Low-resistance oil layer fluid identification method, system and device and storage medium

Abstract

The invention discloses a low-resistance oil layer fluid identification method, system and device and a storage medium, and the method comprises the steps: obtaining a fluid identification relational expression and a fluid identification cross plot of a research region, and the target wide-area apparent resistivity of a to-be-identified stratum in the research region, the fluid identification relational expression represents an algebraic relationship between the wide-area apparent resistivity and a fluid identification factor, the fluid identification factor is used for reflecting reservoir fluid characteristics, and the fluid identification cross plot represents a cross plot of the wide-area apparent resistivity and the fluid identification factor of stratums of different fluid types; determining a target fluid identification factor corresponding to the target wide area apparent resistivity according to the fluid identification relational expression; and determining target fluid properties of the stratum to be identified according to the target wide area apparent resistivity, the target fluid identification factor and the fluid identification cross plot. According to the embodiment of the invention, the accuracy of fluid identification of the low-resistance oil layer can be improved, and fluid identification of the low-resistance oil layer can still be carried out in vast areas lacking logging information.

Description

Technical Field

[0001] The present invention relates to the technical field related to oil and gas exploration and development, and in particular to a method, system, device and storage medium for identifying fluid in a low-resistance oil layer. Background Art

[0002] As oil and gas exploration and development gradually deepen, low-resistivity oil layers have become an important research object for increasing oilfield reserves and production. The well logging data cross plot method is one of the main technical means for fluid identification in oil and gas exploration. Well logging data can accurately identify reservoir fluids at drilling locations, but it is difficult to identify them in the vast undrilled areas due to the "one-hole view". And because the resistivity is slightly different from the resistivity of the surrounding water layers, it is difficult to effectively identify fluids using conventional simple parameter identification charts. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a low-resistance oil layer fluid identification method, which can improve the accuracy of low-resistance oil layer fluid identification and can still identify low-resistance oil layer fluid in areas lacking logging data.

[0004] The present invention also provides a low-resistance oil layer fluid identification system, a control device for executing the low-resistance oil layer fluid identification method, and a computer-readable storage medium.

[0005] According to a first aspect of the present invention, a method for identifying fluid in a low-resistance oil layer comprises: Obtaining a fluid identification relationship, a fluid identification cross-plot, and a target wide-area apparent resistivity of a formation to be identified in the study area, wherein the fluid identification relationship represents an algebraic relationship between the wide-area apparent resistivity and a fluid identification factor, the fluid identification factor is used to reflect reservoir fluid characteristics, and the fluid identification cross-plot represents a cross-plot of the wide-area apparent resistivity and the fluid identification factor of formations with different fluid types; Determining a target fluid identification factor corresponding to the target wide-area apparent resistivity according to the fluid identification relationship; The target fluid property of the to-be-identified formation is determined according to the target wide-area apparent resistivity, the target fluid identification factor and the fluid identification cross-plot.

[0006] The low-resistance oil layer fluid identification method according to the embodiment of the present invention has at least the following beneficial effects: The wide-area electromagnetic method has the characteristics of wide detection range of the seismic method, and is sensitive to the resistivity changes of different fluids. By determining the fluid identification relationship that represents the algebraic relationship between the wide-area apparent resistivity and the fluid identification factor based on limited logging data, the target fluid identification factor of the formation to be identified in the study area where the target wide-area apparent resistivity is known but there is no logging data can be determined, and the target fluid properties of the formation to be identified can be determined based on the fluid identification cross-plot of the predetermined cross-plot of the wide-area apparent resistivity and the fluid identification factor representing the formations of different fluid types, which can improve the accuracy of low-resistivity oil layer fluid identification, and low-resistivity oil layer fluid identification can still be performed in the vast areas where logging data is lacking.

[0007] According to some embodiments of the present invention, the fluid identification relationship is obtained by the following steps: Obtaining wide-area apparent resistivity data and well logging data in the study area; Calculate the fluid identification parameters of the standard layer corresponding to different fluid types according to the logging data in the study area, wherein the fluid identification parameters include the resistivity increase rate, the invasion factor difference and the comprehensive storage and permeability index; Determining fluid identification factors corresponding to standard layers of different fluid types in the study area according to the fluid identification parameters; The fluid identification relationship of the study area is established according to the fluid identification factors corresponding to the standard layers of all fluid types in the study area and the wide-area apparent resistivity data.

[0008] According to some embodiments of the present invention, the fluid identification factor is obtained by the following steps: The first coefficient corresponding to the resistivity increase rate, the second coefficient corresponding to the invasion factor difference and the third coefficient corresponding to the comprehensive storage and permeability index are calculated by using the coefficient of variation method; The fluid identification factor is determined according to the first coefficient, the second coefficient, the third coefficient and the fluid identification parameter.

