Sweet spot comprehensive evaluation method for complex lithology mixed sedimentary rock reservoirs based on logging combination

Abstract

The present application provides a complex lithology mixtite reservoir sweet spot comprehensive evaluation method based on logging combination, comprising the following steps, S1: collecting various data of the block; S2: using logging while drilling and gas logging to establish a mixtite reservoir effectiveness evaluation index E; S3: using logging while drilling capture spectroscopy to establish a variable mineral weight mixtite reservoir compressibility index BRIT; S4: using logging while drilling capture spectroscopy to establish a variable mineral weight acidification index ACID. Through the mixtite reservoir effectiveness evaluation index E, the variable mineral weight compressibility index BRIT and the acidification index ACID, the mixtite reservoir geology and engineering sweet spot can be effectively found, which provides a basis for exploration stage testing and sampling, oilfield development stage perforation scheme formulation and later measures. The present application has wide application range, strong effectiveness and high prediction accuracy, has important guiding significance for exploration and development, and can also be appropriately popularized to other types of reservoirs.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas exploration and development technology, and in particular relates to a comprehensive evaluation method for sweet spots in complex lithological mixed sedimentary rock reservoirs based on a combination of measurement and logging. Background Technology

[0002] Terrigenous clastic-carbonate mixed sedimentary deposits represent a unique sedimentary type. With the deepening of oil and gas exploration, mixed sedimentary rocks are increasingly valued as promising reservoirs. Due to their complex sedimentary characteristics, mixed sedimentary rocks readily form thin interbedded reservoirs. In both horizontal and vertical directions, they exhibit diverse reservoir types, including sandstone, dolomite, limestone, and mixed carbonate sandstone, resulting in a complex and varied lithology. Different types of reservoirs show significant differences in tested production capacity, easily leading to the formation of marginal oilfields characterized by low yields, marginality, and fragmentation. The sweet spots of mixed sedimentary reservoirs primarily encompass reservoir effectiveness (geological sweet spot) and modifiability (engineering sweet spot). The ability to quickly, accurately, and efficiently evaluate the sweet spots of mixed sedimentary reservoirs plays a decisive role in oilfield development plan design and subsequent measure selection.

[0003] Gas logging technology primarily involves measuring and analyzing the composition and content of hydrocarbon gases and liquids entering the drilling fluid, allowing direct acquisition of oil and gas information from the formation regardless of formation lithology. Meanwhile, elemental energy dispersive spectroscopy (EDS) logging, through interpretation of the captured gamma ray spectra and oxygen closure calculations, can yield the dry weights of minerals such as quartz, dolomite, calcite, and illite, providing a foundation for the study of complex lithological mixed sedimentary reservoirs.

[0004] Therefore, there is an urgent need for a comprehensive evaluation method for sweet spots in complex lithological mixed sedimentary reservoirs to improve the evaluation efficiency and accuracy of the effectiveness and modifiability of mixed sedimentary reservoirs. Summary of the Invention

[0005] The problem this invention aims to solve is to provide a comprehensive evaluation method for sweet spots in complex lithological mixed sedimentary rock reservoirs based on a combination of surveying and logging. This method can effectively identify geological and engineering sweet spots in mixed sedimentary rock reservoirs, laying a solid foundation for the exploration, development, and subsequent measures of this type of mixed sedimentary rock.

[0006] This invention provides a comprehensive evaluation method for sweet spots in complex lithological mixed sedimentary reservoirs based on a combination of measurement and logging, comprising the following steps:

[0007] S1: Collect various data for the block;

[0008] S2: Establish the effectiveness evaluation index E of mixed sedimentary reservoirs using logging while drilling and gas logging.

[0009] S3: Establish the BRIT index for compressibility of mixed sedimentary reservoirs by using capture-while-drilling energy spectrum logging;

[0010] S4: Establish the variable mineral weighted acidity index ACID by using drilling capture energy spectrum logging.

[0011] Furthermore, in S1, the data includes logging-while-drilling energy spectrum data, gas logging data, core data, wall core data, cuttings logging data, test data, production data, and logging interpretation results data.

