Carbonate gas reservoir development favorable area optimization and well arrangement method and device
By optimizing the lower limit of dynamic reserves and related parameters of carbonate gas reservoirs, establishing favorable areas and formulating effective well patterns, the problem of uneconomical well placement in the exploration and development of carbonate gas reservoirs has been solved, and more efficient well placement has been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- PETROCHINA CO LTD
- Filing Date
- 2022-09-14
- Publication Date
- 2026-07-24
AI Technical Summary
In the exploration and development of carbonate gas reservoirs, existing technologies lack comprehensive multi-parameter methods to select favorable areas and establish effective well patterns, resulting in uneconomical well placement, especially when reservoir development conditions are poor and it is difficult to meet actual needs.
By determining the lower limit of dynamic reserves for carbonate gas reservoir development, and selecting the lower limits of high-quality reservoir thickness, hill and shoal body thickness, relative elevation of karst paleogeography, degree of karstification, and fracture density, favorable areas are established and effective well patterns are developed, including the layout of horizontal and deviated wells.
It improves the standardization of favorable zone delineation and the pertinence of well patterns, ensures the economic benefits of gas wells, and provides a reference for well location deployment.
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Figure CN117738637B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of comprehensive area selection technology in the evaluation and development stages of oil and gas fields, and particularly to a method and apparatus for selecting favorable areas for the development of carbonate gas reservoirs and for well placement. Background Technology
[0002] During the exploration, evaluation, and development stages of various oil and gas reservoirs, extensive basic geological research and dynamic evaluation of gas well production are conducted. Based on a comprehensive understanding of the existing gas reservoir formation system, it is ultimately necessary to select favorable exploration zones or favorable development and production areas to provide a reference for the next step of reserve declaration or well location deployment. Furthermore, in the well location deployment process, especially in the optimization of well type and well trajectory, it is necessary to comprehensively consider geological, seismic, and other parameters, and to conduct design and implementation under the guidance of effective well models.
[0003] Currently, in the oil and gas reservoir exploration stage, the selection of favorable areas in conventional oil and gas exploration mainly considers the source-reservoir-seal combination and reservoir formation conditions of the target strata. However, in the oil and gas reservoir evaluation and development stage, there are relatively few studies on the selection of favorable areas. Regarding the selection of favorable areas for carbonate oil and gas reservoir development, although some studies have comprehensively considered multiple aspects such as sedimentation, karst, fractures and vulnerabilities, and reservoirs, the determination of the classification criteria and lower limits is quite arbitrary, and the rationality of the selection of favorable areas has not been considered from an economic perspective. In terms of effective well models, existing studies focus on high-yield well models, mainly considering seismic response models under different reservoir thicknesses and combinations. However, when gas reservoir development conditions are poor, existing high-yield well models cannot meet the actual well location deployment requirements. It is necessary to further refine early well models, while also considering the economic benefits of gas wells, so that effective well models established under underdeveloped reservoir conditions can still meet the lower limit of economic efficiency.
[0004] Therefore, establishing a method for selecting favorable areas and placing wells in favorable areas based on economic benefits is of great significance to the actual oil and gas production. Summary of the Invention
[0005] To address the current lack of comprehensive, multi-parameter methods that consider the lower limit of gas well economic benefits in the evaluation and development of carbonate gas reservoirs, this paper focuses on optimizing the most critical factors influencing the distribution of favorable areas in carbonate gas reservoirs, such as the thickness of high-quality reservoirs, the thickness of hills and shoals, the relative elevation of karst paleogeography, the degree of karstification, and the density of fractures. Favorable areas are then selected, and effective well models are established within these areas based on high-quality reservoir combinations. This approach provides a more reliable basis for determining the parameters for defining favorable areas and makes the establishment of effective well models more targeted.
[0006] To achieve the above objectives, the present invention provides a method for selecting favorable development areas and well placement in carbonate gas reservoirs, the method comprising:
[0007] The lower limit of dynamic reserves for carbonate gas reservoir development is determined based on economic benefits, and the lower limit of reservoir parameters for carbonate gas reservoir development is determined based on the lower limit of dynamic reserves for carbonate gas reservoir development.
[0008] Obtain the reservoir parameters of the target layer of the carbonate gas reservoir, and determine the favorable area of the target layer of the carbonate gas reservoir based on the lower limit of the reservoir parameters for the development of the carbonate gas reservoir.
