with the physical simulation chart in step S2 to examine the degree of fit between the two. Among them, the FM obtained in step S3 new The comparison conditions of the numerical simulation map and the physical simulation map of the foam transport model in step S2 are: let the fmdry parameter of the numerical simulation map be a, and the fmdry parameter of the physical simulation map be Set it as b. When a∈[0.05b,1.05b], it is considered to meet the comparison condition, otherwise it is not met. At the same time, the epdrag parameter of the numerical simulation plate is obtained through step S3 and is set to c. Under different liquid flow rates, the fluctuation of the numerical range of c also needs to meet the condition of [0.95c,1.05c].

[0058] When the comparison conditions are met, it means that the fit between the two is very good, and the foam steady-state transport model FM of the coupled CO2 bubble drag force can be accurately fitted to the physical simulation plate new The numerical simulation chart is applied to the formulation of injection schemes in the CO2 foam flooding reservoir simulation stage in oilfield development blocks, such as designing surfactant concentration, injection gas-liquid phase flow rate, foam quality, etc., predicting the rheological behavior of foam in the reservoir and the ability to regulate the gas phase, quantifying the injection capacity and the effect of improving recovery, and obtaining targeted injection schemes, saving time while reducing reservoir development costs and improving mining efficiency.

[0059] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the embodiments of the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for establishing a foam steady-state transmission model coupled with the drag force of a CO2 bubble liquid film, characterized in that: The following steps are involved: Step S1: Collecting data on oil, gas, water physical property parameters and reservoir physical property parameters of the block to be developed; Step S2: Bring the collected oil, gas, water and reservoir physical property parameter data into STARS, and use the LE-IT model to establish a foam transmission model, i.e., a numerical simulation chart; and carry out steady-state flow experiments of relevant physical property parameters to obtain foam pressure gradients at different gas and liquid flow rates, and use the linear trigonometric interpolation method to fit the data calculated by the above parameters to obtain a physical simulation chart of the foam transmission model; Among them, the foam transmission model function is: At the same time, the relative permeability of the liquid phase at the limit water saturation The calculation formula is: Gas phase relative permeability at the ultimate water saturation The calculation formula is: Step S3: Establishing the liquid film drag force model F drag The liquid film drag force model is introduced into the foam transport model established by the LE-IT model in step S2 to obtain the foam steady-state transport model FM coupled with the CO2 bubble liquid film drag force new , input STARS to calculate FM new Numerical simulation plate of Among them, the foam liquid film drag force model F drag for: FM, a steady-state foam transport model coupled with the drag force of CO2 bubbles and liquid films new for: Among them, fmmob is the foam strength, and its calculation formula is: The epcap parameter satisfies the following formula: The slope σ is obtained by drawing a perpendicular line on the horizontal axis of the physical model plate and taking a certain value U w , this point intersects with multiple pressure gradient contour lines in the low dryness isoline area, and a set of gas phase flow rates and corresponding pressure gradient values ​​are processed by double logarithmic numerical processing, and the logarithmic data are linearly fitted to obtain the slope σ; Step S4: The FM obtained in step S3 new The numerical simulation diagram of the foam transport model in step S2 is compared with the physical simulation diagram of the foam transport model in step S2 to introduce F drag FM with accurate post-model fitting and meeting the judgment conditions new Numerical simulation charts are used in the formulation of foam flooding plans for blocks to be developed; In the above formulas, FM is the gas relative permeability reduction factor; fmmob is the foam strength; F n are various physical property functions of the LE-IT foam model; is the relative permeability of gas in the presence of foam; is the relative permeability of gas without foam; U w is the liquid phase flow rate; K is the simulated permeability; is the liquid phase relative permeability at the ultimate water saturation; μ w is the liquid phase viscosity; is the pressure gradient; U g is the gas phase flow rate; is the relative permeability of the gas phase at the ultimate water saturation; fmmob * is the foam strength considering only the water saturation factor; μ g is the gas phase viscosity; is the relative permeability of the water phase endpoint; is the limiting water saturation; S wr is the bound water saturation; S wc is the residual water saturation; S gr is the residual gas saturation; n w is the liquid phase Corey factor; is the relative permeability of the gas phase at the ultimate water saturation; S g is the gas saturation; n g is the gas phase Corey factor; F drag is the foam liquid film drag force model; S w is the water saturation; epdrag is the drag factor in the capillary; fmdry is the critical water saturation; FM new is the foam steady-state transport model coupled with the drag force of the CO2 bubble liquid film; fmcap is the capillary number under a certain pressure gradient; N ca is the reference capillary number; epcap is the shear behavior factor.

2. The method for establishing a foam steady-state transmission model coupled with the drag force of a CO2 bubble liquid film according to claim 1 is characterized in that: The oil, gas and water physical property parameters in step S1 include: liquid phase viscosity, gas phase viscosity, liquid phase factor, gas phase factor, bound water saturation, residual gas saturation, liquid phase relative permeability, gas phase relative permeability, and gas-liquid two-phase surface tension.

3. The method for establishing a foam steady-state transmission model coupled with the drag force of a CO2 bubble liquid film according to claim 1 is characterized in that: The reservoir physical property parameters in step S1 include absolute permeability.

4. The method for establishing a foam steady-state transmission model coupled with the drag force of a CO2 bubble liquid film according to claim 1 is characterized in that: The FM obtained in step S3 new The judgment condition between the numerical simulation plate and the physical simulation plate of the foam transfer model in step S2 is: assuming that the fmdry parameter of the numerical simulation plate is a, the fmdry parameter of the physical simulation plate is b, and the epdrag parameter of the numerical simulation plate is c. When a∈[0.05b,1.05b] and the numerical fluctuation range of c is [0.95c,1.05c], it is considered to meet the judgment condition, otherwise it is not met.

Images