[0012] Furthermore, S2 includes the following steps:

[0013] S21: Adjust the left and right scales of the DEN and RD curves so that the two lines intersect in opposite directions and overlap at the center line in the tight layer section. Define the intersection area as the logging effectiveness evaluation index W of the mixed sedimentary reservoir.

[0014] S22: By measuring and analyzing the composition and content of hydrocarbon gases and liquids entering the drilling fluid, the oil and gas information of the formation is obtained, and the total hydrocarbon value ratio of the mudstone section of this well is defined as the evaluation index T for the effectiveness of logging in mixed sedimentary reservoirs.

[0015] S23: Define the effectiveness evaluation index E for mixed sedimentary reservoirs, and its calculation formula is as follows.

[0016] .

[0017] Furthermore, in step S21, the calculation formula for the logging effectiveness evaluation index W of the mixed sedimentary reservoir is as follows:

[0018]

[0019] Where: Rd is the logging depth resistivity value, Ω·m; Rd 左刻度 、Rd 右刻度 The left and right scale values ​​for the resistivity curve are typically 0.2 Ω·m and 200 Ω·m; DEN is the logging density value in g / cm³. 3 ;DEN 左刻度 DEN 右刻度 The values ​​represent the left and right scales of the density curve; for mixed sedimentary reservoirs, 2.95 g / cm³ is generally chosen. 3 1.95g / cm 3 .

[0020] Furthermore, in step S22, the calculation formula for the effectiveness evaluation index T of the mixed sedimentary reservoir gas logging is as follows:

[0021]

[0022] Where: Tg is the total hydrocarbon value from gas logging, %; Tg 泥岩 The total hydrocarbon matrix of the mudstone section is %.

[0023] Furthermore, step S3 includes the following steps:

[0024] S31: Using the mineral dry weight and logging-while-drilling gamma ray, resistivity, density, and neutron curves measured by the trapped-while-drilling energy spectrum, a multi-mineral model is used to calculate the porosity of dolomite, calcite, quartz, illite, and the total formation. The calculation formulas are as follows.

[0025]

[0026] Where: DEN is the logging density value, g / cm³ 3 CN represents the logging neutron value, f; GR represents the logging natural gamma value, API; DW 白云石 DW 方解石 DW 石英石 DW 伊利石 The dry mineral weights, f and V, of dolomite, calcite, quartz, and illite, respectively. 白云石 V 方解石 V 石英石 V 伊利石 Let f and ρ represent the volumes of dolomite, calcite, quartz, and illite, respectively. 白云石 ρ 方解石 ρ 石英石 ρ 伊利石 The densities of dolomite, calcite, quartz, and illite, respectively, in g / cm³. 3 CN 白云石 CN 方解石 CN 石英石 CN 伊利石 The neutron values, f, and GR, are for dolomite, calcite, quartz, and illite, respectively. 白云石 GR 方解石 GR 石英石 GR 伊利石 The gamma values ​​(API) for dolomite, calcite, quartz, and illite are respectively; φ. T f represents the total porosity of the rock. Sw f represents the water saturation of the rock.

[0027] S32: Dolomite, calcite, quartz, and illite are brittle minerals, while illite is a plastic mineral. Based on existing experimental research, the compressibility index BRIT for metamorphic mineral-weighted mixed sedimentary reservoirs is defined, and the calculation formula is as follows.

[0028]

[0029] Among them: YM 白云石 YM 方解石 YM 石英石 The Young's modulus of dolomite, calcite, and quartz, respectively; PO 白云石 PO 方解石 PO 石英石 PO 伊利石f represents the Poisson's ratio of the minerals dolomite, calcite, quartz, and illite, respectively.

[0030] Furthermore, S4 includes the following steps:

[0031] S41: Based on the analysis of core data from complex lithological mixed sedimentary reservoirs, a permeability K-model for mixed sedimentary reservoirs is established, and the calculation formula is as follows.

[0032] ;

[0033] Where: φ T f represents the total porosity of the rock.

[0034] S42: Based on the degree of reaction between hydrochloric acid and different minerals, the reservoir acidity index ACID is defined, and the calculation formula is as follows.

