A method for fine characterization and evaluation of oil sand bodies based on multi-information fusion

Abstract

The present invention provides a method for fine characterization and evaluation of oil sand bodies based on multi-information fusion. The method comprehensively considers multiple information such as drilling, logging, production dynamics, and seismic information, identifies and divides single sand bodies based on sedimentary feature analysis, understands the correspondence between sand bodies and sedimentary change laws based on multiple information, and compares single sand bodies. The method uses well information and seismic technology to depict sand body microstructures, comprehensively judges reservoir boundaries and oil layer boundaries based on multiple information, marks the top elevation depth of a single sand layer, oil layer thickness, and sand layer thickness beside the well, comprehensively evaluates the oil and water layers encountered in drilling at different water injection development stages, judges the distribution law of oil sand bodies, standardizes the compilation of oil sand body maps, and accurately evaluates oil sand bodies. The method provides an important geological basis for the compilation of oilfield development plans, and improves the accuracy and reliability of remaining oil evaluation.

Description

Technical Field

[0001] The present application relates to oil and gas resource exploration, 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] An oil sand body is a single, three-dimensional, closed space formed by the combination of independent sand bodies, faults, and local structures. It is the smallest unit of oil reservoir formation. With long-term waterflooding, sandstone oilfields, influenced by reservoir heterogeneity, have a highly dispersed distribution of remaining oil. The vertical recovery rate of individual sand layers varies, and the recoverable reserves of remaining oil vary across different oil sand bodies. Accurate characterization of the oil sand bodies is crucial for accurately understanding remaining oil and formulating sound development plans. Current methods for characterizing and mapping oil sand bodies focus solely on comparing and mapping stratification boundaries and conducting comprehensive analysis of oil, gas, and water distribution. These methods fail to capture the subtle structural fluctuations of the reservoir, accurately characterize the variations between reservoir and non-reservoir layers, and poorly assess the distribution of oil, gas, and water. Furthermore, traditional reservoir development often relies on single-source information, such as well logging or seismic data, to understand reservoir architecture and assess remaining oil distribution, limiting a comprehensive understanding of reservoir complexity. As oilfield development deepens, integrating multiple data to accurately assess remaining oil distribution becomes crucial for improving oil 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] This 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 data. Based on sedimentary feature analysis, single sand bodies are identified and divided. Multi-information is used to understand the correspondence between sand bodies and the law of sedimentary changes, and single sand bodies are compared. Well information and seismic technology are used to characterize the microstructure of sand bodies. Multi-information is used to comprehensively determine the reservoir boundary and oil layer boundary. The top elevation depth of a single sand layer, the oil layer thickness, and the sand layer thickness are marked next to the well. The oil and water layers encountered during different water injection development stages are comprehensively evaluated, the distribution law of oil sand bodies is determined, and oil sand body maps are compiled in a standardized manner. Based on the finely characterized oil sand body maps, multiple information sources can be integrated to achieve a method for fine characterization of oil and gas reservoirs and residual oil evaluation, which is of great significance for the efficient development of oil fields.

[0005] To achieve the above objectives, the technical solutions adopted in this application are:

[0006] The method for detailed characterization of oil and gas reservoirs and remaining oil evaluation based on multi-information fusion includes the following steps:

[0007] For oil-bearing sand bodies, single sand bodies are identified and divided based on sedimentary microfacies units;

[0008] Conduct single sand body comparison to derive continuous comparison boundaries, and use seismic inversion methods to determine inter-well sand body changes;

[0009] Use 3D seismic data and dense well pattern data to draw sand body microstructure maps;

[0010] Delineate sandstone boundaries and oil sand body boundaries;

[0011] Comprehensive analysis of drilling, logging, production dynamics and seismic information to correct the distribution and identification of oil sand bodies;

[0012] Prepare oil sand body maps including well point information annotation, scale setting, frame design, map content drawing, and legend creation;

[0013] 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;

[0014] 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.