[0009] The final target layer favorable area of carbonate gas reservoir is determined based on the reserve parameters of the favorable area of the target layer in the preliminary carbonate gas reservoir.
[0010] The well placement method is determined based on the reservoir properties of the favorable area of the final target layer of the carbonate gas reservoir.
[0011] Furthermore, based on economic benefits, the lower limit of dynamic reserves for carbonate gas reservoir development is determined, and based on this lower limit of dynamic reserves, the lower limit of reservoir parameters for carbonate gas reservoir development is determined, including...
[0012] The dynamic reserves at which the internal rate of return (IRR) of carbonate gas reservoirs is equal to the lower limit of profitability are taken as the lower limit of dynamic reserves for carbonate gas reservoirs.
[0013] The thickness of high-quality reservoirs, the thickness of hills and shoals, the relative elevation of karst paleogeography, the thickness of karst zones, and the lower limit of fracture density in carbonate gas reservoirs are determined based on the lower limit of dynamic reserves.
[0014] Furthermore, based on the lower limit of dynamic reserves for carbonate gas reservoir development, the lower limits of high-quality reservoir thickness, hill / shoal body thickness, relative elevation of karst paleogeography, karst zone thickness, and fracture density are determined, specifically including:
[0015] Establish the relationship between the thickness of high-quality reservoirs and dynamic reserves for carbonate gas reservoir development, and determine the lower limit of the thickness of high-quality reservoirs for carbonate gas reservoir development based on the relationship between the lower limit of dynamic reserves for carbonate gas reservoir development and the thickness of high-quality reservoirs and dynamic reserves.
[0016] The thickness of high-quality reservoirs for carbonate gas reservoir development is correlated with the thickness of hills and shoals, the relative elevation of karst paleomorphology, the thickness of karst zones, and the density of fractures. The lower limits of the thickness of high-quality reservoirs for carbonate gas reservoir development, the lower limits of the thickness of hills and shoals, the relative elevation of karst paleomorphology, the thickness of karst zones, and the lower limits of fracture density are determined based on the lower limit of the thickness of high-quality reservoirs for carbonate gas reservoir development.
[0017] Furthermore, reservoir parameters of the target layer in the carbonate gas reservoir are obtained, and favorable areas of the target layer in the preliminary carbonate gas reservoir are determined based on the lower limit of the reservoir parameters for carbonate gas reservoir development, including,
[0018] To obtain the thickness of high-quality reservoirs, hill and shoal bodies, relative elevation of karst paleogeography, thickness of karst zones, and fracture density of target layers in carbonate gas reservoirs;
[0019] In the target layer of carbonate gas reservoirs, the blocks in which the thickness of high-quality reservoirs, the thickness of hills and shoals, the relative elevation of karst paleomorphology, the thickness of karst zones, and the lower limit of fracture density are all greater than those of high-quality reservoirs, hills and shoals, relative elevation of karst paleomorphology, the thickness of karst zones, and the lower limit of fracture density are used for the exploitation of carbonate gas reservoirs are identified as the preliminary favorable areas for the target layer of carbonate gas reservoirs.
[0020] Furthermore, based on the reserve parameters of the preliminary target layer favorable area of the carbonate gas reservoir, the final target layer favorable area of the carbonate gas reservoir is determined, including,
[0021] Based on the area, average effective thickness, average effective porosity, average gas saturation, and volume factor of the favorable area of the target layer in the preliminary carbonate gas reservoir, the reserves of the favorable area of the target layer in the preliminary carbonate gas reservoir are determined.
[0022] The favorable area of the preliminary target layer of carbonate gas reservoir with reserves greater than the lower limit of dynamic reserves is identified as the favorable area of the final target layer of carbonate gas reservoir.
[0023] Furthermore, the well placement method is determined based on the reservoir properties of the favorable area of the final target carbonate gas reservoir, including:
[0024] Analyze the development patterns and geological characteristics of high-quality reservoirs in the favorable areas of the target carbonate gas reservoir, and determine effective well models by combining seismic profile reflections.
[0025] Effective well patterns include horizontal wells and deviated wells.
[0026] This invention also provides a device for selecting favorable development areas of carbonate gas reservoirs and a well placement device thereof, the device comprising,
[0027] The reservoir parameter unit is used to determine the lower limit of dynamic reserves for carbonate gas reservoir development based on economic benefits, and to determine the lower limit of reservoir parameters for carbonate gas reservoir development based on the lower limit of dynamic reserves for carbonate gas reservoir development.