[0009] According to some embodiments of the present invention, the fluid identification cross-plot is obtained by the following steps: Acquiring wide-area apparent resistivity data and well logging data in the study area; Calculate the fluid identification parameters of the standard layer corresponding to different fluid types according to the logging data in the study area, wherein the fluid identification parameters include the resistivity increase rate, the invasion factor difference and the comprehensive storage and permeability index; Determining fluid identification factors corresponding to standard layers of different fluid types in the study area according to the fluid identification parameters; The fluid identification cross-plot of the study area is established based on the wide-area apparent resistivity data corresponding to standard layers of different fluid types in the study area and the fluid identification factors.

[0010] According to some embodiments of the present invention, the fluid identification cross-plot includes a plurality of sub-regions corresponding to a plurality of different fluid types, and the sub-regions corresponding to each fluid type are obtained by the following steps: Determine multiple intersection points corresponding to the same fluid type according to the wide-area apparent resistivity data corresponding to multiple standard layers of the same fluid type in the study area and the fluid identification factor; The sub-regions corresponding to the same fluid type are obtained by dividing according to the positions of the multiple intersection points.

[0011] According to some embodiments of the present invention, determining the target fluid property of the formation to be identified according to the target wide-area apparent resistivity, the target fluid identification factor and the fluid identification cross-plot includes: Determining a target intersection point according to the target wide-area apparent resistivity and the target fluid identification factor; Determine a target sub-region where the target intersection point falls, the target sub-region being one of the multiple sub-regions; The fluid type corresponding to the target sub-region is determined as the target fluid property of the formation to be identified.

[0012] According to some embodiments of the present invention, the fluid identification parameter is obtained by the following steps: Determine characteristic variable data of standard layers corresponding to different fluid types according to the logging data in the study area, wherein the characteristic variable data include deep lateral resistivity, shallow lateral resistivity, standard water layer resistivity, formation water resistivity, average pore throat radius, median pore throat radius, sorting coefficient, porosity, cation exchange capacity, irreducible water saturation and mud content; The fluid identification parameter is calculated based on the characteristic variable data.

[0013] According to a low-resistance oil layer fluid identification system of a second aspect of the present invention, the system comprises: A data acquisition module, used to acquire a fluid identification relationship, a fluid identification cross-plot and a target wide-area apparent resistivity of a formation to be identified in the study area, wherein the fluid identification relationship represents an algebraic relationship between the wide-area apparent resistivity and a fluid identification factor, the fluid identification factor is used to reflect reservoir fluid characteristics, and the fluid identification cross-plot represents a cross-plot of the wide-area apparent resistivity and the fluid identification factor of formations with different fluid types; A target fluid identification factor determination module, used to determine the target fluid identification factor corresponding to the target wide-area apparent resistivity according to the fluid identification relationship; The fluid identification module is used to determine the target fluid property of the formation to be identified according to the target wide-area apparent resistivity, the target fluid identification factor and the fluid identification cross-plot.

[0014] The low-resistance oil layer fluid identification system according to the embodiment of the present invention has at least the following beneficial effects: The wide-area electromagnetic method has the characteristics of wide detection range of the seismic method, and is sensitive to the resistivity changes of different fluids. By determining the fluid identification relationship that represents the algebraic relationship between the wide-area apparent resistivity and the fluid identification factor based on limited logging data, the target fluid identification factor of the formation to be identified in the study area where the target wide-area apparent resistivity is known but there is no logging data can be determined, and the target fluid properties of the formation to be identified can be determined based on the fluid identification cross-plot of the predetermined cross-plot of the wide-area apparent resistivity and the fluid identification factor representing the formations of different fluid types, which can improve the accuracy of low-resistivity oil layer fluid identification, and low-resistivity oil layer fluid identification can still be performed in the vast areas where logging data is lacking.

[0015] The control device according to the third aspect of the present invention comprises a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the low-resistance oil layer fluid identification method as described in the first aspect of the present invention when executing the computer program. Since the control device adopts all the technical solutions of the low-resistance oil layer fluid identification method of the above embodiment, it at least has all the beneficial effects brought by the technical solutions of the above embodiment.

[0016] The computer-readable storage medium according to the fourth aspect of the present invention stores computer-executable instructions, and the computer-executable instructions are used to execute the low-resistance oil layer fluid identification method as described in the first aspect of the present invention. Since the computer-readable storage medium adopts all the technical solutions of the low-resistance oil layer fluid identification method of the above embodiment, it at least has all the beneficial effects brought by the technical solutions of the above embodiment.

[0017] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1 It is a schematic diagram of a fluid identification plate in the prior art; Figure 2 is a flow chart of a method for identifying fluid in a low-resistance oil layer according to an embodiment of the present invention; Figure 3is a schematic diagram of a fluid identification relationship according to an embodiment of the present invention; Figure 4 Schematic diagram of a fluid identification intersection diagram according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0020] In the description of the present invention, if there is a description of first, second, etc., it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0021] In the description of the present invention, it should be understood that descriptions involving orientation, such as orientation or positional relationship indicated as up, down, etc., are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention 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 should not be understood as a limitation on the present invention.

