Shale oil well productivity calculation method and device considering clay hydration expansion influence

Abstract

The invention provides a shale oil well productivity calculation method and device considering the influence of clay hydration expansion, and the method comprises the steps: dividing a reservoir into a plurality of subareas through the shale core component data and fracture network data of a reservoir block; carrying out core imbibition hydration expansion simulation experiments on each reservoir subarea, and correcting the reservoir fracture permeability according to experimental results; and calculating the shale oil well productivity according to the corrected reservoir fracture permeability. According to the method, on the basis of the characteristics that the shale oil reservoir contains a large amount of clay minerals and the influence of hydration expansion on the reservoir cannot be neglected, the reservoir fracture permeability before imbibition is subjected to hydration expansion is corrected by utilizing the reservoir permeability after the clay minerals are subjected to hydration expansion, so that the accuracy of shale oil well productivity calculation is improved; the method has theoretical rationality and practical production application value in the productivity calculation of the shale oil well considering the clay hydration expansion influence.

Description

Technical Field

[0001] The present invention belongs to the field of oil and gas field development, and in particular relates to a method and device for calculating the productivity of shale oil wells taking into account the influence of clay hydration expansion. Background Art

[0002] With the continuous growth of global energy demand and the gradual depletion of conventional oil and gas resources, the development of unconventional oil and gas resources has become a crucial approach to ensuring energy security. Shale oil, in particular, has attracted considerable attention due to its abundant reserves. In recent years, the application of horizontal wells coupled with multi-stage fracturing has significantly improved shale oil recovery efficiency. However, the challenges posed by clay minerals in shale reservoirs remain significant. In particular, clay hydration and swelling, which severely impacts the productivity of shale oil wells, have become a key technical challenge that urgently needs to be addressed. Shale oil will not only be a vital component of human energy supply for decades to come but also have profound implications for promoting sustainable global economic development. Shale oil is deposited in fine-grained sedimentary rocks rich in organic matter and possessing complex micropore structures. Compared to conventional oil and gas reservoirs, shale oil reservoirs generally contain a higher proportion of clay minerals, posing a potential obstacle to effective development. Clay components such as illite and montmorillonite are highly water-absorbent and readily hydrate and swell when exposed to drilling fluids or formation water. This reduces rock porosity and permeability, increases fluid flow resistance, and reduces well production. Summary of the Invention

[0003] The embodiments of the present application provide a method and device for calculating the productivity of shale oil wells that consider the influence of clay hydration expansion. The accuracy of the calculation is improved by correcting the permeability of reservoir fractures by considering the influence of clay hydration expansion. This method has theoretical rationality and practical production application value in the productivity calculation of shale oil wells that considers the influence of clay hydration expansion.

[0004] In a first aspect, embodiments of the present application provide a method for calculating shale oil well productivity taking into account the influence of clay hydration expansion, including:

[0005] The reservoir is divided into multiple zones using shale core composition data and fracture network data of the reservoir block. Core hydration and expansion simulation experiments are conducted on each reservoir zone, and the reservoir fracture permeability is corrected based on the experimental results. The shale oil well productivity is calculated based on the corrected reservoir fracture permeability.

[0006] The reservoir is divided into multiple zones using the shale core composition data and fracture network data of the reservoir block, including:

[0007] Using the fracturing construction data and microseismic detection data of shale oil wells, the fracture network data formed after fracturing construction were obtained: fracture spacing, number of fractures, and fracture half-length. The coordinate origin was set at the midpoint of the fracture network of the shale oil well, and a plane rectangular coordinate system was established with the horizontal segment as the y-axis.

[0008] The reservoir is divided into multiple zones using the shale core composition data and fracture network data of the reservoir block, including:

[0009] Using the shale core composition data and fracture network data of the reservoir block, the reservoir is divided into several reservoir zones according to the difference in clay content in the cores.

[0010] Among them, core imbibition and hydration expansion simulation experiments were conducted on each reservoir zone, and the reservoir fracture permeability was corrected based on the experimental results, including:

[0011] The cores of each reservoir zone were used to conduct core imbibition and hydration expansion simulation experiments to obtain the permeability K of each zone core when it was saturated with imbibition. limit .