[0028] The first determining unit is used to obtain the reservoir parameters of the target layer of the carbonate gas reservoir and to determine the favorable area of the target layer of the carbonate gas reservoir based on the lower limit of the reservoir parameters for the development of the carbonate gas reservoir.
[0029] The second determining unit is used to determine the final target layer favorable area of the carbonate gas reservoir based on the reserve parameters of the target layer favorable area of the preliminary carbonate gas reservoir.
[0030] The well placement determination unit is used to determine the well placement method based on the reservoir properties of the favorable area of the final target layer of the carbonate gas reservoir.
[0031] Furthermore, the reservoir parameter unit includes a dynamic reserve lower limit module and a parameter lower limit module;
[0032] The lower limit module for dynamic reserves is used to define the dynamic reserves of carbonate gas reservoirs as the lower limit of the internal rate of return (IRR) during mining, when the IRR is the lower limit of the profit IRR.
[0033] The parameter lower limit module is used to determine the lower limits of high-quality reservoir thickness, hill and shoal body thickness, relative elevation of karst paleogeography, karst zone thickness, and fracture density for the exploitation of carbonate gas reservoirs based on the lower limit of dynamic reserves of carbonate gas reservoirs.
[0034] Furthermore, the first determining unit includes an acquisition module and a preliminary advantageous area module;
[0035] The acquisition module is used to obtain the thickness of high-quality reservoirs, hill and shoal bodies, relative elevation of karst paleogeography, thickness of karst zones, and fracture density of the target layer in carbonate gas reservoirs.
[0036] The preliminary favorable area module is used to identify blocks in the target carbonate gas reservoir where the thickness of the high-quality reservoir, the thickness of the hill-shoal body, the relative elevation of the karst paleomorphology, the thickness of the karst zone, and the fracture density are all greater than the lower limit of the thickness of the high-quality reservoir, the thickness of the hill-shoal body, the relative elevation of the karst paleomorphology, the thickness of the karst zone, and the fracture density for carbonate gas reservoir development.
[0037] Furthermore, the second determining unit includes a reserve module and a final favorable area module;
[0038] The reserves module is used to determine the reserves of the favorable area of the target layer of the preliminary carbonate gas reservoir based on the area, average effective thickness, average effective porosity, average gas saturation and volume factor of the favorable area of the target layer.
[0039] The final favorable area module is used to identify the favorable areas of the preliminary target layer of carbonate gas reservoirs with reserves greater than the lower limit of dynamic reserves as the final favorable areas of the target layer of carbonate gas reservoirs.
[0040] Compared with the prior art, the present invention has the following beneficial effects:
[0041] This invention uses the internal rate of return (IRR) as the standard to determine the lower limit of dynamic reserves in favorable development areas. It clarifies the lower limit standards for five parameters: high-quality reservoir thickness, hill / shoal body thickness, karst zone thickness, relative elevation of karst paleogeography, and fracture density. This allows for the selection of favorable development areas, the formation of high-quality reservoir development patterns, and the establishment of effective well models. The method of this invention considers the rationality of favorable area selection from an economic perspective, making the determination of parameters for favorable area development in carbonate gas reservoirs more evidence-based and the establishment of effective well models more targeted. The comprehensive selection of favorable areas based on multiple parameters and the establishment of effective well models provide a reference for the deployment of development wells. Attached Figure Description
[0042] Figure 1 A flowchart illustrating a method for selecting favorable development zones and well placement in carbonate gas reservoirs according to an embodiment of the present invention is shown.
[0043] Figure 2 This diagram illustrates the relationship between the internal rate of return (IRR) and the stable production and dynamic reserves of a gas well, according to an embodiment of the present invention.
[0044] Figure 3 This invention illustrates the linear relationship between the thickness of high-quality reservoirs and dynamic reserves in carbonate gas reservoir development according to an embodiment of the present invention.
[0045] Figure 4 This invention illustrates the relationship between the thickness of high-quality reservoirs and the thickness of hill-shoal bodies in carbonate gas reservoir development according to an embodiment of the present invention.
[0046] Figure 5 This invention illustrates the relationship between the thickness of high-quality reservoirs and the relative elevation of karst paleogeography in carbonate gas reservoir development according to an embodiment of the present invention.