[0022] In the description of the present invention, it should be noted that, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0023] Figure 1 This is a schematic diagram of a fluid identification chart in the prior art. The horizontal axis represents porosity, and the vertical axis represents deep lateral resistivity. This method can be well applied when the formation porosity is large, the electrical properties of the formation fluids are greatly different, and the formation resistivity is mainly controlled by the formation fluids. However, in the vast areas where logging data is lacking, the porosity and deep lateral resistivity are unknown, and direct identification is still difficult in these areas. Moreover, for low-resistance oil layers, due to the small electrical property difference between oil and water layers, the above method cannot distinguish the oil layer from the water layer well.

[0024] The embodiment of the present invention proposes a method for identifying fluid in a low-resistance oil layer, which can improve the accuracy of identifying fluid in a low-resistance oil layer, and can still identify fluid in a low-resistance oil layer in areas lacking well logging data.

[0025] The following will be combined Figures 2 to 4A low-resistance oil layer fluid identification method according to an embodiment of the present invention is described clearly and completely. Obviously, the embodiment described below is only a part of the embodiments of the present invention, but not all of the embodiments.

[0026] refer to Figure 2 , Figure 2 It is a flow chart of a method for identifying fluid in a low-resistance oil layer according to an embodiment of the present invention.

[0027] According to a first aspect of the present invention, the method for identifying fluid in a low-resistance oil layer comprises: Obtain the fluid identification relationship, fluid identification crossplot and target wide-area apparent resistivity of the formation to be identified in the study area, wherein the fluid identification relationship represents the algebraic relationship between the wide-area apparent resistivity and the fluid identification factor, the fluid identification factor is used to reflect the reservoir fluid characteristics, and the fluid identification crossplot represents the crossplot of the wide-area apparent resistivity and the fluid identification factor of formations with different fluid types; Determine the target fluid identification factor corresponding to the target wide-area apparent resistivity according to the fluid identification relationship; The target fluid properties of the formation to be identified are determined based on the target wide-area apparent resistivity, the target fluid identification factor and the fluid identification cross-plot.

[0028] It is understandable that for areas with logging data, the fluid identification factor of the corresponding formation can be directly determined through the logging data, thereby determining the fluid properties of the formation, but for areas without logging data, the fluid identification factor is unknown, while the wide-area electromagnetic method has a wide detection range and is sensitive to the resistivity changes of different fluids. It can also detect the wide-area apparent resistivity for areas without logging data, and can well reflect the reservoir fluid properties. By establishing the algebraic relationship between the wide-area apparent resistivity and the fluid identification factor of the entire study area (including areas with logging data and areas without logging data) through the logging data and the wide-area apparent resistivity data of the areas with logging data, the target fluid identification factor of the formation to be identified in the study area with known target wide-area apparent resistivity but no logging data can be determined.

[0029] refer to Figure 3 , Figure 3It is a schematic diagram of the fluid identification relationship of an embodiment of the present invention. The algebraic relationship between the wide-area apparent resistivity and the fluid identification factor is established by statistical analysis of the data of the known samples in the study area. Specifically, the algebraic relationship can be established using data analysis software such as Excel and SPSS, and it is necessary to ensure that the correlation of the algebraic relationship between the wide-area apparent resistivity and the fluid identification factor reaches above 0.8. It should be noted that Excel and SPSS are both prior arts known to those skilled in the art, and their working process and working principle will not be repeated here. In addition, other data analysis software can also be used to establish the algebraic relationship between the wide-area apparent resistivity and the fluid identification factor, not limited to the Excel and SPSS mentioned above.

[0030] refer to Figure 4 , Figure 4 It is a schematic diagram of a fluid identification cross-plot of an embodiment of the present invention, and the fluid identification cross-plot represents a cross-plot of wide-area apparent resistivity and fluid identification factor of different fluid types. It can be understood that the wide-area apparent resistivity can well reflect the reservoir fluid properties, and the fluid identification factor determined by logging data can also accurately reflect the reservoir fluid characteristics. The fluid identification cross-plot of the study area can be established through the data of known samples in the study area, so that the target fluid identification factor of the formation to be identified in the study area with known target wide-area apparent resistivity but no logging data can be determined first, and then the target fluid property of the formation to be identified can be determined based on the predetermined fluid identification cross-plot of the study area, which can improve the accuracy of low-resistivity oil layer fluid identification, and low-resistivity oil layer fluid identification can still be performed for the vast areas lacking logging data.

