Quantitative evaluation methods, systems, equipment, and media for sand body structure in tight sandstone reservoirs

Abstract

This invention belongs to the field of oil and gas extraction technology, and relates to a method, system, equipment, and medium for quantitative evaluation of sand body structure in tight sandstone reservoirs. The method identifies sand body structure types based on well logging curves, sedimentary characteristics, and sand body size, obtaining sand body structure type characteristics. Based on these characteristics, it finely characterizes the vertical stacking and lateral contact relationships of multi-stage channel sedimentary sand bodies. Well logging parameters characterizing the sand body structure are obtained from the well logging curves. Quantitative evaluation parameters for the sand body structure are obtained based on these parameters and the main controlling factors. The internal contact relationships and quantitative evaluation parameters are used to comprehensively evaluate the internal heterogeneity of the tight sandstone reservoir sand body structure. This invention, through the identification and classification of sand body structures, achieves a fine characterization of the spatial combination and distribution of sand bodies, solving the problem of quantitative evaluation of sand body structure and effectively guiding the fine exploration and development of tight sandstone reservoirs.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas extraction technology, and relates to a method, system, equipment and medium for quantitative evaluation of sand body structure in tight sandstone reservoirs. Background Technology

[0002] Following shale gas, tight oil, known as "black gold" in the global oil industry, has become a new highlight in the exploration and development of unconventional oil and gas resources.

[0003] The enrichment degree of lithologic oil and gas reservoirs is mainly controlled by the sand body structure. Therefore, conducting detailed research on the sand body structure characteristics of lithologic oil and gas reservoirs is of great significance for the exploration and development of tight sandstone oil and gas reservoirs.

[0004] Previous researchers have conducted extensive studies on the sedimentary provenance, sand body distribution patterns, and hydrocarbon accumulation of oil and gas reservoirs. For example, Yang Hua et al. explored the definition of tight oil and redefined it based on actual conditions (Yang Hua et al., 2015); Zou Caineng et al. conducted research on the accumulation types, reservoir characteristics, and formation mechanisms of tight oil and provided prospects for its development (Zou Caineng et al., 2012; Fu Jinhua et al., 2022); and Fu Jinhua et al. conducted in-depth research on the accumulation conditions of tight oil (Fu Jinhua et al., 2019; Li Wenhou et al., 2022), analyzing and summarizing the main controlling factors of tight oil accumulation.

[0005] However, existing technologies have limited research on the longitudinal stacking relationship of sand bodies, their spatiotemporal distribution patterns, and the control effect of sand body structure on oil and gas reservoirs. This makes it difficult to accurately obtain the longitudinal stacking relationship, lateral contact relationship, and control effect of sand body structure on oil and gas reservoirs, resulting in a low success rate for oil and gas reservoir exploration. Summary of the Invention

[0006] The purpose of this invention is to provide a method, system, equipment, and medium for quantitative evaluation of sand body structure in tight sandstone reservoirs, in order to solve the technical problem of being unable to accurately obtain the longitudinal stacking relationship, lateral contact relationship, and control effect of sand body structure on oil and gas reservoirs. This invention can accurately obtain the longitudinal stacking relationship, lateral contact relationship, and control effect of sand body structure on oil and gas reservoirs, which is beneficial to the quantitative evaluation of sand body structure.

[0007] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, the present invention provides a method for quantitative evaluation of the sand body structure of tight sandstone reservoirs, comprising the following steps: Based on well logging curves, sedimentary characteristics, and sand body size, the sand body structure type is identified, and the sand body structure type characteristics are obtained. Based on the characteristics of sand body structure types, the vertical stacking and lateral contact relationships of multi-phase channel sedimentary sand bodies are finely characterized to obtain the internal contact relationships of the sand bodies; Well logging parameters for sand body structure are obtained from well logging curves; Quantitative evaluation parameters of sand body structure are obtained based on well logging characterization parameters of sand body structure and main controlling factors of sand body structure. The heterogeneity of the internal structure of tight sandstone reservoirs is comprehensively evaluated based on the internal contact relationships and quantitative evaluation parameters of the sand body structure.

[0008] Secondly, the present invention provides a quantitative evaluation system for the sand body structure of tight sandstone reservoirs, comprising: Sand body structure type feature acquisition module: used to identify sand body structure types and acquire sand body structure type features based on well logging curves, sedimentary characteristics and sand body size; Sand body internal contact relationship acquisition module: used to finely characterize the vertical stacking and lateral contact relationships of multi-phase channel sedimentary sand bodies based on the characteristics of sand body structure type, and to acquire the internal contact relationships of sand bodies; Well logging characterization parameter acquisition module: used to obtain well logging characterization parameters of sand body structure based on well logging curves; Quantitative evaluation parameter acquisition module: used to acquire quantitative evaluation parameters of sand body structure based on well logging characterization parameters of sand body structure and main controlling factors of sand body structure; The comprehensive evaluation module is used to comprehensively evaluate the internal heterogeneity of tight sandstone reservoirs based on the internal contact relationships and quantitative evaluation parameters of the sand body structure.

[0009] Thirdly, the present invention provides an electronic device, comprising: a processor; a memory for storing computer program instructions; and steps for implementing a method for quantitative evaluation of the sand body structure of tight sandstone reservoirs when executing the computer program.

