Oil sand body fine characterization and evaluation method based on multi-information fusion

Abstract

The invention provides an oil sand body fine characterization and evaluation method based on multi-information fusion, which comprehensively considers multiple information such as well drilling, well logging, production dynamics, earthquake and the like, identifies and divides single sand bodies on the basis of sedimentary feature analysis, knows sand body corresponding relations and sedimentary change rules by multiple information, and compares the single sand bodies; the reservoir boundary and the oil layer boundary are comprehensively judged through multiple information; the single-sand-layer top boundary altitude depth, the oil layer thickness and the sand layer thickness are marked beside the well; the drilling oil-water layer conditions in different water injection development stages are comprehensively evaluated; the oil sand body distribution rule is judged; an important geological basis is provided for oilfield development scheme compilation, and the accuracy and reliability of remaining oil evaluation are improved.

Description

Technical Field

[0001] The present application relates to oil and gas resource exploration, and in particular to exploration or detection using comprehensive technical means, and specifically to a method for fine characterization and evaluation of oil sand bodies based on multi-information fusion. Background Art

[0002] Oil sand body refers to a single closed space formed by the combination of independent sand bodies, faults and local structures in three-dimensional space. It is the smallest closed unit formed by oil reservoirs. With the long-term water injection development of sandstone oil fields, affected by the heterogeneity of oil reservoirs, the distribution of remaining oil is extremely scattered, the recovery degree of each single sand layer in the vertical direction is inconsistent, and the recoverable reserves of remaining oil in different oil sand bodies in the plane are inconsistent. To accurately understand the remaining oil and formulate a reasonable development plan, it is necessary to accurately characterize the oil sand body first. At present, the methods of characterizing and mapping oil sand bodies only carry out comparison, mapping and comprehensive analysis of oil, gas and water distribution for the stratification boundaries. The problems are that the subtle structural fluctuations of the reservoir are not reflected, the change form between the reservoir and the non-reservoir is not accurately characterized, and the distribution of oil, gas and water cannot be well judged. At the same time, in the traditional development of oil and gas reservoirs, the understanding of reservoir configuration and the evaluation of remaining oil distribution often rely on a single information source, such as logging or seismic data, which limits the comprehensive understanding of the complexity of oil and gas reservoirs. With the deepening of oil field development, the accurate evaluation of remaining oil distribution by integrating multiple information fusion has become the key to improving recovery.

[0003] How to realize the representation and evaluation mechanism of comprehensive multi-information fusion has formed the innovative demand in this technical field. Summary of the invention

[0004] The present application provides a method for fine characterization and evaluation of oil sand bodies based on multi-information fusion. According to the law of oil reservoir formation, comprehensive consideration is given to multiple information such as drilling, logging, production dynamics, and seismic, and single sand bodies are identified and divided based on sedimentary feature analysis, and the corresponding relationship of sand bodies and the law of sedimentary changes are understood by multiple information, and single sand bodies are compared; the microstructure of sand bodies is characterized by using well information and seismic technology, and the reservoir boundary and oil layer boundary are judged by multiple information. The top boundary elevation depth of a single sand layer, the thickness of the oil layer, and the thickness of the sand layer are marked beside the well, and the oil and water layers encountered during drilling in different water injection development stages are comprehensively evaluated, the distribution law of oil sand bodies is judged, and the oil sand body map is compiled in a standardized manner. Based on the finely characterized oil sand body map, multiple information sources can be integrated to realize the method of fine characterization of oil and gas reservoirs and evaluation of remaining oil, which is of great significance for the efficient development of oil fields.

[0005] To achieve the above purpose, the technical solution adopted by this application is: The method for fine characterization of oil and gas reservoirs and residual oil evaluation based on multi-information fusion includes the following steps: For oil-bearing sand bodies, single sand bodies are identified and divided based on sedimentary microfacies units; Conduct single sand body comparison to obtain continuous comparison boundaries, and use seismic inversion methods to determine inter-well sand body changes; Use 3D seismic data and dense well network data to draw sand body microstructure maps; Delineate sandstone boundaries and oil sand body boundaries; Comprehensive analysis includes drilling, logging, production dynamics and seismic information to correct the distribution and identification of oil sand bodies; Prepare oil sand body maps including well point information annotation, scale setting, frame design, drawing of map content, and legend making; Combined with the oil sand body map, a detailed three-dimensional geological model is established to clarify the distribution characteristics of reservoir quality differences controlled by the configuration; Based on the reservoir configuration and reservoir quality difference distribution, dynamic and static combined analysis and reservoir numerical simulation are used to determine the remaining oil formation mechanism and distribution law, and establish the remaining oil distribution model.

[0006] The above method overcomes the shortcomings of traditional methods in oil sand body characterization and mapping. On the basis of improving the accuracy of oil sand body research, the comprehensive application of multiple information sources can achieve the fine configuration division of oil sand body reservoirs and accurate evaluation of remaining oil distribution, providing strong geological support for the remaining oil research and development plan preparation.

