Method and device for identifying shale oil in-situ conversion section interlayer based on hydrocarbon generation potential

Abstract

The invention discloses a shale oil in-situ conversion section interlayer identification method and device based on hydrocarbon generation potential. The method comprises the following steps: identifying a sandstone single layer according to lithology data of a to-be-in-situ conversion section in a shale bed; judging whether the thickness of the sandstone single layer is greater than a single layer thickness lower limit of the sandstone single layer as a quasi in-situ conversion section interlayer, wherein the single layer thickness lower limit is predetermined based on an average value of hydrocarbon generation potential values of the shale single layer in the shale layer and a plurality of data pairs containing the thickness of the sandstone single layer and the hydrocarbon generation potential values of the sandstone single layer; and if yes, identifying the sandstone single layer as an interlayer. According to the method, for a specific application scene of an organic matter-rich shale section, the limitation that the interlayer is recognized only by means of lithology traditionally is broken through, and the method is more suitable for geological evaluation and related research of shale oil in-situ conversion; according to the method, the lower limit value of the hydrocarbon generation potential of the interlayer is converted into the lower limit value of the thickness of the interlayer which is more visual and easier to obtain, the requirement for data is lowered, and identification of the shale oil quasi-in-situ conversion section interlayer can be achieved only through lithology data.

Description

Technical Field

[0001] The present invention relates to the technical field of geophysical logging and in-situ production of shale oil, and in particular to a method and device for identifying interlayers in an in-situ conversion section of shale oil based on hydrocarbon generation potential. Background Art

[0002] Studies have shown that my country's medium- and low-maturity shale oil resources have great potential. If the corresponding exploration and development technology achieves a breakthrough, it will be of great strategic significance for reducing my country's dependence on foreign crude oil. At present, theoretical and technical exploration in this field is in full swing at home and abroad. The organic matter stored in medium- and low-maturity shales mainly includes two categories: generated retained oil and kerogen that has not been converted into hydrocarbons. The existing unconventional oil and gas development methods that rely on horizontal wells and large-scale hydraulic fracturing are usually not able to effectively develop the two types of organic matter. It is necessary to rely on in-situ heating of shale to convert organic matter into light oil and gas with better fluidity before it can be produced. In this process, the organic-rich shale layer to be heated needs to be finely characterized, especially the interlayer that affects the heating and oil and gas conversion efficiency.

[0003] At present, the technical methods for evaluating interlayers in shale layers are mainly aimed at simple lithologic interlayers. For example, non-shale lithologic interlayers such as sandstone, limestone, dolomite, and mixed sedimentary rocks are identified and characterized in shale. In this type of classification scheme, the thickness, proportion, and development degree of individual interlayers have been studied and reported (Zhu Deshun, Wang Yong, Zhu Deyan, et al. Definition criteria and main controlling factors of interlayer shale oil in the first stratum of Shahejie Formation in Bonan Subsag, 2015; Cheng Ming, Luo Xiaorong, Lei Yuhong, et al. Study on the distribution, fractal characteristics and estimation methods of silty interlayers / lamina in Zhangjiatan shale in Ordos Basin, 2015; Liu Yali, Liu Peng. Characteristics and functions of interlayers in continental organic-rich mudstone - taking Jiyang Depression as an example, 2019; Wang Baohua, Li Hao, Lu Jianlin. Quantitative characterization of the development degree of non-mudstone interlayers in continental shale formations, 2019). In previous studies, the presence of interlayers mainly affects the storage, migration and seepage of generated oil and gas, as well as the hydraulic fracturing effect in the subsequent development stage. Therefore, current research on interlayers mainly focuses on the porosity, permeability, oil and gas saturation and mechanical properties of interlayers.

[0004] In terms of patent technology, the evaluation of interlayers in shale formations is also focused on the effects on the seepage, content or later reservoir transformation of generated oil and gas. For example, the quantitative characterization method of the development degree of permeable interlayers in mudstone (authorization publication number: CN 110569512B), the classification of lithofacies combinations of sandstone interlayer development sections in shale formations (application publication number: CN115876974A), the calculation method and system of the oil content index of sandstone interlayers in shale formations (application publication number: CN114894997A), and the evaluation method of brittleness of continental shale gas reservoirs considering interlayer types (authorization publication number: CN115356772B). Summary of the invention

[0005] The inventors found that for the in-situ conversion of shale oil, the target layer to be developed is the organic-rich shale section, and the mining object is the immobile solid organic matter or the non-flowing viscous retained oil. The traditional identification and evaluation of lithologic interlayers has no significant benefit for the in-situ heating development of low-mature shale oil. In contrast, accurately identifying interlayers with poor hydrocarbon generation potential from the perspective of source rock quality is more practical for the efficient development of shale oil in-situ conversion. At present, there are few studies on the identification and evaluation of interlayers based on differences in hydrocarbon generation potential for organic-rich shale formations. In addition, due to the characteristics of most continental shale formations such as rapid lithologic changes, a large number of interlayers, and thin single-layer thickness, it is difficult to achieve high-precision evaluation of interlayers with low hydrocarbon generation potential in organic-rich shale formations.

[0006] In order to at least partially solve the technical problems existing in the prior art, the inventors have made the present invention, and through a specific implementation method, provide a method and device for identifying interlayers in the in-situ conversion section of shale oil based on hydrocarbon generation potential. The method and device can identify interlayers based on hydrocarbon generation potential, and provide important data basis for realizing efficient development of in-situ conversion of shale oil.

[0007] In a first aspect, an embodiment of the present invention provides a method for identifying interlayers in an in-situ conversion section of shale oil based on hydrocarbon generation potential, comprising:

[0008] Identify sandstone monolayers based on lithological data of proposed in-situ conversion zones within shale formations;

[0009] Determine whether the thickness of the sandstone single layer is greater than the lower limit of the thickness of the sandstone single layer as an interlayer of the pseudo in-situ conversion section, wherein the lower limit of the thickness of the single layer is predetermined based on an average value of the hydrocarbon generation potential value of the shale single layer in the shale layer and a plurality of data pairs including the thickness of the sandstone single layer and its hydrocarbon generation potential value;

[0010] If so, the sandstone monolayer is identified as an interlayer.

