A method, system, equipment and storage medium for evaluating the movable oil content of shale reservoirs.

Abstract

This invention provides a method, system, equipment, and storage medium for evaluating the movable oil content of shale reservoirs. The method includes: acquiring geological thermal maturity parameters, organic carbon content, hydrogen index, and mudstone content of a target shale reservoir; acquiring the movable oil content of non-mudstone high-porosity layers in the target shale reservoir; determining the movable oil content of mudstone in the target shale reservoir based on the geological thermal maturity parameters, organic carbon content, and hydrogen index; and determining the movable oil content of the target shale reservoir based on the movable oil content of non-mudstone high-porosity layers, the movable oil content of mudstone in the target shale reservoir, and the mudstone content of the target shale reservoir. The technical solution provided by this invention enables the determination of movable oil content in medium-to-high thermal maturity shale reservoirs under conventional development models.

Description

Technical Field

[0001] This invention relates to the field of petroleum exploration and development technology, and in particular to a method, system, equipment and storage medium for evaluating the movable oil content of shale reservoirs. Background Technology

[0002] On the one hand, the complexity of mineral composition, sedimentary conditions, burial thermal evolution, and diagenetic processes in organic-rich shale reservoirs leads to diverse forms of crude oil occurrence. On the other hand, different development methods have varying effects on the mobilization of crude oil in different occurrence forms. In assessing movable oil content, existing methods suffer from numerous problems due to differences in samples, testing methods, and understanding of the principles, including missing components, incomplete geological conditions, and discrepancies between laboratory and geological conditions. This makes the evaluation of movable oil content in organic-rich shale reservoirs challenging in terms of both mechanistic reliability and accuracy.

[0003] There are two main methods for evaluating the oil content of existing shale reservoirs. One is the volumetric method (or tectonic method), and the other is the S1 method based on pyrolysis parameters. The former calculates the oil content by testing the porosity and oil saturation of representative rocks at various levels; the other uses a rock pyrolysis instrument to bring underground samples to the surface and test the free hydrocarbon content in the residual hydrocarbons, which is used as the mobile oil content under underground pressure and without the loss of light hydrocarbons.

[0004] Experts have proposed a volumetric method (or tectonic method) for evaluating the oil content of shale reservoirs. This method determines the oil content of shale reservoirs by solvent extraction and nuclear magnetic resonance analysis of reservoir rock samples. Shale reservoirs under formation conditions contain volatile low-carbon hydrocarbons, hydrocarbons adsorbed by organic matter, hydrocarbons adsorbed on mineral surfaces, hydrocarbons encapsulated in minerals, and water-soluble hydrocarbons. During the process of extracting reservoir rock samples from underground to the surface, decompression causes the volatilization of free light hydrocarbons. The oil content determined based on reservoir rock samples does not account for the loss of these free light hydrocarbons. In actual conventional development, most of the high-molecular-weight, high-distillation-point hydrocarbons containing N, S, and O in shale reservoirs remain trapped in the formation and are difficult to recover. Therefore, the oil content of shale reservoirs differs significantly from their mobile oil content. In conclusion, existing methods for evaluating the oil content of shale reservoirs cannot effectively determine the mobile oil content of shale formations.

[0005] Existing methods for evaluating movable oil content mainly rely on empirical parameter methods and simulation experiments. Typically, the pyrolysis free hydrocarbon content (S1) or the oil saturation index (OSI) of reservoir rock samples (OSI equals the pyrolysis free hydrocarbon content S1 divided by the total organic carbon (TOC)) is used as a parameter to characterize movable oil content. However, existing methods for evaluating movable oil content are usually designed for conventional reservoirs and are not suitable for highly heterogeneous, tight mudstone and shale reservoirs.

[0006] Currently, there is no method for determining the movable oil content in shale reservoirs, especially for the conventional development of medium- to high-temperature mature shale reservoirs. Summary of the Invention

[0007] The purpose of this invention is to provide a method, system, equipment, and storage medium for determining the movable oil content in conventional development models of medium-to-high-temperature mature shale reservoirs.

[0008] To achieve the above objectives, the present invention provides the following four technical solutions.

[0009] In a first aspect, the present invention provides a method for evaluating the movable oil content of shale reservoirs, wherein the method includes:

[0010] Obtain the geological thermal maturity parameters, organic carbon content, hydrogen index, and mudstone content of the target mudstone and shale reservoir;

[0011] To obtain the movable oil content of non-mudstone high-porosity laminae in the target mudstone and shale reservoir;

[0012] Based on the geological thermal maturity parameters, organic carbon content, and hydrogen index of the target shale reservoir, the movable oil content of the mudstone in the target shale reservoir is determined.

[0013] The movable oil content of the target shale reservoir is determined based on the movable oil content of the non-mudstone high-porosity laminae in the target shale reservoir, the movable oil content of the mudstone in the target shale reservoir, and the mudstone content of the target shale reservoir.

[0014] In this invention, non-mudstone high-porosity laminae refer to non-mudstone interlayers with greater porosity than mudstone within mudstone and shale sections. Their lithology is usually sandstone, carbonate rock, etc., and they are typically composed of small, thin layers with a thickness of no more than 20 cm that appear repeatedly. The pores of non-mudstone high-porosity laminae are usually mainly intergranular pores supported by large particles or dissolution pores caused by acidic dissolution. The lithology and pores of non-mudstone high-porosity laminae are the same as or similar to those of conventional oil and gas reservoirs.

[0015] Secondly, the present invention provides a system for evaluating the movable oil content of shale reservoirs, wherein the system comprises:

[0016] Target reservoir parameter acquisition module: used to acquire geological and thermal maturity parameters, organic carbon content, hydrogen index, and mudstone content of the target mudstone and shale reservoir;

[0017] High-porosity layer movable oil content acquisition module: used to acquire the movable oil content of non-mudstone high-porosity layers in the target mudstone and shale reservoir;

[0018] The module for determining the movable oil content of mudstone is used to determine the movable oil content of mudstone in a target mudstone and shale reservoir based on the geological thermal maturity parameters, organic carbon content, and hydrogen index of the target mudstone and shale reservoir.

[0019] The target reservoir movable oil content determination module is used to determine the movable oil content of the target shale reservoir based on the movable oil content of non-mudstone high-porosity laminae in the target shale reservoir, the movable oil content of mudstone in the target shale reservoir, and the mudstone content of the target shale reservoir.

[0020] Thirdly, the present invention provides an electronic device, including a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of a method for evaluating the movable oil content of shale reservoirs.

[0021] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of a method for evaluating the movable oil content of shale reservoirs.

[0022] The technical solution provided by this invention determines the movable oil content of reservoirs based on easily obtainable geological thermal maturity parameters, organic carbon content, hydrogen index, mudstone content, and movable oil content data of non-mudstone high-porosity layers. The technical solution provided by this invention is applicable to determining the movable oil content in conventional development models of medium-to-high thermal maturity mudstone and shale reservoirs. The technical solution provided by this invention is low-cost, highly efficient, and easy to implement. Attached Figure Description

[0023] Figure 1 This is a flowchart of a method for evaluating the movable oil content of shale reservoirs in one embodiment.

[0024] Figure 2 This is a framework diagram of a system for evaluating the movable oil content of mudstone and shale reservoirs in one embodiment.

[0025] Figure 3 This is a graph showing the relationship between TOC and S1 / TOC of rock samples from the study area in Example 1.

[0026] Figure 4 This is a graph showing the relationship between S1 / TOC and sandstone content in the rock samples from the study area in Example 1.

[0027] Figure 5 The graph shows the relationship between S1 and TOC for sandstone samples with TOC > 2.0% in Example 1.

[0028] Figure 6 This is a graph showing the relationship between the mobile oil content (Om) and organic carbon content (TOC) of the pure mudstone shale reference sample in the thermal hydrocarbon generation simulation experiment of Example 1 and the vitrinite reflectance (Ro).

[0029] Figure 7This is a graph showing the relationship between the ratio of mobile oil content to organic carbon content (Om / TOC) and the vitrinite reflectance (Ro) in the thermal hydrocarbon generation simulation experiment of the pure mudstone shale reference sample in Example 1.

[0030] Figure 8 This is a graph showing the relationship between the hydrogen index HI and the vitrinite reflectance Ro in the thermal hydrocarbon generation simulation experiment of the pure mudstone shale reference sample in Example 1.

[0031] Figure 9 This is a graph showing the relationship between the current burial depth of the target well location and the vitrinite reflectivity Ro in Example 1.