[0010] Fourthly, the present invention provides a storage medium storing computer program instructions, which are loaded and executed by a processor, wherein the processor performs a method for quantitative evaluation of the sand body structure of a tight sandstone reservoir.

[0011] Fifthly, the present invention provides a computer program product, the computer program product including computer instructions, the computer instructions instructing a computer to execute a method for quantitative evaluation of the sand body structure of tight sandstone reservoirs.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. The method of this invention identifies sand body structure types based on well logging curves, sedimentary characteristics, and sand body scale, obtaining sand body structure type characteristics to facilitate subsequent analysis of internal heterogeneity within the sand body. Based on the sand body structure type characteristics, the vertical stacking and lateral contact relationships of multi-phase channel sedimentary sand bodies are finely characterized, facilitating a deeper understanding of the spatial configuration relationships between sand bodies. Well logging curves are used to obtain well logging characterization parameters of the sand body structure, facilitating a quantitative description of the physical properties of the sand body structure. Based on the well logging characterization parameters and the main controlling factors of the sand body structure, quantitative evaluation parameters of the sand body structure are obtained, providing data support for subsequent quantitative evaluation and helping to more accurately assess the complexity and heterogeneity of the sand body structure. The internal contact relationships and quantitative evaluation parameters of the sand body structure are used to comprehensively evaluate the internal heterogeneity of the tight sandstone reservoir sand body structure. This invention achieves a fine characterization of the spatial combination and distribution of sand bodies through the identification and classification of sand body structures. By utilizing the fluctuation coefficient of logging curves, logging parameters for sand body structure are established, and a comprehensive evaluation coefficient for sand body structure is constructed to quantitatively evaluate the heterogeneity of sand body structure. This solves the problem of quantitative evaluation of sand body structure and can effectively guide the fine exploration and development of tight sandstone reservoirs.

[0013] 2. The system of this invention includes: a sand body structure type feature acquisition module, a sand body internal contact relationship acquisition module, a well logging characterization parameter acquisition module, a quantitative evaluation parameter acquisition module, and a comprehensive evaluation module. The sand body structure type feature acquisition module is used to identify sand body structure types based on well logging curves, sedimentary characteristics, and sand body scale, and acquire sand body structure type features. The sand body internal contact relationship acquisition module is used to finely characterize the vertical stacking and lateral contact relationships of multi-phase channel sedimentary sand bodies based on sand body structure type features, and acquire sand body internal contact relationships. The well logging characterization parameter acquisition module is used to acquire well logging characterization parameters of the sand body structure based on well logging curves. The quantitative evaluation parameter acquisition module is used to acquire quantitative evaluation parameters of the sand body structure based on the well logging characterization parameters and the main controlling factors of the sand body structure. The comprehensive evaluation module is used to comprehensively evaluate the internal heterogeneity of the sand body structure in tight sandstone reservoirs based on the sand body internal contact relationships and the quantitative evaluation parameters of the sand body structure. These modules work together to accurately acquire the vertical stacking relationship, spatiotemporal distribution pattern, and the control effect of the sand body structure on the oil and gas reservoir, which is beneficial for the quantitative evaluation of the sand body structure.

[0014] 3. The electronic equipment, storage medium and computer program products of this invention can also accurately obtain the longitudinal stacking relationship of sand bodies, the spatiotemporal distribution law and the control effect of sand body structure on oil and gas reservoirs, which is beneficial to the quantitative evaluation of sand body structure. Attached Figure Description

[0015] Figure 1 This is a flowchart of the quantitative evaluation method for sand body structure in tight sandstone reservoirs according to an embodiment of the present invention; Figure 2This is a logging response characteristic diagram of different sand body structures in the Chang 8 oil formation of an oilfield, according to an embodiment of the present invention. Figure 2 a represents the well logging response characteristics of the composite box-shaped sand body structure. Figure 2 b is the logging response characteristic diagram of the toothed bell-shaped sand body structure. Figure 2 c represents the logging response characteristics of an isolated box-shaped sand body structure. Figure 2 d is the logging response characteristic diagram of an isolated finger-shaped sand body structure; Figure 3 This is a cross-sectional view of the sand body structure of wells H312~L208~H56~L218 in an oilfield according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the well logging curve fluctuations of the sand body structure in the tight sandstone reservoir of the present invention, wherein, Figure 4 a is a schematic diagram of local fluctuations in well logging curve data. Figure 4 b is a schematic diagram of the overall fluctuation of the well logging curve data; Figure 5 This is a comprehensive logging result diagram of the composite box-shaped sand body structure of well L38 in an oilfield, according to an embodiment of the present invention. Figure 6 This is a comprehensive logging result diagram of the toothed bell-shaped sand body structure in well B35 of an oilfield, according to an embodiment of the present invention. Figure 7 This is a comprehensive logging result diagram of an isolated box-shaped sand body structure in well L82 of an oilfield, according to an embodiment of the present invention. Figure 8 This is a frequency distribution histogram of quantitative evaluation parameters for sand body structure in the study area of ​​this invention embodiment; Figure 9 This is a bar chart showing the daily oil production of different sand body structure types in the study area of ​​this invention, as illustrated in the embodiments of the present invention. Figure 9 a is a bar chart showing the daily oil production of a single well in a composite box-type sand body structure. Figure 9 b is a bar chart showing the daily oil production of a single well in a toothed bell-shaped sand body structure. Figure 9 c is a bar chart showing the daily oil production of a single well in an isolated box-shaped sand body structure. Figure 10 This is a flowchart of the method of the present invention; Figure 11 This is a system module diagram of the present invention. Detailed Implementation