[0011] In a second aspect, an embodiment of the present invention provides a shale oil in-situ conversion section interlayer identification device based on hydrocarbon generation potential, comprising a sandstone single layer identification module, a judgment module, an interlayer single layer thickness lower limit determination module and an interlayer identification module;

[0012] The sandstone single layer identification module is used to identify the sandstone single layer according to the lithology data of the proposed in-situ conversion section in the shale layer;

[0013] The judging module is used to judge whether the thickness of the sandstone single layer is greater than the lower limit of the thickness of the sandstone single layer as the interlayer of the pseudo in-situ conversion section, and the lower limit of the single layer thickness is predetermined by the interlayer single layer thickness lower limit determination module based on the average hydrocarbon generation potential value of the shale single layer in the shale layer and a plurality of data pairs including the thickness of the sandstone single layer and its hydrocarbon generation potential value;

[0014] The interlayer identification module is used to identify the sandstone single layer as an interlayer if the judgment module determines that it is yes.

[0015] In a third aspect, an embodiment of the present invention provides a computer storage medium, in which computer executable instructions are stored. When the computer executable instructions are executed by a processor, the above-mentioned method for identifying interlayers in the in-situ conversion section of shale oil based on hydrocarbon generation potential is implemented.

[0016] In a fourth aspect, an embodiment of the present disclosure provides a server, 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 above-mentioned method for identifying interlayers in the in-situ conversion section of shale oil based on hydrocarbon generation potential is implemented.

[0017] The beneficial effects of the above technical solution provided by the embodiment of the present invention include at least:

[0018] (1) The method for identifying interlayers in the in-situ conversion section of shale oil based on hydrocarbon generation potential provided in an embodiment of the present invention predetermines the lower limit of the single-layer thickness of the sandstone single layer as the interlayer of the proposed in-situ conversion section based on the average value of the hydrocarbon generation potential of the shale single layer in the shale layer and multiple data pairs including the thickness of the sandstone single layer and its hydrocarbon generation potential value; if it is determined that the thickness of the sandstone single layer is greater than the lower limit of the single-layer thickness of the interlayer, it is determined to be an interlayer, otherwise, even if the lithology is sandstone, it is not determined to be an interlayer. First of all, this method is targeted at specific application scenarios of organic-rich shale sections, breaking the limitations of traditional interlayer identification based solely on lithology, and is more suitable for geological evaluation and related research on in-situ conversion of shale oil; in addition, this method converts the lower limit of the hydrocarbon generation potential of the interlayer into a more intuitive and easier to obtain lower limit of the interlayer thickness, reducing the requirements for data, and only lithology data is needed to realize the identification of interlayers in the proposed in-situ conversion section of shale oil. The direct reason why the lower limit of the hydrocarbon generation potential of the interlayer can be converted into the lower limit of the thickness of the interlayer in this way is that the thickness of the interlayer has a relatively significant statistical relationship with the hydrocarbon generation potential of the interlayer; and the fundamental reason is that the enrichment of organic matter requires an extremely low deposition rate, and the smaller the thickness of the interlayer single layer and the faster the deposition rate, the more difficult it is to enrich the organic matter, and the worse the hydrocarbon generation potential is.

[0019] (2) In the method for identifying interlayers in situ conversion sections of shale oil based on hydrocarbon generation potential provided in an embodiment of the present invention, the data relied on for determining the lower limit of the single-layer thickness of a sandstone single layer as an interlayer in a pseudo-in situ conversion section are the average value of the hydrocarbon generation potential of the shale single layer in the shale layer and a plurality of data pairs including the thickness of the sandstone single layer and its hydrocarbon generation potential value, which are obtained in the following manner: identifying the pseudo-in situ conversion section from the coring section based on the centimeter-level core description data of the continuous coring section in the shale layer and the upper limit of the sandstone proportion in the in situ conversion section; dividing the pseudo-in situ conversion section into a plurality of units according to the sedimentary cycle, determining the type of each unit according to the thickness ratio of the pseudo-in situ conversion section, and selecting at least one unit from each type of unit; performing millimeter-level lithology description on the selected units, dividing the units into a plurality of shale single layers and sandstone single layers according to the description results, cutting rock samples from the single layers, and determining the hydrocarbon generation potential value of the rock samples through pyrolysis testing; and obtaining the average value of the hydrocarbon generation potential of the shale single layer and a plurality of data pairs including the thickness of the sandstone single layer and its hydrocarbon generation potential value by statistics. Fully considering the geological characteristics of continental shale formations such as rapid lithology changes and thin single layer thickness, through lithology combination division, multi-level core detailed description, and multi-scale sampling layer screening, the basic workload was greatly reduced while taking into account the lithology representativeness and high sampling accuracy of the collected samples.

[0020] (3) The method for identifying interlayers in the in-situ conversion section of shale oil based on hydrocarbon generation potential provided by the embodiment of the present invention is to cut rock samples from the unit, including: determining the reference plane direction according to the extension direction of the bedding plane of the screened unit, cutting and leveling the top and bottom surfaces of the unit in a direction parallel to the reference plane, cutting the side surfaces of the unit in a direction perpendicular to the reference plane, so that the shape of the cross section of the unit parallel to the reference plane is consistent; cutting the unit into a first rock sample and a second rock sample in a direction perpendicular to the reference plane; obtaining an XRF scan of the cut surface of the second rock sample, and obtaining a sequence of segmentation lines arranged in an upper and lower order according to the data difference in the scan, wherein the segmentation lines are consistent with the bedding plane direction at the corresponding position; and cutting the first rock sample in sequence according to the segmentation line sequence to obtain multiple rock samples. The continuous section preparation for the microscopic heterogeneity of fine-grained sedimentary rocks improves work efficiency and reduces sample loss rate; the segmentation lines are consistent with the bedding plane direction at the corresponding position, the obtained rock samples are of full types, the heterogeneity representativeness is good, and the rock samples are homogeneous, which provides a basis for realizing fast and high-resolution sample property judgment.