[0047] Figure 6 This invention illustrates the relationship between the thickness of high-quality reservoirs and the thickness of karst zones in carbonate gas reservoir development according to an embodiment of the present invention.
[0048] Figure 7 A scatter plot of high-quality reservoir thickness and fracture density for carbonate gas reservoir development according to an embodiment of the present invention is shown.
[0049] Figure 8 The thickness diagram of the hill-shoal body in the target layer of the carbonate gas reservoir according to an embodiment of the present invention is shown;
[0050] Figure 9 The map showing the distribution of relative elevations of karst paleogeography in the target layer of the carbonate gas reservoir according to an embodiment of the present invention is illustrated.
[0051] Figure 10 This invention illustrates a planar thickness diagram of the karst zone in the target layer of a carbonate gas reservoir according to an embodiment of the present invention.
[0052] Figure 11 A fracture density planar diagram of the target layer in a carbonate gas reservoir according to an embodiment of the present invention is shown;
[0053] Figure 12 This invention illustrates a planar thickness diagram of the target layer in a carbonate gas reservoir according to an embodiment of the present invention.
[0054] Figure 13 This invention illustrates the development pattern of the target high-quality reservoir in a carbonate gas reservoir according to an embodiment of the present invention.
[0055] Figure 14 The results of determining the favorable area of the target layer in a preliminary carbonate gas reservoir according to an embodiment of the present invention are shown.
[0056] Figure 15 A schematic diagram of a preferred development area for carbonate gas reservoirs and its well placement device according to an embodiment of the present invention is shown. Detailed Implementation
[0057] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.
[0058] like Figure 1 As shown, one embodiment of the present invention provides a method for selecting favorable development areas and well placement in carbonate gas reservoirs, comprising the following steps:
[0059] S101. Determine the lower limit of dynamic reserves for carbonate gas reservoir development based on economic benefits, and determine the lower limit of reservoir parameters for carbonate gas reservoir development based on the lower limit of dynamic reserves for carbonate gas reservoir development.
[0060] S102. Obtain the reservoir parameters of the target layer of the carbonate gas reservoir, and determine the favorable area of the target layer of the carbonate gas reservoir based on the lower limit of the reservoir parameters for the development of the carbonate gas reservoir.
[0061] S103. Determine the final favorable area of the target layer of the carbonate gas reservoir based on the reserve parameters of the favorable area of the target layer in the preliminary carbonate gas reservoir.
[0062] S104. Determine the well placement method based on the reservoir properties of the favorable area of the final target layer of the carbonate gas reservoir.
[0063] The following analysis, using a carbonate gas reservoir in a specific block of the Sichuan Basin, details the method of the above-described embodiments of the present invention. It should be noted that... Figures 8 to 14 In this diagram, GS and MX are well designations, Elevation indicates height in meters (m), Thickness indicates thickness in meters (m), and Density indicates density.
[0064] Step 1: The dynamic reserves at which the internal rate of return (IRR) of carbonate gas reservoirs meets the lower limit of profitability during exploitation are taken as the lower limit of dynamic reserves for carbonate gas reservoirs; based on the lower limit of dynamic reserves, the thickness of high-quality reservoirs, the thickness of hills and shoals, the relative elevation of karst paleogeography, the thickness of karst zones, and the lower limit of fracture density are determined for exploitation of carbonate gas reservoirs.
[0065] Figure 2The diagram illustrates the relationship between stable production and dynamic reserves of gas wells when the internal rate of return (IRR) is 4.275%, 8%, and 20%. Based on these three IRR thresholds, gas wells are classified into four categories: Category I (IRR > 20%), Category II (8% < IRR < 20%), Category III (4.275% < IRR < 8%), and Category IV (IRR < 4.275%). Wells with an IRR above 8% are considered profitable, meaning Category I and Category II wells are profitable. Therefore, this embodiment selects an IRR of 8% as the lower limit of profitability, and uses the lowest dynamic reserves at an IRR of 8% as the lower limit of dynamic reserves for carbonate gas reservoirs, at which point the dynamic reserves are 430 million cubic meters. Establish the relationship between the thickness of high-quality reservoirs and dynamic reserves for carbonate gas reservoir development. Determine the lower limit of the thickness of high-quality reservoirs for carbonate gas reservoir development based on the relationship between the lower limit of dynamic reserves and the thickness of high-quality reservoirs. Establish relationships between the thickness of high-quality reservoirs for carbonate gas reservoir development and the thickness of hills and shoals, the relative elevation of karst paleogeography, the thickness of karst zones, and the density of fractures. Determine the lower limits of the thickness of hills and shoals, the relative elevation of karst paleogeography, the thickness of karst zones, and the density of fractures for carbonate gas reservoir development based on the lower limit of the thickness of high-quality reservoirs.