[0007] This method is based on the law of oil reservoir formation, comprehensively considers drilling, logging, production dynamics, seismic and other information, identifies and divides single sand bodies on the basis of sedimentary characteristics analysis, understands the correspondence between sand bodies and sedimentary change laws with multiple information, and compares single sand bodies; uses well information and seismic technology to depict sand body microstructures, comprehensively judges reservoir boundaries and oil layer boundaries with multiple information, marks the top elevation depth of single sand layer, oil layer thickness, and sand layer thickness beside the well, comprehensively evaluates the drilling and encountering of oil and water layers at different water injection development stages, judges the distribution law of oil sand bodies, and standardizes the preparation of oil sand body maps. Through the precise characterization and mapping of oil sand bodies, combined with production dynamic analysis, it is possible to intuitively judge the remaining oil potential, water flooding conditions, and the degree of perfection of the injection and production well network, and provide accurate geological maps for the preparation of comprehensive adjustment plans.

[0008] By integrating multiple sources of information such as geology, geophysics, logging, and production dynamics, the reservoir architecture units of oil and gas reservoirs can be more accurately identified and divided. This multi-information fusion method helps to reduce the errors that may be caused by a single information source and improve the accuracy of the description of the geological characteristics of oil and gas reservoirs. Comprehensive analysis of the geological characteristics, production dynamics, and numerical simulation results of oil and gas reservoirs can more accurately evaluate the distribution and recoverable reserves of remaining oil sources. This method can identify the remaining oil-rich areas and provide a scientific basis for subsequent development adjustments and measures to improve recovery. The evaluation results can provide a more scientific basis for development decisions of oil and gas reservoirs. For example, based on the evaluation results of the remaining oil distribution, targeted development adjustment strategies can be formulated, such as adjusting the injection and production well network, implementing infill drilling, and adopting enhanced recovery technology. It can also more effectively develop oil and gas resources and improve the overall economic benefits of oil and gas fields. Accurately identifying and developing dominant sand bodies and effectively exploiting remaining oil can extend the economic life of oil and gas fields and improve the recovery rate of oil and gas resources.

[0009] Through the multi-information fusion method, we can more comprehensively understand the geological characteristics and fluid distribution of oil and gas reservoirs, which helps to reduce the technical and economic risks in the exploration and development process. Accurate geological models and evaluation of the distribution of remaining oil sources can guide exploration and development activities and reduce unnecessary investment and waste of resources.

[0010] The analysis and evaluation method based on multi-information fusion also provides an innovative idea, which comprehensively applies a variety of advanced technologies, such as high-resolution seismic technology, fine logging interpretation, reservoir numerical simulation, etc. The implementation of the method has promoted the progress and innovation of related technologies, promoted the development of oil and gas exploration and development technology, and provided inspiration and research and development ideas for subsequent in-depth and refined research.

[0011] In a preferred embodiment, a microfacies unit contains only one sand body or one dominant sand body.

[0012] Dominant sand bodies refer to sand bodies with relatively good reservoir characteristics in oil and gas reservoirs, such as higher porosity, permeability and thicker sand layer thickness, and are conducive to oil and gas accumulation and flow. These sand bodies are usually the main targets in oil and gas exploration and development because they can provide higher productivity and better economic benefits.

[0013] Predominant sand bodies usually have higher porosity and permeability, which means that they can store more oil and gas, and the resistance to the flow of oil and gas in them is smaller, which is conducive to the extraction of oil and gas. The thickness of the sand layer of the dominant sand body is larger, which not only increases the reserves of oil and gas, but also facilitates the formation of continuous flow channels and improves the extraction efficiency of oil and gas. Predominant sand bodies are often formed in environments that are conducive to sandy deposition, such as rivers, deltas, beaches, etc. These environments can form sand bodies with stable structures and good sorting. In some cases, the dominant sand body may be located in a structural background that is conducive to the accumulation of oil and gas, such as anticlines, fault shields, etc. These structures can serve as traps for oil and gas reservoirs and increase the enrichment of oil and gas. The fluids (oil, gas, water) in the dominant sand body usually have good fluidity, which helps to increase the extraction rate and recovery rate of oil and gas. In the process of oil and gas exploration and development, it is very important to identify and evaluate the dominant sand bodies because they are the main carriers of oil and gas resources. By comprehensively applying various information such as geology, geophysics, logging and production dynamics, the dominant sand bodies can be effectively identified and divided, providing a scientific basis for the development of oil and gas fields.

[0014] In a preferred embodiment, single sand body comparison is performed by using one or more comparison methods selected from the group consisting of equal elevation comparison, time unit comparison, phase-controlled isochronous comparison, and downcut sand body comparison, combined with seismic inversion technology.

[0015] Each correlation method has its own applicable geological conditions and sedimentary environment. By selecting the appropriate correlation method and combining it with the interwell information provided by seismic inversion technology, individual sand bodies can be more accurately identified and correlated, especially in complex sedimentary environments, which can improve the accuracy and reliability of the correlation.