[0015] This approach overcomes the shortcomings of traditional methods in oil sand body characterization and mapping. While improving the accuracy of oil sand body research, it also integrates multiple information sources to achieve detailed structural delineation of oil sand reservoirs and accurate assessment of remaining oil distribution. This provides strong geological support for remaining oil research and development planning.

[0016] This method, based on reservoir formation patterns, comprehensively considers multiple information sources, including drilling, logging, production dynamics, and seismic data. It identifies and divides individual sand bodies based on sedimentary feature analysis, uses multiple information sources to understand sand body correspondences and sedimentary variation patterns, and compares individual sand bodies. It uses well information and seismic technology to characterize sand body microstructures, comprehensively determines reservoir and oil layer boundaries, and annotates the top elevation depth of individual sand layers, oil layer thickness, and sand layer thickness near the wells. It comprehensively evaluates the oil and water layers encountered during different waterflooding development stages, determines the distribution patterns of oil sand bodies, and standardizes the compilation of oil sand body maps. Through precise characterization and mapping of oil sand bodies, combined with production dynamic analysis, it is possible to intuitively determine remaining oil potential, waterlogging conditions, and the degree of integrity of the injection-production well network, providing accurate geological maps for the preparation of comprehensive adjustment plans.

[0017] By integrating multiple sources of information, including geology, geophysics, well logging, and production performance, reservoir architecture units within oil and gas reservoirs can be more accurately identified and delineated. This multi-information fusion approach helps reduce errors potentially introduced by single-source information and improves the accuracy of reservoir geological characterization. Comprehensive analysis of reservoir geological characteristics, production performance, and numerical simulation results enables a more accurate assessment of the distribution of remaining oil sources and recoverable reserves. This approach can identify areas of remaining oil concentration, providing a scientific basis for subsequent development adjustments and enhanced oil recovery measures. The assessment results can provide a more scientific basis for reservoir development decisions. For example, based on the assessment of remaining oil distribution, targeted development adjustment strategies can be formulated, such as adjusting injection and production patterns, implementing infill drilling, and employing enhanced oil recovery technologies. It can also enable more efficient development of oil and gas resources, improving 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 oil and gas resource recovery.

[0018] Multi-information fusion methods provide a more comprehensive understanding of the geological characteristics and fluid distribution of oil and gas reservoirs, helping to reduce technical and economic risks during exploration and development. Accurate geological models and assessments of remaining oil source distribution can guide exploration and development activities, reducing unnecessary investment and resource waste.

[0019] This multi-information fusion-based analysis and evaluation method also offers an innovative approach, integrating multiple advanced technologies, such as high-resolution seismic, sophisticated well logging interpretation, and reservoir numerical simulation. Its implementation has promoted advancements and innovations in related technologies, advancing the development of oil and gas exploration and development technologies, and providing insights and research ideas for subsequent, in-depth, refined research.

[0020] In a preferred embodiment, a microfacies unit contains only one sand body or one dominant sand body.

[0021] Preferential sand bodies are sand bodies with relatively good reservoir properties within an oil and gas reservoir, such as high porosity, permeability, and thick sand layers, and are conducive to oil and gas accumulation and flow. These sand bodies are typically the main targets in oil and gas exploration and development because they can provide higher productivity and better economic benefits.

[0022] Preferential sand bodies typically have higher porosity and permeability, meaning they can store more oil and gas and face less resistance to oil and gas flow, facilitating oil and gas recovery. The greater thickness of the sand layers within these sand bodies not only increases oil and gas reserves but also facilitates the formation of continuous flow pathways, improving oil and gas recovery efficiency. Preferential sand bodies often form in environments favorable for sandy deposition, such as rivers, deltas, and beaches, which foster the formation of structurally stable and well-sorted sand bodies. In some cases, they may be located in tectonic settings favorable for oil and gas accumulation, such as anticlines and fault barriers. These structures can serve as traps for oil and gas reservoirs, increasing oil and gas enrichment. Fluids (oil, gas, and water) within these sand bodies typically have good mobility, which helps increase oil and gas production rates and recovery ratios. The identification and evaluation of preferred sand bodies is crucial in oil and gas exploration and development, as they are the primary carriers of oil and gas resources. By comprehensively applying various information such as geology, geophysics, well logging and production dynamics, dominant sand bodies can be effectively identified and divided, providing a scientific basis for the development of oil and gas fields.