[0031] In some embodiments, Figure 4 The intersection points of the three styles in the figure all represent the known wide-area apparent resistivity, fluid identification factor and fluid type of the strata in the study area, dividing the study area into multiple strata with different fluid types. Figure 4 Each intersection point in the graph represents a sample of a known fluid type in the study area, and the blank part represents the stratum of the fluid type to be identified in the study area. For example, the intersection points (triangles) representing water layers are gathered together, so a rough range can be circled, and within this range, all represent water layers (i.e. Figure 4 After the target wide-area apparent resistivity of the formation to be identified is known, the corresponding target fluid identification factor is first determined by the fluid identification relationship. If the intersection point corresponding to the target wide-area apparent resistivity and the target fluid identification factor falls within the range of the water layer, the target fluid property of the formation to be identified is the water layer.

[0032] The regional division of oil-water layers and oil layers is similar to that of water layers and will not be elaborated here.

[0033] The low-resistivity oil layer fluid identification method of the embodiment of the present invention can rely on wide-area apparent resistivity data for fluid identification by establishing a fluid identification relationship in the study area and dividing the fluid identification intersection diagram instead of relying solely on logging data as in the prior art. This can not only improve the accuracy of low-resistivity oil layer fluid identification, but also enable low-resistivity oil layer fluid identification to be performed in areas that lack logging data.

[0034] According to the low-resistivity oil layer fluid identification method of an embodiment of the present invention, the wide-area electromagnetic method has the characteristics of a wide detection range of the seismic method, and is sensitive to the resistivity changes of different fluids. By determining the fluid identification relationship that represents the algebraic relationship between the wide-area apparent resistivity and the fluid identification factor based on limited logging data, the target fluid identification factor of the formation to be identified in the study area with a known target wide-area apparent resistivity but no logging data can be determined, and the target fluid properties of the formation to be identified can be determined based on the fluid identification cross-plot of the predetermined cross-plot of the wide-area apparent resistivity and the fluid identification factor representing the formations of different fluid types, which can improve the accuracy of low-resistivity oil layer fluid identification, and low-resistivity oil layer fluid identification can still be performed in the vast areas that lack logging data.

[0035] In some embodiments of the present invention, reference Figure 3 , FIG. is a schematic diagram of a fluid identification equation according to an embodiment of the present invention, and the fluid identification equation is obtained by the following steps: Obtain wide-area apparent resistivity data and well logging data in the study area; The fluid identification parameters of the standard layers corresponding to different fluid types are calculated based on the well logging data in the study area. The fluid identification parameters include the resistivity increase rate, invasion factor difference and comprehensive storage and permeability index. Determine the fluid identification factors corresponding to the standard layers of different fluid types in the study area based on the fluid identification parameters; The fluid identification relationship in the study area is established based on the fluid identification factors corresponding to the standard layers of all fluid types in the study area and the wide-area apparent resistivity data.

[0036] In some embodiments of the present invention, the fluid identification parameters are obtained by the following steps: The characteristic variable data of the standard layer corresponding to different fluid types are determined based on the well logging data in the study area. The characteristic variable data include deep lateral resistivity , shallow lateral resistivity , Standard water layer resistivity , formation water resistivity , average pore throat radius , median pore throat radius , sorting coefficient , Porosity , cation exchange capacity , Irreducible water saturation and mud content ; The fluid identification parameters are calculated based on the characteristic variable data.

[0037] In some embodiments, the average pore throat radius , median pore throat radius , sorting coefficient and porosity Measured by pressure pump test; cation exchange capacity Measured by rock physics experiments; irreducible water saturation Measured by nuclear magnetic resonance experiment; mud content Measured by X-ray diffraction whole-rock experiment.

[0038] Fluid identification parameters include resistivity increase rate, invasion factor difference and comprehensive reservoir permeability index. The influencing factors of low-resistivity oil layers include thin interlayers of sandstone and mudstone, formation water salinity, bound water saturation, conductive mineral content, micropores in particles and clay mineral content. There are two types of low-resistivity oil layers. One is the oil layer with a resistivity ratio of less than 2 to the pure water layer in the same oil-water system, that is, low-contrast oil layer; the other is the oil layer with a relatively low absolute resistivity, generally less than 5. , that is, a low resistivity oil layer. The embodiment of the present invention considers several influencing factors that usually play a major role and introduces fluid identification parameters.

[0039] The constraint formula for the resistance increase rate is: / ;Formula (1) in, represents the resistance increase rate, represents the deep lateral resistivity, Represents the standard water layer resistivity.

[0040] The characteristic of low-resistivity oil layer formed by high-mineralization formation water is that the absolute resistivity of the oil layer is low, but significantly higher than the resistivity of the water layer. The ratio between the two is used to standardize the differences between different samples.

[0041] The constraint formula of the intrusion factor difference is: ;Formula (2) Q= ( - ) / ;Formula (3) in, represents the difference in intrusion factor, Q represents the invasion factor, represents the water layer intrusion factor, represents the oil layer invasion factor, represents the shallow lateral resistivity, Represents deep lateral resistivity.

