A method for identifying fluid properties of low-permeability reservoirs in complex water-oil zones based on array induction logging and dual-induction-octuple-lateral logging
Patent Information
- Application Number
- CN202310828070.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-07-07
- Publication Date
- 2026-09-18
- Estimated Expiration
- 2043-07-07
AI Technical Summary
由于工程原因或地质特征差异导致钻井液侵入范围较大的储层，深感应电阻率可能无法反映原状地层的电阻率
1）充分考虑淡水钻井液钻井中，阵列感应、双感应—八侧向测井资料中各项参数对复杂地层水油区低渗储层流体性质的响应特征，通过对比分析阵列感应、双感应—八侧向测井响应特征的异同点，利用阵列感应、双感应—八侧向资料径向电阻率特征构建流体识别敏感参数并进行交会处理，确保流体性质识别精度。
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of exploration and well logging technology, specifically involving a method for identifying the fluid properties of low-permeability reservoirs in complex formation water-oil zones based on array induction logging and dual-induction-eight-lateral logging. Background Technology
[0002] The complex and variable lithology, physical properties, pore structure, and formation water properties of low-permeability reservoirs in complex formation water-oil areas lead to complex oil-bearing properties and resistivity responses. Furthermore, the influence of drilling and logging operations results in the coexistence of conventional oil-bearing layers (oil layers, oil-water co-existing layers), water-bearing layers (oil-water layers, water layers), low-resistivity oil-bearing layers (oil layers, oil-water co-existing layers), and high-resistivity water-bearing layers (oil-water layers, water layers). The limited detection range of dual-induction-eight-lateral logging instruments, coupled with the complex and variable geological characteristics of the oil layers and the limitations of logging detection range, makes it difficult to identify fluid properties using conventional dual-induction-eight-lateral logging data. Therefore, extracting effective information from conventional logging data and improving the accuracy of fluid property identification in low-permeability reservoirs in complex formation water-oil areas is an economical and efficient choice for improving the effectiveness of oil and gas field exploration and development.
[0003] Resistivity logging data plays a crucial role in identifying and evaluating reservoir oil-bearing properties. Array induction logging can provide data at 1 ft (30.5 cm), 2 ft (61 cm), and 4 ft. The system offers three vertical resolutions: t (122 cm). Each vertical resolution has resistivity curves at six different depths: 10 in, 20 in, 30 in, 60 in, 90 in, and 120 in (25.4 cm, 50.8 cm, 76.2 cm, 152.4 cm, 228.6 cm, and 304.8 cm). These curves are combined to generate resistivity curves for M1R1, M1R2, M1R3, M1R6, M1R91, M1RX, M2R1, M2R2, M2R3, M2R6, M2R9, M2RX, and M3R1, M3R2, M3R3, M3R6, M3R9, M3RX. Therefore, array induction logging can be used to delineate effective permeable layers, identify reservoir fluid properties, determine the resistivity of undisturbed formations, evaluate thin layers, and describe formation invasion characteristics.
[0004] The dual-induction-eight-lateral logging system used for formation resistivity measurement has a deep induction detection range of 163 cm and a vertical resolution of 1.2 m; a medium induction detection range of 81 cm and a vertical resolution of 0.8 m; and an eight-lateral detection range of 24–33 cm.
[0005] In array induction logging with a vertical resolution of 2ft (61cm), for medium-thin reservoirs with a thickness greater than 0.5m, the detection range of the eight-lateral logging is close to that of array induction M2R1, the detection range of the medium induction logging is close to that of array induction M2R3, and the detection range of the deep induction logging is close to that of array induction M2R6. Therefore, by comparing and analyzing the radial resistivity characteristics of dual-induction-eight-lateral logging with the radial resistivity characteristics of array induction combinations M2R1, M2R2, M2R3, M2R6, M2R9, and M2RX with a vertical resolution of 2ft (61cm), and considering the limitations of the dual-induction-eight-lateral detection capability, fluid properties are inferred based on the comparison relationship between reservoir radial resistivity.