[0023] In a preferred embodiment, single sand body comparison is performed by using one or more comparison methods selected from the group consisting of contour comparison, time unit comparison, phase-controlled isochronous comparison, and downcut sand body comparison, combined with seismic inversion technology.

[0024] Each correlation method has its own applicable geological conditions and sedimentary environments. By selecting the appropriate correlation method and combining it with the cross-well information provided by seismic inversion technology, individual sand bodies can be more accurately identified and correlated, especially in complex sedimentary environments, thereby improving the accuracy and reliability of the correlation.

[0025] Different correlation methods reflect different sedimentary processes and environmental characteristics. For example, contour correlation is suitable for river floodplains and channel-fill deposits, while temporal unit correlation is suitable for strongly incised river deposits. By combining these methods, we can enhance our understanding of the sedimentary environment of oil and gas reservoirs.

[0026] The temporal unit correlation method is applicable to situations where the strong incision of rivers leads to the inheritance of river channel positions over different periods. Sediments from each period of river flow may be eroded and diverted by subsequent rivers, resulting in the superposition of channel sands from different periods into thick composite sand bodies. This method helps identify superimposed sand bodies based on their thickness and curvilinear morphology, and helps understand the superposition of multi-period river sedimentation and the complex structure of sand bodies.

[0027] Phase-controlled isochronous correlation is applicable to thin interbeds of siltstone and mudstone, representing simultaneous, isochronous microfacies "event bodies." These sand bodies are often located at channel margins or in levee subfacies. Phase-controlled isochronous correlation can identify different microfacies formed during the same depositional event, helping to understand microfacies variations within a sedimentary system and lateral phase transitions within sand bodies.

[0028] Methods such as downcut sandbody correlation and facies-controlled isochronous correlation can reveal the internal structure and sedimentary sequence of sand bodies, such as the scour surface and superposition relationship of sand bodies. This information is crucial for understanding the connectivity of sand bodies and fluid flow paths.

[0029] Accurately identifying and comparing individual sand bodies helps optimize reservoir development strategies. For example, injection-production well patterns can be designed based on the distribution and connectivity of sand bodies to improve the efficiency of waterflood development, or enhanced oil recovery measures can be implemented for sand bodies rich in residual oil. Seismic inversion technology can provide information on the distribution and physical properties of interwell sand bodies. Combined with specific comparison methods, seismic inversion results can be more effectively utilized, improving the application of seismic data in reservoir characterization. By combining multiple comparison methods and seismic inversion techniques, the geological characteristics of oil and gas reservoirs can be more comprehensively assessed, reducing technical and economic risks during exploration and development. Accurate geological models help guide exploration and development activities and reduce unnecessary investment and resource waste.

[0030] 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 has promoted technological innovation and method integration, and promoted the development of oil and gas exploration and development technology.

[0031] In a preferred embodiment, microstructural interpretation is performed using 3D seismic data and dense well pattern data;

[0032] Collect and organize 3D seismic data and dense well pattern data. 3D seismic data includes detailed images of underground structures, while dense well pattern data includes precise geological information at the well points, including lithology, formation interfaces, and faults.

[0033] Process 3D seismic data, including denoising, migration, and velocity analysis, to improve the quality and resolution of seismic imaging;

[0034] Interpret the processed seismic data, including identifying and tracing bed interfaces, faults, and sand body boundaries; and using seismic attribute analysis, including amplitude, frequency, and phase, to further clarify the internal structure and distribution characteristics of the sand bodies.