[0042] Freshwater drilling fluid invasion reduces the apparent resistivity of the oil layer and increases the apparent resistivity of the water layer. At the same time, the difference between the deep and shallow resistivity of the oil layer is not large, while the difference between the deep and shallow resistivity of the water layer is obvious. Therefore, the invasion factor can amplify the electrical difference between the oil layer and the water layer. The invasion factor is calculated using the deep and shallow lateral resistivity values ​​in the characteristic variable data, and then the invasion factor of each sample is subtracted from the standard water layer invasion factor to obtain the invasion factor difference.

[0043] The constraint formula of the comprehensive storage and permeability index is: ;Formula (4) = + + + ;Formula (5) =1- ;Formula (6) = ;Formula (7) in, represents the comprehensive storage-permeability index, It represents the pumping coefficient. Indicates oil saturation, represents the cation exchange capacity, represents the bound water saturation, , , and is the weight coefficient, represents the average pore throat radius, represents the median pore throat radius, represents the sorting coefficient, represents the porosity, represents water saturation, represents the formation water resistivity, a , b is the lithology coefficient, m is the cementation index, n is the saturation index, Represents deep lateral resistivity.

[0044] , , and The coefficient of variation method is used to obtain the specific calculation process: ,i =1, 2, 3, 4; formula (8) in, Indicates i The standard deviation coefficient of the variable, Indicates i The standard deviation of a variable, Indicates i The variables mentioned above are the average of , , and .

[0045] After obtaining the standard deviation coefficient, calculate the weight coefficient of each variable: Formula (9) in, is the weight coefficient of the ith variable.

[0046] In some embodiments of the present invention, the fluid recognition factor is obtained by the following steps: The first coefficient corresponding to the resistivity increase rate, the second coefficient corresponding to the invasion factor difference and the third coefficient corresponding to the comprehensive storage and permeability index are calculated by using the coefficient of variation method; A fluid identification factor is determined based on the first coefficient, the second coefficient, the third coefficient, and the fluid identification parameter.

[0047] The constraint formula of the fluid identification factor is: L= I+ + T ;Formula (10) in, L represents the fluid identification factor, I represents the resistance increase rate, represents the difference in intrusion factor, T represents the comprehensive storage-permeability index, represents the first coefficient, represents the second coefficient, represents the third coefficient.

[0048] The principle and process of calculating the coefficient using the coefficient of variation method have been explained in the process of calculating the weight parameter of the pressure pump coefficient, and will not be repeated here.

[0049] It should be noted that the study area can be divided into different blocks of the same oilfield. The water layers, oil-water layers and oil layers in different blocks have different resistivity increase rates, invasion factor differences and comprehensive storage-permeability indexes corresponding to the standard layers. Therefore, different fluid identification factor relationship equations need to be established for different blocks. Finally, the fluid identification relationship equation for the study area is established based on the fluid identification factors corresponding to the standard layers of all fluid types in all blocks in the study area and the wide-area apparent resistivity data.

[0050] Conventional fluid identification charts are composed of a single parameter, such as a fluid identification chart composed of a porosity and deep lateral resistivity intersection diagram. The clustering of templates established by a single parameter is usually not so obvious, and because resistivity is sometimes not completely single and is controlled by fluid properties, if the influence of other factors on resistivity is not considered, it is easy to make misjudgments for mixed fluid formations. The fluid identification parameters of the fluid identification factor of the embodiment of the present invention include resistivity increase rate, invasion factor difference and comprehensive reservoir permeability index. On the one hand, the above fluid identification parameters can expand the difference between the low-resistance oil layer and the water layer or make it easier to observe, making the fluid identification of the low-resistance oil layer simpler; on the other hand, the fluid identification factor of the embodiment of the present invention comprehensively considers the influence of various factors on the formation, can minimize the influence of other factors, improve data clustering and recognition accuracy, and is more accurate and reliable than the fluid identification template established using a single parameter.

[0051] In some embodiments of the present invention, reference Figure 4 , Figure 4 FIG. 1 is a schematic diagram of a fluid identification cross-plot according to an embodiment of the present invention. The fluid identification cross-plot is obtained by the following steps: Obtain wide-area apparent resistivity data and well logging data in the study area; The fluid identification parameters of the standard layers corresponding to different fluid types are calculated based on the well logging data in the study area. The fluid identification parameters include the resistivity increase rate, invasion factor difference and comprehensive storage and permeability index. Determine the fluid identification factors corresponding to the standard layers of different fluid types in the study area based on the fluid identification parameters; The fluid identification cross-plot of the study area is established based on the wide-area apparent resistivity data and fluid identification factors corresponding to the standard layers of different fluid types in the study area.