[0012] Among them, core imbibition and hydration expansion simulation experiments were conducted on each reservoir zone, and the reservoir fracture permeability was corrected based on the experimental results, including:

[0013] The density of the liquid in the flowing suspension is obtained based on the experimental parameters of the cores in different reservoir partitions. l,f , the density of the liquid in the solid matrix ρ l,so , calculate the core imbibition constant B:

[0014] B=-D(ρ 1,so -ρ l,f )a / (πD) 1 / 2

[0015] Where ρ l,f represents the density of the liquid in the flowing suspension, ρ l,so represents the density of the liquid in the solid matrix, a represents the solid-liquid contact surface per unit volume, and D represents the diffusion coefficient.

[0016] Among them, core imbibition and hydration expansion simulation experiments were conducted on each reservoir zone, and the reservoir fracture permeability was corrected based on the experimental results, including:

[0017] Calculate the permeability K of different reservoir zones after hydration and swelling based on experimental data sw :

[0018]

[0019] Where K sw represents the permeability at t days after imbibition, K0 represents the permeability before imbibition occurs, K limit represents the permeability at imbibition saturation, C represents the integration constant, A represents the rate constant, B represents the core imbibition constant, and t represents the time when core imbibition occurs.

[0020] The shale oil well productivity is calculated based on the corrected reservoir fracture permeability, including:

[0021] The productivity of each fracture in different reservoir partitions is calculated based on the fracture parameters of each reservoir partition:

[0022]

[0023] Where q represents the productivity of a single crack, K sw represents the permeability at t days of imbibition, h represents the oil layer thickness, μ represents the viscosity of the fluid, and B o Represents the volume coefficient, P e represents the supply boundary pressure, P wf represents the bottom hole flow pressure, α represents the starting pressure coefficient, and x f represents the crack half-length, r e represents the effective drainage radius, r represents the distance from the fracture center to the midpoint of the horizontal well, and arcosh is the inverse function of the hyperbolic cosine function.

[0024] The shale oil well productivity is calculated based on the corrected reservoir fracture permeability, including:

[0025] The final shale oil well productivity is calculated using the productivity of each fracture, taking into account the effect of clay hydration expansion:

[0026]

[0027] Where N0 represents the number of cracks, q i represents the productivity of the i-th crack, K sw represents the permeability at t days of imbibition, h represents the oil layer thickness, μ represents the viscosity of the fluid, and B o Represents the volume coefficient, P e represents the supply boundary pressure, P wf represents the bottom hole flowing pressure, d represents half of the fracture spacing, α represents the starting pressure coefficient, and x f represents the crack half-length, r e Indicates the effective oil leakage radius.

[0028] In a second aspect, the present application provides a shale oil well productivity calculation device that takes into account the influence of clay hydration expansion, including: a division unit for dividing the reservoir into multiple partitions using shale core component data and fracture network data of the reservoir block; a correction unit for performing core imbibition hydration expansion simulation experiments on each reservoir partition, and correcting the reservoir fracture permeability based on the experimental results; a calculation unit for calculating the shale oil well productivity based on the corrected reservoir fracture permeability.

[0029] In a third aspect, the present application provides a computer system comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any of the above methods when executing the program.

[0030] The shale oil well productivity calculation method and device considering the influence of clay hydration expansion in the embodiment of the present application have the following beneficial effects:

[0031] This application is based on the characteristic that shale oil reservoirs contain a large amount of clay minerals and the influence of hydration expansion on the reservoir cannot be ignored. By using the reservoir permeability after hydration expansion of clay minerals to correct the reservoir fracture permeability before hydration expansion occurs due to imbibition, the accuracy of shale oil well production capacity calculation is improved. The method of this application has theoretical rationality and practical production application value in the production capacity calculation of shale oil wells considering the influence of clay hydration expansion. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a flow chart of a method for calculating shale oil well productivity taking into account the influence of clay hydration expansion in an embodiment of the present application;

[0033] Figure 2 This is another flow chart of a method for calculating shale oil well productivity taking into account the influence of clay hydration expansion according to an embodiment of the present application;

[0034] Figure 3 A schematic diagram of the rectangular coordinate system used in this application;

[0035] Figure 4 This is the capacity prediction curve for this application;

[0036] Figure 5 Schematic diagram of the structure of a shale oil well productivity calculation device taking into account the influence of clay hydration expansion in an embodiment of the present application. DETAILED DESCRIPTION

[0037] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0038] In the following description, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. The following description provides multiple embodiments of the present invention, and different embodiments can be replaced or combined, so this application can also be considered to include all possible combinations of the same and / or different embodiments described. Therefore, if one embodiment includes features A, B, and C, and another embodiment includes features B and D, then this application should also be considered to include embodiments containing one or more of all other possible combinations of features A, B, C, and D, even though such embodiments may not be explicitly described in the following text.