[0035] Integrate the dense well network data with the seismic interpretation results, and accurately map the seismic interpretation results to geological ages and stratigraphic sequences based on the precise stratigraphic calibration provided by the dense well network data;

[0036] Combine seismic interpretation results with dense well pattern data to conduct detailed interpretation of sand body microstructure, including identifying small stratigraphic reliefs, faults, fractures and their effects on sand body distribution and fluid flow;

[0037] Based on the interpretation results, a sand body microstructural model is established, which includes the spatial distribution and microstructural characteristics of the sand body;

[0038] The accuracy of the microstructural interpretation is verified by comparing it with production dynamic data, and the model is modified based on the verification results.

[0039] 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 oil and gas reservoir characterization and remaining oil and gas analysis.

[0040] Accurate microstructural information helps optimize injection-production well pattern design, improve waterflood development efficiency, and rationally deploy enhanced oil recovery measures. Detailed microstructural interpretation helps identify potential development risks, such as faults hindering fluid flow and the impact of microstructure on the oil-water interface, enabling appropriate risk control measures to be implemented.

[0041] 3D seismic data provides a macroscopic image of the subsurface structure, while dense well pattern data provides precise geological information at the well points. Combining these two types of information allows for a more comprehensive understanding of the distribution and microstructural characteristics of sand bodies. Single-sandbody correlation methods focus on identifying and correlating individual sand bodies using well data and seismic inversion techniques. These methods provide detailed information on the internal structure and sedimentary sequence of sand bodies. Combining these two methods can provide a comprehensive understanding of the geological characteristics of oil and gas reservoirs.

[0042] When interpreting sand body microstructures in detail, seismic data interpretation requires precise calibration of well data, and well data interpretation, in turn, requires verification and expansion of the interwell information provided by seismic data. Similarly, single sand body comparison methods also require the use of seismic inversion technology to assist in determining interwell sand body variations and connectivity. The synergistic use of these two methods can improve the accuracy of understanding sand body distribution and microstructural characteristics.

[0043] When establishing and revising reservoir geological models, the finely interpreted sand body microstructures and single sand body comparison results need to be mutually verified. For example, the sand body boundaries and sedimentary sequences determined through single sand body comparison can be used to verify the rationality of the sand body distribution interpreted from seismic analysis; conversely, the sand body distribution and microstructural characteristics interpreted from seismic analysis can also be used to verify the accuracy of single sand body comparison results.

[0044] Detailed interpretation of sand microstructures and comparison of individual sand bodies are crucial for decision-making in oil and gas reservoir development. For example, when designing injection and production well patterns, it is important to consider the distribution and connectivity of 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 results of oil and gas fields.

[0045] In a preferred embodiment, delineating sandstone boundaries and oil sand body boundaries includes

[0046] Sandstone boundaries are determined through seismic multi-attribute prediction and dense well network data; oil sand body boundaries are divided according to reservoir type and oil-water relationship.

[0047] Determining the sandstone boundary involves using the sand-to-ground ratio predicted by seismic multi-attribute predictions as a primary constraint to distinguish between mudstone and sandstone. Based on dense well network data, the area between sandstone and non-sandstone controlled by two wells at a given spacing is divided into three equal parts, with the sand-mud reservoir boundary defined at the non-sandstone third.

[0048] Determination of oil sand body boundaries includes

[0049] Structural oil reservoirs have oil sand bodies with clear oil-water interfaces, and the boundaries of the oil sand bodies are divided according to the oil-water boundary.

[0050] The fault block reservoir is full of oil and is completely filled with oil layers.

[0051] 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 and the sandstone boundary.

[0052] In a preferred embodiment, comprehensive analysis includes drilling, logging, production dynamics and seismic information to correct the oil sand body distribution identification, including

[0053] When conflicts arise between oil and water, comprehensive analysis of multiple information is conducted, including

[0054] If the single sand body comparison is incorrect, re-compare the single sand body;

[0055] If the well logging interpretation is inaccurate, the oil and water layers should be reinterpreted;

[0056] If the wells were drilled at different times and the new wells were flooded later, they would be treated according to the original reservoir status before water injection development.