[0032] Figure 10 This is a graph showing the movable oil content and key parameters of the target shale reservoir at the target well location in Example 1. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0034] Conventional development of medium-to-high heat mature shale reservoirs targets the extraction of retained liquid hydrocarbons, employing development methods based on vertical or horizontal wells involving water injection, gas injection, and / or fracturing. During conventional development of medium-to-high heat mature shale reservoirs, under the influence of fluid pressure differentials and hydrocarbon concentration diffusion, movable liquid hydrocarbons from the relatively high porosity and permeability pore-microfractures are extracted from the formation. These movable liquid hydrocarbons include free C5-C6 from the original relatively high porosity and permeability pore-microfractures. 14 Light hydrocarbons and C 15 -C 34 Normal oil also includes organic-adsorbed hydrocarbons that are released into the relatively high-porosity and high-permeability pore-microfractures during development due to depressurization. This portion of mobile liquid hydrocarbons in the reservoir is the true mobile oil in conventional development models of medium-to-high-temperature mature shale reservoirs. To determine the content of this portion of mobile liquid hydrocarbons, this invention provides the technical solution shown in the following embodiments.

[0035] See Figure 1 A specific embodiment of the present invention provides a method for evaluating the movable oil content of shale reservoirs, wherein the method includes:

[0036] Step S1: Obtain the geological thermal maturity parameters, organic carbon content, hydrogen index, and mudstone content of the target shale reservoir;

[0037] Step S2: Obtain the movable oil content of non-mudstone high-porosity laminae (usually sandstone layers, dolomite layers, etc.) in the target mudstone and shale reservoir;

[0038] Step S3: Based on the geological thermal maturity parameters, organic carbon content, and hydrogen index of the target shale reservoir, determine the movable oil content of the mudstone in the target shale reservoir;

[0039] Step S4: Determine the movable oil content of the target shale reservoir based on the movable oil content of the non-mudstone high-porosity laminae in the target shale reservoir, the movable oil content of the mudstone in the target shale reservoir, and the mudstone content of the target shale reservoir.

[0040] The method for evaluating the movable oil content of shale reservoirs provided by this invention can quickly and cost-effectively determine the movable oil content of medium- to high-temperature mature shale reservoirs under conventional development models. This method requires only a small amount of readily available data and is applicable in areas with low exploration levels and conventional oil exploration areas. The method is applicable to both marine and lacustrine shale formations that are primarily oil-generating. It is suitable for both pure mudstone shale reservoirs and shale reservoirs containing interlayers of non-mudstone elements such as sandstone and carbonate rocks, and the results accurately indicate the movable oil content under conventional development models.

[0041] In one embodiment, step S2, obtaining the movable oil content of non-mudstone high-porosity layers in the target shale reservoir, includes:

[0042] Step S21: Obtain the porosity of the non-mudstone high-porosity layer, the oil saturation of the non-mudstone high-porosity layer, the crude oil density, and the density of the non-mudstone high-porosity layer in the target mudstone and shale reservoir;

[0043] Step S22: Based on the porosity of the non-mudstone high-porosity layer in the target shale reservoir, the oil saturation of the non-mudstone high-porosity layer, the crude oil density, and the density of the non-mudstone high-porosity layer, determine the movable oil content of the non-mudstone high-porosity layer in the target shale reservoir.

[0044] Furthermore, in step S22, the movable oil content of the non-mudstone high-porosity laminae in the target shale reservoir is determined using the following formula:

[0045]

[0046] In the formula, O ms The value represents the movable oil content in non-mudstone highly porous laminae within mudstone and shale reservoirs, expressed in mg / g. S represents the porosity of non-mudstone high-porosity laminae in shale reservoirs, in %; os ρ represents the oil saturation of non-mudstone highly porous laminae in shale reservoirs, in dimensionless units. oDensity of crude oil in shale reservoirs, in g / cm³ 3 ;ρ r Density of non-mudstone high-porosity laminar layers in shale reservoirs, in g / cm³ 3 .

[0047] In one embodiment, step S3, determining the movable oil content of the mudstone in the target shale reservoir based on the geological thermal maturity parameters, organic carbon content, and hydrogen index of the target shale reservoir, includes:

[0048] Step S31: Obtain the model for determining the movable oil content of mudstone; wherein, the model for determining the movable oil content of mudstone is a calculation model based on geological thermal maturity parameters, organic carbon content and hydrogen index.

[0049] Step S32: Based on the geological thermal maturity parameters, organic carbon content, and hydrogen index of the target mudstone and shale reservoir, determine the movable oil content of the mudstone in the target mudstone and shale reservoir using the movable oil content determination model.

[0050] In one embodiment, step S31, obtaining the model for determining the movable oil content of mudstone, includes:

[0051] Step S311: Obtain the movable oil content and organic carbon content of pure mudstone reference samples at different geological thermal maturity;

[0052] Step S312: Based on the movable oil content and organic carbon content of pure mudstone shale reference samples at different geological thermal maturity, determine the movable oil content model of pure mudstone shale reference samples; wherein, the movable oil content model of pure mudstone shale reference samples is a calculation model based on the ratio of movable oil content to organic carbon content of pure mudstone shale reference samples based on geological thermal maturity.

[0053] The preferred model for the movable oil content of the pure mudstone shale reference sample is:

[0054]

[0055] In the formula, a, b, c, and d are dimensionless coefficients, which can be determined by the mobile oil content and organic carbon content of pure mudstone shale reference samples at different geological thermal maturity levels; Ro is vitrinite reflectance or equivalent vitrinite reflectance (vitrinite reflectance and equivalent vitrinite reflectance are geological thermal maturity parameters that can reflect geological thermal maturity), in percentage; TOC is organic carbon content, in percentage; O mmo The values ​​represent the movable oil content of pure mudstone and shale reference samples, in mg / g; for example, a = -7.581102226, b = 24.4777074, c = -15.03825026, d = -7.259934287.

[0056] Step S313: Based on the calculation model of the movable oil content determination model of pure mudstone reference sample, and combined with the positive correlation between organic matter porosity and hydrogen index, construct the movable oil content determination model of mudstone.

[0057] The preferred model for determining the movable oil content of mudstone is as follows:

[0058]

[0059] In the formula, O mm 1. Movable oil content of mudstone in shale reservoir, in mg / g; 2. Ro, vitrinite reflectance or equivalent vitrinite reflectance of target mudstone (vitrinite reflectance and equivalent vitrinite reflectance are geological thermal maturity parameters that can reflect geological thermal maturity), in %; 3. TOC, organic carbon content of target mudstone, in %; 4. f(Ro), the ratio of movable oil content to organic carbon content of pure mudstone reference sample at geological thermal maturity of Ro, in mg / g; 5. HI s HI represents the hydrogen index of a pure mudstone reference sample at a geological thermal maturity of Ro, expressed in mg / g TOC; HI represents the hydrogen index of the target mudstone shale, expressed in mg / g TOC.

[0060] Furthermore, in step S311, the movable oil content of the pure mudstone shale reference sample includes the pyrolysis free hydrocarbon content as well as the light hydrocarbon loss and pressure drop hydrocarbon expulsion loss per unit of pure mudstone shale reference sample.

[0061] Furthermore, step S311, obtaining the movable oil content and organic carbon content of pure mudstone shale reference samples at different geological thermal maturity includes:

[0062] Step 3111: Determine the temperature and pressure for the thermal hydrocarbon generation simulation experiment based on the burial history of the target shale reservoir;

[0063] For example, based on the burial depth history of the target shale reservoir, the burial static pressure and fluid pressure corresponding to the experimental temperature point are set. The experimental temperature is determined by calculation using thermodynamic equations, and the hydrocarbon expulsion control pressure is determined based on the formation fluid pressure value.

[0064] Step 3112: Select an immature pure mudstone shale sample as a reference sample for pure mudstone shale;

[0065] Immature pure mudstone samples from the target mudstone and shale reservoir can be selected as reference samples for pure mudstone and shale. If immature pure mudstone samples from the target mudstone and shale reservoir cannot be obtained, immature pure mudstone samples from other mudstone and shale reservoirs can be obtained. Immature pure mudstone samples with organic matter type I are preferred.

[0066] Step 3113: Under the determined temperature and pressure conditions of the thermal hydrocarbon generation simulation experiment, a thermal hydrocarbon generation simulation experiment (i.e., a full-process experiment of hydrocarbon generation and expulsion) was conducted using pure mudstone and shale reference samples to obtain the pyrolysis free hydrocarbon content, light hydrocarbon loss per unit pure mudstone and shale reference sample, pressure drop hydrocarbon expulsion loss, and organic carbon content at different geological thermal maturity levels.

[0067] For example, to determine the mobile oil content and organic carbon content at a certain geological thermal maturity, after the corresponding thermal hydrocarbon generation simulation experiment ends and the temperature drops to normal, the collected effluent hydrocarbons and the hydrocarbons obtained by rinsing the sample surface with dichloromethane can be combined to obtain the light hydrocarbon loss and pressure drop hydrocarbon loss. The solid residue after rinsing is then subjected to conventional pyrolysis analysis using a Rock Eval pyrolysis analyzer to determine the pyrolysis free hydrocarbon content. The organic carbon content can be obtained by testing the organic carbon in the solid residue after rinsing using a carbon-sulfur analyzer. After thoroughly washing the solid residue after rinsing with dichloromethane, the pyrolysis peak temperature can be obtained by pyrolysis analysis of the washed solid residue. Based on the pyrolysis peak temperature, the vitrinite reflectance or equivalent vitrinite reflectance can be obtained.