[0006] Array induction logging is a specialized logging series, with high engineering costs, and is generally limited to key wells to address prominent issues. Most wells lack array induction logging data. Dual-induction-eight-lateral logging, as a conventional combined logging series, provides resistivity data and is implemented in most wells, facilitating widespread application. However, the resistivity data from dual-induction-eight-lateral logging is limited by the detection range, only interpreting the reservoir resistivity and its relative changes within a 163cm detection range around the wellbore. In wells where array induction logging is implemented, dual-induction-eight-lateral logging is generally not performed. Comparative analysis of array induction logging characteristics within the detection range of dual-induction-eight-lateral logging, combined with comprehensive analysis of actual production data from well testing, is beneficial for uncovering the fluid information contained in dual-induction-eight-lateral logging, achieving the goal of economically and efficiently identifying reservoir fluid properties.
[0007] The complex and variable porosity, permeability, pore structure, and formation water properties of low-permeability reservoirs lead to complex and variable oil-bearing properties, further resulting in complex and variable resistivity parameters in low-permeability oil-bearing reservoirs. Furthermore, the intrusion of freshwater drilling fluid during drilling causes a series of changes in the resistivity around the wellbore in low-permeability oil-bearing layers. Based on differences in intrusion time and degree, and the relative permeability of oil and water in the oil-bearing layer, array induction logging reveals three types of radial resistivity characteristics in low-permeability oil-bearing layers: drag-reducing intrusion, low-resistivity annulus, and high-resistivity annulus. Low-resistivity and high-resistivity annulus characteristics are strong evidence of movable oil and gas shows and are also effective means of identifying oil layers, especially low-resistivity oil and gas layers. As the time or extent of freshwater drilling fluid intrusion into the reservoir increases, the low-resistivity annulus migrates towards the original formation and gradually disappears. Additionally, with the formation of mud cake in the wellbore, the high-resistivity annulus migrates towards the wellbore. The induced radial resistivity characteristics of aquifer arrays include two types: resistance-reducing intrusion (high resistivity aquifers) and resistance-increasing intrusion (low resistivity aquifers).
[0008] Dual-induction-eight-lateral logging, limited by its detection range, primarily reveals the formation resistivity characteristics and variations within a 163cm radius around the wellbore. In reservoirs where drilling fluid intrusion is extensive due to engineering reasons or geological differences, deep-induction resistivity may not reflect the resistivity of the original formation. For example, in low-resistivity annexes within the reservoir, as the intrusion time or range increases, the annexes migrate towards the original formation and gradually disappear. The low-resistivity portions within the annexes gradually move away from the wellbore. Deep-induction resistivity detection may only reveal the resistivity of relatively low-resistivity portions within the annexes, while dual-induction-eight-lateral logging reveals the reservoir resistivity characteristics and radial variations of the low-resistivity annexes closer to the wellbore. Conversely, in oil-bearing formations with high-resistivity annexes, these annexes are located near the wellbore, and their radial resistivity characteristics are easily revealed by dual-induction-eight-lateral logging data.
[0009] For low-permeability reservoirs in complex formation water-oil zones, the dual-induction-eight lateral radial resistivity characteristics of oil-bearing layers include four types: resistivity-reducing invasion, low-resistivity rings, high-resistivity rings, and resistivity-increasing invasion. The radial resistivity characteristics of aquifers include two types: resistivity-reducing invasion (high-resistivity aquifers) and resistivity-increasing invasion (low-resistivity aquifers). Specifically, the dual-induction-eight lateral radial resistivity reveals that oil-bearing layers with resistivity-increasing invasion characteristics have similar characteristics to low-resistivity aquifers; while the dual-induction-eight lateral radial resistivity reveals that oil-bearing layers with resistivity-reducing invasion characteristics have similar characteristics to high-resistivity aquifers with low formation water salinity.