[0039] Example 1

[0040] like Figure 1 As shown, the method for calculating the productivity of shale oil wells considering the influence of clay hydration expansion in the present application includes: S101, using the shale core component data and fracture network data of the reservoir block, dividing the reservoir into multiple partitions; S103, conducting a core imbibition hydration expansion simulation experiment on each reservoir partition, and correcting the reservoir fracture permeability based on the experimental results; S105, calculating the shale oil well productivity based on the corrected reservoir fracture permeability.

[0041] This application is based on the characteristic that shale oil reservoirs contain a large amount of clay minerals and the influence of hydration expansion on the reservoir cannot be ignored. By using the reservoir permeability after hydration expansion of clay minerals to correct the reservoir fracture permeability before hydration expansion occurs due to imbibition, the accuracy of shale oil well production capacity calculation is improved. The method of this application has theoretical rationality and practical production application value in the production capacity calculation of shale oil wells considering the influence of clay hydration expansion.

[0042] Example 2

[0043] like Figure 1-2 As shown, the shale oil well productivity calculation method considering the influence of clay hydration expansion in this application includes:

[0044] The first step, such as Figure 3 As shown in the figure, the fracture network data formed after the fracturing construction is obtained by using the fracturing construction data of shale oil wells and microseismic detection data: fracture spacing d, number of fractures N, fracture half length x fi , the coordinate origin is set at the midpoint of the fracture network of the shale oil well, and a plane rectangular coordinate system is established with the horizontal segment as the y-axis.

[0045] In the second step, the shale core composition data and fracture network data of the reservoir block are used to divide the reservoir into several reservoir zones according to the differences in clay content in the cores.

[0046] The third step is to use the cores of each reservoir zone to conduct core imbibition and hydration expansion simulation experiments to obtain the permeability K of each zone core when it is saturated with imbibition. limit .

[0047] The fourth step is to obtain the density of the liquid in the flowing suspension according to the experimental parameters of the cores in different reservoir partitions ρ l,f , the density of the liquid in the solid matrix ρ l,so , calculate the core imbibition constant B:

[0048] B=-D(ρ 1,so -ρ l,f )a / (πD) 1 / 2

[0049] Where ρ l,f represents the density of the liquid in the flowing suspension, ρl,so represents the density of the liquid in the solid matrix, a represents the solid-liquid contact surface per unit volume, and D represents the diffusion coefficient.

[0050] Step 5: Calculate the permeability K of different reservoir zones after hydration and expansion based on experimental data. sw :

[0051]

[0052] Where K sw represents the permeability at t days after imbibition, K0 represents the permeability before imbibition occurs, K limit represents the permeability at imbibition saturation, C represents the integration constant, A represents the rate constant, B represents the core imbibition constant, and t represents the time when core imbibition occurs.

[0053] The sixth step is to calculate the productivity of each fracture in different reservoir partitions based on the fracture parameters of each reservoir partition:

[0054]

[0055] Where q represents the productivity of a single crack, K sw represents the permeability at t days of imbibition, h represents the oil layer thickness, μ represents the viscosity of the fluid, and B o Represents the volume coefficient, P e represents the supply boundary pressure, P wf represents the bottom hole flow pressure, α represents the starting pressure coefficient, and x f represents the crack half-length, r e represents the effective drainage radius, r represents the distance from the fracture center to the midpoint of the horizontal well, and arcosh is the inverse function of the hyperbolic cosine function.

[0056] Step 7: Use the productivity of each fracture to calculate the final productivity of the shale oil well taking into account the effect of clay hydration expansion:

[0057]

[0058] Where N0 represents the number of cracks, q i represents the productivity of the i-th crack, K sw represents the permeability at t days of imbibition, h represents the oil layer thickness, μ represents the viscosity of the fluid, and B o Represents the volume coefficient, P e represents the supply boundary pressure, P wf represents the bottom hole flowing pressure, d represents half of the fracture spacing, α represents the starting pressure coefficient, and x f represents the crack half-length, r e Indicates the effective oil leakage radius.