[0068] Step 3114: The movable oil content at different geological thermal maturity can be obtained by using the pyrolysis free hydrocarbon content at different geological thermal maturity, the light hydrocarbon loss and pressure drop hydrocarbon expulsion loss of a unit pure mudstone shale reference sample;

[0069] For example, for a certain geological thermal maturity, the movable oil content can be obtained by summing the pyrolysis free hydrocarbon content, the light hydrocarbon loss per unit pure mudstone and shale reference sample, and the hydrocarbon loss due to pressure drop.

[0070] In one embodiment, the model for determining the movable oil content of mudstone is as follows:

[0071] O mm =[a×Ro 2 +b×Ro+c+d×Ln(Ro)]×TOC×HI÷HI s

[0072] In the formula, a, b, c, and d are dimensionless coefficients (which can be obtained by fitting a pure shale reference sample); Ro is the vitrinite reflectance or equivalent vitrinite reflectance of the shale reservoir (vitrinite reflectance and equivalent vitrinite reflectance are geological thermal maturity parameters that can reflect geological thermal maturity), in %; TOC is the organic carbon content of the shale reservoir, in %; O mm HI represents the movable oil content of mudstone in shale reservoirs, in mg / g; HI represents the hydrogen index of shale reservoirs, in mg / g TOC; HI s The hydrogen index (in mg / gTOC) is given for a pure mudstone reference sample (this mudstone sample was used to fit and determine the dimensionless coefficients a, b, c, d) at a geological thermal maturity of Ro.

[0073] For example, a = -7.581102226, b = 24.4777074, c = -15.03825026, d = -7.259934287, HI s = -478.53Ro 3 +741.92Ro 2 -793.91Ro+1061.7.

[0074] In one embodiment, in step S4, the movable oil content of the target shale reservoir is determined based on the following formula:

[0075] O m =O mm ×V m +O mmo

[0076] In the formula, O m The movable oil content of shale reservoirs, in mg / g; O mm V represents the movable oil content of mudstone in shale reservoirs, in mg / g. m The mudstone content in the shale reservoir is expressed as a percentage (%). ms The value represents the movable oil content in non-mudstone highly porous laminar layers of shale reservoirs, expressed in mg / g.

[0077] In one embodiment, the geological thermal maturity parameters of the target shale reservoir can be determined using, but are not limited to, conventional methods for determining geological thermal maturity parameters; for example, maturity analysis can be performed using core samples or rock fragments from the target shale reservoir to determine the geological thermal maturity parameters of the target shale reservoir.

[0078] In one embodiment, step S1, obtaining the geological thermal maturity parameters of the target shale reservoir, includes:

[0079] Step S11: Obtain geological thermal maturity parameters based on the calculation model at the current burial depth;

[0080] Step S12: Obtain the current burial depth of the target shale reservoir;

[0081] Step S13: Based on the current burial depth of the target shale reservoir, use the calculation model based on the current burial depth to determine the geological and thermal maturity parameters of the target shale reservoir;

[0082] Further, step S11, obtaining the geological thermal maturity parameters based on the calculation model at the current burial depth, includes:

[0083] Determine the geological and thermal maturity parameters and current burial depth of different source rock samples in the tectonic region where the target shale reservoir is located; based on the geological and thermal maturity parameters and current burial depth of each source rock sample, fit the relationship between the geological and thermal maturity parameters and the current burial depth: Ro=exp[(D c -A)÷B], where Ro is the vitrinite reflectance or equivalent vitrinite reflectance, in %; D c The current burial depth is in meters (m); A and B are dimensionless parameters.

[0084] Based on the relationship between geological thermal maturity parameters and current burial depth, the current burial depth is determined when the vitrinite reflectance or equivalent vitrinite reflectance is 0.21. The negative of the current burial depth when the vitrinite reflectance or equivalent vitrinite reflectance is 0.21 is the original erosion amount in the structural region where the target mudstone and shale reservoir is located.

[0085] Obtain the amount of erosion of the formation at the current burial depth of the target shale reservoir at the target well location (the well location where the target shale reservoir is located) and the thickness of the formation above the erosion surface at the target well location;

[0086] Based on the dimensionless parameters A and B in the relationship between geological thermal maturity parameters and current burial depth, the original erosion amount of the structural region where the target shale reservoir is located, the erosion amount of the strata at the current burial depth of the target shale reservoir in the target well location, and the strata thickness above the erosion surface in the target well location, a calculation model for geological thermal maturity parameters based on the current burial depth is determined; among which...

[0087] When the erosion amount of the formation at the current burial depth of the target shale reservoir in the target well location is less than the formation thickness above the erosion surface in the target well location, the calculation model for the geological thermal maturity parameter based on the current burial depth is: Ro = exp[(D c -H eu +H e -H eo -A)÷B];

[0088] When the erosion of the target shale reservoir at its current burial depth is greater than or equal to the formation thickness above the erosion surface at the target well location, the calculation model for the geological thermal maturity parameter based on the current burial depth is: Ro = exp[(D c -H eo -A)÷B]

[0089] In the formula, Ro is the vitrinite reflectance or equivalent vitrinite reflectance of the target shale reservoir, in %; D c The current burial depth of the target shale reservoir; H e For the target well location at depth D c The amount of erosion of the strata; H eu H represents the formation thickness above the erosion surface at the target well location.eo A represents the original erosion amount in the structural region where the target shale reservoir is located; A and B are dimensionless parameters.

[0090] Furthermore, the calculation model for geological thermal maturity parameters based on the current burial depth is as follows:

[0091] When H eu <H e At that time, Ro = exp[(D c -H eu +H e -H eo -A)÷B]

[0092] When H eu ≥H e At that time, Ro = exp[(D c -H eo -A)÷B]

[0093] In the formula, Ro is the vitrinite reflectance or equivalent vitrinite reflectance of the target shale reservoir, in %; D c The current burial depth of the target shale reservoir; H e For the target well location at depth D c The amount of erosion of the strata; H eu H represents the formation thickness above the erosion surface at the target well location. eo A represents the original erosion amount in the structural region where the target shale reservoir is located; A and B are dimensionless parameters.

[0094] In one embodiment, the organic carbon content of the target shale reservoir can be determined using, but is not limited to, conventional methods for determining organic carbon content. For example, the organic carbon content of the target shale reservoir can be determined using a Delta Log R model based on the vitrinite reflectance or equivalent vitrinite reflectance of the target shale reservoir. Alternatively, the organic matter abundance can be determined by performing organic matter abundance analysis on core or rock fragments of the target shale reservoir.

[0095] In one embodiment, the hydrogen index of the target shale reservoir can be determined using, but is not limited to, conventional hydrogen index determination methods; for example, by performing rock pyrolysis analysis on cores or rock fragments of the target shale reservoir to determine the organic carbon content of the target shale reservoir.

[0096] In one embodiment, the mudstone content of the target shale reservoir can be determined using, but is not limited to, conventional mudstone content determination methods; for example, based on well logging information such as neutron, density, and acoustic waves.

[0097] In one embodiment, the porosity of the non-mudstone high-porosity laminae in the target shale reservoir can be determined, but is not limited to, using conventional porosity determination methods; for example, based on well logging information such as neutron, density, and acoustic waves; for example, using density or neutron-density cross plot methods.

[0098] In one embodiment, the mudstone content of the target shale reservoir and the porosity of the non-mudstone high-porosity laminae in the target shale reservoir are determined by the following formula:

[0099]

[0100]

[0101] In the formula, V m The mudstone content in the mudstone-shale reservoir is expressed as a percentage (%). Porosity of non-mudstone high-porosity laminae in shale reservoirs, in %; RHOB is the rock density curve value from well logging of shale reservoirs, in g / cm³. 3 NPHI represents the neutron value in well logging of shale reservoirs, in V / V; NPHI_MA represents the neutron framework value of sandstone in shale reservoirs, in v / v; NPHI_FL represents the neutron value of fluids in shale reservoirs, in v / v; NPHI_m represents the neutron value of the pure mudstone framework in shale reservoirs, in v / v; RHO_MA represents the density curve value of sandstone in shale reservoirs, in g / cm³. 3 RHO_FL represents the fluid density curve value of the shale reservoir, in g / cm³. 3 RHO_m represents the density curve value of the pure mudstone skeleton of the shale reservoir, in g / cm³. 3 .

[0102] In one embodiment, the oil saturation of the high-porosity mudstone layer can be determined, but is not limited to, using conventional methods for determining oil saturation; for example, it can be determined by using Archie's formula through empirical values ​​of formation resistivity and formation factors.

[0103] In one embodiment, the crude oil density and non-mudstone high-porosity laminated density in the target shale reservoir can be determined, but are not limited to, using conventional methods for determining crude oil density and non-mudstone high-porosity laminated density; typically, the non-mudstone high-porosity laminated density can be compared to a sandstone density of 2.6 g / cm³. 3 .