[0052] Understandably, Figure 4 The intersection points of the three patterns in the above all represent the known wide-area apparent resistivity, fluid identification factor and fluid type of the strata in the study area, dividing the study area into multiple strata with different fluid types. Figure 4Each intersection point in the graph represents a sample of a known fluid type in the study area, and the blank part represents the stratum of the fluid type to be identified in the study area. For example, the intersection points (triangles) representing water layers are gathered together, so a rough range can be circled, and within this range, all represent water layers (i.e. Figure 4 After the target wide-area apparent resistivity of the formation to be identified is known, the corresponding target fluid identification factor is first determined by the fluid identification relationship. If the intersection point corresponding to the target wide-area apparent resistivity and the target fluid identification factor falls within the range of the water layer, the target fluid property of the formation to be identified is the water layer.

[0053] The regional division of oil-water layers and oil layers is similar to that of water layers and will not be elaborated here.

[0054] In some embodiments of the present invention, reference Figure 4 , Figure 4 This is a schematic diagram of a fluid identification cross-plot according to an embodiment of the present invention. The fluid identification cross-plot includes a plurality of sub-regions corresponding to a plurality of different fluid types. The sub-regions corresponding to each fluid type are obtained by the following steps: Determine multiple intersection points corresponding to the same fluid type based on the wide-area apparent resistivity data and fluid identification factors corresponding to multiple standard layers of the same fluid type in the study area; Sub-areas corresponding to the same fluid type are obtained according to the positions of multiple intersection points.

[0055] exist Figure 4 In the figure, the sub-regions corresponding to different fluid types are water layer sub-regions, oil-water layer sub-regions, and oil layer sub-regions. Taking the water layer sub-region as an example, the intersection points (triangles) representing the water layer are gathered together, so a rough range can be circled, and the water layer is represented within this range, that is, Figure 4 The dotted rectangular box formed by points (0, 1), (3, 1), (0, 10) and (3, 10) in FIG. 1 is a water layer sub-area.

[0056] The division method of the oil-water same layer sub-area and the oil layer sub-area is similar to that of the water layer sub-area, which will not be repeated here.

[0057] In some embodiments of the present invention, reference Figure 4 , Figure 4 This is a schematic diagram of a fluid identification cross-plot according to an embodiment of the present invention, and the target fluid property of the formation to be identified is determined according to the target wide-area apparent resistivity, the target fluid identification factor and the fluid identification cross-plot, including: Determine the target intersection point based on the target wide-area apparent resistivity and the target fluid identification factor; Determine a target sub-region where the target intersection point falls, where the target sub-region is one of the multiple sub-regions; The fluid type corresponding to the target sub-region is determined as the target fluid property of the formation to be identified.

[0058] In some embodiments, taking the target wide-area apparent resistivity equal to 4 and the target fluid identification factor equal to 2 as an example, the coordinates of the target intersection point are (2, 4). Figure 4 It can be seen from the figure that the target intersection point falls into the water layer sub-area, and the target fluid property of the formation to be identified is the water layer.

[0059] According to the low-resistivity oil layer fluid identification system of the second embodiment of the present invention, the system includes a data acquisition module, a target fluid identification factor determination module and a fluid identification module.

[0060] A data acquisition module is used to obtain a fluid identification relationship, a fluid identification cross-plot, and a target wide-area apparent resistivity of a formation to be identified in the study area, wherein the fluid identification relationship represents an algebraic relationship between the wide-area apparent resistivity and the fluid identification factor, the fluid identification factor is used to reflect reservoir fluid characteristics, and the fluid identification cross-plot represents a cross-plot of the wide-area apparent resistivity and the fluid identification factor of formations with different fluid types; A target fluid identification factor determination module is used to determine the target fluid identification factor corresponding to the target wide-area apparent resistivity according to a fluid identification relationship; The fluid identification module is used to determine the target fluid properties of the formation to be identified based on the target wide-area apparent resistivity, the target fluid identification factor and the fluid identification cross-plot.

[0061] It is understandable that for areas with logging data, the fluid identification factor of the corresponding formation can be directly determined through the logging data, thereby determining the fluid properties of the formation, but for areas without logging data, the fluid identification factor is unknown, while the wide-area electromagnetic method has a wide detection range and is sensitive to the resistivity changes of different fluids. It can also detect the wide-area apparent resistivity for areas without logging data, and can well reflect the reservoir fluid properties. By establishing the algebraic relationship between the wide-area apparent resistivity and the fluid identification factor of the entire study area (including areas with logging data and areas without logging data) through the logging data and the wide-area apparent resistivity data of the areas with logging data, the target fluid identification factor of the formation to be identified in the study area with known target wide-area apparent resistivity but no logging data can be determined.

[0062] refer to Figure 3 , Figure 3It is a schematic diagram of the fluid identification relationship of an embodiment of the present invention. The algebraic relationship between the wide-area apparent resistivity and the fluid identification factor is established by statistical analysis of the data of the known samples in the study area. Specifically, the algebraic relationship can be established using data analysis software such as Excel and SPSS, and it is necessary to ensure that the correlation of the algebraic relationship between the wide-area apparent resistivity and the fluid identification factor reaches above 0.8. It should be noted that Excel and SPSS are both prior arts known to those skilled in the art, and their working process and working principle will not be repeated here. In addition, other data analysis software can also be used to establish the algebraic relationship between the wide-area apparent resistivity and the fluid identification factor, not limited to the Excel and SPSS mentioned above.