[0021] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 This is a flow chart of a method for determining a lower limit of the thickness of a single layer of sandstone as an interlayer in Example 1 of the present invention;

[0025] Figure 2 This is a flow chart of the method for identifying interlayers in the in-situ conversion section of shale oil based on hydrocarbon generation potential in Example 2 of the present invention;

[0026] Figure 3 This is a flow chart of the method for preparing a sample of an organic-rich shale section in Example 3 of the present invention;

[0027] Figure 4 The typical dissection well histogram and the distribution of three sampling points in the fourth embodiment of the present invention;

[0028] Figure 5 for Figure 4 The millimeter-level silt interlayer, shale single layer division and sampling plan diagram of "Sampling Point 1" in the figure;

[0029] Figure 6 for Figure 4 The millimeter-level silt interlayer, shale single layer division and sampling plan diagram of "sampling point 2" and "sampling point 3";

[0030] Figure 7 A graph showing the relationship between the ratio of the average value of the hydrocarbon generation potential of the sandstone single layer to that of the shale and the thickness of the sandstone single layer in Example 4 of the present invention;

[0031] Figure 8 for Figure 4 "Sampling point 1" is based on the comparison between the lithology profile evaluated in this embodiment and the conventional lithology profile;

[0032] Fig. 9 It is a schematic diagram of the structure of the interlayer identification device of the shale oil in-situ conversion section based on the hydrocarbon generation potential in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0034] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0035] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which the invention belongs. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0036] Embodiment 1

[0037] Embodiment 1 of the present invention provides a method for determining the lower limit of the thickness of a sandstone single layer as an interlayer of a pseudo-in-situ conversion section of a shale layer, specifically determining the lower limit of the thickness of a sandstone interlayer identified from a pseudo-in-situ conversion section, i.e., an organic-rich shale section, in a shale layer, with reference to Figure 1 As shown, the following steps are included:

[0038] Step S11: Based on the centimeter-level core description data of the continuous coring section in the shale layer and the upper limit of the sandstone proportion of the in-situ conversion section, identify the quasi-in-situ conversion section from the coring section, divide the identified quasi-in-situ conversion section into multiple units, determine the type of each unit according to the thickness ratio of the quasi-in-situ conversion section, and screen at least one unit from each type of unit.

[0039] First, typical dissected wells used to identify interlayers with low hydrocarbon generation potential are selected. Generally, typical dissected wells must meet the following requirements:

[0040] (1) The dissecting well must be located in the shale oil in-situ conversion development block, or at least adjacent to the development block;

[0041] (2) at least one well;

[0042] (3) There is a continuous coring section in the shale section to be heated for in-situ conversion of shale oil.

[0043] Based on the lithology description data, the pseudo-in-situ conversion section, i.e., the organic-rich shale section, is identified from the core section of the typical dissecting well.

[0044] The thickness ratio of the sandstone in the proposed in-situ conversion section identified shall not exceed the upper limit of the sandstone ratio in the in-situ conversion section. The upper limit of the sandstone ratio in the in-situ conversion section can usually be set to 20%, and optionally, it can also be set to other values ​​according to relevant regulations or actual research needs.

[0045] In some embodiments, the quasi-in-situ conversion section can be divided into multiple units according to the sedimentation cycle, that is, divided into multiple sedimentation cycles, with a single sedimentation cycle as a unit.

[0046] Each unit is classified into one of the following types according to its thickness ratio to the proposed in-situ conversion section:

[0047] (1) The thickness ratio of the proposed in-situ conversion section is less than 1%,

[0048] (2) The thickness ratio of the proposed in-situ conversion section is not less than 1% and not more than 5%,

[0049] (3) The thickness ratio of the proposed in-situ conversion section is greater than 5% and less than 10%,

[0050] (4) The thickness ratio of the proposed in-situ conversion section is greater than 10%.

[0051] The basis for this classification is that the thickness of a single sedimentary cycle is affected by the comprehensive influence of the sedimentary paleoenvironment, which will affect the abundance of organic matter in the lithological combination section.

[0052] Screening the same number of units from each type of unit can be done by screening a typical unit from each type of unit, or by screening multiple units if the research time and conditions permit.

[0053] Step S12: Conduct millimeter-level lithology description on the screened units, divide the units into multiple shale monolayers and sandstone monolayers according to the description results, cut rock samples from the monolayers, and determine the hydrocarbon generation potential of the rock samples through pyrolysis testing.

[0054] (1) Using wire cutting technology, cut each lithologic single layer of each unit (sampling layer) along the lithologic single layer plane, and prepare independent flaky rock samples for each lithologic single layer. The thickness of the rock sample is the thickness of the single layer, and the volume of a single rock sample must meet the mass required for rock pyrolysis (preferably, not less than 5 grams); (2) Conduct rock pyrolysis test on each rock sample; (3) Calculate the sum of free hydrocarbons (S1) (unit: mg / g, the amount of free hydrocarbons in the rock per unit mass) and pyrolysis hydrocarbons (S2) (unit: mg / g, the amount of hydrocarbons generated after pyrolysis of the rock per unit mass) of each pyrolysis rock sample as the hydrocarbon generation potential value of the rock sample.

[0055] Optionally, multiple lithology single-layer rock samples are cut from each unit (sampling layer section), and the method in the following embodiment 3 may also be used.

[0056] Step S13: Statistically obtain the average value of the hydrocarbon generation potential of the shale single layer and a plurality of data pairs including the thickness of the sandstone single layer and its hydrocarbon generation potential.