[0010] Therefore, taking into full account the characteristics of reservoir fluid properties, as well as the characteristics of drilling engineering, logging series, and logging implementation time, comparing and analyzing the similarities and differences between array induction and dual-induction-eight lateral radial resistivity characteristics, mining the fluid information contained in the dual-induction-eight lateral radial resistivity characteristics, constructing sensitive fluid identification parameters, and forming a method for identifying the fluid properties of low-permeability reservoirs in complex formation water-oil areas based on array induction logging and dual-induction-eight lateral logging has become a practical need for exploration and development. Summary of the Invention
[0011] The purpose of this invention is to provide a method for identifying the fluid properties of low-permeability reservoirs in complex water-oil formations based on array induction logging and dual-induction-eight-lateral logging. Fluid identification is a key aspect of reservoir evaluation, especially for low-permeability reservoirs in complex water-oil formations, which are influenced by multiple factors. This invention analyzes the characteristics of low-permeability reservoirs in complex water-oil formations, considering the radial resistivity characteristics and variations of array induction logging and dual-induction-eight-lateral logging under different fluid properties, thus forming a method for identifying the fluid properties of low-permeability reservoirs in complex water-oil formations based on these two methods.
[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for identifying the fluid properties of low-permeability reservoirs in complex formation water-oil zones based on array induction logging and dual-induction-eight-lateral logging includes the following steps: Step 1: Statistical analysis of array induction logging and dual-induction-eight lateral radial resistivity characteristics and their changes in the oil testing section of low-permeability reservoirs in complex formation water-oil areas is conducted. The combined characteristics of array induction logging and dual-induction-eight lateral radial resistivity for oil-bearing layers (oil layer, oil-water co-layer) and water-bearing layers (oil-water layer, water layer) under freshwater drilling fluid drilling conditions are summarized as follows: drag-reducing invasion, low-resistivity annulus, high-resistivity annulus, and drag-increasing invasion.
[0013] Step 2: Next, compare and analyze the similarities and differences in the radial resistivity combination characteristics of array induction logging for oil-bearing and water-bearing formations, and dual-induction-eight-lateral logging. When drilling with freshwater drilling fluid, the radial resistivity characteristics of array induction logging in oil-bearing formations include three types: drag-reducing invasion, low-resistivity annulus, and high-resistivity annulus. The low-resistivity and high-resistivity annulus characteristics are strong evidence of movable oil and gas shows and are also effective means of identifying oil layers, especially low-resistivity oil and gas layers. As the time or extent of freshwater drilling fluid invasion into the reservoir increases, the low-resistivity annulus migrates towards the original formation and gradually disappears. Furthermore, with the formation of mud cake in the wellbore, the high-resistivity annulus migrates towards the wellbore. The radial resistivity characteristics of array induction logging in water-bearing formations include two types: drag-reducing invasion (high-resistivity water-bearing formations) and drag-increasing invasion (low-resistivity water-bearing formations). The dual-induction-eight lateral radial resistivity characteristics of oil-bearing reservoirs include four types: resistivity-reducing intrusion, low-resistivity rings, high-resistivity rings, and resistivity-increasing intrusion. The radial resistivity characteristics of aquifers include two types: resistivity-reducing intrusion (high-resistivity aquifers) and resistivity-increasing intrusion (low-resistivity aquifers). Specifically, the dual-induction-eight lateral radial resistivity reveals that oil-bearing reservoirs with resistivity-increasing intrusion characteristics have similar dual-induction-eight lateral radial resistivity characteristics to some low-resistivity aquifers; while oil-bearing reservoirs with resistivity-reducing intrusion characteristics have similar dual-induction-eight lateral radial resistivity characteristics to high-resistivity aquifers with low formation water salinity.
[0014] Step 3: Construct fluid identification sensitivity parameters F1=(M2R1-M2R3) / M2R3, F2=(M2R6-M2R3) / M2R3, or F1=(R LL8 -R ILm ) / R ILm F2 = (R) ILd -R ILm ) / R ILm The purpose of utilizing the radial resistivity difference ratio characteristic of the same reservoir is to eliminate the influence of reservoir lithology, physical properties, pore structure, and formation water salinity, and to highlight the reservoir fluid properties and their variations. Simultaneously, the denominator selects M2R3 of the array induction logging resistivity or medium induction logging resistivity (R...ILm It utilizes M2R3 or R ILm The response to resistivity characteristics, especially in the intrusion zone and transition zone, is highly sensitive, facilitating comparative analysis of reservoir radial characteristics and their variations. An F1-F2 cross plot (F1 as the x-axis, F2 as the y-axis, origin at (0, 0)) is drawn to analyze the dominant distribution areas of oil-bearing reservoirs exhibiting drag-reducing intrusion, low-resistivity ring zones, high-resistivity ring zones, and drag-increasing intrusion characteristics, as well as water-bearing reservoirs exhibiting drag-reducing and drag-increasing intrusion characteristics, in the F1-F2 cross plot.