[0057] In oil and gas exploration and development, an "oil-water discrepancy" occurs when the observed oil-water distribution, flow, or output during actual production differs from the oil-water relationship predicted based on geological models. This discrepancy can manifest in the following ways:

[0058] The oil-water interface position does not match, that is, the oil-water interface position measured in actual production deviates from 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.

[0059] 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.

[0060] Inaccurate prediction of flooded areas, that is, the flooded areas that occur in actual production are inconsistent with the flooded areas predicted based on the geological model, which may be because the model fails to accurately predict the flow path of water or the range of injected water.

[0061] 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 performance to be inconsistent with the initial model prediction.

[0062] When oil-water relationship conflicts arise, it is necessary to re-evaluate and revise the geological model through comprehensive analysis of multiple sources of information, including drilling, logging, production dynamics, and seismic data, to more accurately reflect the actual distribution patterns of the oil sands. This typically involves the following steps:

[0063] Collect relevant drilling data, well logs, production performance records and seismic data, and conduct detailed analysis to identify changes in oil-water contact and abnormal reservoir physical properties.

[0064] Seismic data, especially high-resolution seismic data, are used to analyze reservoir architecture and fluid interfaces to identify the distribution and physical property changes of sand bodies between wells.

[0065] Comprehensive analysis of drilling, logging, production dynamics and seismic data is conducted to identify the root causes of oil-water relationship contradictions, and the original geological model is revised based on the comprehensive analysis results.

[0066] Based on the revised geological model, corresponding development adjustment strategies are formulated, and the accuracy of the model is verified by comparing it with production dynamic data, and the model is further revised when necessary.

[0067] 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, determine the oil sand body classification boundaries, and classify and evaluate the oil sand body potential.

[0068] Appropriate evaluation parameters can be determined through oil sand bodies, and the Feci method can be used to classify and evaluate oil sand bodies.

[0069] Detailed oil sands maps provide a wealth of geological information, including lithology, structure, thickness, and distribution, providing a solid data foundation for the Feci method. Clear boundary demarcation helps define the scope of the evaluation, ensuring accuracy and consistency of the evaluation objects.

[0070] The multidimensional information contained in the oil sands map, such as porosity, permeability, and organic matter content, can be used directly or indirectly as evaluation factors in the Feci method. This allows the evaluation to consider the potential of the oil sands from multiple angles and in an all-round manner, improving the comprehensiveness and accuracy of the evaluation.

[0071] Clear demarcation of oil sand body boundaries facilitates refined management of these bodies. The Feci method can evaluate each individual oil sand body, thereby guiding the rational allocation of resources, optimizing development strategies, and improving development efficiency and economic benefits.

[0072] Detailed oil sands maps and clear boundary delineation 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 the waste of resources caused by blind development.

[0073] 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.

[0074] In a preferred embodiment, a multivariate classification comprehensive index method is used to calculate unified comprehensive classification evaluation parameters of oil sand bodies and determine the classification boundaries of oil sand bodies. The classification evaluation of oil sand body potential includes:

[0075] Comprehensively consider the oil sand body reserves and recovery control factors to select evaluation parameters;

[0076] The unified comprehensive classification evaluation parameters of oil sand bodies are calculated using the multivariate classification comprehensive index method;

[0077] 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;

[0078] The oil sands potential is evaluated based on the classification results.

[0079] 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;

[0080] The formula for calculating unified comprehensive classification evaluation parameters of oil sand bodies using the multivariate classification comprehensive index method is:

[0081] ;

[0082] in, h 0 , s 0, k 0, φ 0, μ 0 respectively represents 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 the minimum values ​​of oil layer thickness, oil-bearing area, permeability and porosity of all oil sand bodies respectively; μ max is the maximum viscosity of underground crude oil;

[0083] The attribute values ​​of all oil sand bodies are clustered using the clustering method, and the number of clusters is 3.