[0035]

[0036] Where: V 白云石 V 方解石 V 石英石 V 伊利石 Let f and φ represent the volumes of dolomite, calcite, quartz, and illite in the mixed sedimentary reservoir, respectively. T f represents the total porosity of the rock.

[0037] Furthermore, the present invention also provides an apparatus for operating the above-described comprehensive evaluation method.

[0038] Furthermore, the present invention also provides an apparatus including a memory, a processor, and an algorithm stored in the memory and executable on the processor, wherein the processor implements the comprehensive evaluation method when executing the computer program.

[0039] Furthermore, the present invention also provides a computer-readable storage medium storing a computer algorithm, which, when executed by a processor, implements the comprehensive evaluation method described above.

[0040] The advantages and positive effects of this invention are:

[0041] This invention innovatively establishes a reservoir effectiveness index E based on well logging and gas logging to classify high-quality mixed sedimentary reservoirs, utilizing drilling-capture energy dispersive spectroscopy (EDS) data combined with pressure measurement, sampling, and testing conclusions from the exploration phase. It also innovatively establishes reservoir modifiability evaluation techniques using elemental EDS data, namely the variable mineral weighted mixed sedimentary reservoir fracturing index BRIT and acidity index ACID. The mixed sedimentary reservoir effectiveness evaluation index E, the variable mineral weighted fracturing index BRIT, and the acidity index ACID can effectively identify geological and engineering sweet spots in mixed sedimentary reservoirs, providing a basis for testing and sampling during the exploration phase, perforation scheme formulation during oilfield development, and subsequent measures. This method can effectively identify geological and engineering sweet spots in mixed sedimentary reservoirs, laying a solid foundation for the exploration, development, and subsequent measures of this type of mixed sedimentary rock. This invention has a wide range of applications, strong effectiveness, and high predictive accuracy, and has important guiding significance for the exploration and development of mixed sedimentary reservoirs. It can also be appropriately extended to other types of oil reservoirs. Attached Figure Description

[0042] Figure 1 This is an overall flowchart of an embodiment of the present invention.

[0043] Figure 2 This is a cross-plot of porosity-permeability of core samples from complex lithological mixed sedimentary rocks in the study area of ​​this invention embodiment.

[0044] Figure 3 This is a comprehensive analysis diagram of the sweet spot of the complex lithological mixed sedimentary rock reservoir in Well A of the study area in this embodiment of the invention.

[0045] Figure 4 This is a comparison chart of the actual production capacity of a single well and the reservoir effectiveness evaluation index E in the study area of ​​this invention embodiment.

[0046] Figure 5 This is a comparison chart of actual production capacity and compressibility index BRIT and acidity index ACID before and after the measures in the study area of ​​this invention embodiment. Detailed Implementation

[0047] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] The embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0049] like Figure 1 As shown, the comprehensive evaluation method for sweet spots in complex lithological mixed sedimentary reservoirs based on a combination of measurement and logging includes the following steps.

[0050] S1: Collect drilling-capture spectral logging data, gas logging data, core data, wall core data, cuttings logging data, test data, production data, and logging interpretation results for the block.

[0051] Specifically, the data collected includes drilling-capture spectral logging data, gas logging data, core data, wall core data, cuttings logging data, test data, production data, and logging interpretation results. Since gas logging data is affected by drilling, instrument, and engineering parameters, it is necessary to correct the gas logging data before application to eliminate the influence of drilling parameters and thus remove the impact of drilling factors on gas logging values.

[0052] S2: Establish the effectiveness evaluation index E of mixed sedimentary reservoirs using logging while drilling and gas logging.