[0066] Figure 3 The linear relationship between the thickness of high-quality reservoirs and dynamic reserves in carbonate gas reservoir development is shown: y (dynamic reserves, unit: 100 million cubic meters) = 0.5491x (thickness of high-quality reservoirs, unit: meters) + 1.3972, R 2 =0.6082. Based on the lower limit of dynamic reserves of 430 million cubic meters, the lower limit of high-quality reservoir thickness is determined to be 5m.
[0067] Figure 4 The relationship between the thickness of high-quality reservoirs and the thickness of hill-shoal bodies in carbonate gas reservoir development is shown. Figure 5 This shows the relationship between the thickness of high-quality reservoirs and the relative elevation of karst paleogeography in carbonate gas reservoir development. Figure 6 The relationship between the thickness of high-quality reservoirs and the thickness of karst zones in carbonate gas reservoir development is shown. Table 1 shows the corresponding linear equations.
[0068] Table 1 Corresponding Linear Equations
[0069] <![CDATA[y=0.3411x-8.2219,R 2 =0.623]]> y is the thickness of high-quality reservoirs, and x is the thickness of hillock bodies. <![CDATA[y=0.1107x-40.953,R 2 =0.5552]]> y High-quality reservoir thickness, x Relative elevation of karst paleogeography <![CDATA[y=0.2222x+0.0638,R 2 =0.6069]]> y is the thickness of high-quality reservoirs, and x is the thickness of karst zones.
[0070] Substituting the lower limit of the high-quality reservoir thickness of 5m into the corresponding linear equation in Table 1, the thickness of the hill and shoal body, the relative elevation of the karst paleogeography, and the lower limit of the karst zone thickness for carbonate gas reservoir development are determined to be 40m, 415m, and 23m, respectively.
[0071] Figure 7A scatter plot of high-quality reservoir thickness and fracture density for carbonate gas reservoir development is shown. It can be seen that, generally speaking, the greater the fracture density, the greater the high-quality reservoir thickness. Based on the lower limit of 5m for high-quality reservoir thickness, the lower limit of fracture density is determined to be 1.5.
[0072] Step 2: Obtain the thickness of high-quality reservoirs, hill-shoal bodies, relative elevation of karst paleomorphology, thickness of karst zones, and fracture density of the target carbonate gas reservoir; identify the preliminary favorable areas of the target carbonate gas reservoir where the thickness of high-quality reservoirs, hill-shoal bodies, relative elevation of karst paleomorphology, thickness of karst zones, and fracture density are all greater than the lower limits of the thickness of high-quality reservoirs, hill-shoal bodies, relative elevation of karst paleomorphology, thickness of karst zones, and fracture density for carbonate gas reservoir development.
[0073] In this embodiment, based on the logging data of existing exploration and appraisal wells of the target layer in the carbonate gas reservoir, single-well hill-shoal bodies are divided, seismic identification and prediction of the hill-shoal bodies are carried out, and a thickness map of the hill-shoal bodies of the target layer in the carbonate gas reservoir is drawn under the constraints of this model. Figure 8 As shown, the thickness of the hill-shoal body is obtained, and the thickness of the hill-shoal body in the target layer of the carbonate gas reservoir is between 30m and 150m.
[0074] The relative elevation of the karst paleogeography above the target layer of the carbonate gas reservoir was reconstructed using the impression method. A distribution map of the relative elevation of the karst paleogeography above the target layer of the carbonate gas reservoir is shown below. Figure 9 As shown, the relative elevation of the karst paleogeography above the target layer of the carbonate gas reservoir ranges from 320m to 540m. Using existing well data, vertical karst zones were delineated, and a planar thickness map of the karst zone of the target layer of the carbonate gas reservoir was drawn, as shown below. Figure 10 As shown, the thickness of the karst zone of the target layer in the carbonate gas reservoir is obtained, wherein the planar thickness of the karst zone of the target layer in the carbonate gas reservoir is 5 to 75 m.
[0075] By optimizing the seismic coherence and curvature properties of the target layer in the carbonate gas reservoir, predicting fracture development intensity, and drawing a fracture density planar map of the target layer, such as... Figure 11 As shown, the fracture density of the target layer in the carbonate gas reservoir is obtained.