[0057] Step S14: According to each data pair, a sample point is obtained, which includes the ratio of the thickness and hydrocarbon generation potential value of the sandstone single layer to the average value of the hydrocarbon generation potential value of the shale single layer.

[0058] Step S15: Project the sample points into a coordinate system, obtain a trend line by fitting, and determine the ratio of the hydrocarbon generation potential value to the average value of the shale monolayer hydrocarbon generation potential value according to the trend line as the sandstone monolayer thickness corresponding to the set ratio, and determine the thickness as the lower limit of the sandstone monolayer thickness as the interlayer of the quasi-in-situ conversion section.

[0059] The coordinate system uses the thickness of a sandstone single layer and the ratio of the hydrocarbon generation potential value of a sandstone single layer to the average hydrocarbon generation potential value of a shale single layer (sandstone single layer hydrocarbon generation potential value / shale single layer hydrocarbon generation potential value average) as coordinate axes.

[0060] The above-mentioned set ratio is usually 38% to 42%; preferably, it is 40%.

[0061] Taking the setting ratio of 40% as an example, 40% of the average hydrocarbon generation potential value of all shale single layers in the quasi-in-situ conversion section is used as the lower limit of the hydrocarbon generation potential of the interlayer of the quasi-in-situ conversion section; then, through the above-mentioned thickness conversion, the lower limit of the single layer thickness of the sandstone single layer as the interlayer of the quasi-in-situ conversion section is obtained.

[0062] The direct reason why Example 1 of the present application can convert the lower limit value of the hydrocarbon generation potential of the interlayer into the lower limit value of the thickness of the interlayer is that the thickness of the interlayer has a relatively significant statistical relationship with the hydrocarbon generation potential of the interlayer; and the fundamental reason is that the enrichment of organic matter requires an extremely low deposition rate, and the smaller the thickness of the interlayer single layer, the faster the deposition rate, the more difficult it is to enrich the organic matter, and the worse the hydrocarbon generation potential is.

[0063] Embodiment 2

[0064] The second embodiment of the present invention provides a method for identifying interlayers in situ conversion section of shale oil based on hydrocarbon generation potential, which identifies sandstone interlayers from the quasi-in situ conversion section in the shale layer, i.e., the organic-rich shale section. Figure 2 As shown, the following steps are included:

[0065] Step S21: Identify a sandstone single layer based on the lithology data of the proposed in-situ conversion section in the shale layer.

[0066] Lithology data can be data obtained by interpreting conventional logging curves, so its resolution can be consistent with the resolution of the logging curves.

[0067] Step S22: determining whether the thickness of the sandstone single layer is greater than the lower limit of the thickness of the sandstone single layer as the interlayer of the simulated in-situ conversion section.

[0068] The lower limit of the single layer thickness is predetermined based on the average value of the hydrocarbon generation potential value of the shale single layer in the shale layer and multiple data pairs including the thickness of the sandstone single layer and its hydrocarbon generation potential value. The specific determination method is described in the previous embodiment 1 and will not be repeated here.

[0069] If the judgment result of step S22 is yes, step S23 is executed; if the judgment result of step S22 is no, it is determined that the sandstone single layer is not an interlayer.

[0070] Step S23: Identify the sandstone single layer as an interlayer.

[0071] The method for identifying interlayers in the in-situ conversion section of shale oil based on hydrocarbon generation potential provided in Example 2 of the present invention predetermines the lower limit of the single-layer thickness of the sandstone single layer as the interlayer of the proposed in-situ conversion section based on the average value of the hydrocarbon generation potential of the shale single layer in the shale layer and multiple data pairs including the thickness of the sandstone single layer and its hydrocarbon generation potential value; if it is determined that the thickness of the sandstone single layer is greater than the lower limit of the single-layer thickness of the interlayer, it is determined to be an interlayer, otherwise, even sandstone is not considered to be an interlayer. First of all, this method is targeted at specific application scenarios of organic-rich shale sections, breaking the limitations of traditional interlayer identification that relies solely on lithology, and is more suitable for geological evaluation and related research on in-situ conversion of shale oil; in addition, this method converts the lower limit value of the hydrocarbon generation potential of the interlayer into a more intuitive and easier to obtain lower limit value of the interlayer thickness, reducing the requirements for data, and only lithology data is needed to realize the identification of interlayers in the proposed in-situ conversion section of shale oil.

[0072] In a method for identifying interlayers in situ conversion sections of shale oil based on hydrocarbon generation potential, a second embodiment of the present invention provides a method for identifying interlayers in situ conversion sections of shale oil based on hydrocarbon generation potential. The data relied on for determining the lower limit of the single-layer thickness of a sandstone single layer as an interlayer in a pseudo-in-situ conversion section are the average value of the hydrocarbon generation potential of the shale single layer in the shale layer and multiple data pairs including the thickness of the sandstone single layer and its hydrocarbon generation potential value, which are obtained in the following manner: according to the centimeter-level core description data of the continuous coring section in the shale layer and the upper limit of the sandstone proportion in the in-situ conversion section, the pseudo-in-situ conversion section is identified from the coring section; the pseudo-in-situ conversion section is divided into multiple units according to the sedimentary cycle, the type of each unit is determined according to the thickness ratio of the pseudo-in-situ conversion section, and at least one unit is selected from each type of unit; millimeter-level lithology description is performed on the selected units, and the units are divided into multiple shale single layers and sandstone single layers according to the description results, rock samples are cut from the single layers, and the hydrocarbon generation potential values ​​of the rock samples are determined by pyrolysis testing; the average value of the hydrocarbon generation potential value of the shale single layer and multiple data pairs including the thickness of the sandstone single layer and its hydrocarbon generation potential value are statistically obtained. Fully considering the geological characteristics of continental shale formations such as rapid lithology changes and thin single layer thickness, through lithology combination division, multi-level core detailed description, and multi-scale sampling layer screening, the basic workload was greatly reduced while taking into account the lithology representativeness and high sampling accuracy of the collected samples.