[0053] Specifically, for complex lithological mixed sedimentary reservoirs, their effectiveness mainly depends on the amount of clay content, the quality of reservoir properties, and the abundance of hydrocarbons. Whole-rock analysis of clay content and well logging resistivity analysis show that increased clay content in mixed sedimentary reservoirs leads to a significant decrease in resistivity, while reservoir tightness results in an increase in resistivity. A low reservoir density (DEN) and high resistivity (RD) indicate good reservoir properties and high hydrocarbon potential. Therefore, the intersection of DEN and RD is positively correlated with reservoir properties and hydrocarbon potential. Based on this, by adjusting the left and right scales of the DEN and RD curves to make the two lines intersect in opposite directions, and overlap at the midline in the tight layer section, the intersection area is defined as the well logging effectiveness evaluation index W for mixed sedimentary reservoirs, and its calculation formula is as follows:

[0054] (1)

[0055] Where: Rd is the logging depth resistivity value, Ω·m; Rd 左刻度 、Rd 右刻度 The left and right scale values ​​for the resistivity curve are typically 0.2 Ω·m and 200 Ω·m; DEN is the logging density value in g / cm³. 3 ;DEN 左刻度 DEN 右刻度 The values ​​represent the left and right scales of the density curve; for mixed sedimentary reservoirs, 2.95 g / cm³ is generally chosen. 3 1.95g / cm 3 .

[0056] Gas logging technology primarily involves measuring and analyzing the composition and content of hydrocarbon gases and liquids entering the drilling fluid. This allows for the direct acquisition of hydrocarbon-bearing information from the formation, unaffected by formation lithology. Considering inter-well consistency, the ratio of the total hydrocarbon value to the total hydrocarbon matrix of the mudstone section in this well is defined as the gas logging effectiveness evaluation index T for mixed sedimentary reservoirs. Its calculation formula is as follows:

[0057] (2)

[0058] Where: Tg is the total hydrocarbon value from gas logging, %; Tg 泥岩 The total hydrocarbon matrix of the mudstone section is %.

[0059] The effectiveness evaluation index E of mixed sedimentary reservoirs is defined, and its calculation formula is as follows:

[0060] (3)

[0061] S3: Using capture-while-drilling energy spectrum logging, establish the compressibility index BRIT for mixed sedimentary reservoirs with varying mineral weights.

[0062] Specifically, using the mineral dry weight and logging-while-drilling gamma ray, resistivity, density, and neutron curves measured by the capture-while-drilling energy spectrum, a multi-mineral model was used to calculate the porosity of dolomite, calcite, quartz, illite, and the total formation porosity.

[0063] (4)

[0064] Where: DEN is the logging density value, g / cm³ 3 CN represents the logging neutron value, f; GR represents the logging natural gamma value, API; DW 白云石 DW 方解石 DW 石英石 DW 伊利石 The dry mineral weights, f and V, of dolomite, calcite, quartz, and illite, respectively. 白云石 V 方解石 V 石英石 V 伊利石 Let f and ρ represent the volumes of dolomite, calcite, quartz, and illite, respectively. 白云石 ρ 方解石 ρ 石英石 ρ 伊利石 The densities of dolomite, calcite, quartz, and illite, respectively, in g / cm³. 3 CN 白云石 CN 方解石 CN 石英石 CN 伊利石 The neutron values, f, and GR, are for dolomite, calcite, quartz, and illite, respectively. 白云石 GR 方解石 GR 石英石 GR 伊利石 The gamma values ​​(API) for dolomite, calcite, quartz, and illite are respectively; φ. T f represents the total porosity of the rock. Sw f represents the water saturation of the rock.

[0065] Formations with higher Young's modulus and lower Poisson's ratio are more brittle and more prone to fracture networks. Dolomite, calcite, quartz, and illite are brittle minerals, while illite is a ductile mineral. Traditional mineral composition methods do not consider the different rock mechanical parameters of various minerals. Based on existing experimental research, the BRIT (Brake Indices for Compressibility of Mixed Sedimentary Reservoirs) is defined as follows:

[0066] (5)

[0067] Among them: YM 白云石 YM 方解石 YM 石英石 The Young's modulus of dolomite, calcite, and quartz, respectively; PO 白云石 PO 方解石 PO 石英石 PO 伊利石 f represents the Poisson's ratio of the minerals dolomite, calcite, quartz, and illite, respectively.

[0068] S4: Establish the variable mineral weighted acidity index ACID by using drilling capture energy spectrum logging.

[0069] Specifically, such as Figure 2 As shown, based on the analysis of core data from complex lithological mixed sedimentary reservoirs, a permeability K-model for mixed sedimentary reservoirs is established, and its calculation formula is as follows:

[0070] (6)

[0071] Where: φT is the total porosity of the rock, f.