[0016] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0017] It should be noted that the terms "first," "second," etc., in the specification and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0018] The present invention will now be described in further detail with reference to the accompanying drawings: See Figure 10 This invention discloses a method for quantitative evaluation of sand body structure in tight sandstone reservoirs, comprising the following steps: Based on well logging curves, sedimentary characteristics, and sand body size, we can identify sand body structure types and obtain sand body structure type characteristics to accurately distinguish different types of sand body structures and facilitate subsequent analysis of the heterogeneity within the sand body.

[0019] Based on the structural characteristics of the sand bodies, the vertical stacking and lateral contact relationships of multi-stage channel sedimentary sand bodies are finely characterized to obtain the internal contact relationships of the sand bodies, which facilitates a deeper understanding of the spatial configuration relationships between the sand bodies.

[0020] Well logging curves are used to obtain well logging characterization parameters of sand body structure, which facilitates quantitative description of the physical properties of sand body structure.

[0021] Based on the well logging characterization parameters and the main controlling factors of sand body structure, quantitative evaluation parameters of sand body structure are obtained, which provides data support for subsequent quantitative evaluation and helps to more accurately assess the complexity and heterogeneity of sand body structure.

[0022] The heterogeneity of the internal structure of tight sandstone reservoirs is comprehensively evaluated based on the internal contact relationships and quantitative evaluation parameters of the sand body structure.

[0023] This invention achieves a detailed characterization of the spatial combination and distribution of sand bodies through the identification and classification of sand body structures. By utilizing the well logging curve fluctuation coefficient, well logging characterization parameters for sand body structures are established, and a comprehensive evaluation coefficient for sand body structures is constructed to quantitatively evaluate the heterogeneity of sand body structures. This method is applicable to the exploration and evaluation of tight sandstone reservoirs in continental basins, reservoir and oil reservoir evaluation during the development stage, and the selection of favorable blocks. Based on this method, the accurate identification and classification of sand body structures using conventional well logging parameters can be achieved, accurately obtaining the vertical stacking relationship, spatiotemporal distribution patterns, and the control effect of sand body structures on oil and gas reservoirs. This facilitates the quantitative evaluation of sand body structures, solves the problem of quantitative evaluation of sand body structures, and effectively guides the detailed exploration and development of tight sandstone reservoirs.

[0024] Example 1: See Figure 10 This invention discloses a method for quantitative evaluation of sand body structure in tight sandstone reservoirs, comprising the following steps: S1. Based on well logging curves, sedimentary characteristics, and sand body size, identify the sand body structure type and obtain the sand body structure type characteristics; Preferably, the process for obtaining well logging curves, sedimentary characteristics, and sand body size is as follows: Based on field outcrops, core samples, and well logging data, sand body logging response characteristic analysis was used to obtain combined well logging curves, sedimentary characteristics, and sand body size. Preferably, the logging curves include: natural gamma curve, clay content curve, sonic transit time curve, density curve, and resistivity curve.

[0025] S2. Based on the characteristics of sand body structure, the vertical stacking and lateral contact relationships of multi-phase channel sedimentary sand bodies are finely characterized to obtain the internal contact relationships of the sand bodies, as detailed below: By analyzing the structural characteristics of sand bodies and combining them with the structural type characteristics of sand bodies, we can finely depict the vertical stacking and lateral contact relationships of multi-stage channel sedimentary sand bodies, clarify the spatial distribution of tight sandstone reservoir sand bodies, and obtain the internal contact relationships of sand bodies.

[0026] S3. Based on the logging curves, obtain the logging characterization parameters of the sand body structure, as follows: A difference sequence is constructed based on the logging curves, and the fluctuation coefficient and variation function of the logging curves are obtained based on the difference sequence. A smoothing function for the logging curve is constructed based on the fluctuation coefficient and variation function of the logging curve. Well logging characterization parameters of sand body structure are obtained based on the smoothing function of the logging curve, the natural gamma logging parameter value, and the clay content.

[0027] S4. Based on the well logging characterization parameters of the sand body structure and the main controlling factors of the sand body structure, quantitative evaluation parameters of the sand body structure are obtained as follows: Quantitative evaluation parameters of sand body structure are obtained based on well logging characterization parameters of sand body structure, sand-to-soil ratio, total sand body thickness, maximum single sand body thickness, and stratification coefficient. Preferably, the calculation formula for the quantitative evaluation parameters of the sand body structure is as follows:

[0028] in, Parameters for quantitative evaluation of sand body structure. This is the weighting coefficient for the sandy soil ratio. For sandy soil ratio, This is a weighting coefficient for the total thickness of the sand body. The total thickness of the sand body. The weighting coefficient is the maximum thickness of a single sand body. For the maximum thickness of a single sand body, The weighting coefficients of the stratification coefficients. For stratification coefficients, These are the weighting coefficients for well logging parameters characterizing sand body structure. These are logging parameters characterizing the sand body structure.