[0084] Oil layer thickness reflects the vertical scale of an oil sand body and is an important parameter for assessing its resource abundance. Thicker oil layers generally indicate greater reserves, which has a direct impact on the economic value of the oil sand body.

[0085] Oil-bearing area represents the distribution of oil sands on a plane and is a key indicator for estimating oil sand reserves and development potential. A larger oil-bearing area improves the economic efficiency and feasibility of oil sand development.

[0086] Permeability describes the ease with which fluids flow through oil sands, directly impacting their recovery rate and production efficiency. Oil sands with high permeability are more conducive to fluid flow, thereby improving crude oil extraction efficiency.

[0087] 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.

[0088] The viscosity of underground crude oil is a key factor influencing the choice and cost of oil sands extraction technology. High-viscosity crude oil is difficult to extract, often requiring specialized techniques such as thermal recovery and solvent injection, which increases development costs.

[0089] In the carefully mapped oil sands, it can be seen that after demarcation, individual oil sands can be compared. Combined with the verification results, the five parameters mentioned above also show intuitive differences in the oil sands map, based on differences in reservoir potential. Ultimately, based on the clustering results, it was determined that the number of clusters was set to 3, which can objectively reflect the potential characterization range based on oil sands mapping. The results of the classification evaluation can directly determine the potential of individual oil sands. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] 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:

[0091] Figure 1This is a flowchart of a method for detailed characterization of oil and gas reservoirs and remaining oil evaluation using comprehensive multi-information fusion in one embodiment of the present invention.

[0092] Figure 2 This is a comprehensive histogram of logging curves of a certain oil field in one embodiment of the present invention.

[0093] Figure 3 This is a comparison chart of the stratigraphic structures of five wells in an oil field.

[0094] Figure 4 This is a microstructural map of a single sand body block in an oil field.

[0095] Figure 5 This is a boundary map of a single sand body fault block rock in an oil field.

[0096] Figure 6 This is the boundary map of the oil sand body in a single sand body block of an oil field.

[0097] Figure 7 This is the boundary map of the oil sand body in a single sand body block of an oil field.

[0098] Figure 8 This is a map of the oil-bearing area of ​​a single sand body block in an oil field. DETAILED DESCRIPTION

[0099] In order to more clearly illustrate the overall concept of the present application, a detailed description is given below in combination with the accompanying drawings by way of examples.

[0100] 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 can 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.

[0101] In the description of this application, it should be understood that the terms "upper," "lower," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. In this application, unless otherwise expressly provided or limited, a first feature being "above" or "below" a second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary.

[0102] In this application, unless otherwise specified or limited, terms such as "mounted" and "connected" should be interpreted broadly. For example, they can refer to fixed connections, removable connections, or integration; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. However, the term "direct connection" indicates that the two connected entities are not connected through a transition structure, but are connected solely through a connecting structure to form a single entity. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0103] In this application, references to "first," "second," and the like are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include at least one of these features.

[0104] An oil sand body refers to a single closed space in three dimensions formed by the combination of independent sand bodies, faults and local structures. It is the smallest closed unit of oil reservoir formation.

[0105] With long-term waterflooding, sandstone oilfields, affected by reservoir heterogeneity, have a highly dispersed distribution of remaining oil. The vertical recovery rates of individual sand layers are inconsistent, and the horizontal recoverable reserves of different oil sand bodies vary. To accurately understand the remaining oil and formulate a reasonable development plan, the oil sand bodies must be accurately characterized. One of the key points of this invention is how to use multi-well and multi-information data from oilfield development to accurately characterize and compile oil sand body maps, providing an important geological foundation for formulating oilfield development plans.

[0106] Due to complex geological conditions, difficulty in exploration, difficulty in data acquisition, limited research results, economic benefit considerations, and technical challenges, configuration analysis of some sandstone oil fields has been seldom carried out. On the basis of compiling accurate oil sand body maps, residual oil evaluation methods can be developed based on the detailed characterization of oil and gas reservoirs, which is another focus of the present invention.