[0072] Based on the degree of reaction between hydrochloric acid and different minerals, calcite reacts most vigorously, dolomite reacts less strongly, while quartz and illite are both insoluble in hydrochloric acid, and an increase in illite content significantly reduces the degree of carbonate acidification. The better the rock's porosity and structure, the easier it is for acid to penetrate the formation, increasing the reaction area and resulting in a better acidification effect. The reservoir acidity index (ACID) is defined and its calculation formula is as follows.

[0073] (7)

[0074] Where: V 白云石 V 方解石 V 石英石 V 伊利石 The volumes (volume fractions) of dolomite, calcite, quartz, and illite in the mixed sedimentary reservoir are f and φ, respectively. T f represents the total porosity of the rock.

[0075] like Figure 3As shown, channel 5 represents the formation mineral volume (VOL) and total formation porosity (PHIT) calculated using drilling-captured energy spectrum data; channel 6 represents the permeability (K) calculated based on the core model; and channel 7 represents the water saturation (SW) calculated from well logging. Channels 9-11 represent the reservoir effectiveness evaluation index E, the reservoir compressibility index BRIT, and the acidity index ACID, respectively. Through these three core parameters, sweet spots in complex lithological mixed sedimentary reservoirs were selected, such as... Figure 3 As shown in the Chinese box, a sample was successfully taken at 1265m. Figure 4 The figure shows the relationship between the effectiveness evaluation index E of mixed sedimentary reservoirs and the production ratio of actual exploration wells and development wells. It can be found that the higher the effectiveness evaluation index E, the better the reservoir productivity. Figure 5 The figure shows the relationship between the acidity index ACID of mixed sedimentary reservoirs and the increase in production ratio after acidizing in development wells. It can be found that the higher the acidity index ACID, the better the acidizing effect.

[0076] In summary, the effectiveness evaluation index E, the weighted compressibility index BRIT, and the acidity index ACID can effectively identify geological and engineering sweet spots in mixed sedimentary reservoirs, providing a basis for testing and sampling during the exploration phase, perforation scheme formulation during the oilfield development phase, and subsequent measures. This invention has a wide range of applications, strong effectiveness, and high predictive accuracy, and is of great guiding significance for exploration and development. It can also be appropriately extended to other types of oil reservoirs.

[0077] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A comprehensive evaluation method for sweet spots in complex lithological mixed sedimentary reservoirs based on a combination of surveying and logging, characterized by: Includes the following steps, S1: Collect various data for the block; S2: Establish the effectiveness evaluation index E of mixed sedimentary reservoirs using logging while drilling and gas logging. S2 includes the following steps. S21: Adjust the left and right scales of the DEN and RD curves so that the two lines intersect in opposite directions and overlap at the center line in the tight layer section. Define the intersection area as the logging effectiveness evaluation index W of the mixed sedimentary reservoir. S22: By measuring and analyzing the composition and content of hydrocarbon gases and liquids entering the drilling fluid, oil and gas information of the formation is obtained. The ratio of the total hydrocarbon value to the total hydrocarbon matrix of the mudstone section in this well is defined as the logging effectiveness evaluation index T for mixed sedimentary reservoirs. The calculation formula for the logging effectiveness evaluation index T for mixed sedimentary reservoirs is as follows. Where: Tg is the total hydrocarbon value from gas logging, %; Tg 泥岩 The total hydrocarbon matrix of the mudstone section is % S23: Define the effectiveness evaluation index E for mixed sedimentary reservoirs, and its calculation formula is as follows. ； S3: Establish the BRIT index for compressibility of mixed sedimentary reservoirs by using capture energy spectrum logging while drilling; S4: Establish the variable mineral weighted acidity index ACID using drilling-while-drilling energy spectral logging. S4 includes the following steps. S41: Based on the analysis of core data from complex lithological mixed sedimentary reservoirs, a permeability K-model for mixed sedimentary reservoirs is established, and the calculation formula is as follows. ； in: φ T f represents the total porosity of the rock. S42: Based on the degree of reaction between hydrochloric acid and different minerals, the reservoir acidity index ACID is defined, and the calculation formula is as follows. Where: V 白云石 V 方解石 V 石英石 V 伊利石 f represents the volume of dolomite, calcite, quartz, and illite in the mixed sedimentary reservoir, respectively. φ T f represents the total porosity of the rock. When the target reservoir section has high values ​​for the mixed sedimentary reservoir effectiveness evaluation index E, the metamorphic mineral weighted mixed sedimentary reservoir compressibility index BRIT, and the metamorphic mineral weighted acidity index ACID, it is judged as a high-quality sweet spot of mixed sedimentary reservoir.