[0015] Where F1 and F2 are fluid identification sensitive parameters, M2R1, M2R3, M2R6, and M2R3 are resistivity curves, and R... ILm For medium-induction logging resistivity, R LL8 For the eight lateral resistivity, R ILd Deeply induced resistivity; Step 4: Based on steps 1), 2), and 3), calculate the F1 and F2 parameters using array sensing and dual-sensor-eight lateral data. Based on their positions in the F1-F2 cross-plot, effectively identify the low-resistivity annular oil-bearing layer in quadrant I and the high-resistivity annular oil-bearing layer in quadrant III of the F1-F2 cross-plot. Also identify the drag-reducing intrusive oil-bearing layer and the drag-reducing intrusive high-resistivity aquifer in quadrant II of the F1-F2 cross-plot. Due to the difference between the fluid displaced by freshwater drilling fluid in the oil-bearing reservoir and the water displaced by freshwater drilling fluid in the aquifer reservoir, the water in the aquifer is displaced more easily, resulting in different radial resistivity changes in the oil-bearing and aquifer layers. Each has its own distribution advantage area, making identification easier. The main components in quadrant IV of the F1-F2 cross-plot are aquifers with drag-intrusive characteristics and mixed-in oil-bearing layers with drag-intrusive characteristics. The oil-bearing layers in quadrant IV of the F1-F2 cross plot are limited by the range of the dual-induction-eight-lateral logging method. The dual-induction-eight-lateral logging method reveals the resistivity characteristics of oil-bearing layers deeply intruded by freshwater drilling fluid around the wellbore, equivalent to the characteristics of the low-resistivity annulus near the wellbore revealed by array induction logging. Therefore, for oil-bearing layers mixed in quadrant IV of the F1-F2 cross plot, further analysis using deep-penetration logging data is needed, such as adding array induction logging in the well. Thus, a method for identifying the fluid properties of low-permeability reservoirs in complex formation water-oil zones based on array induction logging and dual-induction-eight-lateral logging has been established.
[0016] The beneficial effects of this invention are: 1) Fully consider the response characteristics of various parameters in array induction and dual-induction-eight-lateral logging data to the fluid properties of low-permeability reservoirs in complex formation water-oil areas during freshwater drilling. By comparing and analyzing the similarities and differences in the response characteristics of array induction and dual-induction-eight-lateral logging, the radial resistivity characteristics of array induction and dual-induction-eight-lateral logging data are used to construct fluid identification sensitive parameters and perform cross-interaction processing to ensure the accuracy of fluid property identification.
[0017] 2) By implementing each step, including oil testing data analysis, drilling engineering, logging series and logging response characteristic analysis, and fluid response sensitive parameter construction, we focus on identifying the fluid properties of low-permeability reservoirs in complex formation water-oil areas, quickly identifying reservoir fluid properties under complex geological conditions and improving the accuracy of logging evaluation.
[0018] In summary, this approach helps to rapidly identify the fluid properties of low-permeability reservoirs in complex formations and improve the accuracy of reservoir fluid identification under complex geological conditions in well logging evaluation. Attached Figure Description
[0019] Figure 1 Radial resistivity characteristic map of the oil-bearing formation of the Chang 61 sub-oil layer group in the LH area; Figure 2 Radial resistivity characteristic map of array induction logging of the aquifer in the Chang 61 sub-oil layer group in the LH area; Figure 3 Radial resistivity characteristic map of dual-induction-eight lateral logging of oil-bearing layers in the Chang 61 sub-oil layer group of LH area; Figure 4 Radial resistivity characteristics of the aquifer in the LH region's Chang 61 sub-oil layer group, in the dual-induction-eight-lateral direction. Figure 5 This is a cross diagram of F1-F2 of the Chang 61 sub-oil layer group in the LH region. Detailed Implementation
[0020] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to the following embodiments.