[0076] In carbonate gas reservoirs, single-well high-quality reservoirs are identified and delineated within the target layer. Seismic attributes are used to predict the thickness of these high-quality reservoirs, and a planar thickness map of the high-quality reservoirs within the target layer is drawn under these constraints. Figure 12As shown, the thickness of the high-quality reservoir in the target carbonate gas reservoir is obtained, where the thickness ranges from 0m to 40m. Furthermore, the vertical combination pattern of the high-quality reservoir in the target carbonate gas reservoir is determined, and development models of high-quality reservoirs in different well areas on the plane are established. There are four models: Model 1 is thick layers both above and below; Model 2 is thick at the top and thin at the bottom; Model 3 is thick at the bottom and thin at the top; and Model 4 is thin layers both above and below. The development models of the high-quality reservoir in the target carbonate gas reservoir are as follows: Figure 13 As shown.
[0077] In the target layer of carbonate gas reservoirs, the blocks in which the thickness of high-quality reservoirs, the thickness of hills and shoals, the relative elevation of karst paleomorphology, the thickness of karst zones, and the lower limit of fracture density are all greater than those of high-quality reservoirs, hills and shoals, relative elevation of karst paleomorphology, the thickness of karst zones, and the lower limit of fracture density are used for the exploitation of carbonate gas reservoirs are identified as the preliminary favorable areas for the target layer of carbonate gas reservoirs.
[0078] Preliminary results of determining the favorable area of the target layer in carbonate gas reservoirs are as follows: Figure 14 As shown, it can be seen that the preliminary carbonate gas reservoir target layer favorable area is divided into 17 blocks. Among them, there are 8 favorable areas in mode 1, labeled 4, 5, 6, 9, 10, 12, 14 and 16; 4 favorable areas in mode 2, labeled 7, 8, 13 and 17; and 5 favorable areas in mode 3, labeled 1, 2, 3, 11 and 15.
[0079] Step 3: Determine the reserves of the favorable area of the target layer of the preliminary carbonate gas reservoir based on the area, average effective thickness, average effective porosity, average gas saturation and volume coefficient. The favorable area of the target layer of the preliminary carbonate gas reservoir with reserves greater than the lower limit of the dynamic reserves of the carbonate gas reservoir shall be determined as the favorable area of the target layer of the final carbonate gas reservoir.
[0080] Areas with reserves greater than 430 million cubic meters in the preliminary target layer of carbonate gas reservoirs are identified as the final target layer of carbonate gas reservoirs.
[0081] Step 4: Analyze the development pattern and geological characteristics of high-quality reservoirs in the favorable area of the target carbonate gas reservoir, and determine the effective well model by combining seismic profile reflection.
[0082] Table 2 details the criteria for determining effective well modes. Seismic profile reflection characteristics of relatively weak amplitude at the top, wide wave valleys, and weak continuous reflection at the bottom are defined as volume mode 1; seismic profile reflection characteristics of narrow wave valleys and weak continuous low-frequency reflection at the bottom are defined as volume mode 2. Seismic profile reflection characteristics of relatively weak amplitude at the top and narrow wave valley reflections are defined as layer modes.
[0083] Based on the favorable area of the target layer of the final carbonate gas reservoir, three effective well models are established in two categories: "body model" and "layer model". Body model 1 and body model 2 are both developed in the high-quality reservoir model 1 and are suitable for the development of highly deviated wells; the layer model is developed in the high-quality reservoir model 2 and is suitable for the development of horizontal wells.
[0084] Table 2. Determination conditions for effective well models
[0085]
[0086] In summary, this invention, taking the economic benefits of gas wells as its starting point, determines that the dynamic reserves corresponding to an 8% internal rate of return (IRR) for gas wells in the target formation of the study area are 430 million cubic meters. It establishes four high-quality reservoir development models and determines the lower limits for five parameters: high-quality reservoir thickness, hill / shoal body thickness, karst zone thickness, relative elevation of karst paleogeography, and fracture density. The method of this invention makes the determination of favorable zone delineation parameters more evidence-based and the establishment of effective well models more targeted, providing a reference for the deployment of development well locations.