[0029] S5. The heterogeneity of the internal structure of tight sandstone reservoirs is comprehensively evaluated based on the internal contact relationship and quantitative evaluation parameters of the sand body structure.

[0030] Example 2: See Figure 1 This embodiment discloses a method for quantitative evaluation of sand body structure in tight sandstone reservoirs, including the following steps: Step 1: Based on field outcrops, core samples, and well logging data, sand body well logging response characteristics analysis is used to obtain combined well logging curves, sedimentary characteristics, and sand body size. Based on the well logging curves, sedimentary characteristics, and sand body size, the sand body structure type is identified and classified. The characteristics of different sand body structure types are analyzed. The sand body structure type characteristics include: superimposed box type, toothed bell type, isolated box type, and isolated finger type. Step 2: Using sand body structure characteristic analysis, combined with the characteristics of sand body structure type, the vertical stacking and lateral contact relationship of multi-stage channel sedimentary sand bodies are finely characterized to clarify the spatial distribution of tight sandstone reservoir sand bodies; Step 3: Calculate the logging curve fluctuation coefficient using the sensitivity logging curves of the sand body structure. A smoothing function for the logging curve is constructed based on the fluctuation coefficient of the logging curve. Logging characterization parameters of sand body structure ; Step 4: Using hierarchical cluster analysis, the main controlling factors of sand body structure are selected, the weight coefficient of each main controlling factor is calculated, and combined with linear regression, quantitative evaluation parameters of sand body structure are established. By combining the internal contact relationships of the sand body, the heterogeneity of the internal structure of the tight sandstone reservoir is comprehensively evaluated, thereby obtaining high-quality sand bodies.

[0031] The logging curves in step 1 include: natural gamma curve, clay content curve, sonic transit time curve, density curve, and resistivity curve; The sand body scale includes: stratification coefficient, sand body thickness, and maximum single sand body thickness; Sand body structure types are classified as: superimposed box type, toothed bell type, isolated box type and isolated finger type, and the logging curve morphology shows box type, micro-toothed box type, bell type and funnel type characteristics; The sand body structure feature analysis in step 2 includes: using core analysis, well logging and other data, adopting single-well comprehensive columnar section and sand body structure well-connected profile, studying the vertical stacking and lateral contact relationship of sand bodies, and clarifying the spatial distribution of sand bodies in tight sandstone reservoirs; The sensitivity logging curves for sand body structure in step 3 include: natural gamma curve, density curve, and clay content curve; logging curve smoothing function. This reflects the duration of the hydrodynamic environment's modification of sediments; In step 3, a smoothing function for the logging curve is constructed. First, a difference sequence a2-a1, a3-a2, ..., an-an-1 must be constructed. The difference sequence refers to the fluctuation positions of the high and low points of the logging curve. The number of difference sequences... It can reflect the number of serrations, while variance It can reflect the magnitude of the overall data volatility, and the calculation formula is:

[0032]

[0033]

[0034] in, and All figures represent the number of sawtooth patterns in the logging curve per unit thickness. The number of difference sequences. The separation distance between the two sample spaces. This refers to the variance, specifically the fluctuation coefficient of the well logging curve. The number of difference sequences. For each difference sequence, the corresponding well logging curve parameter values ​​are... This is the average value of the logging curve parameter values ​​corresponding to all difference sequences; To reflect the size and number of serrations using a single parameter, a variogram from geostatistics is introduced. It reflects the degree of variation of a regionalized variable within a certain distance in a certain direction, and can reflect the randomness and structure of the regionalized variable. Its calculation formula is as follows:

[0035] in, It is a variation function. It is the separation distance between the two sample spaces. The interval is Data pairs ( , The number of ) It is a regional variable In spatial location The measured value at that location It is a regional variable In spatial location The measured value at that location =1, 2, ..., The variogram reflects the magnitude of local fluctuations in the data; Because the variogram reflects the magnitude of local fluctuations in the data, and This reflects the magnitude of the overall data volatility; therefore, combining the two constitutes the root variance of the variation, i.e., the smoothing function of the logging curve. The solution can comprehensively reflect the overall fluctuation magnitude and the number and size of sawtooth patterns in the curve segment, thus using this function to characterize the smoothness of the curve data. The calculation formula is as follows:

[0036] in, The solution to the smoothing function of the well logging curve. Let be the variation function of the logging curve parameters corresponding to the first difference sequence. The variation function of the logging curve parameters corresponding to the second difference sequence. It is a variation function. For variance, Spatial sample separation distance; Regarding spatial sample separation distance For well logging curves, since the sampling interval is equal, generally one value is measured every 0.125 meters. Since the goal is to reflect the magnitude of local fluctuations, then... The smaller the better, to ensure accuracy. If = 1, 2, then the above formula simplifies to:

[0037] in The smaller the value, the smoother the curve, the less undulation the curve, and the closer the sand body is to a massive shape; conversely... The larger the value, the less smooth the curve, the greater the variability of the curve, and the closer the sand body morphology is to sand-mud interbedded layers; therefore, the logging curve smoothing function can be used. Well logging characterization parameters for constructing sand body structure The calculation formula is as follows:

[0038] in, These are logging parameters characterizing the sand body structure. These are natural gamma logging parameter values. For well logging curve smoothing function, The content of clay; Sand body structure logging characterization parameters This reflects the heterogeneity of the sand body structure. The higher the value, the stronger the degree of heterogeneity within the sand body. The smaller the value, the weaker the non-uniformity inside the sand body, and the more homogeneous the sand body; In step 4, principal component analysis is used to optimize the main controlling factors of sand body structure, including: sand-to-land ratio. Total thickness of sand body Maximum single sand body thickness Stratification coefficient and sand body structural parameters Then, hierarchical cluster analysis is used to calculate the weight coefficients of each controlling factor, and combined with linear regression, quantitative evaluation parameters for sand body structure are established. The calculation formula is as follows:

[0039] in, Parameters for quantitative evaluation of sand body structure. Sandy soil ratio The weighting coefficients, For sandy soil ratio, Total thickness of the sand body The weighting coefficients, The total thickness of the sand body. Maximum single sand body thickness The weighting coefficients, For the maximum thickness of a single sand body, Stratification coefficient The weighting coefficients, For stratification coefficients, Well logging characterization parameters for sand body structure The weighting coefficients, These are logging parameters characterizing the sand body structure.

[0040] Quantitative evaluation parameters of sand body structure It reflects the degree of homogeneity within the sand body. The higher the value, the more homogeneous the sand body, indicating thick-layered massive sandstone with good structural quality; conversely, a lower value indicates a less homogeneous sandstone body. The smaller the value, the stronger the heterogeneity inside the sand body, the more developed the muddy interlayers and physical property interlayers, the more the sand body is a thin interlayer of sand and mud, and the poorer the quality of the sand body structure. This invention establishes a sand body structure identification and classification system based on core analysis and well logging data, enabling a detailed characterization of the spatial combination and distribution of sand bodies. By utilizing the well logging curve fluctuation coefficient, well logging characterization parameters for sand body structure are established. Simultaneously, hierarchical clustering and multiple linear regression methods are combined to construct a comprehensive evaluation coefficient for sand body structure, quantitatively evaluating the heterogeneity of the sand body structure. This avoids the problem of overly idealistic sand body structure identification using conventional well logging analysis methods in existing technologies, and also overcomes the shortcomings of poor applicability and low accuracy of quantitative sand body structure models established using statistical methods in existing technologies.

[0041] This method is applicable to reservoir evaluation, oil reservoir evaluation, and selection of favorable blocks during the exploration, evaluation, and development stages of tight sandstone reservoirs in continental basins. Based on this method, the sand body structure can be accurately identified and classified using conventional logging parameters, solving the problem of quantitative evaluation of sand body structure and effectively guiding the detailed exploration and development of tight sandstone reservoirs.

[0042] Example 3: See Figure 10 This embodiment discloses a method for quantitative evaluation of sand body structure in tight sandstone reservoirs, as detailed below: The Chang 8 reservoir in a certain oilfield is a typical tight sandstone reservoir. The study area is controlled by two major source sources in the northwest and southwest, exhibiting a delta front subfacies. Channel sandbars and subaqueous distributary channel sand bodies are the main reservoir bodies, widely distributed with a thickness of 10–40 m, and featuring multiple superimposed channel sand bodies in the central region. Exploration and development data indicate that the Chang 8 reservoir has proven geological reserves of 470 million tons, representing significant exploration and development potential. However, due to the reservoir sand body structure and heterogeneity, exploration and development in the entire area are challenging, with numerous uncertainties in new well deployment and development adjustments. The method of this invention can quickly and accurately evaluate the sand body structure and reservoir heterogeneity of the Chang 8 oil formation in this study area, providing a scientific basis for exploration deployment and development adjustments. The Chang 8 reservoir in this oilfield is used as a specific implementation example of this invention, and the implementation steps of the technical solution are as follows: Figure 1 As shown.

[0043] Step S101: Based on field outcrops, core samples, and well logging data, sand body well logging response characteristics analysis is used. Combined with curve morphology, sedimentary characteristics, and sand body scale, sand body structure types are identified and classified, and the characteristics of different sand body structure types are analyzed.

[0044] The sand body structure types in the study area are classified as: superimposed box type, toothed bell type, isolated box type, and isolated finger type; The logging curves exhibit box-shaped, micro-toothed box-shaped, bell-shaped, and funnel-shaped characteristics. The specific analysis results are shown in Table 1.

[0045] Table 1. Sand body structure types and characteristics of the Chang 8 reservoir in the study area:

[0046] Step S102: Using sand body structural feature analysis, the vertical stacking and lateral contact relationship of multi-stage channel sedimentary sand bodies are finely characterized to clarify the spatial distribution of tight sandstone reservoir sand bodies.

[0047] The analysis of sand body structure characteristics includes: using core analysis, well logging, and other data, employing single-well composite columnar sections and well-connected profiles of sand body structure, studying the vertical stacking and lateral contact relationships of sand bodies, and clarifying the spatial distribution of sand bodies in tight sandstone reservoirs; the vertical stacking relationships of sand bodies in the study area are as follows: Figure 2 As shown, the lateral contact relationship of the sand body is as follows: Figure 3 As shown.