[0021] Example 1: Taking the Chang 6 oil layer and Chang 61 sub-oil layer of the Triassic Yanchang Formation in the LH area of the Ordos Basin as an example.
[0022] The first step involves the Chang 6 oil-bearing formation and the Chang 61 sub-oil-bearing formation of the Triassic Yanchang Formation in the LH area of the Ordos Basin, with reservoir permeability ranging from 0.1 to 5 × 10⁻⁶. - 3μm 2The formation water salinity ranges from 23,000 to 123,000 PPM, exhibiting a wide variation. The 61 sub-oil layer in the LH zone was drilled using freshwater drilling fluid. Array induction logging and dual-induction-eight-layer lateral radial resistivity characteristics and their variations were statistically analyzed in 60 test sections. The combined radial resistivity characteristics of array induction logging in oil-bearing layers (oil layer, oil-water co-layer) and water-bearing layers (oil-water layer, water layer) were summarized. Three types of radial resistivity characteristics were found in the array induction logging of oil-bearing layers. Figure 1 ): Low-resistivity intrusion, low-resistivity ring zone, and high-resistivity ring zone; the aquifer exists in two types ( Figure 2 ): Reduced resistance intrusion, increased resistance intrusion; There are four types of combined characteristics of dual-induction-eight lateral radial resistivity in oil-bearing reservoirs. Figure 3 ): The aquifer's dual-induction-eight lateral radial resistivity combination characteristics exhibit two types: drag-reducing intrusion and drag-increasing intrusion. Figure 4 ).
[0023] The second step involves a comparative analysis of the similarities and differences in the radial resistivity characteristics of array induction logging and dual-induction-eight-lateral logging combinations in oil-bearing and water-bearing formations. Under freshwater drilling conditions in the LH area, the radial resistivity characteristics of array induction logging in the Chang 61 sub-oil layer group include three types: drag-reducing invasion, low-resistivity annulus, and high-resistivity annulus. The low-resistivity and high-resistivity annulus characteristics are strong evidence of movable oil and gas shows and are also effective means of identifying oil layers, especially low-resistivity oil and gas layers. As the time or extent of freshwater drilling fluid invasion into the reservoir increases, the low-resistivity annulus migrates towards the original formation and gradually disappears. Furthermore, with the formation of mud cake in the wellbore, the high-resistivity annulus migrates towards the wellbore. The radial resistivity characteristics of array induction logging in the Chang 61 sub-oil layer group aquifer include two types: drag-reducing invasion (high-resistivity aquifer) and drag-increasing invasion (low-resistivity aquifer). The oil-bearing layers of the Chang 61 sub-oil layer group exhibit four types of dual-inductive-eight lateral radial resistivity characteristics: resistivity-reducing intrusion, low-resistivity rings, high-resistivity rings, and resistivity-increasing intrusion. The aquifer radial resistivity characteristics include two types: resistivity-reducing intrusion (high-resistivity aquifer) and resistivity-increasing intrusion (low-resistivity aquifer). Specifically, the oil-bearing layers in the Chang 61 sub-oil layer group exhibiting resistivity-increasing intrusion characteristics are similar to those in low-resistivity aquifers; while the oil-bearing layers exhibiting resistivity-reducing intrusion characteristics are similar to those in high-resistivity aquifers with low formation water salinity.