[0104] In one embodiment, the target shale reservoir is a medium-to-high thermally mature (vitrinite reflectance greater than 0.7%) shale reservoir.

[0105] This invention also provides a specific implementation of a system for evaluating the movable oil content of shale reservoirs. This system is used to implement the aforementioned method embodiment for evaluating the movable oil content of shale reservoirs. See also... Figure 2 The system includes:

[0106] Target reservoir parameter acquisition module 21: used to acquire geological thermal maturity parameters, organic carbon content, hydrogen index, and mudstone content of the target mudstone and shale reservoir;

[0107] High-porosity layer movable oil content acquisition module 22: used to acquire the movable oil content of non-mudstone high-porosity layers (usually sandstone layers, dolomite layers, etc.) in the target mudstone and shale reservoir;

[0108] Module 23 for determining the movable oil content of mudstone: Based on the geological thermal maturity parameters, organic carbon content, and hydrogen index of the target mudstone and shale reservoir, it is used to determine the movable oil content of mudstone in the target mudstone and shale reservoir.

[0109] Target reservoir movable oil content determination module 24: used to determine the movable oil content of the target shale reservoir based on the movable oil content of non-mudstone high-porosity laminae in the target shale reservoir, the movable oil content of mudstone in the target shale reservoir, and the mudstone content of the target shale reservoir.

[0110] In one embodiment, the high-porosity layer movable oil content acquisition module 22 includes:

[0111] First parameter acquisition submodule 221: used to acquire the porosity of non-mudstone high-porosity layers, oil saturation of non-mudstone high-porosity layers, crude oil density, and density of non-mudstone high-porosity layers in the target mudstone and shale reservoir;

[0112] Submodule 222 for determining the movable oil content of high-porosity layers: Based on the porosity of non-mudstone high-porosity layers in the target shale reservoir, the oil saturation of non-mudstone high-porosity layers, the crude oil density, and the density of non-mudstone high-porosity layers in the target shale reservoir, the movable oil content of non-mudstone high-porosity layers is determined.

[0113] Furthermore, the high-porosity layer movable oil content determination submodule 222 uses the following formula to determine the movable oil content of non-mudstone high-porosity layers in the target shale reservoir:

[0114]

[0115] In the formula, O ms The value represents the movable oil content in non-mudstone highly porous laminae within mudstone and shale reservoirs, expressed in mg / g. S represents the porosity of non-mudstone high-porosity laminae in shale reservoirs, in %; os ρ represents the oil saturation of non-mudstone highly porous laminae in shale reservoirs, in dimensionless units. o Density of crude oil in shale reservoirs, in g / cm³ 3 ;ρ r Density of non-mudstone high-porosity laminar layers in shale reservoirs, in g / cm³ 3 .

[0116] In one embodiment, the mudstone movable oil content determination module 23 includes:

[0117] First model acquisition submodule 231: used to acquire the model for determining the movable oil content of mudstone; wherein, the model for determining the movable oil content of mudstone is a calculation model for the movable oil content of mudstone based on geological thermal maturity parameters, organic carbon content and hydrogen index;

[0118] Submodule 232 for determining the movable oil content of mudstone: Based on the geological thermal maturity parameters, organic carbon content, and hydrogen index of the target mudstone and shale reservoir, this module uses the movable oil content determination model of mudstone to determine the movable oil content of mudstone in the target mudstone and shale reservoir.

[0119] In one embodiment, the first model acquisition submodule 231 includes:

[0120] Reference sample parameter acquisition unit 2311: used to acquire the movable oil content and organic carbon content of pure mudstone shale reference samples at different geological thermal maturity;

[0121] Reference sample model determination unit 2312: used to determine the movable oil content model of pure mudstone reference samples based on the movable oil content and organic carbon content of pure mudstone reference samples at different geological thermal maturity; wherein, the movable oil content model of pure mudstone reference samples is a calculation model of the ratio of movable oil content to organic carbon content of pure mudstone reference samples based on geological thermal maturity.

[0122] The preferred model for the movable oil content of the pure mudstone shale reference sample is:

[0123]

[0124] In the formula, a, b, c, and d are dimensionless coefficients, which can be determined by the mobile oil content and organic carbon content of pure mudstone shale reference samples at different geological thermal maturity levels; Ro is vitrinite reflectance or equivalent vitrinite reflectance (vitrinite reflectance and equivalent vitrinite reflectance are geological thermal maturity parameters that can reflect geological thermal maturity), in percentage; TOC is organic carbon content, in percentage; O mmo The values ​​represent the movable oil content of pure mudstone and shale reference samples, in mg / g; for example, a = -7.581102226, b = 24.4777074, c = -15.03825026, d = -7.259934287.

[0125] First model determination unit 2313: a calculation model for determining the movable oil content of mudstone based on pure mudstone reference samples. It combines the positive correlation between organic matter porosity and hydrogen index to construct a model for determining the movable oil content of mudstone.

[0126] The preferred model for determining the movable oil content of mudstone is as follows:

[0127]

[0128] In the formula, O mm 1. Movable oil content of mudstone in shale reservoir, in mg / g; 2. Ro, vitrinite reflectance or equivalent vitrinite reflectance of target mudstone (vitrinite reflectance and equivalent vitrinite reflectance are geological thermal maturity parameters that can reflect geological thermal maturity), in %; 3. TOC, organic carbon content of target mudstone, in %; 4. f(Ro), the ratio of movable oil content to organic carbon content of pure mudstone reference sample at geological thermal maturity of Ro, in mg / g; 5. HI s HI represents the hydrogen index of a pure mudstone reference sample at a geological thermal maturity of Ro, expressed in mg / g TOC; HI represents the hydrogen index of the target mudstone shale, expressed in mg / g TOC.

[0129] Furthermore, the movable oil content of the pure mudstone shale reference sample in the reference sample parameter acquisition unit 2311 includes the pyrolysis free hydrocarbon content as well as the light hydrocarbon loss and pressure drop hydrocarbon expulsion loss per unit of pure mudstone shale reference sample.

[0130] Furthermore, the reference sample parameter acquisition unit 2311 includes:

[0131] Experimental Condition Determination Subunit 23111: Used to determine the temperature and pressure for the thermal hydrocarbon generation simulation experiment based on the burial depth history of the target shale reservoir;

[0132] For example, based on the burial depth history of the target shale reservoir, the burial static pressure and fluid pressure corresponding to the experimental temperature point are set. The experimental temperature is determined by calculation using thermodynamic equations, and the hydrocarbon expulsion control pressure is determined based on the formation fluid pressure value.

[0133] Reference sample acquisition subunit 23112: used to select immature pure mudstone shale samples as pure mudstone shale reference samples;

[0134] Immature pure mudstone samples from the target mudstone and shale reservoir can be selected as reference samples for pure mudstone and shale. If immature pure mudstone samples from the target mudstone and shale reservoir cannot be obtained, immature pure mudstone samples from other mudstone and shale reservoirs can be obtained. Immature pure mudstone samples with organic matter type I are preferred.

[0135] First reference sample parameter acquisition subunit 23113: used to conduct a thermal hydrocarbon generation simulation experiment (i.e., a full process experiment of hydrocarbon generation and expulsion) using pure mudstone and shale reference samples under the determined temperature and pressure conditions of the thermal hydrocarbon generation simulation experiment, and to obtain the pyrolysis free hydrocarbon content, light hydrocarbon loss and pressure drop hydrocarbon expulsion loss per unit of pure mudstone and shale reference sample, as well as the organic carbon content at different geological thermal maturity.

[0136] For example, to determine the mobile oil content and organic carbon content at a certain geological thermal maturity, after the corresponding thermal hydrocarbon generation simulation experiment ends and the temperature drops to normal, the collected effluent hydrocarbons and the hydrocarbons obtained by rinsing the sample surface with dichloromethane can be combined to obtain the light hydrocarbon loss and pressure drop hydrocarbon loss. The solid residue after rinsing is then subjected to conventional pyrolysis analysis using a Rock Eval pyrolysis analyzer to determine the pyrolysis free hydrocarbon content. The organic carbon content can be obtained by testing the organic carbon in the solid residue after rinsing using a carbon-sulfur analyzer. After thoroughly washing the solid residue after rinsing with dichloromethane, the pyrolysis peak temperature can be obtained by pyrolysis analysis of the washed solid residue. Based on the pyrolysis peak temperature, the vitrinite reflectance or equivalent vitrinite reflectance can be obtained.

[0137] Second reference sample parameter acquisition subunit 23114: The movable oil content at different geological thermal maturity can be obtained by using the pyrolysis free hydrocarbon content at different geological thermal maturity and the light hydrocarbon loss and pressure drop hydrocarbon expulsion loss of a unit pure mudstone shale reference sample.

[0138] For example, for a certain geological thermal maturity, the movable oil content can be obtained by summing the pyrolysis free hydrocarbon content, the light hydrocarbon loss per unit pure mudstone and shale reference sample, and the hydrocarbon loss due to pressure drop.