2. The comprehensive evaluation method for sweet spots in complex lithological mixed sedimentary reservoirs based on the combination of measurement and logging as described in claim 1, characterized in that: In S1, the data includes logging-while-drilling energy spectrum data, gas logging data, core data, wall core data, cuttings logging data, test data, production data, and logging interpretation results.

3. The comprehensive evaluation method for sweet spots in complex lithological mixed sedimentary reservoirs based on a combination of measurement and logging, as described in claim 1 or 2, is characterized in that: In step S21, the calculation formula for the logging effectiveness evaluation index W of the mixed sedimentary reservoir is as follows: Where: Rd is the logging depth resistivity value, Ω·m; Rd 左刻度 、Rd 右刻度 The left and right scale values ​​for the resistivity curve are typically 0.2 Ω·m and 200 Ω·m; DEN is the logging density value in g / cm³. 3 ;DEN 左刻度 DEN 右刻度 The values ​​represent the left and right scales of the density curve; for mixed sedimentary reservoirs, 2.95 g / cm³ is generally chosen. 3 1.95g / cm 3 .

4. The comprehensive evaluation method for sweet spots in complex lithological mixed sedimentary reservoirs based on a combination of measurement and logging, as described in claim 1 or 2, is characterized in that: S3 includes the following steps: S31: Using the mineral dry weight and logging-while-drilling gamma ray, resistivity, density, and neutron curves measured by the trapped-while-drilling energy spectrum, a multi-mineral model is used to calculate the porosity of dolomite, calcite, quartz, illite, and the total formation. The calculation formulas are as follows. Where: DEN is the logging density value, g / cm³ 3 CN represents the logging neutron value, f; GR represents the logging natural gamma value, API; DW 白云石 DW 方解石 DW 石英石 DW 伊利石 The dry mineral weights, f and V, of dolomite, calcite, quartz, and illite, respectively. 白云石 V 方解石 V 石英石 V 伊利石 Let f and ρ represent the volumes of dolomite, calcite, quartz, and illite, respectively. 白云石 ρ 方解石 ρ 石英石 ρ 伊利石 The densities of dolomite, calcite, quartz, and illite, respectively, in g / cm³. 3 CN 白云石 CN 方解石 CN 石英石 CN 伊利石 The neutron values, f, and GR, are for dolomite, calcite, quartz, and illite, respectively. 白云石 GR 方解石 GR 石英石 GR 伊利石 The gamma values ​​(API) for dolomite, calcite, quartz, and illite are respectively; φ. T f represents the total porosity of the rock; S represents the total porosity of the rock. w f represents the water saturation of the rock. S32: Dolomite, calcite, quartz, and illite are brittle minerals, while illite is a plastic mineral. Based on existing experimental research, the compressibility index BRIT for metamorphic mineral-weighted mixed sedimentary reservoirs is defined, and the calculation formula is as follows. Among them: YM 白云石 YM 方解石 YM 石英石 The Young's modulus of dolomite, calcite, and quartz, respectively; PO dolomite, PO 方解石 PO 石英石 PO 伊利石 f represents the Poisson's ratio of the minerals dolomite, calcite, quartz, and illite, respectively.

5. An apparatus, characterized in that: Run the comprehensive evaluation method as described in any one of claims 1 to 4.

6. An apparatus comprising a memory, a processor, and an algorithm stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, it implements the comprehensive evaluation method as described in any one of claims 1 to 4.

7. A computer-readable storage medium storing a computer algorithm, characterized in that, When the computer algorithm is executed by the processor, it implements the comprehensive evaluation method as described in any one of claims 1 to 4.

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