[0063] refer to Figure 4 , Figure 4 It is a schematic diagram of a fluid identification cross-plot of an embodiment of the present invention, and the fluid identification cross-plot represents a cross-plot of wide-area apparent resistivity and fluid identification factor of different fluid types. It can be understood that the wide-area apparent resistivity can well reflect the reservoir fluid properties, and the fluid identification factor determined by logging data can also accurately reflect the reservoir fluid characteristics. The fluid identification cross-plot of the study area can be established through the data of known samples in the study area, so that the target fluid identification factor of the formation to be identified in the study area with known target wide-area apparent resistivity but no logging data can be determined first, and then the target fluid property of the formation to be identified can be determined based on the predetermined fluid identification cross-plot of the study area, which can improve the accuracy of low-resistivity oil layer fluid identification, and low-resistivity oil layer fluid identification can still be performed for the vast areas lacking logging data.

[0064] In some embodiments, Figure 4 The intersection points of the three patterns in the above all represent the known wide-area apparent resistivity, fluid identification factor and fluid type of the strata in the study area, dividing the study area into multiple strata with different fluid types. Figure 4 Each intersection point in the graph represents a sample of a known fluid type in the study area, and the blank part represents a sample of a fluid type to be identified in the study area. For example, the intersection points (triangles) representing water layers are gathered together, so a rough range can be circled, and within this range, all water layers (i.e. Figure 4 After the target wide-area apparent resistivity of the formation to be identified is known, the corresponding target fluid identification factor is first determined by the fluid identification relationship. If the intersection point corresponding to the target wide-area apparent resistivity and the target fluid identification factor falls within the range of the water layer, the target fluid property of the formation to be identified is the water layer.

[0065] The regional division of oil-water layers and oil layers is similar to that of water layers and will not be elaborated here.

[0066] The low-resistivity oil layer fluid identification system of the embodiment of the present invention can rely on wide-area apparent resistivity data for fluid identification by establishing a fluid identification relationship in the study area and dividing the fluid identification intersection diagram instead of relying solely on logging data as in the prior art. This can not only improve the accuracy of low-resistivity oil layer fluid identification, but also enable low-resistivity oil layer fluid identification to be performed in areas that lack logging data.

[0067] According to the low-resistivity oil layer fluid identification system of the embodiment of the present invention, the wide-area electromagnetic method has the characteristics of a wide detection range of the seismic method, and is sensitive to the resistivity changes of different fluids. By determining the fluid identification relationship that represents the algebraic relationship between the wide-area apparent resistivity and the fluid identification factor based on limited logging data, the target fluid identification factor of the formation to be identified in the study area where the target wide-area apparent resistivity is known but there is no logging data can be determined, and the target fluid properties of the formation to be identified can be determined based on the fluid identification cross-plot of the predetermined cross-plot of the wide-area apparent resistivity and the fluid identification factor representing the formations of different fluid types, which can improve the accuracy of low-resistivity oil layer fluid identification, and low-resistivity oil layer fluid identification can still be performed in the vast areas that lack logging data.

[0068] In addition, an embodiment of the present invention further provides a control device, which includes: a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor and the memory may be connected via a bus or other means.

[0069] The memory, as a non-transient computer-readable storage medium, can be used to store non-transient software programs and non-transient computer executable programs. In addition, the memory may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some embodiments, the memory may optionally include a memory remotely disposed relative to the processor, and these remote memories may be connected to the processor via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0070] The non-transient software program and instructions required to implement the low-resistance oil layer fluid identification method of the above embodiment are stored in the memory, and when executed by the processor, the low-resistance oil layer fluid identification method of the above embodiment is executed.

[0071] The device embodiments described above are merely illustrative, and the units described as separate components may or may not be physically separated, that is, they may be located in one place or distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0072] In addition, an embodiment of the present invention also provides a computer-readable storage medium, which stores computer-executable instructions, and the computer-executable instructions are executed by a processor or controller, for example, by the processor of the above embodiment, so that the above processor can execute the low-resistance oil layer fluid identification method in the above embodiment.

[0073] It will be appreciated by those skilled in the art that all or some of the steps and systems in the methods disclosed above may be implemented as software, firmware, hardware, and appropriate combinations thereof. Some or all physical components may be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or transient medium). As known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically embodies computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0074] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A method for identifying fluid in a low-resistance oil layer, characterized in that: The method comprises: Obtaining a fluid identification relationship, a fluid identification cross-plot, and a target wide-area apparent resistivity of a formation to be identified in the study area, wherein the fluid identification relationship represents an algebraic relationship between the wide-area apparent resistivity and a fluid identification factor, the fluid identification factor is used to reflect reservoir fluid characteristics, and the fluid identification cross-plot represents a cross-plot of the wide-area apparent resistivity and the fluid identification factor of formations with different fluid types; Determining a target fluid identification factor corresponding to the target wide-area apparent resistivity according to the fluid identification relationship; The target fluid property of the to-be-identified formation is determined according to the target wide-area apparent resistivity, the target fluid identification factor and the fluid identification cross-plot.