[0139] In one embodiment, the model for determining the movable oil content of mudstone is as follows:

[0140] O mm =[a×Ro 2 +b×Ro+c+d×Ln(Ro)]×TOC×HI÷HI s

[0141] In the formula, a, b, c, and d are dimensionless coefficients (which can be obtained by fitting a pure shale reference sample); Ro is the vitrinite reflectance or equivalent vitrinite reflectance of the shale reservoir (vitrinite reflectance and equivalent vitrinite reflectance are geological thermal maturity parameters that can reflect geological thermal maturity), in %; TOC is the organic carbon content of the shale reservoir, in %; O mm HI represents the movable oil content of mudstone in shale reservoirs, in mg / g; HI represents the hydrogen index of shale reservoirs, in mg / g TOC; HI sThe hydrogen index (in mg / gTOC) is given for a pure mudstone reference sample (this mudstone sample was used to fit and determine the dimensionless coefficients a, b, c, d) at a geological thermal maturity of Ro.

[0142] For example, a = -7.581102226, b = 24.4777074, c = -15.03825026, d = -7.259934287, HI s = -478.53Ro 3 +741.92Ro 2 -793.91Ro+1061.7.

[0143] In one embodiment, the target reservoir movable oil content determination module 24 determines the movable oil content of the target shale reservoir based on the following formula:

[0144] O m =O mm ×V m +O mmo

[0145] In the formula, O m The movable oil content of shale reservoirs, in mg / g; O mm V represents the movable oil content of mudstone in shale reservoirs, in mg / g. m The mudstone content in the shale reservoir is expressed as a percentage (%). ms The value represents the movable oil content in non-mudstone highly porous laminar layers of shale reservoirs, expressed in mg / g.

[0146] In one embodiment, the geological thermal maturity parameters of the target shale reservoir can be determined using, but are not limited to, conventional methods for determining geological thermal maturity parameters; for example, maturity analysis can be performed using core samples or rock fragments from the target shale reservoir to determine the geological thermal maturity parameters of the target shale reservoir.

[0147] In one embodiment, the target reservoir parameter acquisition module 21 is specifically used to acquire the geological thermal maturity parameters of the target shale reservoir in the following manner:

[0148] A calculation model based on the current burial depth is used to obtain the geological thermal maturity parameters; the current burial depth of the target shale reservoir is obtained; based on the current burial depth of the target shale reservoir, the geological thermal maturity parameters of the target shale reservoir are determined using the calculation model based on the current burial depth.

[0149] Furthermore, calculation models for obtaining geological thermal maturity parameters based on current burial depth include:

[0150] Determine the geological and thermal maturity parameters and current burial depth of different source rock samples in the tectonic region where the target shale reservoir is located; based on the geological and thermal maturity parameters and current burial depth of each source rock sample, fit the relationship between the geological and thermal maturity parameters and the current burial depth: Ro=exp[(D c -A)÷B], where Ro is the vitrinite reflectance or equivalent vitrinite reflectance, in %; D c The current burial depth is in meters (m); A and B are dimensionless parameters.

[0151] Based on the relationship between geological thermal maturity parameters and current burial depth, the current burial depth is determined when the vitrinite reflectance or equivalent vitrinite reflectance is 0.21. The negative of the current burial depth when the vitrinite reflectance or equivalent vitrinite reflectance is 0.21 is the original erosion amount in the structural region where the target mudstone and shale reservoir is located.

[0152] Obtain the amount of erosion of the formation at the current burial depth of the target shale reservoir at the target well location (the well location where the target shale reservoir is located) and the thickness of the formation above the erosion surface at the target well location;

[0153] Based on the dimensionless parameters A and B in the relationship between geological thermal maturity parameters and current burial depth, the original erosion amount of the structural region where the target shale reservoir is located, the erosion amount of the strata at the current burial depth of the target shale reservoir in the target well location, and the strata thickness above the erosion surface in the target well location, a calculation model for geological thermal maturity parameters based on the current burial depth is determined; among which...

[0154] When the erosion amount of the formation at the current burial depth of the target shale reservoir in the target well location is less than the formation thickness above the erosion surface in the target well location, the calculation model for the geological thermal maturity parameter based on the current burial depth is: Ro = exp[(D c -H eu +H e -H eo -A)÷B];

[0155] When the erosion of the target shale reservoir at its current burial depth is greater than or equal to the formation thickness above the erosion surface at the target well location, the calculation model for the geological thermal maturity parameter based on the current burial depth is: Ro = exp[(D c -H eo -A)÷B]

[0156] In the formula, Ro is the vitrinite reflectance or equivalent vitrinite reflectance of the target shale reservoir, in %; D c The current burial depth of the target shale reservoir; H e For the target well location at depth D c The amount of erosion of the strata; H eu H represents the formation thickness above the erosion surface at the target well location.eo A represents the original erosion amount in the structural region where the target shale reservoir is located; A and B are dimensionless parameters.

[0157] Furthermore, the calculation model for geological thermal maturity parameters based on the current burial depth is as follows:

[0158] When H eu <H e At that time, Ro = exp[(D c -H eu +H e -H eo -A)÷B]

[0159] When H eu ≥H e At that time, Ro = exp[(D c -H eo -A)÷B]

[0160] In the formula, Ro is the vitrinite reflectance or equivalent vitrinite reflectance of the target shale reservoir, in %; D c The current burial depth of the target shale reservoir; H e For the target well location at depth D c The amount of erosion of the strata; H eu H represents the formation thickness above the erosion surface at the target well location. eo A represents the original erosion amount in the structural region where the target shale reservoir is located; A and B are dimensionless parameters.

[0161] In one embodiment, the organic carbon content of the target shale reservoir can be determined using, but is not limited to, conventional methods for determining organic carbon content. For example, the organic carbon content of the target shale reservoir can be determined using a Delta Log R model based on the vitrinite reflectance or equivalent vitrinite reflectance of the target shale reservoir. Alternatively, the organic matter abundance can be determined by performing organic matter abundance analysis on core or rock fragments of the target shale reservoir.

[0162] In one embodiment, the hydrogen index of the target shale reservoir can be determined using, but is not limited to, conventional hydrogen index determination methods; for example, by performing rock pyrolysis analysis on cores or rock fragments of the target shale reservoir to determine the organic carbon content of the target shale reservoir.

[0163] In one embodiment, the mudstone content of the target shale reservoir can be determined using, but is not limited to, conventional mudstone content determination methods; for example, based on well logging information such as neutron, density, and acoustic waves.

[0164] In one embodiment, the porosity of the non-mudstone high-porosity laminae in the target shale reservoir can be determined, but is not limited to, using conventional porosity determination methods; for example, based on well logging information such as neutron, density, and acoustic waves; for example, using density or neutron-density cross plot methods.

[0165] In one embodiment, the mudstone content of the target shale reservoir and the porosity of the non-mudstone high-porosity laminae in the target shale reservoir are determined by the following formula:

[0166]

[0167]

[0168] In the formula, V m The mudstone content in the mudstone-shale reservoir is expressed as a percentage (%). Porosity of non-mudstone high-porosity laminae in shale reservoirs, in %; RHOB is the rock density curve value from well logging of shale reservoirs, in g / cm³. 3 NPHI represents the neutron value in well logging of shale reservoirs, in V / V; NPHI_MA represents the neutron framework value of sandstone in shale reservoirs, in v / v; NPHI_FL represents the neutron value of fluids in shale reservoirs, in v / v; NPHI_m represents the neutron value of the pure mudstone framework in shale reservoirs, in v / v; RHO_MA represents the density curve value of sandstone in shale reservoirs, in g / cm³. 3 RHO_FL represents the fluid density curve value of the shale reservoir, in g / cm³. 3 RHO_m represents the density curve value of the pure mudstone skeleton of the shale reservoir, in g / cm³. 3 .

[0169] In one embodiment, the oil saturation of the high-porosity mudstone layer can be determined, but is not limited to, using conventional methods for determining oil saturation; for example, it can be determined by using Archie's formula through empirical values ​​of formation resistivity and formation factors.

[0170] In one embodiment, the crude oil density and non-mudstone high-porosity laminated density in the target shale reservoir can be determined, but are not limited to, using conventional methods for determining crude oil density and non-mudstone high-porosity laminated density; typically, the non-mudstone high-porosity laminated density can be compared to a sandstone density of 2.6 g / cm³. 3 .