[0048] Step S103: Using the sensitivity logging curves of sand body structure, calculate the logging curve fluctuation coefficient and construct the logging curve smoothing function. Logging characterization parameters of sand body structure ; Sensitivity logging curves for sand body structure include: natural gamma curve, density curve, and clay content; logging curve smoothing function. This reflects the duration of the hydrodynamic environment's modification of sediments; Constructing a smoothing function for well logging curves First, difference sequences a2-a1, a3-a2, ..., an-an-1 must be constructed, and the number of difference sequences is... It can reflect the number of serrations, while variance It can reflect the magnitude of the overall data fluctuation. A schematic diagram of the overall fluctuation of well logging curve data is shown below. Figure 4 As shown in b, the calculation formula is:

[0049]

[0050]

[0051] To reflect the size and number of serrations using a single parameter, a variogram from geostatistics is introduced. It reflects the degree of variation of a regionalized variable within a certain distance in a certain direction, and can reflect the randomness and structure of the regionalized variable. Its calculation formula is as follows:

[0052] It is the separation distance between the two sample spaces. The interval is Data pairs ( , The number of ) It is a regional variable In spatial location The measured value at that location It is a regional variable In spatial location The measured value at that location =1, 2, ..., The variability function reflects the magnitude of local fluctuations in the data. A schematic diagram of local fluctuations in well logging data is shown below. Figure 4 As shown in a.

[0053] Because the variogram reflects the magnitude of local fluctuations in the data, and This reflects the magnitude of the overall data volatility; therefore, combining the two constitutes the root variance of the variation, i.e., the smoothing function of the logging curve. The solution can comprehensively reflect the overall fluctuation magnitude and the number and size of sawtooth patterns in the curve segment, thus using this function to characterize the smoothness of the curve data. The calculation formula is as follows:

[0054] in, The solution to the smoothing function of the well logging curve. Let be the variation function of the logging curve parameters corresponding to the first difference sequence. The variation function of the logging curve parameters corresponding to the second difference sequence. It is a variation function. For variance, Spatial sample separation distance; So how do we select the spatial sample separation distance? How much should be taken? For well logging curves, since their intervals are equal, a value is generally measured every 0.125 meters. Since the goal is to reflect the magnitude of local fluctuations, then... The smaller the better, to ensure accuracy. If = 1, 2, then the above formula simplifies to:

[0055] in The smaller the value, the smoother the curve, the less undulation the curve, and the closer the sand body is to a massive shape; conversely... The larger the value, the less smooth the curve, the greater the variability of the curve, and the closer the sand body morphology is to sand-mud interbedded layers; therefore, the logging curve smoothing function can be used. Well logging characterization parameters for constructing sand body structure The calculation formula is as follows:

[0056] in, These are logging parameters characterizing the sand body structure. These are natural gamma logging parameter values. For well logging curve smoothing function, The content of clay; Sand body structure logging characterization parameters This reflects the heterogeneity of the sand body structure. The higher the value, the stronger the degree of heterogeneity within the sand body. The smaller the value, the weaker the heterogeneity within the sand body, and the more homogeneous the sand body. The logging characterization parameters for different sand body structures in the Chang 8 reservoir of the study area were calculated using the above method. The corresponding well logging results are shown in the figure below. Figures 5-7 As shown.

[0057] Step S104: Using hierarchical cluster analysis, the main controlling factors of sand body structure are selected, the weight coefficient of each main controlling factor is calculated, and combined with linear regression, quantitative evaluation parameters of sand body structure are established. ; Principal component analysis was used to optimize the main controlling factors of sand body structure, including: sand-to-land ratio. Total thickness of sand body Maximum single sand body thickness Stratification coefficient and sand body structural parameters Then, hierarchical cluster analysis is used to calculate the weight coefficients of each controlling factor, and combined with linear regression, quantitative evaluation parameters for sand body structure are established. The calculation formula is as follows:

[0058] Quantitative evaluation parameters of sand body structure It reflects the degree of homogeneity within the sand body. The higher the value, the more homogeneous the sand body, indicating thick-layered massive sandstone with good structural quality; conversely, a lower value indicates a less homogeneous sandstone body. The smaller the value, the stronger the heterogeneity inside the sand body, the more developed the muddy interlayers and physical property interlayers, the more the sand body is a thin interlayer of sand and mud, and the poorer the quality of the sand body structure. This method was used to evaluate the oil-bearing potential of 25 wells with oil testing and production data in the study area. The evaluation results for 21 of these wells were consistent with the actual production situation. Parameter evaluation of the oil-bearing potential of tight sandstone reservoirs is relatively reliable.

[0059] like Figures 5-7 The figures show examples of sand body structure parameter calculations for wells L38, B35, and L82 in the study area. The curves are as follows: the first curve shows the spontaneous potential and natural gamma curves; the second curve shows the logging resistivity curve; the third curve shows the sonic transit time and density curves; the fourth curve shows the sand body structure parameters calculated using the curve smoothness function; the fifth curve shows the oil testing conclusions and interpretation conclusions; and the sixth curve shows the sandstone-mudstone profile.