[0107] The following is an example of an oil field. Figure 1 The implementation process of the comprehensive multi-information fusion method for oil and gas reservoir fine characterization and remaining oil evaluation is illustrated.

[0108] First, we conduct precise characterization and mapping of the oil sand bodies in a certain oil field. The process is as follows:

[0109] Step 1: Single sand body identification and division

[0110] refer to Figure 2 Based on 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.

[0111] Step 2: Single sand body comparison

[0112] Five wells were selected for multi-well single sandbody lateral comparison, mainly using the iso-elevation comparison method. The top and bottom surfaces of the sandbody equidistant from the same marker layer were taken as isochronous surfaces, and the sandbody between two isochronous surfaces was divided into the same single sandbody. 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.

[0113] Step 3: Microstructural interpretation

[0114] Based on seismic interpretation, microstructural analysis was conducted on the top boundary of the NmⅣ-9-3 sand body. The strata in this area are relatively flat, so 1-meter-spaced contour lines were used to interpolate the contour lines and draw a microstructural map. Figure 4 .

[0115] Step 4: Determination of reservoir boundaries

[0116] 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 controlled by two wells with a well spacing is divided into three equal parts. The boundary between sandstone and mudstone is taken as the boundary between sandstone and sandstone, such as Figure 5 .

[0117] Step 5: Determine the boundaries of the oil sand body

[0118] 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 the sandstone boundary and the oil layer between the sandstone boundary and the oil layer, which is a lithologic reservoir near Well 20-1 and Well 67-49. Figure 6 .

[0119] Step 6: Understanding Oil Sands

[0120] Wells 1, 2, 10, and 88 were drilled in the later 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, the oil layer treatment, Figure 7 .

[0121] Step 7: Oil sand body map preparation

[0122] Map the NmⅣ-9-3 oil sand body. Figure 8 Well point information includes coordinates, single sand layer top depth, sand layer thickness, and oil and gas layer thickness. The scale is 1:10,000 line segment scale. The frame is a double-line frame, thicker on the outside and thinner on the inside, with coordinates marked. Contour lines are marked with negative values; fault lines are distinguished by line thickness, with the descending line thicker than the ascending line, and the ascending line slightly thicker than the contour line; oil and gas-bearing areas are red in oil layers; sandstone pinchout lines ; The legend is in the lower right corner, with an outer frame on both sides overlapping with the inner frame of the figure; the drawing time is outside the frame in the upper right corner, with numbers in uppercase Chinese characters; the drawing unit is in the lower left corner outside the frame; the responsibility column is in the lower right corner outside the frame; the order of map compilation, drawing, responsibility, and review.

[0123] Step 8: Classification and evaluation of oil sands potential

[0124] (1) Parameter optimization

[0125] Taking into account the factors controlling oil sand reserves and recovery rate as reflected in the oil sand map, five major parameters, namely oil layer thickness, oil-bearing area, permeability, porosity, and underground crude oil viscosity, were optimized.

[0126] (2) Multivariate classification comprehensive index (Feci)

[0127] The unified comprehensive classification evaluation parameters of oil sand bodies are calculated using the multivariate classification comprehensive index method. The formula is as follows:

[0128]

[0129] 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.

[0130] (3) Determine the classification boundaries of oil sand bodies

[0131] The attribute values ​​of all oil sand bodies are clustered by clustering method, the number of clusters is 3, and the attribute value distribution interval of each type of oil sand body is counted to determine the reasonable Feci Classification boundaries. The results are shown in Table 1:

[0132]

[0133] 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.