[0171] Embodiments of the present invention also provide a specific implementation of an electronic device capable of performing all steps in the above-described method for evaluating the movable oil content of shale reservoirs. The electronic device specifically includes the following components:

[0172] Processor, memory, communication interface, and bus;

[0173] The processor, memory, and communication interface communicate with each other via a bus. The communication interface is used to transmit information between server-side devices and client-side devices. The processor calls the computer program in the memory. When the processor executes the computer program, it implements all the steps in the method for evaluating the movable oil content of shale reservoirs in the above embodiments. For example, when the processor executes the computer program, it implements the following steps:

[0174] Step S1: Obtain the geological thermal maturity parameters, organic carbon content, hydrogen index, and mudstone content of the target shale reservoir;

[0175] Step S2: Obtain the movable oil content of non-mudstone high-porosity laminae in the target mudstone and shale reservoir;

[0176] Step S3: Based on the geological thermal maturity parameters, organic carbon content, and hydrogen index of the target shale reservoir, determine the movable oil content of the mudstone in the target shale reservoir;

[0177] Step S4: Determine the movable oil content of the target shale reservoir based on the movable oil content of the non-mudstone high-porosity laminae in the target shale reservoir, the movable oil content of the mudstone in the target shale reservoir, and the mudstone content of the target shale reservoir.

[0178] Embodiments of the present invention also provide a computer-readable storage medium capable of implementing all steps of the method for evaluating the mobile oil content of shale reservoirs in the above embodiments. The computer-readable storage medium stores a computer program that, when executed by a processor, implements all steps of the method for evaluating the mobile oil content of shale reservoirs in the above embodiments. For example, when the processor executes the computer program, it implements the following steps:

[0179] Step S1: Obtain the geological thermal maturity parameters, organic carbon content, hydrogen index, and mudstone content of the target shale reservoir;

[0180] Step S2: Obtain the movable oil content of non-mudstone high-porosity laminae in the target mudstone and shale reservoir;

[0181] Step S3: Based on the geological thermal maturity parameters, organic carbon content, and hydrogen index of the target shale reservoir, determine the movable oil content of the mudstone in the target shale reservoir;

[0182] Step S4: Determine the movable oil content of the target shale reservoir based on the movable oil content of the non-mudstone high-porosity laminae in the target shale reservoir, the movable oil content of the mudstone in the target shale reservoir, and the mudstone content of the target shale reservoir.

[0183] Example 1

[0184] This embodiment utilizes the mobile oil content evaluation method for shale and mudstone reservoirs provided by the present invention to evaluate the mobile oil content of a shale and mudstone reservoir at a target well location under conventional development conditions. The shale and mudstone reservoir at the target well location is a medium-to-high heat mature shale and mudstone reservoir.

[0185] 1. Analyze and identify the key factors affecting the size of free hydrocarbon S1 from pyrolysis of mudstone and shale.

[0186] Using the basin where the target well is located as the study area, core and cuttings samples from each well in the study area were obtained as rock samples for rock pyrolysis, organic matter abundance, and sandstone content testing and analysis. The pyrolysis free hydrocarbon content (S1), organic carbon content (TOC), and sandstone content of each rock sample were obtained, and their relationships were statistically analyzed. Figures 3-5 As shown. By Figure 3 It can be seen that when TOC ≥ 2.0%, the S1 / TOC ratio decreases with increasing TOC, and the maximum value of S1 / TOC approaches 100 mg / g TOC. This indicates that the pyrolysis free hydrocarbons retained in pure mudstone and shale exhibit a maximum value pattern. However, when TOC < 2.0%, this pattern is not obvious, and the S1 / TOC ratio shows abnormally high values. Figure 4 It can be seen that the S1 / TOC ratio of rock samples with low sandstone content converges to 150 mg / g TOC, with the main values ​​concentrated around 100 mg / g TOC. For example... Figure 5 As shown, for rock samples with TOC ≥ 2.0%, S1 is positively correlated with TOC. Furthermore, with a slope of 100 mg / g TOC as the boundary, the high sand content sample points and the pure mudstone and shale sample points are located on the upper and lower sides of this slope, respectively, indicating that S1 is not only related to TOC, but also to lithology.

[0187] 2. Obtain a model for determining the movable oil content of mudstone; wherein, the model for determining the movable oil content of mudstone is the movable oil content O of mudstone. mm The calculation model is based on vitrinite reflectance (Ro), organic carbon content (TOC), and hydrogen index (HI).

[0188] 2.1 Based on the insights gained in Step 1, further analysis was conducted on the variation patterns of total organic carbon (TOC) content and the amount of movable oil generated in pure mudstone shale samples during thermal evolution, establishing an O2O... mm / The relationship between TOC and Ro.

[0189] Immature pure mudstone shale samples of type I organic matter were obtained as reference samples for pure mudstone shale. Thermal hydrocarbon generation simulation experiments (i.e., full-process hydrocarbon generation and expulsion experiments) were conducted on the pure mudstone shale reference samples to measure the amount of movable oil at different thermal maturity levels. The original pure mudstone shale reference samples had a TOC value of 4.95%, a Tmax value of 433℃, and a hydrogen index (HI) of 837 mg / g TOC.

[0190] In the thermal hydrocarbon generation simulation experiment, the temperature and pressure are determined based on the burial history of representative well locations in the sedimentary depression center of the basin where the target shale reservoir is located. The burial static rock pressure and fluid pressure corresponding to the experimental temperature point are set. The experimental temperature is calculated using thermodynamic equations (the experimental temperature does not exceed 374℃), and the hydrocarbon expulsion control pressure is determined based on the formation fluid pressure value. The thermal hydrocarbon generation simulation experiment simulates the process of simultaneous generation and expulsion.

[0191] Movable oil includes light hydrocarbons, liquid hydrocarbons discharged from the sample surface after the formation fluid pressure is reduced to laboratory ambient temperature and pressure, and free hydrocarbons (S1) from rock pyrolysis at 300℃. The movable oil content at a specific geological thermal maturity is determined as follows: After the corresponding thermal hydrocarbon generation simulation experiment ends and the pressure is reduced to ambient temperature and pressure for 72 hours, the discharged hydrocarbons are collected at -50℃ and protected with a solvent. The sample surface is rinsed with dichloromethane, and both measurements are combined. The solid residue after rinsing is subjected to conventional pyrolysis analysis using a Rock Eval pyrolysis analyzer to determine the pyrolysis free hydrocarbon content (S1). The sum of these three components is the pure mudstone movable oil content (O). mm The organic carbon content (TOC) of the solid residue after rinsing can be obtained by testing the organic carbon content using a carbon-sulfur analyzer. After thoroughly washing the solid residue with dichloromethane, the pyrolysis peak temperature (Tmax) can be obtained by performing pyrolysis analysis on the washed solid residue. The vitrinite reflectance (Ro) can then be determined based on the pyrolysis peak temperature (Tmax).

[0192] Based on the movable oil content O of pure shale reference samples at different vitrinite reflectances Ro. mm Fit the organic carbon content (TOC) to the data, such as... Figure 6 , Figure 7 As shown, the movable oil content model of the pure mudstone shale reference sample is obtained:

[0193]

[0194] Where a, b, c, and d are dimensionless coefficients, a = -7.581102226, b = 24.4777074, c = -15.03825026, and d = -7.259934287; Ro is vitrinite reflectance, in %; TOC is organic carbon content, in %; O mmo The value represents the movable oil content of a pure mudstone shale reference sample, expressed in mg / g.

[0195] 2.2 Calculation model for determining the movable oil content of mudstone based on pure mudstone reference samples. This model is constructed by considering the positive correlation between organic matter porosity and hydrogen index.

[0196]

[0197] In the formula, Ro is the vitrinite reflectance of the target mudstone, in %; TOC is the organic carbon content of the target mudstone, in %; f(Ro) is the ratio of mobile oil content to organic carbon content of a pure mudstone reference sample at a geological thermal maturity of Ro, in mg / g; HI s HI represents the hydrogen index of the pure mudstone reference sample at a vitrinite reflectance of Ro, in mg / g TOC; HI represents the hydrogen index of the target mudstone, in mg / g TOC.

[0198] Obtain a scatter plot of the hydrogen index HI as a function of vitrinite reflectance Ro for a pure mudstone shale reference sample, as shown below. Figure 8 As shown, the hydrogen index HI of the pure mudstone shale reference sample was obtained by fitting the calculation model based on the vitrinite reflectance Ro: HI s = -478.53Ro 3 +741.92Ro 2 -793.91Ro +1061.7;

[0199] Core samples were obtained from the target shale reservoir at the target well location. Rock pyrolysis, maturity, and organic matter abundance analyses were performed on these core samples to obtain the hydrogen index (HI) and vitrinite reflectance (Ro) data. Based on the vitrinite reflectance (Ro) of the target shale reservoir at the target well location, the hydrogen index (HI) of the pure shale reference sample was determined using a calculation model based on the vitrinite reflectance (Ro) of the pure shale reference sample. s .

[0200] It should be noted that samples with a total organic carbon (TOC) content of less than 2.0% are not representative of shale oil reservoirs. Therefore, core samples from the target mudstone and shale reservoir at the target well location with an organic matter abundance (TOC) of less than 2.0% need to be discarded. In this embodiment, the ratio α of the hydrogen index of the target mudstone and shale to that of the pure mudstone and shale reference sample at a vitrinite reflectance of Ro is 0.90-0.96, with a narrow distribution, indicating a stable sedimentary environment and a single source of organic matter parent material. The average value of 0.94 is taken as the α value of the target mudstone and shale reservoir at the target well location.