[0060] The gamma ray logging curve in well L38 of the study area is a medium-amplitude box shape with micro-tooth pattern, indicating a massive sand body with good overall homogeneity. The values ​​are relatively small, averaging 11.5, indicating low reservoir heterogeneity and suggesting a pure oil layer as interpreted by well logging. These are the quantitative evaluation parameters of the sand body structure in this well. The value was 5.3, indicating good sand quality. The well produced 20.9 t / d of oil during the test, which is relatively high.

[0061] The natural gamma curves in well B35 in the study area exhibit serrated bell-shaped and finger-shaped characteristics, indicating interbedded sand and mud layers with poor overall homogeneity of the sand body. The value is 15.2, a quantitative evaluation parameter for sand body structure. The well has a strength of 3.9, indicating it is a medium-quality sand body with low oil saturation, poor reservoir properties, and strong oil heterogeneity. Well logging interpretation indicates it is a poor oil layer. The well's daily oil production during testing was 6.46 t / d.

[0062] Based on the calculated sand body structure parameters and oil-bearing parameters, the smoothness of well L38 is significantly better than that of well B35. According to the evaluation results of logging parameters and actual production conditions, the reservoir sand body structure and oil-bearing properties of well L38 are superior to those of well B35.

[0063] Figure 7 This study uses the L82 well as an example to calculate sand body structure parameters in the L82 well reservoir. The L82 well exhibits the worst sand body structure, with strong heterogeneity. Quantitative evaluation parameters for the sand body structure are provided. The value is 1.2, indicating poor sand quality and the reservoir does not contain oil.

[0064] Figure 8 Quantitative evaluation parameters for reservoir sand body structure in the study area Distribution frequency of values, sand body structure parameters in the study area The values ​​are mainly concentrated between 2.0 and 4.5, with an average of 2.9, indicating that the reservoir sand bodies in the study area are of medium quality.

[0065] Based on the statistical analysis of oil trial data in the study area, such as Figure 9As shown, the stacked box-shaped sand body structure exhibited better oil production during testing, with daily oil production concentrated between 5 and 15 tons, reaching a maximum of 50.3 tons per day. The toothed bell-shaped sand body showed daily oil production concentrated between 0 and 10 tons, with a maximum of 24.4 tons per day. Isolated box-shaped sand bodies produced less than 5 tons of oil per day. The peak oil production values ​​were the same for both blocky and layered stacked box-shaped sand bodies, but the blocky stacked box-shaped sand bodies had a higher proportion of high-yield wells.

[0066] The detailed characterization of sand body structures and the study of the vertical and planar distribution patterns of individual sand bodies are of great guiding significance for the exploration and development of oil reservoirs. This invention, based on the analysis of the logging response and morphological characteristics of individual sand bodies, comprehensively utilizes sedimentary, sand body, and logging data. Using sand body structure characteristic analysis, it finely characterizes the vertical stacking and lateral contact relationships of multi-phase channel sedimentary sand bodies, clarifying the spatial distribution of sand bodies in tight sandstone reservoirs. Furthermore, by utilizing the sensitivity logging curves of sand body structure, it constructs logging characterization parameters for sand body structure, quantitatively evaluates the sand body structure of tight sandstone reservoirs, and identifies high-quality oil-bearing sand bodies.

[0067] Based on the above method, this invention also discloses a quantitative evaluation system for sand body structure in tight sandstone reservoirs, see [link to relevant documentation]. Figure 11 ,include: Sand body structure type feature acquisition module: used to identify sand body structure types and acquire sand body structure type features based on well logging curves, sedimentary characteristics and sand body size; Sand body internal contact relationship acquisition module: used to finely characterize the vertical stacking and lateral contact relationships of multi-phase channel sedimentary sand bodies based on the characteristics of sand body structure type, and to acquire the internal contact relationships of sand bodies; Well logging characterization parameter acquisition module: used to obtain well logging characterization parameters of sand body structure based on well logging curves; Quantitative evaluation parameter acquisition module: used to acquire quantitative evaluation parameters of sand body structure based on well logging characterization parameters of sand body structure and main controlling factors of sand body structure; The comprehensive evaluation module is used to comprehensively evaluate the internal heterogeneity of tight sandstone reservoirs based on the internal contact relationships and quantitative evaluation parameters of the sand body structure.

[0068] The various modules of the system in this invention work together to accurately obtain the longitudinal stacking relationship of sand bodies, the spatiotemporal distribution pattern, and the control effect of sand body structure on oil and gas reservoirs, which is beneficial for the quantitative evaluation of sand body structure.

[0069] An electronic device includes: a processor; a memory for storing computer program instructions; and steps for implementing a method for quantitatively evaluating the sand body structure of tight sandstone reservoirs when executing the computer program.

[0070] A storage medium storing computer program instructions, which are loaded and executed by a processor, wherein the processor performs a method for quantitative evaluation of the sand body structure of a tight sandstone reservoir.

[0071] A computer program product comprising computer instructions that instruct a computer to execute a method for quantitative evaluation of the sand body structure of tight sandstone reservoirs.