[0024] The third step involves using array sensing or dual sensing—eight lateral data sources to construct fluid identification sensitive parameters F1=(M2R1-M2R3) / M2R3, F2=(M2R6-M2R3) / M2R3, or F1=(R LL8 -R ILm ) / RILm F2 = (R) ILd -R ILm ) / R ILm The purpose of utilizing the radial resistivity difference ratio characteristic of the same reservoir is to eliminate the influence of reservoir lithology, physical properties, pore structure, and formation water salinity, and to highlight the reservoir fluid properties and their variations; the denominator uses array induction M2R3 or medium induction logging resistivity (R ILm It utilizes M2R3 or R ILm The resistivity response of intrusion zones, especially transition zones, is highly sensitive, facilitating comparative analysis of reservoir radial characteristics and their variations. An F1-F2 cross plot (F1 on the x-axis, F2 on the y-axis, origin at (0, 0)) is plotted to analyze the dominant distribution areas of oil-bearing reservoirs exhibiting drag-reducing intrusion, low-resistivity ring zones, high-resistivity ring zones, and drag-increasing intrusion characteristics, as well as water-bearing reservoirs exhibiting drag-reducing and drag-increasing intrusion characteristics, in the F1-F2 cross plot. Figure 5 ).
[0025] Fourth, after implementing the above steps, the F1 and F2 parameters are calculated based on array sensing and dual-sensor-eight lateral data. Based on the distribution of data points in the F1-F2 cross-plot, the low-resistivity annular oil-bearing layer in the first quadrant of the F1-F2 cross-plot and the high-resistivity annular oil-bearing layer in the third quadrant of the F1-F2 cross-plot are effectively identified (see...). Figure 5 The drag-reducing intrusion oil-bearing layers and drag-reducing intrusion high-resistivity aquifers, distributed in quadrant II of the F1-F2 cross diagram, exhibit different radial resistivity variations due to the difference between the fluids displaced by freshwater drilling fluid in oil-bearing reservoirs and the water displaced by freshwater drilling fluid in aquifer reservoirs. Each type of aquifer has its own dominant distribution area, making them easy to identify (see...). Figure 5 The fourth quadrant of the F1-F2 cross plot mainly consists of water-bearing formations with enhanced resistance invasion characteristics, as well as mixed oil-bearing formations with enhanced resistance invasion characteristics, with a fluid identification rate of 83.3%. The oil-bearing formations in the fourth quadrant of the F1-F2 cross plot are limited by the range of the dual-induction-eight-lateral detection method. The dual-induction-eight-lateral method reveals the resistivity characteristics within a 163cm radius around the wellbore after the deep invasion of freshwater drilling fluid into the oil-bearing formation, which is equivalent to the low-resistivity annulus near the wellbore revealed by array induction logging. Therefore, for oil-bearing formations mixed into the fourth quadrant of the F1-F2 cross plot, further analysis using deep-penetration logging data is needed, such as adding array induction logging in the well.
[0026] Through the above steps, a method for identifying the fluid properties of low-permeability reservoirs in complex formation water-oil zones based on array induction logging and dual-induction-eight-lateral logging has been developed, which helps to improve the accuracy of fluid identification under complex geological conditions.
Claims
1. A method for identifying the fluid properties of low-permeability reservoirs in complex formation water-oil zones based on array induction logging and dual-induction-eight-lateral logging, characterized in that, Includes the following steps: Step 1: Statistical analysis of array induction logging and dual-induction-eight lateral radial resistivity characteristics and their changes in the oil testing section of low-permeability reservoirs in complex formation water-oil areas is conducted. The combined characteristics of array induction logging and dual-induction-eight lateral radial resistivity of oil-bearing and water-bearing layers under freshwater drilling fluid drilling conditions are summarized. Step 2: When drilling with freshwater drilling fluid, compare and analyze the similarities and differences in the radial resistivity combination characteristics of array induction logging and dual-induction-eight-lateral logging in oil-bearing and water-bearing layers. Step 3: Construct fluid identification sensitive parameters F1=(M2R1-M2R3) / M2R3, F2=(M2R6-M2R3) / M2R3, or F1= (R LL8 -R ILm ) / R ILm F2 = (R ILd -R ILm ) / R ILm Draw the F1-F2 cross plot, with F1 as the horizontal axis and F2 as the vertical axis, and the origin as (0, 0). Analyze the dominant distribution areas of oil-bearing layers with drag-reducing intrusion, low-resistivity ring zone, high-resistivity ring zone, and drag-increasing intrusion characteristics, as well as water-bearing layers with drag-reducing intrusion and drag-increasing intrusion characteristics in the F1-F2 cross plot. Among them, F1 and F2 are fluid identification sensitive parameters, M2R1, M2R3, and M2R6 are array induction logging resistivity curves, and R ILm For medium-induction logging resistivity, R LL8 For the eight lateral resistivity, R ILd For deep induced resistivity; Step 4: Based on Steps 1, 2, and 3, calculate the F1 and F2 parameters using array induction logging and dual-induction-eight-lateral logging data. Based on their positions in the F1-F2 cross plot, identify the low-resistivity annular oil-bearing layer in Quadrant I, the high-resistivity annular oil-bearing layer in Quadrant III, the drag-reducing intrusive oil-bearing layer in Quadrant II, and the mixed high-resistivity aquifer with drag-reducing intrusion characteristics. The main components in Quadrant IV of the F1-F2 cross plot are low-resistivity aquifers with drag-increasing intrusion characteristics and mixed oil-bearing layers with drag-increasing intrusion characteristics.