2. The method for identifying fluid in a low-resistance oil layer according to claim 1, characterized in that: The fluid identification relationship is obtained by the following steps: Acquiring wide-area apparent resistivity data and well logging data in the study area; Calculate the fluid identification parameters of the standard layer corresponding to different fluid types according to the logging data in the study area, wherein the fluid identification parameters include the resistivity increase rate, the invasion factor difference and the comprehensive storage and permeability index; Determining fluid identification factors corresponding to standard layers of different fluid types in the study area according to the fluid identification parameters; The fluid identification relationship of the study area is established according to the fluid identification factors corresponding to the standard layers of all fluid types in the study area and the wide-area apparent resistivity data.

3. The method for identifying fluid in a low-resistance oil layer according to claim 2, characterized in that: The fluid recognition factor is obtained by the following steps: The first coefficient corresponding to the resistivity increase rate, the second coefficient corresponding to the invasion factor difference and the third coefficient corresponding to the comprehensive storage and permeability index are calculated by using the coefficient of variation method; The fluid identification factor is determined based on the first coefficient, the second coefficient, the third coefficient, and the fluid identification parameter.

4. The method for identifying fluid in a low-resistance oil layer according to claim 1, characterized in that: The fluid identification cross-plot is obtained by the following steps: Acquiring wide-area apparent resistivity data and well logging data in the study area; Calculate the fluid identification parameters of the standard layer corresponding to different fluid types according to the logging data in the study area, wherein the fluid identification parameters include the resistivity increase rate, the invasion factor difference and the comprehensive storage and permeability index; Determining fluid identification factors corresponding to standard layers of different fluid types in the study area according to the fluid identification parameters; The fluid identification cross-plot of the study area is established based on the wide-area apparent resistivity data corresponding to standard layers of different fluid types in the study area and the fluid identification factor.

5. The method for identifying fluid in a low-resistance oil layer according to claim 4, characterized in that: The fluid identification cross-plot includes a plurality of sub-regions corresponding to a plurality of different fluid types, and the sub-regions corresponding to each fluid type are obtained by the following steps: Determine multiple intersection points corresponding to the same fluid type according to the wide-area apparent resistivity data corresponding to multiple standard layers of the same fluid type in the study area and the fluid identification factor; The sub-regions corresponding to the same fluid type are obtained by dividing according to the positions of the multiple intersection points.

6. The method for identifying fluid in a low-resistance oil layer according to claim 4, characterized in that: The step of determining the target fluid property of the formation to be identified according to the target wide-area apparent resistivity, the target fluid identification factor and the fluid identification cross-plot comprises: Determining a target intersection point according to the target wide-area apparent resistivity and the target fluid identification factor; Determine a target sub-region where the target intersection point falls, the target sub-region being one of the multiple sub-regions; The fluid type corresponding to the target sub-region is determined as the target fluid property of the formation to be identified.

7. The method for identifying fluid in a low-resistance oil layer according to claim 4, characterized in that: The fluid identification parameters are obtained by the following steps: Determine characteristic variable data of standard layers corresponding to different fluid types according to the logging data in the study area, wherein the characteristic variable data include deep lateral resistivity, shallow lateral resistivity, standard water layer resistivity, formation water resistivity, average pore throat radius, median pore throat radius, sorting coefficient, porosity, cation exchange capacity, irreducible water saturation and mud content; The fluid identification parameter is calculated based on the characteristic variable data.

8. A low-resistance oil layer fluid identification system, characterized in that: The system comprises: A data acquisition module, used to acquire a fluid identification relationship, a fluid identification cross-plot, and a target wide-area apparent resistivity of a formation to be identified in the study area, wherein the fluid identification relationship represents an algebraic relationship between the wide-area apparent resistivity and a fluid identification factor, the fluid identification factor is used to reflect reservoir fluid characteristics, and the fluid identification cross-plot represents a cross-plot of the wide-area apparent resistivity and the fluid identification factor of formations with different fluid types; A target fluid identification factor determination module, used to determine the target fluid identification factor corresponding to the target wide-area apparent resistivity according to the fluid identification relationship; The fluid identification module is used to determine the target fluid property of the formation to be identified according to the target wide-area apparent resistivity, the target fluid identification factor and the fluid identification cross-plot.

9. A control device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the low-resistance oil layer fluid identification method according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium storing computer-executable instructions, characterized in that: The computer executable instructions are used to execute the low-resistance oil layer fluid identification method according to any one of claims 1 to 7.

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