[0072] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0073] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0074] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0075] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0076] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A quantitative evaluation method for sand body structure in tight sandstone reservoirs, characterized in that, Includes the following steps: Based on well logging curves, sedimentary characteristics, and sand body size, the sand body structure type is identified, and the sand body structure type characteristics are obtained. Based on the characteristics of sand body structure types, the vertical stacking and lateral contact relationships of multi-phase channel sedimentary sand bodies are finely characterized to obtain the internal contact relationships of the sand bodies; Well logging parameters for sand body structure are obtained from well logging curves; Quantitative evaluation parameters of sand body structure are obtained based on well logging characterization parameters of sand body structure and main controlling factors of sand body structure. The heterogeneity of the internal structure of tight sandstone reservoirs is comprehensively evaluated based on the internal contact relationships and quantitative evaluation parameters of the sand body structure.

2. The method for quantitative evaluation of sand body structure in tight sandstone reservoirs according to claim 1, characterized in that, The process of obtaining well logging curves, sedimentary characteristics, and sand body size is as follows: Based on field outcrops, core samples, and well logging data, sand body logging response characteristics analysis was used to obtain combined logging curves, sedimentary characteristics, and sand body size.

3. The method for quantitative evaluation of sand body structure in tight sandstone reservoirs according to claim 1, characterized in that, The logging curves include: natural gamma curve, clay content curve, sonic transit time curve, density curve, and resistivity curve.

4. The method for quantitative evaluation of sand body structure in tight sandstone reservoirs according to claim 1, characterized in that, The vertical stacking and lateral contact relationships of multi-phase channel sedimentary sand bodies are finely characterized based on the characteristics of sand body structure types to obtain the internal contact relationships of the sand bodies, as detailed below: By analyzing the structural characteristics of sand bodies and combining them with the structural type characteristics of sand bodies, we can finely depict the vertical stacking and lateral contact relationships of multi-stage channel sedimentary sand bodies, clarify the spatial distribution of tight sandstone reservoir sand bodies, and obtain the internal contact relationships of sand bodies.

5. The method for quantitative evaluation of sand body structure in tight sandstone reservoirs according to claim 1, characterized in that, The well logging characterization parameters of the sand body structure obtained from the well logging curves are as follows: A difference sequence is constructed based on the logging curves, and the fluctuation coefficient and variation function of the logging curves are obtained based on the difference sequence. A smoothing function for the logging curve is constructed based on the fluctuation coefficient and variation function of the logging curve. Well logging characterization parameters of sand body structure are obtained based on the smoothing function of the logging curve, the natural gamma logging parameter value, and the clay content.

6. The method for quantitative evaluation of sand body structure in tight sandstone reservoirs according to claim 1, characterized in that, The quantitative evaluation parameters of sand body structure are obtained based on the well logging characterization parameters of sand body structure and the main controlling factors of sand body structure, as detailed below: Quantitative evaluation parameters of sand body structure are obtained based on well logging characterization parameters, sand-to-soil ratio, total sand body thickness, maximum single sand body thickness, and stratification coefficient.

7. The method for quantitative evaluation of sand body structure in tight sandstone reservoirs according to claim 1, characterized in that, The calculation formulas for the quantitative evaluation parameters of the sand body structure are as follows: in, Parameters for quantitative evaluation of sand body structure. This is the weighting coefficient for the sandy soil ratio. For sandy soil ratio, This is a weighting coefficient for the total thickness of the sand body. The total thickness of the sand body. The weighting coefficient is the maximum thickness of a single sand body. For the maximum thickness of a single sand body, The weighting coefficients of the stratification coefficients. For stratification coefficients, These are the weighting coefficients for well logging parameters characterizing sand body structure. These are logging parameters characterizing the sand body structure.

8. A quantitative evaluation system for sand body structure in tight sandstone oil reservoirs, characterized in that, include: Sand body structure type feature acquisition module: used to identify sand body structure types and acquire sand body structure type features based on well logging curves, sedimentary characteristics and sand body size; Sand body internal contact relationship acquisition module: used to finely characterize the vertical stacking and lateral contact relationships of multi-phase channel sedimentary sand bodies based on the characteristics of sand body structure type, and to acquire the internal contact relationships of sand bodies; Well logging characterization parameter acquisition module: used to obtain well logging characterization parameters of sand body structure based on well logging curves; Quantitative evaluation parameter acquisition module: used to acquire quantitative evaluation parameters of sand body structure based on well logging characterization parameters of sand body structure and main controlling factors of sand body structure; The comprehensive evaluation module is used to comprehensively evaluate the internal heterogeneity of tight sandstone reservoirs based on the internal contact relationships and quantitative evaluation parameters of the sand body structure.

9. An electronic device, comprising: A processor; a memory, an electronic device for storing computer program instructions; characterized in that, when executing the computer program, it implements the steps of the quantitative evaluation method for the sand body structure of tight sandstone reservoirs as described in any one of claims 1-7.

10. A storage medium storing computer program instructions, characterized in that, When the computer program instructions are loaded and run by the processor, the processor executes the quantitative evaluation method for sand body structure of tight sandstone reservoirs as described in any one of claims 1-7.

11. A computer program product, said computer program product comprising computer instructions, characterized in that, The computer instructions instruct the computer to execute the quantitative evaluation method for sand body structure of tight sandstone reservoirs as described in any one of claims 1-7.

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