[0073] Embodiment 3

[0074] Embodiment 3 of the present invention provides a method for cutting and preparing a core unit sample of an organic-rich shale section, referring to Figure 3 As shown, the following steps are included:

[0075] Step S31: Determine the reference plane direction according to the extension direction of the sample's bedding plane, cut the top and bottom surfaces of the sample parallel to the reference plane, and cut the side surfaces of the sample perpendicular to the reference plane so that the shape of the cross section of the sample parallel to the reference plane is consistent.

[0076] The top and bottom surfaces of the sample are two end surfaces perpendicular to the axial direction of the coring section.

[0077] The reference plane direction is perpendicular to the dominant bedding plane direction and can be determined by either of the following two methods:

[0078] (1) Count the bedding plane directions of the samples and determine the direction with the most bedding planes as the reference plane direction.

[0079] (2) Based on the directions of the bedding planes of the sample, the reference plane direction is obtained by cluster analysis.

[0080] For example, the reference plane direction finally determined is the direction with the smallest sum of differences with each reference plane, and the difference with each reference plane is determined respectively, and the direction with the smallest sum of differences is determined as the reference plane direction.

[0081] Taking the direction of the reference plane as P and the direction perpendicular to the reference plane as V as an example, the side of the sample is cut along the direction perpendicular to the reference plane so that the shape of the cross section of the sample parallel to the reference plane is consistent. This can be done by using the sample minimum cross-sectional area polygon parallel to P or any shape smaller than the minimum cross-sectional area polygon as the boundary, set as Z, and cutting the sample polygon Z along vector V so that the cross-sectional area of ​​the sample along the direction of vector P is equal.

[0082] Step S32: cutting the sample into a first rock sample and a second rock sample along a direction perpendicular to the reference plane.

[0083] Grind the cut section to make it level with a height difference of no more than 1mm.

[0084] The first rock sample is used as a scanning and reference rock sample, and the second rock sample is used as a cut rock sample, so the volume of the first rock sample does not need to be too large. Preferably, the volume ratio of the first rock sample to the second rock sample is greater than 10.

[0085] Step S33: Obtain an XRF scan of the cut surface of the second rock sample, and obtain a segmentation line sequence arranged in an upper and lower order according to data differences in the scan.

[0086] The second rock sample is placed in the Micro-XRF (micro-area X-ray fluorescence spectrometer) instrument, and the profile is adjusted to a horizontal state; the profile is scanned using Micro-XRF to generate an XRF scan image (data), which is a content distribution map of multiple set elements.

[0087] The conditions for performing XRF scanning along vector V may be: a resolution of 5 microns, a scanning width W = 1 to 2 cm (correspondingly, the width of the cutting surface of the second rock sample is required to be 1 to 5 cm), and a scanning length H, where H is the length of the sample within the range required for heterogeneity research, preferably 1 cm to 30 cm, and the maximum does not exceed HMax or the upper limit of the sample bin of the XRF scanner. HMax is the maximum height of the rock sample, which is the vertical distance between the top and bottom surfaces of the sample.

[0088] In some embodiments, obtaining the segmentation line sequence may include:

[0089] For each XRF scan image, the points whose content change rate of the corresponding element is higher than the set threshold are identified to obtain a scatter point set. Through the scatter point clustering analysis method, multiple possible segmentation lines are obtained from the scatter point set, and the two endpoints of each possible segmentation line are respectively on the two opposite sides of the cutting surface of the second rock sample; through the line clustering analysis method, the possible segmentation lines obtained according to each XRF scan image are clustered and analyzed to obtain a segmentation line sequence arranged in upper and lower order.

[0090] The dividing line determined by the above method is a line formed by points whose corresponding element content change rates of the horizontally matched positions are higher than the set threshold value, so the dividing line is consistent with the direction of the bedding plane at the corresponding position; specifically, each dividing line is located on a bedding plane and is the line where the bedding plane intersects the cutting plane.

[0091] After obtaining the segmentation line sequence by the image method, it can also include determining whether the distance between two adjacent segmentation lines is less than a set distance threshold; if so, deleting one of the segmentation lines, or merging two adjacent segmentation lines whose distance is less than the set distance threshold according to the merging rule of the clustering analysis similarity principle to obtain a new segmentation line.

[0092] The above-mentioned set distance threshold is usually set to 0.2 mm.

[0093] Step S34: cutting the first rock sample in sequence according to the segmentation line sequence to obtain a plurality of rock samples.

[0094] The first rock sample can be cut according to the cutting line sequence by using a diamond wire cutting instrument.

[0095] Furthermore, since the dividing line is consistent with the direction of the bedding plane at the corresponding position, but not necessarily parallel to the reference plane, and the dividing lines are not necessarily parallel to each other, after completing the cutting of the first rock sample according to the dividing line sequence, the cut rock sample can be cut again according to the principle of maximum volume, so that the top and bottom surfaces of the rock sample are parallel; optionally, if the rock type is only used for rock pyrolysis testing, because the rock sample needs to be ground into powder, it is not necessary to level the top and bottom surfaces.

[0096] In the same vertical direction, multiple rock samples can be cut according to research needs. Therefore, in some embodiments, it can include: determining at least one cutting direction perpendicular to the reference plane according to research needs, and completing vertical cutting of the first rock sample according to each cutting direction; wrapping the cut first rock sample with a set material (industrial wax can be used for wrapping), and cutting the wrapped first rock sample in sequence according to the dividing line sequence to obtain multiple rock samples.

[0097] Furthermore, the cut rock sample can be further cut according to the principle of maximum volume so that the top and bottom surfaces of the rock sample are parallel.

[0098] Finally, multiple shale samples and sandstone samples were obtained.