[0201] 3. Obtain the mudstone content (V) of the target shale reservoir at the target well location based on the neutron-density cross-plot of the well logging. m and sandstone porosity

[0202] By using core data from the target shale reservoir at the target well location, and combining this data with neutron-density cross-plots of the target shale reservoir at the target well location, sandstone and mudstone framework points are determined, thereby determining the mudstone content (V) of the target shale reservoir. m Porosity of sandstone in the target shale reservoir The formula is as follows:

[0203]

[0204]

[0205] In the formula, V m The mudstone content in the mudstone-shale reservoir is expressed as a percentage (%). Porosity of non-mudstone high-porosity laminae in shale reservoirs, in %; RHOB is the rock density curve value from well logging of shale reservoirs, in g / cm³. 3 NPHI represents the neutron value in well logging of shale reservoirs, in V / V; NPHI_MA represents the neutron framework value of sandstone in shale reservoirs, in v / v; NPHI_FL represents the neutron value of fluids in shale reservoirs, in v / v; NPHI_m represents the neutron value of the pure mudstone framework in shale reservoirs, in v / v; RHO_MA represents the density curve value of sandstone in shale reservoirs, in g / cm³. 3 RHO_FL represents the fluid density curve value of the shale reservoir, in g / cm³. 3 RHO_m represents the density curve value of the pure mudstone skeleton of the shale reservoir, in g / cm³. 3 .

[0206] In another embodiment, the sandstone density skeleton value is 2.64 g / cm³. 3 The neutron framework uses a classic framework value of -0.02 v / v, while the mudstone framework value is 2.56 g / cm³. 3 The neutron framework value is 0.45v / v, and the mudstone content (V) of the target shale reservoir is... m and sandstone porosity like Figure 10 As shown.

[0207] 4. Obtain the vitrinite reflectance Ro of the target shale reservoir.

[0208] 4.1 Calculation model for obtaining vitrinite reflectance Ro based on current burial depth Dc

[0209] Source rock samples with different current burial depths (Dc) belonging to the same tectonic region as the target shale reservoir were selected for thermal maturity testing and analysis. A formula was fitted to determine the relationship between the current burial depth (Dc) and vitrinite reflectance (Ro) (e.g., Figure 9 As shown): Ro = exp[(D c -2768.8)÷1988.04], where Dc is in meters and Ro is in percent.

[0210] The corresponding Dc for Ro = 0.21% is -438m, based on which we know that the original erosion amount Heo = 438m.

[0211] Based on previous stratigraphic erosion thickness maps, the erosion thickness at the target well location is read as He = 1200m, and the burial depth of the strata above the erosion surface is Heu = 526m. Therefore, the vitrinite reflectance Ro is calculated based on the current burial depth Dc using the following model: Ro = exp[(D c -526+1200-438-2768.8)÷1988.04], where Dc is in meters and Ro is in percent.

[0212] 4.2 Obtain the current burial depth of the target shale reservoir;

[0213] 4.3. Based on the current burial depth of the target shale reservoir, the vitrinite reflectance Ro of the target shale reservoir is determined using a calculation model based on the current burial depth Dc; the results are as follows. Figure 10 As shown.

[0214] 5. Determine the total organic matter abundance (TOC) of the target shale reservoir.

[0215] Sensitivity analysis of the relationship between well logging parameters and TOC revealed that the most sensitive well logging information parameter related to TOC is rock density RHOZ. Then, using the Delta Log R model, the density RHOZ parameter was selected to recover and predict the organic matter abundance (TOC) at any well depth. The specific calculation formula and values ​​are as follows:

[0216] TOC=ΔLgR×10^(2.297-0.1688×LOM)

[0217] ΔLgR=Lg(Rt÷Rtbaseline)-2.5×(RHOB-RHOBbaseline)

[0218] LOM=0.0989×Ro^5-2.1587×Ro^4+12.392×Ro^3-29.032×Ro^2+32.53×Ro-3.0338

[0219] In the formula, Rt is the rock resistivity logging value, Ω·m; RHOB is the rock density logging value, g / cm³. 3 The rock resistivity logging value Rt corresponding to the pure mudstone layer when TOC=0% is used as the Rt baseline; the rock density logging value RHOB corresponding to the pure mudstone layer when TOC=0% is used as the RHOB baseline.

[0220] TOC of the target shale reservoir, such as Figure 10 As shown.

[0221] 6. Determine the oil saturation (Sos) of the sandstone in the target shale reservoir.

[0222] The oil saturation of the sandstone in the target shale reservoir, Sos = 1 - Sw, was determined using the Total-shale formula.

[0223] The total-shale formula is as follows:

[0224]

[0225] In the formula, S w R represents water saturation, in %; w Rt is the formation water resistivity, Ω·m; V is the formation resistivity, Ω·m; m The content of clay, %; R m The resistivity of mudstone is given in Ω·m. Porosity, %;

[0226] Oil saturation Sos of sandstone in the target shale reservoir Figure 10 As shown.

[0227] 7. Based on the porosity, oil saturation, crude oil density, and sandstone density of the sandstone in the target shale reservoir, determine the movable oil content of the sandstone in the target shale reservoir; based on the geological thermal maturity parameters, organic carbon content, and hydrogen index of the target shale reservoir, use the movable oil content determination model of the mudstone to determine the movable oil content of the mudstone in the target shale reservoir; based on the movable oil content of the sandstone in the target shale reservoir, the movable oil content of the mudstone in the target shale reservoir, and the mudstone content of the target shale reservoir, determine the movable oil content of the target shale reservoir;

[0228] The movable oil content of the sandstone in the target shale reservoir is determined using the following formula:

[0229]

[0230] In the formula, O ms The value represents the movable oil content of sandstone in shale reservoirs, expressed in mg / g. S represents the porosity of sandstone in shale reservoirs, expressed as a percentage (%). os ρ represents the oil saturation of sandstone in shale reservoirs, in dimensionless units. o Density of crude oil in shale reservoirs, in g / cm³ 3 The value is 0.9 g / cm³. 3 ;ρ r Density of sandstone in shale reservoirs, in g / cm³ 3 The value is 2.6 g / cm³. 3 ;

[0231] The movable oil content of the target shale reservoir is determined using the following formula:

[0232] Om =O mm ×V m +O mmo

[0233] In the formula, O m The movable oil content of shale reservoirs, in mg / g; O mm V represents the movable oil content of mudstone in shale reservoirs, in mg / g. m The mudstone content in the shale reservoir is expressed as a percentage (%). ms This represents the movable oil content of sandstone in shale reservoirs, expressed in mg / g.

[0234] The movable oil content of the target shale reservoir is as follows Figure 10 As shown.

[0235] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for evaluating the movable oil content of shale reservoirs, wherein, The method includes: Obtain the geological thermal maturity parameters, organic carbon content, hydrogen index, and mudstone content of the target mudstone and shale reservoir; To obtain the movable oil content of non-mudstone high-porosity laminae in the target mudstone and shale reservoir; Based on the geological thermal maturity parameters, organic carbon content, and hydrogen index of the target shale reservoir, the movable oil content of the mudstone in the target shale reservoir is determined. The movable oil content of the target shale reservoir is determined based on the movable oil content of the non-mudstone high-porosity layer in the target shale reservoir, the movable oil content of the mudstone in the target shale reservoir, and the mudstone content of the target shale reservoir. in, The movable oil content in non-mudstone high-porosity laminae of the target shale reservoir is determined using the following formula: THE ms =1000× s ×S os ×ρ o ÷ρ r In the formula, O ms The value represents the movable oil content in non-mudstone highly porous laminae within mudstone and shale reservoirs, expressed in mg / g. s Porosity of non-mudstone high-porosity laminae in shale reservoirs, in %; S os ρ represents the oil saturation of non-mudstone highly porous laminae in shale reservoirs, in dimensionless units. o Density of crude oil in shale reservoirs, in g / cm³ 3 ;ρ r Density of non-mudstone high-porosity laminar layers in shale reservoirs, in g / cm³ 3 ; The model for determining the movable oil content of mudstone is as follows: A mm =[a×Ro 2 +b×Ro+c+d×Ln(Ro)]×TOC×HI÷HI s In the formula, a, b, c, and d are dimensionless coefficients; Ro is the vitrinite reflectance or equivalent vitrinite reflectance of the shale reservoir, in %; TOC is the organic carbon content of the shale reservoir, in %; O mm HI represents the movable oil content of mudstone in shale reservoirs, in mg / g; HI represents the hydrogen index of shale reservoirs, in mg / g TOC; HI s The hydrogen index of a pure mudstone shale reference sample at a geological thermal maturity of Ro is expressed in mg / gTOC. The movable oil content of the target shale reservoir is determined based on the following formula: The m =O mm ×V m + O ms In the formula, O m The movable oil content of shale reservoirs, in mg / g; O mm V represents the movable oil content of mudstone in shale reservoirs, in mg / g. m The mudstone content in the shale reservoir is expressed as % (%). ms The value represents the movable oil content in non-mudstone highly porous laminar layers of shale reservoirs, expressed in mg / g.