[0059] This application addresses the problem of high proportions of clay minerals in shale reservoirs hydrating and expanding when exposed to drilling fluid or formation water, resulting in reduced rock porosity and permeability, leading to low accuracy in shale oil well productivity calculations. This application analyzes shale oil well fracturing construction data and microseismic data, combines shale core sample data with fracture network data, divides the reservoir into multiple zones, and conducts hydration and expansion simulation experiments. By considering the influence of clay hydration expansion and correcting the reservoir fracture permeability, the accuracy of the calculation is improved, resulting in more accurate permeability calculation results.

[0060] Example 3

[0061] A shale oil reservoir is developed using horizontal well fracturing. Through hydraulic fracturing, the horizontal section length is 1200m. The clay component content of the reservoir in this block is similar, ranging from about 25% to 30%. Therefore, the reservoir here is divided into one zone. According to the data of this shale oil reservoir:

[0062] Shale reservoir data

[0063]

[0064] Fracturing data

[0065]

[0066] Crude oil viscosity μ=6.12mPa·s, volume coefficient B o =1.124, starting pressure coefficient α = 0.023μm / s, combined with experimental data, the permeability before imbibition K0 = 0.015mD, the permeability after saturated imbibition K limit =0.006mD, and the calculation formula of permeability after imbibition is obtained after fitting: At 20 days of imbibition, K sw =0.01mD.

[0067] When the formation pressure is 56 MPa and the bottomhole pressure is 21 MPa, the productivity of a single fracture is calculated based on the fracture parameters of each reservoir partition:

[0068]

[0069] Bottom hole pressure (MPa) 25 30 35 40 45 50 55 Production capacity of the first crack (t / d) 0.867 0.844 0.792 0.701 0.560 0.355 0.069

[0070] like Figure 4 As shown, the cumulative formula for calculating the productivity of each fracture is then used to calculate the final productivity of the shale oil well considering the influence of clay hydration expansion. To simplify the calculation, the same fracture length is taken here:

[0071]

[0072] Bottom hole pressure (MPa) 25 30 35 40 45 50 55 Production capacity (t / d) 75.99 74.05 69.48 61.51 49.13 31.13 6.03

[0073] This application considers the impact of clay hydration expansion in shale oil reservoirs on productivity, improves the accuracy of calculation results, and the calculation method is more suitable for hydraulically fractured shale reservoirs and is easy to promote.

[0074] like Figure 5 As shown, the present application also provides a shale oil well productivity calculation device that takes into account the influence of clay hydration expansion, including: a division unit 201, used to divide the reservoir into multiple partitions using shale core component data and fracture network data of the reservoir block; a correction unit 202, used to perform core imbibition hydration expansion simulation experiments on each reservoir partition, and correct the reservoir fracture permeability based on the experimental results; a calculation unit 203, used to calculate the shale oil well productivity based on the corrected reservoir fracture permeability.

[0075] In this application, an embodiment of a shale oil well productivity calculation device considering the influence of clay hydration expansion is basically similar to an embodiment of a shale oil well productivity calculation method considering the influence of clay hydration expansion. For relevant matters, please refer to the introduction of the embodiment of the shale oil well productivity calculation method considering the influence of clay hydration expansion.

[0076] The present application also provides a computer system comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps of the above-mentioned method for calculating the productivity of shale oil wells taking into account the influence of clay hydration expansion are implemented.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for calculating shale oil well productivity considering the influence of clay hydration expansion, characterized in that: include: Using the shale core composition data and fracture network data of the reservoir block, the reservoir is divided into multiple zones; Core imbibition and hydration expansion simulation experiments were conducted on each reservoir zone, and the reservoir fracture permeability was corrected based on the experimental results; the shale oil well productivity was calculated based on the corrected reservoir fracture permeability.

2. The method for calculating shale oil well productivity considering the influence of clay hydration expansion according to claim 1, characterized in that: Using the shale core composition data and fracture network data of the reservoir block, the reservoir is divided into multiple zones, including: Using the fracturing construction data and microseismic detection data of shale oil wells, the fracture network data formed after fracturing construction were obtained: fracture spacing, number of fractures, and fracture half-length. The coordinate origin was set at the midpoint of the fracture network of the shale oil well, and a plane rectangular coordinate system was established with the horizontal segment as the y-axis.