[0099] The sample preparation method provided in Example 3 of the present invention is aimed at the continuous slice preparation of organic-rich shale sections, which improves work efficiency and reduces sample loss rate; the dividing line is consistent with the direction of the bedding plane at the corresponding position, the prepared rock samples are of full types, the heterogeneity is well represented, and the rock samples are homogeneous, which provides a basis for achieving fast and high-resolution sample property judgment.

[0100] Embodiment 4

[0101] Embodiment 4 of the present invention provides a specific application of a method for identifying interlayers in situ conversion sections of shale oil based on hydrocarbon generation potential, and identifies sandstone interlayers from a shale layer that is a situ conversion section, i.e., an organic-rich shale section, including the following steps:

[0102] S1: A well with continuous coring in an organic-rich shale interval was selected as a typical dissection well ( Figure 4 ).

[0103] S2: Based on the centimeter-level core description, the organic-rich shale section is divided into 10 sedimentary cycles. Each sedimentary cycle has a positive rhythm, that is, the bottom is a set of siltstone or silty mud shale, and the sediment grain size becomes finer and the lithology gradually changes to shale upward. In terms of sedimentary genesis, the siltstone or silty mud shale at the bottom of each cycle in this embodiment is a first-stage gravity flow deposit. According to the different ratios of the thickness of a single sedimentary cycle to the total thickness of the proposed heating section, this embodiment defines the four types of lithology combinations with ratios below 1%, 1% (inclusive) to 5% (inclusive), 5% to 10% (inclusive), and greater than 10% as Type I (0), Type II (1), Type III (4), and Type IV (5), as shown below. Figure 4 In this embodiment, lithologic combination sections No. 1, No. 5 and No. 9 are selected as sample collection sections.

[0104] S3: Select millimeter-scale core description and sample collection points for the type II, type III and type IV lithology combinations developed in this example ( Figure 4 ). The details are as follows: In the No. 1 lithologic combination section, select a sample collection point and code it as "sampling point 1" ( Figure 4 In the 5th and 9th lithologic combination sections, one sampling point was selected and named as “sampling point 2” ( Figure 4 2 in the figure) and "sampling point 3" ( Figure 4 Large thin sections were made for the samples collected from the three sampling points. The lithology of the three sampling points was described at the millimeter level with the help of the large thin sections. A total of 24 lithology single layers were divided at "sampling point 1" (as shown in Figure 3). Figure 5 shown), Figure 5 1-24 in the figure represent a single lithology layer, and 12 and 4 single lithology layers are divided in "sampling point 2" and "sampling point 3" respectively (e.g. Figure 6 As shown in the figure, the lithology single layer of "sampling point 2" includes ① to ③ of "sampling point 2-1", ① and ② of "sampling point 2-2", ① to ③ of "sampling point 2-3" and ① to ④ of "sampling point 2-4", a total of 12; the lithology single layer of "sampling point 3" includes ① to ④, a total of 4. In this embodiment, the lithology types of all lithology single layers include shale and silty interlayer.

[0105] S4: All monolayers are sampled using wire cutting technology. After each monolayer sample is prepared, a pyrolysis experiment is performed, and the sum of the pyrolysis free hydrocarbons S1 and the pyrolysis hydrocarbons S2 is taken as the hydrocarbon generation potential value of the monolayer.

[0106] S5: Count the hydrocarbon generation potential values ​​of the shale monolayers in all the monolayers and calculate their average value. 40% of the average value of the hydrocarbon generation potential values ​​of all the shale monolayers is taken as the lower limit of the hydrocarbon generation potential of the shale interlayer for in-situ conversion heating of shale oil. The remaining monolayers are regarded as silty sand interlayers.

[0107] S6: Put the ratio of the hydrocarbon generation potential of the 15 silty interlayers at the three sampling points to the average hydrocarbon generation potential of the shale single layer, and the thickness of each interlayer into the same coordinate system in the form of a scatter plot. Since the only lithology of the non-shale interlayer in this embodiment is the silty interlayer, only one scatter plot plate is needed. In this embodiment, the ordinate is the ratio of the hydrocarbon generation potential of the silty interlayer to the average hydrocarbon generation potential of the shale single layer, and the abscissa is the single layer thickness of each interlayer. Set a trend line of 15 data points, and take the thickness corresponding to the intersection of the trend line and the horizontal line with a ordinate value of 40% as the lower limit of the thickness of the low hydrocarbon generation potential interlayer. That is, in this embodiment, siltstone and silty mud shale with a single layer thickness not exceeding 10 mm are all considered to have a large hydrocarbon generation potential and are not considered as interlayers; siltstone and silty mud shale with a single layer thickness exceeding 10 mm are all considered as interlayers ( Figure 7 ).

[0108] S7: Identify and determine the interlayer of the shale oil in-situ conversion heating shale section according to the lower limit of the interlayer thickness described in step S6. Take the core section of "sampling point 1" in this embodiment as an example to reconstruct the lithology profile, and regard the silty sand interlayer with a thickness of less than 10 mm as shale. Finally, the lithology profile of the shale oil in-situ conversion shale section based on hydrocarbon generation potential is established, such as Figure 8 As shown. Figure 8 and Figure 5 The comparison shows that Figure 5 Many silty interlayers are Figure 8 This practice of ignoring lithologic interlayers is exactly what is needed for in-situ conversion of shale oil, because these ignored interlayers can also generate hydrocarbons without being considered as interlayers.

[0109] Based on the inventive concept of the present invention, the embodiment of the present invention also provides a shale oil in-situ conversion section interlayer identification device based on hydrocarbon generation potential, the structure of the device is as follows: Fig. 9 As shown, it includes a sandstone single layer identification module 91, a judgment module 92, an interlayer single layer thickness lower limit determination module 93 and an interlayer identification module 94;

[0110] The sandstone single layer identification module 91 is used to identify the sandstone single layer according to the lithology data of the proposed in-situ conversion section in the shale layer;

[0111] A judging module 92 is used to judge whether the thickness of the sandstone single layer is greater than the lower limit of the thickness of the sandstone single layer as the interlayer of the proposed in-situ conversion section, wherein the lower limit of the single layer thickness is predetermined by the interlayer single layer thickness lower limit determining module 93 based on the average hydrocarbon generation potential value of the shale single layer in the shale layer and a plurality of data pairs including the thickness of the sandstone single layer and its hydrocarbon generation potential value;

[0112] The interlayer identification module 94 is used to identify the sandstone single layer as an interlayer if the determination module 92 determines that it is yes.