[0016] Different correlation methods reflect different sedimentary processes and environmental characteristics. For example, contour correlation is suitable for river floodplains and channel fill deposits, while time unit correlation is suitable for strongly incised river deposits. By combining these methods, we can enhance our understanding and knowledge of the sedimentary environment of oil and gas reservoirs.

[0017] The time unit comparison method is applicable to the situation where, due to the strong cutting action of the river and the inheritance of the river channel position in different periods, the river sediments of each period may be eroded and diverted by the later river, and the river channel sands of different periods are superimposed into thick composite sand bodies. This method helps to distinguish superimposed sand bodies from thickness and curve morphology, and understand the superposition relationship of multi-period river sediments and the complex structure of sand bodies.

[0018] The phase-controlled isochronous correlation method is applicable to thin interbeds composed of siltstone and mudstone, which are isochronous "event bodies" of different microfacies deposited simultaneously. Such sand bodies are mostly located at the edge of the river channel or the levee subfacies. Through phase-controlled isochronous correlation, different microfacies formed in the same sedimentary event can be identified, which helps to understand the microfacies changes of the sedimentary system and the lateral phase changes of the sand body.

[0019] Methods such as downcut sand body correlation and phase-controlled isochronal correlation can reveal the internal structure and sedimentary sequence of the sand body, such as the scour surface and superposition relationship of the sand body. This information is crucial for understanding the connectivity of the sand body and the flow path of the fluid.

[0020] Accurately identifying and comparing single sand bodies can help optimize the development strategy of oil and gas reservoirs. For example, the injection and production well network can be designed according to the distribution and connectivity of the sand bodies to improve the efficiency of water injection development; or measures to improve the recovery rate can be implemented for sand bodies rich in residual oil. Seismic inversion technology can provide information on the distribution and physical properties of sand bodies between wells. Combined with specific comparison methods, seismic inversion results can be used more effectively to improve the application effect of seismic data in oil and gas reservoir characterization. By comprehensively applying a variety of comparison methods and seismic inversion technologies, the geological characteristics of oil and gas reservoirs can be more comprehensively evaluated, reducing technical and economic risks in the exploration and development process. Accurate geological models help guide exploration and development activities and reduce unnecessary investment and waste of resources.

[0021] At the same time, the use of multiple comparison methods combined with seismic inversion technology requires the integration of interdisciplinary knowledge and technology. The implementation of this method promotes technological innovation and method integration, and promotes the development of oil and gas exploration and development technology.

[0022] In a preferred embodiment, microstructural interpretation is performed using three-dimensional seismic data and dense well pattern data; including: Collect and organize 3D seismic data and dense well network data. 3D seismic data includes detailed images of underground structures, while dense well network data includes precise geological information at the well points, including lithology, formation interfaces, and faults. Process 3D seismic data, including denoising, migration, and velocity analysis, to improve the quality and resolution of seismic imaging; Interpret the processed seismic data, including identifying and tracing stratigraphic interfaces, faults, and sand body boundaries; use seismic attribute analysis, including amplitude, frequency, and phase, to further clarify the internal structure and distribution characteristics of the sand body; Integrate the dense well network data with the seismic interpretation results, and accurately correspond the seismic interpretation results to geological ages and stratigraphic sequences based on the precise stratigraphic calibration provided by the dense well network data; Combine seismic interpretation results with dense well pattern data to conduct detailed interpretation of sand body microstructure, including identification of tiny stratigraphic fluctuations, faults, fractures and their effects on sand body distribution and fluid flow; Based on the interpretation results, a sand body microstructural model is established, which includes the spatial distribution and microstructural characteristics of the sand body; The accuracy of microstructural interpretation is verified by comparing with production dynamic data, and the model is modified based on the verification results.

[0023] By carefully interpreting the sand body microstructure, the accuracy of the geological model can be improved, the underground geological conditions can be more realistically reflected, and a more reliable geological basis can be provided for accurate reservoir characterization and residual oil and gas analysis.

[0024] Accurate microstructural information helps optimize the design of injection and production well patterns, improve the efficiency of water injection development, and rationally deploy measures to enhance oil recovery. Detailed microstructural interpretation helps identify potential development risks, such as the obstruction of fluid flow by faults and the impact of microstructures on the oil-water interface, so that corresponding risk control measures can be taken.

[0025] At the same time, 3D seismic data provides a macroscopic image of the underground structure, while dense well network data provides precise geological information at the well points. By combining these two types of information, a more comprehensive understanding of the distribution and microstructural characteristics of sand bodies can be achieved. Single sand body comparison methods focus on using well data and seismic inversion techniques to identify and compare individual sand bodies. These methods provide detailed information on the internal structure and sedimentary sequence of the sand bodies. The combination of the two can form a comprehensive understanding of the geological characteristics of oil and gas reservoirs.