2. The method for identifying the fluid properties of low-permeability reservoirs in complex formation water-oil zones based on array induction logging and dual-induction-eight-lateral logging, as described in claim 1, is characterized in that... The array induction logging and dual-induction-eight lateral radial resistivity combination features include four types: drag reduction invasion, low-resistivity ring band, high-resistivity ring band, and drag increase invasion.
3. The method for identifying the fluid properties of low-permeability reservoirs in complex formation water-oil zones based on array induction logging and dual-induction-eight-lateral logging, as described in claim 1, is characterized in that... The oil-bearing layer is an oil layer and an oil-water layer in the same layer, and the water-bearing layer is an oil-water layer and a water layer.
4. The method for identifying the fluid properties of low-permeability reservoirs in complex formation water-oil zones based on array induction logging and dual-induction-eight-lateral logging, as described in claim 1, is characterized in that... When drilling with freshwater drilling fluid, the radial resistivity characteristics of the oil-bearing reservoir in array induction logging include three types: drag-reducing invasion, low-resistivity annulus, and high-resistivity annulus. Among them, the low-resistivity annulus and high-resistivity annulus are strong evidence of movable oil and gas shows, and also effective means of identifying low-resistivity oil and gas reservoirs. As the time or extent of freshwater drilling fluid invasion into the reservoir increases, the low-resistivity annulus migrates towards the original formation and gradually disappears; at the same time, with the formation of mud cake in the well, the high-resistivity annulus migrates towards the wellbore. When drilling with freshwater drilling fluid, the induced radial resistivity characteristics of the aquifer array include two types: drag-reducing invasion and drag-increasing invasion.
5. The method for identifying the fluid properties of low-permeability reservoirs in complex formation water-oil zones based on array induction logging and dual-induction-eight-lateral logging according to claim 1, characterized in that, When drilling with freshwater drilling fluid, the dual-induction-eight lateral radial resistivity characteristics of oil-bearing formations include four types: drag-reducing invasion, low-resistivity annulus, high-resistivity annulus, and drag-increasing invasion. The dual-induction-eight lateral radial resistivity characteristics of water-bearing formations include two types: drag-reducing invasion and drag-increasing invasion. Among them, oil-bearing formations with drag-increasing invasion characteristics have similar dual-induction-eight lateral radial resistivity characteristics to low-resistivity water-bearing formations; oil-bearing formations with drag-reducing invasion characteristics have similar dual-induction-eight lateral radial resistivity characteristics to high-resistivity water-bearing formations with low formation water salinity.
6. The method for identifying the fluid properties of low-permeability reservoirs in complex formation water-oil zones based on array induction logging and dual-induction-eight-lateral logging according to claim 1, characterized in that, Due to the limitation of the dual-induction-eight lateral detection range, the oil-bearing layers distributed in the fourth quadrant of the F1-F2 cross plot can only reveal the resistivity characteristics and changes of the oil-bearing layers within a 163cm range around the wellbore after deep intrusion by freshwater drilling fluid. This is equivalent to the characteristics of the low-resistivity annulus near the wellbore revealed by array induction logging. Therefore, for the oil-bearing layers mixed in the fourth quadrant of the F1-F2 cross plot, further analysis is needed using deep exploration logging data, and array induction logging should be added in the well.