2. The method according to claim 1, wherein, Obtaining the movable oil content of non-mudstone high-porosity laminae in the target shale reservoir includes: To obtain the porosity of non-mudstone high-porosity laminae, the oil saturation of non-mudstone high-porosity laminae, the crude oil density, and the density of non-mudstone high-porosity laminae in the target mudstone and shale reservoir; Based on the porosity of the non-mudstone high-porosity laminae in the target shale reservoir, the oil saturation of the non-mudstone high-porosity laminae, the crude oil density, and the density of the non-mudstone high-porosity laminae, the movable oil content of the non-mudstone high-porosity laminae in the target shale reservoir is determined.

3. The method according to claim 1, wherein, Based on the geological thermal maturity parameters, organic carbon content, and hydrogen index of the target shale reservoir, the movable oil content of the mudstone in the target shale reservoir is determined as follows: A model for determining the movable oil content of mudstone was obtained; wherein, the model for determining the movable oil content of mudstone is a calculation model based on geological thermal maturity parameters, organic carbon content and hydrogen index. Based on the geological thermal maturity parameters, organic carbon content, and hydrogen index of the target shale reservoir, the movable oil content of the mudstone in the target shale reservoir is determined using a model for determining the movable oil content of mudstone.

4. The method according to claim 3, wherein, Models for determining the movable oil content of mudstone include: To obtain the movable oil content and organic carbon content of pure mudstone shale reference samples at different geological thermal maturity; Based on the movable oil content and organic carbon content of pure mudstone shale reference samples at different geological thermal maturity, a movable oil content model for pure mudstone shale reference samples is determined; wherein, the movable oil content model for pure mudstone shale reference samples is a calculation model based on the ratio of movable oil content to organic carbon content of pure mudstone shale reference samples based on geological thermal maturity. A computational model for determining the movable oil content of mudstone was constructed based on a reference sample of pure mudstone. This model incorporates the positive correlation between organic matter porosity and hydrogen index.

5. The method according to claim 4, wherein, The model for the movable oil content of the pure mudstone shale reference sample is as follows: In the formula, a, b, c, and d are dimensionless coefficients; Ro is vitrinite reflectance or equivalent vitrinite reflectance, in %; TOC is organic carbon content, in %; O mmo The value represents the movable oil content of a pure mudstone shale reference sample, expressed in mg / g.

6. The method according to claim 4, wherein, The model for determining the movable oil content of mudstone is as follows: In the formula, O mm HI represents the movable oil content of mudstone in the shale reservoir, in mg / g; TOC represents the hydrogen index of the shale reservoir, in mg / g; Ro represents the vitrinite reflectance or equivalent vitrinite reflectance of the target mudstone, in %; and TOC represents the organic carbon content of the target mudstone, in %%. The ratio of mobile oil content to organic carbon content in a pure mudstone shale reference sample at a geological thermal maturity of Ro is given in mg / g. HI s HI represents the hydrogen index of the pure mudstone reference sample at a geological thermal maturity of Ro, in mg / g TOC; HI represents the hydrogen index of the target mudstone, in mg / g TOC.

7. The method according to claim 4, wherein, The movable oil content of pure mudstone shale reference samples includes the content of pyrolysis free hydrocarbons, as well as the amount of light hydrocarbons lost per unit of pure mudstone shale reference sample and the amount of hydrocarbons expelled due to pressure drop.

8. The method according to claim 1, wherein, The geological thermal maturity parameters of the target shale reservoir include: Geological thermal maturity parameters are obtained based on a calculation model at the current burial depth; Obtain the current burial depth of the target shale reservoir; Based on the current burial depth of the target shale reservoir, the geological and thermal maturity parameters of the target shale reservoir are determined using a calculation model based on the current burial depth and geological and thermal maturity parameters.

9. The method according to claim 8, wherein, The calculation models for obtaining geological thermal maturity parameters based on the current burial depth include: Determine the geological and thermal maturity parameters and current burial depth of different source rock samples in the tectonic region where the target shale reservoir is located; based on the geological and thermal maturity parameters and current burial depth of each source rock sample, fit the relationship between the geological and thermal maturity parameters and the current burial depth: Ro=exp[(D c -A)÷B], where Ro is the vitrinite reflectance or equivalent vitrinite reflectance, in units of %; D c The current burial depth is in meters (m); A and B are dimensionless parameters. Based on the relationship between geological thermal maturity parameters and current burial depth, the current burial depth is determined when the vitrinite reflectance or equivalent vitrinite reflectance is 0.

21. The negative of the current burial depth when the vitrinite reflectance or equivalent vitrinite reflectance is 0.21 is the original erosion amount in the structural region where the target mudstone and shale reservoir is located. Obtain the amount of erosion of the target mudstone and shale reservoir at the current burial depth in the target well location and the thickness of the formation above the erosion surface in the target well location; Based on the dimensionless parameters A and B in the relationship between geological thermal maturity parameters and current burial depth, the original erosion amount of the structural region where the target shale reservoir is located, the erosion amount of the strata at the current burial depth of the target shale reservoir in the target well location, and the strata thickness above the erosion surface in the target well location, a calculation model for geological thermal maturity parameters based on the current burial depth is determined; among which... When the erosion amount of the formation at the current burial depth of the target shale reservoir in the target well location is less than the formation thickness above the erosion surface in the target well location, the calculation model for the geological thermal maturity parameter based on the current burial depth is: Ro = exp[(D c -H eu +H e -H eo -A)÷B]; When the erosion of the target shale reservoir at its current burial depth is greater than or equal to the formation thickness above the erosion surface at the target well location, the calculation model for the geological thermal maturity parameter based on the current burial depth is: Ro = exp[(D c -H eo -A)÷B] In the formula, Ro is the vitrinite reflectance or equivalent vitrinite reflectance of the target shale reservoir, in units of %; D c The current burial depth of the target shale reservoir; H e For the target well location at depth D c The amount of erosion of the strata; H eu H represents the formation thickness above the erosion surface at the target well location. eo A represents the original erosion amount in the structural region where the target shale reservoir is located; A and B are dimensionless parameters.

10. A system for evaluating the movable oil content of shale reservoirs, wherein, The system includes: Target reservoir parameter acquisition module: used to acquire geological and thermal maturity parameters, organic carbon content, hydrogen index, and mudstone content of the target mudstone and shale reservoir; High-porosity layer movable oil content acquisition module: used to acquire the movable oil content of non-mudstone high-porosity layers in the target mudstone and shale reservoir; The module for determining the movable oil content of mudstone is used to determine the movable oil content of mudstone in a target mudstone and shale reservoir based on the geological thermal maturity parameters, organic carbon content, and hydrogen index of the target mudstone and shale reservoir. The target reservoir movable oil content determination module is used to determine the movable oil content of the target shale reservoir based on the movable oil content of non-mudstone high-porosity layers in the target shale reservoir, the movable oil content of mudstone in the target shale reservoir, and the mudstone content of the target shale reservoir. in: The movable oil content in non-mudstone high-porosity laminae of the target shale reservoir is determined using the following formula: THE ms =1000× s ×S os ×ρ o ÷ρ r In the formula, O ms The value represents the movable oil content in non-mudstone highly porous laminae within mudstone and shale reservoirs, expressed in mg / g. s Porosity of non-mudstone high-porosity laminae in shale reservoirs, in %; S os ρ represents the oil saturation of non-mudstone highly porous laminae in shale reservoirs, in dimensionless units. o Density of crude oil in shale reservoirs, in g / cm³ 3 ;ρ r Density of non-mudstone high-porosity laminar layers in shale reservoirs, in g / cm³ 3 ; The model for determining the movable oil content of mudstone is as follows: A mm =[a×Ro 2 +b×Ro+c+d×Ln(Ro)]×TOC×HI÷HI s In the formula, a, b, c, and d are dimensionless coefficients; Ro is the vitrinite reflectance or equivalent vitrinite reflectance of the shale reservoir, in %; TOC is the organic carbon content of the shale reservoir, in %; O mm HI represents the movable oil content of mudstone in shale reservoirs, in mg / g; HI represents the hydrogen index of shale reservoirs, in mg / g TOC; HI s The hydrogen index of a pure mudstone shale reference sample at a geological thermal maturity of Ro is expressed in mg / gTOC. The movable oil content of the target shale reservoir is determined based on the following formula: The m =O mm ×V m + O ms In the formula, O m The movable oil content of shale reservoirs, in mg / g; O mm V represents the movable oil content of mudstone in shale reservoirs, in mg / g. m The mudstone content in the shale reservoir is expressed as % (%). ms The value represents the movable oil content in non-mudstone highly porous laminar layers of shale reservoirs, expressed in mg / g.

11. An electronic device comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the method for evaluating the movable oil content of shale reservoirs as described in any one of claims 1-9.

12. A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method for evaluating the movable oil content of a shale reservoir according to any one of claims 1-9.

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