[0026] When interpreting sand body microstructure in detail, the interpretation of seismic data requires accurate calibration of well data, and the interpretation of well data requires verification and expansion of inter-well information provided by seismic data. Similarly, in the process of comparison, the single sand body comparison method also needs to use seismic inversion technology to assist in judging the changes and connectivity of inter-well sand bodies. The coordinated use of these two methods can improve the accuracy of understanding sand body distribution and microstructural characteristics.

[0027] When establishing and revising the geological model of oil and gas reservoirs, the finely interpreted sand body microstructure and the single sand body comparison results need to be verified with each other. For example, the sand body boundaries and sedimentary sequences determined by single sand body comparison can be used to verify whether the sand body distribution interpreted by seismic analysis is reasonable; conversely, the sand body distribution and microstructural characteristics interpreted by seismic analysis can also be used to verify whether the results of single sand body comparison are accurate.

[0028] The finely interpreted sand microstructure and single sand body comparison results are important bases for oil and gas reservoir development decisions. For example, when designing the injection and production well pattern, it is necessary to consider the distribution and connectivity of the sand bodies, as well as the impact of microstructure on fluid flow. The information provided by these two methods can help optimize development strategies and improve the overall development effect of oil and gas fields.

[0029] In a preferred embodiment, delineating sandstone boundaries and oil sand body boundaries includes The sandstone boundary is determined through seismic multi-attribute prediction and dense well network data; the oil sand body boundary is divided according to the reservoir type and oil-water relationship.

[0030] Among them, determining the sandstone boundary includes using the sand-to-ground ratio predicted by seismic multi-attributes as the first-level constraint to distinguish mudstone from sandstone. According to the dense well network data, the sandstone and non-sandstone under the control of two wells at a well spacing are divided into three equal parts, and the one-third of the non-sandstone is used as the sand-mud reservoir boundary.

[0031] Determination of oil sand body boundaries includes The structural oil reservoir has an oil sand body with a clear oil-water interface, and the boundaries of the oil sand body are divided according to the oil-water boundary.

[0032] Fault block reservoirs are full of oil and are completely filled with oil layers.

[0033] The oil sand body boundary of the lithologic reservoir is divided at the sandstone boundary and one-third of the distance between the oil layer wells close to the sandstone boundary.

[0034] In a preferred embodiment, comprehensive analysis includes drilling, logging, production dynamics and seismic information to correct the oil sand body distribution identification, including When conflicts arise between oil and water, comprehensive analysis of multiple information, including If the single sand body comparison is incorrect, re-compare the single sand body; If the logging interpretation is inaccurate, the oil and water layers are reinterpreted; If the wells are drilled at different times and the new wells are flooded at a later stage, they will be treated according to the original reservoir state before water injection development.

[0035] In oil and gas exploration and development, "oil-water contradiction" refers to the inconsistency between the oil-water distribution, flow or output observed in the actual production process and the oil-water relationship predicted based on the geological model. This contradiction may manifest in the following situations: The oil-water interface position does not match, that is, there is a deviation between the oil-water interface position measured in actual production and the position predicted by the geological model. This may be because the model fails to accurately reflect the complex underground geological structure or fluid distribution.

[0036] Abnormal oil-water production ratio, that is, in some wells, the actual oil-water ratio produced does not match the expected one, which may be due to changes in local geological conditions, such as the existence of faults and cracks, which affect the flow path of the fluid.

[0037] The prediction of flooded areas is inaccurate, that is, the flooded areas that occur in actual production are inconsistent with the flooded areas predicted based on the geological model. This may be because the model fails to accurately predict the flow path of water or the range of injected water.

[0038] Reservoir dynamic changes, that is, as development progresses, the oil-water relationship inside the reservoir may change, such as a decrease in reservoir pressure and an increase in the oil-water contact surface. These changes may cause the actual production dynamics to be inconsistent with the initial model predictions.

[0039] When there is a contradiction between oil and water, it is necessary to re-evaluate and revise the geological model through comprehensive analysis of multiple sources of information such as drilling, logging, production dynamics, and seismic information to more accurately reflect the actual distribution pattern of the oil sand body. This usually includes the following steps: Collect relevant drilling data, well logging curves, production performance records and seismic data, and conduct detailed analysis to identify changes in oil-water interface and abnormal reservoir properties.

[0040] Seismic data, especially high-resolution seismic data, are used to analyze reservoir configuration and fluid interfaces to identify the distribution and physical property changes of sand bodies between wells.

[0041] The drilling, logging, production dynamics and seismic data are comprehensively analyzed to identify the root causes of the oil-water relationship contradiction, and the original geological model is revised based on the comprehensive analysis results.

[0042] Based on the revised geological model, formulate corresponding development adjustment strategies, and verify the accuracy of the model by comparing it with production dynamic data, and further revise the model when necessary.