3. The method for calculating shale oil well productivity considering the influence of clay hydration expansion according to claim 2, characterized in that: Using the shale core composition data and fracture network data of the reservoir block, the reservoir is divided into multiple zones, including: Using the shale core composition data and fracture network data of the reservoir block, the reservoir is divided into several reservoir zones according to the difference in clay content in the cores.

4. The method for calculating shale oil well productivity considering the influence of clay hydration expansion according to any one of claims 1 to 3, characterized in that: Core hydration expansion simulation experiments were conducted for each reservoir zone, and the reservoir fracture permeability was calibrated based on the experimental results, including: The cores of each reservoir zone were used to conduct core imbibition and hydration expansion simulation experiments to obtain the permeability K of each zone core when it was saturated with imbibition. limit .

5. The method for calculating shale oil well productivity considering the influence of clay hydration expansion according to claim 4, characterized in that: Core hydration expansion simulation experiments were conducted for each reservoir zone, and the reservoir fracture permeability was calibrated based on the experimental results, including: The density of the liquid in the flowing suspension is obtained based on the experimental parameters of the cores in different reservoir partitions. l,f , the density of the liquid in the solid matrix ρ lso , calculate the core imbibition constant B: B=-D(ρ 1,so -r l,f )a / (πD) 1 / 2 Where ρ l,f represents the density of the liquid in the flowing suspension, ρ l,so represents the density of the liquid in the solid matrix, a represents the solid-liquid contact surface per unit volume, and D represents the diffusion coefficient.

6. The method for calculating shale oil well productivity considering the influence of clay hydration expansion according to claim 5, characterized in that: Core hydration expansion simulation experiments were conducted for each reservoir zone, and the reservoir fracture permeability was calibrated based on the experimental results, including: Calculate the permeability K of different reservoir zones after hydration and swelling based on experimental data sw : Where K sw represents the permeability at t days after imbibition, K0 represents the permeability before imbibition occurs, K limit represents the permeability at imbibition saturation, C represents the integration constant, A represents the rate constant, B represents the core imbibition constant, and t represents the time when core imbibition occurs.

7. The method for calculating shale oil well productivity considering the influence of clay hydration expansion according to any one of claims 1 to 3, characterized in that: Calculate shale oil well productivity based on the corrected reservoir fracture permeability, including: The productivity of each fracture in different reservoir partitions is calculated based on the fracture parameters of each reservoir partition: Where q represents the productivity of a single crack, K sw represents the permeability at t days of imbibition, h represents the oil layer thickness, μ represents the viscosity of the fluid, and B o Represents the volume coefficient, P e represents the supply boundary pressure, P wf represents the bottom hole flow pressure, α represents the starting pressure coefficient, x f represents the crack half-length, r e represents the effective drainage radius, r represents the distance from the fracture center to the midpoint of the horizontal well, and arcosh is the inverse function of the hyperbolic cosine function.

8. The method for calculating shale oil well productivity considering the influence of clay hydration expansion according to claim 7, characterized in that: Calculate shale oil well productivity based on the corrected reservoir fracture permeability, including: The final shale oil well productivity is calculated using the productivity of each fracture, taking into account the effect of clay hydration expansion: Where N0 represents the number of cracks, q i represents the productivity of the i-th crack, K sw represents the permeability at t days of imbibition, h represents the oil layer thickness, μ represents the viscosity of the fluid, and B o Represents the volume coefficient, P e represents the supply boundary pressure, P wf represents the bottom hole flowing pressure, d represents half of the fracture spacing, α represents the starting pressure coefficient, and x f represents the crack half-length, r e Indicates the effective oil leakage radius.

9. A shale oil well productivity calculation device considering the influence of clay hydration expansion, characterized in that: include: The division unit is used to divide the reservoir into multiple zones using the shale core composition data and fracture network data of the reservoir block; the correction unit is used to conduct core hydration expansion simulation experiments on each reservoir zone and correct the reservoir fracture permeability based on the experimental results; The calculation unit is used to calculate the shale oil well productivity based on the corrected reservoir fracture permeability.

10. A computer system comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the steps of the method according to any one of claims 1 to 8 are implemented.

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