[0113] In some embodiments, the interlayer single layer thickness lower limit determination module 93 is used to:

[0114] According to each of the data pairs, a sample point is obtained, including the thickness of the sandstone single layer and the ratio of the hydrocarbon generation potential value to the average value of the hydrocarbon generation potential value of the shale single layer; the sample point is projected into a coordinate system, and a trend line is obtained by fitting; according to the trend line, the ratio of the hydrocarbon generation potential value to the average value of the hydrocarbon generation potential value of the shale single layer is determined to be the sandstone single layer thickness corresponding to the set ratio, and the thickness is determined as the lower limit of the single layer thickness of the sandstone single layer as the interlayer of the quasi-in-situ conversion section.

[0115] In some embodiments, the interlayer single layer thickness lower limit determination module 93 is used to:

[0116] According to the centimeter-level core description data of continuous coring sections in the shale layer, a pseudo-in-situ conversion section is identified from the coring section, the identified pseudo-in-situ conversion section is divided into multiple units, the type of each unit is determined according to the thickness ratio of the pseudo-in-situ conversion section, and at least one unit of each type is screened; a millimeter-level lithology description is carried out on the screened units, and the units are divided into multiple shale monolayers and sandstone monolayers according to the description results, rock samples are cut from the monolayers, and the hydrocarbon generation potential values ​​of the rock samples are determined through pyrolysis tests; and the average value of the hydrocarbon generation potential values ​​of the shale monolayers and multiple data pairs including the thickness of the sandstone monolayers and their hydrocarbon generation potential values ​​are statistically obtained.

[0117] In some embodiments, the interlayer single layer thickness lower limit determination module 93 is used to:

[0118] The coring section is divided into a plurality of units according to the sedimentation cycle.

[0119] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0120] Based on the inventive concept of the present invention, an embodiment of the present invention also provides a computer storage medium, in which computer executable instructions are stored. When the computer executable instructions are executed by a processor, the above-mentioned shale oil in-situ conversion section interlayer identification method based on hydrocarbon generation potential is implemented.

[0121] Based on the inventive concept of the present invention, an embodiment of the present invention also provides a server, including: 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 above-mentioned method for identifying interlayers in the in-situ conversion section of shale oil based on hydrocarbon generation potential is implemented.

[0122] Unless otherwise specifically stated, terms such as processing, computing, calculating, determining, displaying, etc. may refer to the actions and / or processes of one or more processing or computing systems, or similar devices, which operate and convert data represented as physical (e.g., electronic) quantities within registers or memories of a processing system into other data similarly represented as physical quantities within memories, registers, or other such information storage, transmission, or display devices of the processing system. Information and signals may be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, light fields or particles, or any combination thereof.

[0123] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of protection of the present disclosure. The attached method claims present the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0124] In the above detailed description, various features are grouped together in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that an embodiment of the claimed subject matter requires more features than those set forth in each claim. On the contrary, as reflected in the appended claims, the invention is in a state of having less than all the features of the disclosed individual embodiments. Therefore, the appended claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0125] Those skilled in the art will also appreciate that the various illustrative logic blocks, modules, circuits, and algorithmic steps described in conjunction with the embodiments herein can all be implemented as electronic hardware, computer software, or a combination thereof. In order to clearly illustrate the interchangeability between hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described above around their functions. Whether such functions are implemented as hardware or software depends on specific applications and the design constraints imposed on the entire system. A skilled person can implement the described functions in an alternative manner for each specific application, but such implementation decisions should not be interpreted as departing from the scope of protection of the present disclosure.

[0126] The steps of the method or algorithm described in conjunction with the embodiments herein may be directly embodied as hardware, a software module executed by a processor, or a combination thereof. The software module may be located in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a mobile disk, a CD-ROM, or any other form of storage medium well known in the art. An exemplary storage medium is connected to the processor so that the processor can read information from the storage medium and can write information to the storage medium. Of course, the storage medium may also be an integral part of the processor. The processor and the storage medium may be located in an ASIC. The ASIC may be located in a user terminal. Of course, the processor and the storage medium may also be present in a user terminal as discrete components.

[0127] For software implementation, the techniques described in this application can be implemented with modules (e.g., procedures, functions, etc.) that perform the functions described in this application. These software codes can be stored in a memory unit and executed by a processor. The memory unit can be implemented within the processor or outside the processor. In the latter case, it is coupled to the processor in a communication manner via various means, which are well known in the art.

[0128] The above description includes examples of one or more embodiments. Of course, it is impossible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but it should be recognized by those skilled in the art that the various embodiments can be further combined and arranged. Therefore, the embodiments described herein are intended to cover all such changes, modifications and variations that fall within the scope of protection of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, the word is covered in a manner similar to the term "including", just as "including," explained as a transitional word in the claims. In addition, any term "or" used in the specification of the claims is intended to represent "non-exclusive or". The terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance.

Claims

1. A method for identifying interlayers in situ conversion sections of shale oil based on hydrocarbon generation potential, characterized in that: include: Identify sandstone monolayers based on lithological data of proposed in-situ conversion zones within shale formations; Determine whether the thickness of the sandstone single layer is greater than the lower limit of the thickness of the sandstone single layer as an interlayer of the pseudo in-situ conversion section, wherein the lower limit of the thickness of the single layer is predetermined based on an average value of the hydrocarbon generation potential value of the shale single layer in the shale layer and a plurality of data pairs including the thickness of the sandstone single layer and its hydrocarbon generation potential value; If so, the sandstone monolayer is identified as an interlayer.