[0043] In a preferred embodiment, based on the oil sand body map, the multivariate classification comprehensive index (Feci) method is applied to the oil sand bodies with demarcated boundaries to calculate unified oil sand body comprehensive classification evaluation parameters, and the oil sand body classification boundaries are determined to classify and evaluate the oil sand body potential.

[0044] Appropriate evaluation parameters can be determined through oil sand bodies, and the Feci method can be used to classify and evaluate oil sand bodies. The detailed oil sand body map provides rich geological information, including lithology, structure, thickness, distribution range, etc., which provides a solid data foundation for the Feci method. Clear boundary demarcation helps to define the scope of the evaluation and ensure the accuracy and consistency of the evaluation object.

[0045] The multi-dimensional information contained in the oil sand body map, such as porosity, permeability, organic matter content, etc., can be directly or indirectly used as evaluation factors in the Feci method. This enables the evaluation to consider the potential of the oil sand body from multiple angles and in an all-round way, improving the comprehensiveness and accuracy of the evaluation.

[0046] Clear demarcation of oil sand body boundaries helps to achieve refined management of oil sand bodies. The Feci method can evaluate each independent oil sand body, thereby guiding the rational allocation of resources, optimizing development strategies, and improving development efficiency and economic benefits.

[0047] The detailed oil sands map and clear boundary demarcation enable the Feci method to provide more accurate classification and evaluation results, providing a more scientific reference for decision makers. This helps to make reasonable plans in the early stages of oil sands development and avoid waste of resources caused by blind development.

[0048] As new data are continuously acquired during oilfield development, the oil sand body map can be updated, and the evaluation parameters and weights of the Feci method can be adjusted accordingly to achieve dynamic evaluation and ensure that the evaluation results are synchronized with the actual geological conditions.

[0049] In a preferred embodiment, a multivariate classification comprehensive index method is used to calculate unified comprehensive classification evaluation parameters of oil sand bodies, and to determine the classification boundaries of oil sand bodies. Classification evaluation of oil sand body potential includes: Comprehensively consider the oil sand body reserves and recovery control factors to select evaluation parameters; The unified comprehensive classification evaluation parameters of oil sand bodies are calculated using the multivariate classification comprehensive index method; The attribute values ​​of all oil sand bodies are clustered by clustering method, the attribute value distribution interval of each type of oil sand body is counted, and the Feci classification boundary is determined; The oil sand body potential is evaluated based on the classification results.

[0050] In a preferred embodiment, the evaluation parameters selected by comprehensively considering the oil sand body reserves and recovery rate control factors include: oil layer thickness, oil-bearing area, permeability, porosity, and underground crude oil viscosity; The formula for calculating unified comprehensive classification evaluation parameters of oil sand bodies using the multivariate classification comprehensive index method is: ; in, h 0 , s 0, k 0, φ 0, μ 0 respectively represent the oil layer thickness, oil-bearing area, permeability, porosity, and underground crude oil viscosity of a single oil sand body; h min , s min , k min , φ min , which are respectively the minimum value of oil layer thickness, minimum value of oil-bearing area, minimum value of permeability, and minimum value of porosity of all oil sand bodies; μ max It is the maximum value of underground crude oil viscosity; The attribute values ​​of all oil sand bodies are clustered by clustering method, and the number of clusters is 3.

[0051] The thickness of the oil layer reflects the vertical scale of the oil sand body and is an important parameter for evaluating the amount of oil sand resources. Thicker oil layers usually mean larger reserves, which has a direct impact on the economic value of the oil sand body.

[0052] The oil-bearing area indicates the distribution range of oil sand bodies on the plane and is a key indicator for estimating the reserves and development potential of oil sand bodies. A larger oil-bearing area is conducive to improving the economy and feasibility of oil sand body development.

[0053] Permeability describes the difficulty of fluid flow in oil sand bodies, which directly affects the recovery rate and production efficiency of oil sand bodies. Oil sand bodies with high permeability are more conducive to the flow of fluids, thereby improving the efficiency of crude oil extraction.

[0054] Porosity reflects the proportion of pore space in the oil sand body. The higher the porosity, the larger the volume of fluid that can be stored and released in the oil sand body, which has an important impact on the oil storage capacity and oil recovery efficiency of the oil sand body.

[0055] The viscosity of underground crude oil is a key factor affecting the choice and cost of oil sand mining technology. High-viscosity crude oil is difficult to mine and usually requires special technologies such as thermal recovery and solvent injection, which increases development costs.

[0056] In the finely drawn oil sand body map, it can also be found that after the boundaries are demarcated, the individual oil sand bodies are compared. Combined with the verification results, according to the differences in reservoir potential, the above five parameters also have intuitive differences in the oil sand body map. Finally, according to the clustering results, it is determined that the number of clusters is determined to be 3, which can objectively reflect the potential characterization interval based on the oil sand body map. According to the results of classification evaluation, the potential size of a single oil sand body can be directly obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 The figure is a flowchart of a method for detailed characterization of oil and gas reservoirs and residual oil evaluation by integrating multiple information in one embodiment of the present invention.