[0134] The oil sand bodies of a certain oil field, which were previously characterized by fine oil sand body classification, were classified and evaluated according to the oil sand body classification boundaries:

[0135] 1. Determine the oil sand body parameter values

[0136] h0=6.2m,s0=1.2km 2 , k0=908mD, φ0=25%, μ0=10.4mPa·s

[0137] 2. Calculate the comprehensive classification evaluation parameters of oil sand bodies using the formula

[0138] Feci = ln((6.2 / 1.5)*(1.2 / 0.13)*(908 / 15)*(25 / 16.1)*(305.5 / 10.4))=11.57

[0139] 3. Determine potential types based on classification boundaries

[0140] 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.

[0141] Anything not described in this application can be achieved by adopting or drawing on existing technologies.

[0142] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0143] The foregoing is merely 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 principles of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for detailed 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 derive continuous comparison boundaries, and use seismic inversion methods to determine inter-well sand body changes; Conduct microstructural interpretation using 3D seismic data and dense well pattern data; Delineate sandstone boundaries and oil sand body boundaries; Comprehensive analysis of drilling, logging, production dynamics and seismic information to correct the distribution and identification of oil sand bodies; Prepare oil sands body maps including well point information; Based on the oil sand body map, the multivariate classification comprehensive index method is applied to the oil sand body with defined boundaries to calculate the unified oil sand body comprehensive classification evaluation parameters, determine the oil sand body classification boundaries, and conduct classification evaluation of the oil sand body potential, 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; Evaluate the potential of oil sand bodies based on the classification results; 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: Among them, h0, s0, k0, μ0 represents the oil layer thickness, oil-bearing area, permeability, porosity, and underground crude oil viscosity of a single oil sand body respectively; h min , s min , k min , They are the minimum oil layer thickness, minimum oil-bearing area, minimum permeability, and minimum porosity of all oil sand bodies respectively; μ max is the maximum viscosity of underground crude oil; The attribute values ​​of all oil sand bodies are clustered using the clustering method, and the number of clusters is 3.

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

3. The method according to claim 2, wherein Single sand body comparison is performed by using one or more comparison methods selected from contour 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, wherein The contour comparison method is applicable to river floodplains and channel fill deposits. These deposits should be at the same level and 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. By contour comparison, sand bodies formed in the same sedimentary event can be identified. The temporal unit correlation method is applicable to situations where, due to the strong incision of rivers, the positions of river channels at different times are inherited, and the sediments of each period of river may be eroded and diverted by later rivers, resulting in the superposition of river channel sands from different periods into thick composite sand bodies. It is used to identify superimposed sand bodies based on thickness and curve morphology, and to 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. Phase-controlled isochronous correlation is used to identify different microfacies formed in the same sedimentary event. The downcut sandbody comparison method is applicable to situations where sand bodies are significantly "downcut" and have a small distribution range due to the strongest scouring near the main stream of the river. It is used to identify downcut sand bodies formed by river scouring and understand the erosion and filling processes of river sediments. Seismic inversion technology is suitable for situations where the properties of sand and mudstones change rapidly in the horizontal direction, the phase change is obvious, resulting in discontinuous reflection interfaces and frequent changes. Seismic inversion technology can assist in judging the changes and connectivity of sand bodies between wells.

5. The method according to claim 4, wherein Conduct microstructural interpretation using 3D seismic data and dense well pattern data; include Collect and organize 3D seismic data and dense well pattern data. 3D seismic data includes detailed images of underground structures, while dense well pattern 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 bed interfaces, faults, and sand body boundaries; and using seismic attribute analysis, including amplitude, frequency, and phase, to further clarify the internal structure and distribution characteristics of the sand bodies. Integrate the dense well network data with the seismic interpretation results, and accurately map 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 identifying small stratigraphic reliefs, 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 the microstructural interpretation is verified by comparing it with production dynamic data, and the model is modified based on the verification results.

6. The method according to claim 1, wherein Delineation of sandstone boundaries and oil sand body boundaries includes Sandstone boundaries are determined through seismic multi-attribute prediction and dense well network data; oil sand body boundaries are divided according to reservoir type and oil-water relationship.

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

Images