2. The method according to claim 1, characterized in that The lower limit of the thickness of the sandstone monolayer as the interlayer of the proposed in-situ conversion section is predetermined by: According to each of the data pairs, a sample point is obtained, including the ratio of the thickness and hydrocarbon generation potential value of the sandstone single layer to the average value of the hydrocarbon generation potential value of the shale single layer; The sample points are projected into a coordinate system, and a trend line is obtained by fitting. According to the trend line, the ratio of the hydrocarbon generation potential value to the average value of the hydrocarbon generation potential value of the shale single layer is determined as the sandstone single layer thickness corresponding to the set ratio, and the thickness is determined as the lower limit of the sandstone single layer thickness as the interlayer of the quasi-in-situ conversion section.

3. The method according to claim 2, characterized in that The set ratio is 38% to 42%.

4. The method according to claim 1, characterized in that: The average value of the hydrocarbon generation potential value of the shale single layer in the shale layer and a plurality of data pairs including the thickness of the sandstone single layer and its hydrocarbon generation potential value are obtained by the following method: According to centimeter-level core description data of continuous coring sections in the shale layer and the upper limit of the sandstone ratio of the in-situ conversion section, a pseudo-in-situ conversion section is identified from the coring section, the identified pseudo-in-situ conversion section is divided into a plurality of units, the type of each unit is determined according to the thickness ratio of the pseudo-in-situ conversion section, and at least one unit is selected from each type of unit; Carry out millimeter-level lithology description on the selected units, divide the units into multiple shale monolayers and sandstone monolayers according to the description results, cut rock samples from the monolayers, and determine the hydrocarbon generation potential of the rock samples through pyrolysis tests; The average value of the hydrocarbon generation potential of a shale layer and multiple data pairs including the thickness of a sandstone layer and its hydrocarbon generation potential are obtained by statistics.

5. The method according to claim 4, characterized in that The identified proposed in-situ conversion section is divided into a plurality of units, including: The identified pseudo-in situ conversion sections were divided into multiple units according to the sedimentary cycles.

6. The method according to claim 4, characterized in that The type of each unit is determined according to the thickness ratio of the proposed in-situ conversion section, including: Each unit is classified into one of the following types: The thickness ratio of the proposed in-situ conversion section is less than 1%, the thickness ratio of the proposed in-situ conversion section is not less than 1% and not more than 5%, the thickness ratio of the proposed in-situ conversion section is greater than 5% and not more than 10%, and the thickness ratio of the proposed in-situ conversion section is greater than 10%.

7. The method according to claim 4, characterized in that The method further comprises: carrying out millimeter-level lithology description on the screened units, dividing the units into a plurality of shale monolayers and sandstone monolayers according to the description results, and cutting rock samples from the monolayers; Determine the direction of the reference plane according to the extension direction of the bedding plane of the screened unit, cut and level the top and bottom surfaces of the unit in a direction parallel to the reference plane, and cut the side surfaces of the unit in a direction perpendicular to the reference plane so that the shapes of the cross sections of the unit parallel to the reference plane are consistent; cutting the unit into a first rock sample and a second rock sample along a direction perpendicular to the reference plane; Obtaining an XRF scan of the cut surface of the second rock sample, and obtaining a sequence of segmentation lines arranged in a vertical order according to data differences in the scan, wherein the segmentation lines are consistent in direction with the bedding planes at corresponding positions; The first rock sample is cut in sequence according to the segmentation line sequence to obtain a plurality of rock samples.

8. The method according to claim 7, characterized in that The XRF scans are multiple distribution diagrams of the content of set elements. The segmentation line sequence arranged in a vertical order is obtained according to the data differences in the scans, including: For each XRF scan image, points whose content change rate of the corresponding element is higher than a set threshold are identified to obtain a scattered point set, and multiple possible segmentation lines are obtained from the scattered point set by a scattered point clustering analysis method, wherein two endpoints of each possible segmentation line are respectively on two opposite sides of the cut surface of the second rock sample; By using the line clustering analysis method, possible segmentation lines obtained from each XRF scanning image are clustered and analyzed to obtain a segmentation line sequence arranged in an upper and lower order.

9. The method according to claim 8, characterized in that Also includes: Determine whether the distance between two adjacent segmentation lines is less than the set distance threshold; If so, delete one of the segmentation lines, or merge two adjacent segmentation lines whose distance is less than the set distance threshold according to the merging rule of the cluster analysis similarity principle to obtain a new segmentation line.

10. The method according to claim 1, characterized in that The hydrocarbon generation potential value is the sum of free hydrocarbon S1 and pyrolysis hydrocarbon S2 per unit mass of rock.

11. A device for identifying interlayers in situ conversion section of shale oil based on hydrocarbon generation potential, characterized in that: The device comprises a sandstone single layer identification module, a judgment module, an interlayer single layer thickness lower limit determination module and an interlayer identification module; The sandstone single layer identification module is used to identify the sandstone single layer according to the lithology data of the proposed in-situ conversion section in the shale layer; The judging module is used to judge whether the thickness of the sandstone single layer is greater than the lower limit of the thickness of the sandstone single layer as the interlayer of the pseudo in-situ conversion section, and the lower limit of the single layer thickness is predetermined by the interlayer single layer thickness lower limit determination module based on the average hydrocarbon generation potential value of the shale single layer in the shale layer and a plurality of data pairs including the thickness of the sandstone single layer and its hydrocarbon generation potential value; The interlayer identification module is used to identify the sandstone single layer as an interlayer if the judgment module determines that it is yes.

12. A computer storage medium, characterized in that: The computer storage medium stores computer executable instructions, and when the computer executable instructions are executed by the processor, the method for identifying interlayers in situ conversion sections of shale oil based on hydrocarbon generation potential according to any one of claims 1 to 10 is implemented.

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