[0058] Figure 2 It is a comprehensive histogram of a well logging curve of a certain oil field in one embodiment of the present invention.

[0059] Figure 3 This is a comparison chart of the stratigraphic structures of five wells in an oil field.

[0060] Figure 4 This is a microstructural map of a single sand body block in an oil field.

[0061] Figure 5 This is a single sand body fault block rock boundary map of a certain oil field.

[0062] Figure 6 This is the boundary map of the oil sand body in a single sand body block of an oil field.

[0063] Figure 7This is the boundary map of the oil sand body in a single sand body block of an oil field.

[0064] Figure 8 This is a map of the oil-bearing area of ​​a single sand body block in an oil field. DETAILED DESCRIPTION

[0065] In order to more clearly illustrate the overall concept of the present application, a detailed description is given below in an illustrative manner in conjunction with the accompanying drawings.

[0066] It should be noted that many specific details are set forth in the following description to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific implementation methods disclosed below.

[0067] In the description of the present application, it should be understood that the terms "upper", "lower", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In the present application, unless otherwise clearly specified and limited, a first feature being "upper" or "lower" than a second feature may be that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium.

[0068] In this application, unless otherwise clearly specified and limited, the terms "installation", "connection" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. However, if it is indicated as a direct connection, it means that the two connected bodies are not connected through a transition structure, but are only connected to form a whole through a connecting structure. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0069] In this application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0070] Oil sand body refers to a single closed space formed by the combination of independent sand bodies, faults and local structures in three dimensions. It is the smallest closed unit of oil reservoir formation.

[0071] With the long-term water injection development, sandstone oilfields are affected by the heterogeneity of the reservoir, and the remaining oil distribution is extremely scattered. The extraction degree of each single sand layer in the vertical direction is inconsistent, and the recoverable reserves of the remaining oil in different oil sand bodies in the plane are inconsistent. To accurately understand the remaining oil and formulate a reasonable development plan, the oil sand body must be accurately characterized first. How to use multi-well and multi-information data in oil field development to accurately characterize the oil sand body, accurately compile the oil sand body map, and provide an important geological basis for the formulation of oil field development plans is one of the focuses of this invention.

[0072] Due to complex geological conditions, great exploration difficulty, difficulty in data acquisition, limited research results, economic benefit considerations, technical challenges and other reasons, the configuration analysis of some sandstone oil fields has been seldom carried out. On the basis of compiling accurate oil sand body maps, the remaining oil evaluation method can be carried out based on the detailed characterization of oil and gas reservoirs, which is another focus of the present invention.

[0073] The following is an example of an oil field. Figure 1 The implementation process of the comprehensive multi-information fusion method for detailed characterization of oil and gas reservoirs and remaining oil evaluation is illustrated.

[0074] First, we conduct precise characterization and mapping of the oil sand bodies in a certain oil field. The process is as follows: Step 1: Single sand body identification and division

[0075] refer to Figure 2 According to the logging curve characteristics and sand body interpretation results, a certain oil field analyzed the sedimentary microfacies units and divided a total of 24 single sand bodies in combination with the dominant sand bodies.

[0076] Step 2: Single sand body comparison

[0077] Five wells were selected for multi-well single sand body lateral comparison, mainly using the iso-elevation comparison method, taking the top and bottom surfaces of the sand bodies equidistant from the same marker layer as isochronous surfaces, and the sand bodies between two isochronous surfaces are divided into the same single sand body. Figure 3 The sand bodies of NmⅣ-9-3 in Wells 1 and 2 have similar characteristics. Well 3 has two stratified sand bodies. The lower sand body in Well 4 is annihilated. The sand body in Well 5 is not developed at all.

[0078] Step 3: Microstructural interpretation

[0079] Based on the seismic interpretation, the microstructure analysis was conducted on the top boundary of the NmⅣ-9-3 sand body. The strata in this area are relatively flat, and the microstructure map was drawn by using 1-meter-spaced contour lines and contour line interpolation, such as Figure 4 .

[0080] Step 4: Determination of reservoir boundaries

[0081] According to the distribution of sandstone in each well in the dense well network, the distribution range of sandstone is clarified, and the area between sandstone and non-sandstone under the control of two wells of one well spacing is divided into three equal parts, and the one-third of the non-sandstone is used as the sand-mud sandstone boundary, such as Figure 5 .

[0082] Step 5: Determination of oil sand body boundaries

[0083] The NmⅣ-9-3 sand body has a clear oil-water interface near Well 79, and the oil sand body boundary is divided according to the oil-water boundary. The oil sand body boundary is divided at one-third of the sandstone boundary between the sandstone boundary and the oil layer well near the sandstone boundary near Well 20-1 and Well 67-49 for lithological oil reservoirs, such as Figure 6 .

[0084] Step 6: Understanding Oil-Bearing Sands

[0085] Wells 1, 2, 10, and 88 were drilled in the late stage of water injection development. The NmⅣ-9-3 sand body was flooded. According to the distribution of oil layers before water injection development, that is, oil layer treatment, Figure 7 .

[0086] Step 7: Preparation of oil sand body map

[0087] Compile a map of the NmⅣ-9-3 oil sand body. Figure 8 Well point information includes coordinates, single sand layer top depth, sand layer thickness, oil and gas layer thickness. The scale is 1:10000 line segment scale. The frame is a double-line frame, thick outside and thin inside, with coordinates marked. Contour lines are marked with negative values; fault lines: the upper and lower plates are distinguished by line thickness, the descending plate is thicker than the ascending plate, and the ascending plate is slightly thicker than the contour line; the oil layer in the oil and gas area is red; sandstone pinch-out line ; Legend map in the lower right corner, with an outer frame on both sides overlapping with the inner frame; Drawing time outside the frame in the upper right corner, with numbers in uppercase Chinese characters; Drawing unit in the lower left corner; Responsibility column in the lower right corner; Sequence of map compilation, drawing, responsibility, and review.

[0088] Step 8: Classification and evaluation of oil sand potential (1) Parameter optimization Taking into account the control factors of oil sand body reserves and recovery rate reflected in the oil sand body map, five major parameters including oil layer thickness, oil-bearing area, permeability, porosity and underground crude oil viscosity were optimized.

[0089] (2) Multivariate classification comprehensive index (Feci) The unified comprehensive classification evaluation parameters of oil sand bodies are calculated using the multivariate classification comprehensive index method. The formula is as follows:

[0090] Where: h 0 ,s 0, k 0, φ 0, μ 0, the attribute values ​​of a single oil sand body, which are oil layer thickness, oil-bearing area, permeability, porosity, and underground crude oil viscosity; h min , s min , k min , φ min They are the thickness of oil layers, oil-bearing area, permeability and porosity of all oil sand bodies respectively; μ max , which is the maximum viscosity of underground crude oil.

[0091] (3) Determining the classification boundaries of oil sand bodies The attribute values ​​of all oil sand bodies are clustered by clustering method, the number of clusters is 3, and the distribution range of attribute values ​​of each type of oil sand body is counted to determine the reasonable Feci Classification boundaries. The results are shown in Table 1:

[0092] According to the above table, the classification boundaries of oil sand bodies are determined as follows: Feci ≥ 10, which is Class I oil sand body; 6 ≤ Feci < 10, which is Class II oil sand body; Feci < 6, which is Class III oil sand body.

[0093] The oil sand bodies of a certain oil field, which were characterized in detail in the previous article, were classified and evaluated according to the classification boundaries of the oil sand bodies: 1. Determine the oil sand body parameter values h0=6.2m, s0=1.2km 2 , k0=908mD, φ0=25%, μ0=10.4mPa·s 2. Calculate the parameters of comprehensive classification and evaluation of oil sand bodies by formula Feci = ln((6.2 / 1.5)*(1.2 / 0.13)*(908 / 15)*(25 / 16.1)*(305.5 / 10.4))=11.57 3. Determine potential types based on classification boundaries According to the classification boundary of oil sand bodies, the oil sand body Feci≥10, which is a Class I oil sand body and can be identified as an oil sand body with relatively rich potential.

[0094] Anything not described in this application can be achieved by adopting or drawing on existing technologies.

[0095] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0096] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A method for fine characterization of oil and gas reservoirs and residual oil evaluation based on multi-information fusion, comprising the following steps: For oil-bearing sand bodies, single sand bodies are identified and divided based on sedimentary microfacies units; Conduct single sand body comparison to obtain continuous comparison boundaries, and use seismic inversion methods to determine inter-well sand body changes; Microstructural interpretation using 3D seismic data and dense well pattern data; Delineate sandstone boundaries and oil sand body boundaries; Comprehensive analysis includes drilling, logging, production dynamics and seismic information to correct the distribution and identification of oil sand bodies; Prepare oil sand body maps including well point information annotations; Based on the oil sands map, the potential of the demarcated oil sands is evaluated.

2. The method according to claim 1, characterized in that A microfacies unit contains only one sand body or one dominant sand body.

3. The method according to claim 2, characterized in that Single sand body comparison is performed by using one or more comparison methods selected from equal elevation comparison, time unit comparison, phase-controlled isochronous comparison, and downcut sand body comparison, combined with seismic inversion technology.

4. The method according to claim 3, characterized in that The contour comparison method is applicable to river floodplains and channel filling deposits. These deposits should be at the same level and are used to identify and compare sand bodies formed in the same sedimentary event. The top and bottom surfaces of these sand bodies are equidistant from the same marker layer. Through contour comparison, sand bodies formed in the same sedimentary event can be identified. The time unit comparison method is applicable to the situation where the river channel positions of different periods are inherited due to the strong cutting action of the river, and the river sediments of each period may be eroded and diverted by the later river, and the river channel sands of different periods are superimposed into thick composite sand bodies. It is used to distinguish superimposed sand bodies from thickness and curve morphology, and understand the superposition relationship of multi-period river sediments and the complex structure of sand bodies. The phase-controlled isochronous correlation method is applicable to thin interbeds composed of siltstone and mudstone, which are "event bodies" of isochronous and different microfacies deposited simultaneously. Through phase-controlled isochronous correlation, different microfacies formed in the same sedimentary event can be identified. The downcut sand body comparison method is applicable to the situation where the sand body is obviously "downcut" and has a small distribution range due to the strongest scouring near the mainstream of the river. It is used to identify the downcut sand body formed by river scouring and understand the erosion and filling process of river sediments. Seismic inversion technology is suitable for situations where the sand and mudstone properties change rapidly in the lateral direction, the phase change is obvious, resulting in discontinuous reflection interfaces and frequent changes. Seismic inversion technology can be used to assist in judging the changes and connectivity of sand bodies between wells.

5. The method according to claim 4, characterized in that Microstructural interpretation using 3D seismic data and dense well pattern data; include Collect and organize 3D seismic data and dense well network data. 3D seismic data includes detailed images of underground structures, while dense well network data includes precise geological information at the well points, including lithology, formation interfaces, and faults. Process 3D seismic data, including denoising, migration, and velocity analysis, to improve the quality and resolution of seismic imaging; Interpret the processed seismic data, including identifying and tracing stratigraphic interfaces, faults, and sand body boundaries; use seismic attribute analysis, including amplitude, frequency, and phase, to further clarify the internal structure and distribution characteristics of the sand body; Integrate the dense well network data with the seismic interpretation results, and accurately correspond the seismic interpretation results to geological ages and stratigraphic sequences based on the precise stratigraphic calibration provided by the dense well network data; Combine seismic interpretation results with dense well pattern data to conduct detailed interpretation of sand body microstructure, including identification of tiny stratigraphic fluctuations, faults, fractures and their effects on sand body distribution and fluid flow; Based on the interpretation results, a sand body microstructural model is established, which includes the spatial distribution and microstructural characteristics of the sand body; The accuracy of microstructural interpretation is verified by comparing with production dynamic data, and the model is modified based on the verification results.

6. The method according to claim 1, characterized in that Delineation of sandstone boundaries and oil sand body boundaries includes The sandstone boundary is determined through seismic multi-attribute prediction and dense well network data; the oil sand body boundary is divided according to the reservoir type and oil-water relationship.

7. The method according to claim 6, characterized in that Comprehensive analysis includes drilling, logging, production dynamics and seismic information to correct the distribution and identification of oil sand bodies, including When conflicts arise between oil and water, comprehensive analysis of multiple information, including If the single sand body comparison is incorrect, re-compare the single sand body; If the logging interpretation is inaccurate, the oil and water layers are reinterpreted; If the wells are drilled at different times and the new wells are flooded at a later stage, they will be treated according to the original reservoir state before water injection development.

8. The method according to any one of claims 1 to 7, characterized in that Based on the oil sand body map, the multivariate classification comprehensive index method is used to calculate unified oil sand body comprehensive classification evaluation parameters for the delineated oil sand bodies, and the classification boundaries of the oil sand bodies are determined to classify and evaluate the oil sand body potential.

9. The method according to claim 8, characterized in that The multivariate classification comprehensive index method is used to calculate the unified comprehensive classification evaluation parameters of oil sand bodies, determine the classification boundaries of oil sand bodies, and classify and evaluate the potential of oil sand bodies, including Comprehensively consider the oil sand body reserves and recovery control factors to select evaluation parameters; The unified comprehensive classification evaluation parameters of oil sand bodies are calculated using the multivariate classification comprehensive index method; The attribute values ​​of all oil sand bodies are clustered by clustering method, the attribute value distribution interval of each type of oil sand body is counted, and the Feci classification boundary is determined; The oil sand body potential is evaluated based on the classification results.

10. The method according to claim 9, characterized in that The evaluation parameters selected by comprehensively considering the oil sand body reserves and recovery control factors include: oil layer thickness, oil-bearing area, permeability, porosity, and underground crude oil viscosity; The formula for calculating unified comprehensive classification evaluation parameters of oil sand bodies using the multivariate classification comprehensive index method is: ； in, h 0 , s 0, k 0, φ 0, μ 0 respectively represent the oil layer thickness, oil-bearing area, permeability, porosity, and underground crude oil viscosity of a single oil sand body; h min , s min , k min , φ min , which are respectively the minimum value of oil layer thickness, minimum value of oil-bearing area, minimum value of permeability, and minimum value of porosity of all oil sand bodies; μ max It is the maximum value of underground crude oil viscosity; The attribute values ​​of all oil sand bodies are clustered by clustering method, and the number of clusters is 3.

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