[0087] like Figure 15 As shown, one embodiment of the present invention also provides a method for selecting favorable development areas of carbonate gas reservoirs and a well placement device thereof, comprising,
[0088] The reservoir parameter unit is used to determine the lower limit of dynamic reserves for carbonate gas reservoir development based on economic benefits, and to determine the lower limit of reservoir parameters for carbonate gas reservoir development based on the lower limit of dynamic reserves for carbonate gas reservoir development.
[0089] The first determining unit is used to obtain the reservoir parameters of the target layer of the carbonate gas reservoir and to determine the favorable area of the target layer of the carbonate gas reservoir based on the lower limit of the reservoir parameters for the development of the carbonate gas reservoir.
[0090] The second determining unit is used to determine the final target layer favorable area of the carbonate gas reservoir based on the reserve parameters of the target layer favorable area of the preliminary carbonate gas reservoir.
[0091] The well placement determination unit is used to determine the well placement method based on the reservoir properties of the favorable area of the final target layer of the carbonate gas reservoir.
[0092] The reservoir parameter unit includes a dynamic reserve lower limit module and a parameter lower limit module;
[0093] The lower limit module for dynamic reserves is used to define the dynamic reserves of carbonate gas reservoirs as the lower limit of the internal rate of return (IRR) when the internal rate of return is equal to the lower limit of the profit IRR.
[0094] The parameter lower limit module is used to determine the lower limits of high-quality reservoir thickness, hill and shoal body thickness, relative elevation of karst paleogeography, karst zone thickness, and fracture density for the exploitation of carbonate gas reservoirs based on the lower limit of dynamic reserves of carbonate gas reservoirs.
[0095] The first determining unit includes an acquisition module and a preliminary advantageous area module;
[0096] The acquisition module is used to obtain the thickness of high-quality reservoirs, hill and shoal bodies, relative elevation of karst paleogeography, thickness of karst zones, and fracture density of the target layer in carbonate gas reservoirs.
[0097] The preliminary favorable area module is used to identify blocks in the target carbonate gas reservoir where the thickness of the high-quality reservoir, the thickness of the hill-shoal body, the relative elevation of the karst paleomorphology, the thickness of the karst zone, and the fracture density are all greater than the lower limit of the thickness of the high-quality reservoir, the thickness of the hill-shoal body, the relative elevation of the karst paleomorphology, the thickness of the karst zone, and the fracture density for carbonate gas reservoir development.
[0098] The second determining unit includes a reserve module and a final favorable area module;
[0099] The reserves module is used to determine the reserves of the favorable area of the target layer of the preliminary carbonate gas reservoir based on the area, average effective thickness, average effective porosity, average gas saturation and volume factor of the favorable area of the target layer.
[0100] The final favorable area module is used to identify the favorable areas of the preliminary target layer of carbonate gas reservoirs with reserves greater than the lower limit of dynamic reserves as the final favorable areas of the target layer of carbonate gas reservoirs.
[0101] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for selecting favorable development areas and well placement in carbonate gas reservoirs, characterized in that, The method includes determining the lower limit of dynamic reserves for carbonate gas reservoir development based on economic benefits, and determining the lower limit of reservoir parameters for carbonate gas reservoir development based on the lower limit of dynamic reserves for carbonate gas reservoir development, including: taking the dynamic reserves at which the internal rate of return (IRR) during carbonate gas reservoir development is the lower limit of profitability IRR as the lower limit of dynamic reserves for carbonate gas reservoir development; and determining the lower limits of high-quality reservoir thickness, hill / shoal body thickness, relative elevation of karst paleogeography, karst zone thickness, and fracture density for carbonate gas reservoir development based on the lower limit of dynamic reserves for carbonate gas reservoir development, including: establishing the relationship between the high-quality reservoir thickness and dynamic reserves for carbonate gas reservoir development, and determining the lower limit of high-quality reservoir thickness for carbonate gas reservoir development based on the relationship between the lower limit of dynamic reserves for carbonate gas reservoir development and the relationship between the high-quality reservoir thickness and dynamic reserves for carbonate gas reservoir development. The relationship between the thickness of the high-quality reservoir for carbonate gas reservoir development and the thickness of the hill and shoal body, the relative elevation of the karst paleomorphology, the thickness of the karst zone, and the fracture density is established. The lower limit of the thickness of the high-quality reservoir for carbonate gas reservoir development is determined based on the lower limit of the thickness of the high-quality reservoir. Obtain the reservoir parameters of the target layer of the carbonate gas reservoir, and determine the favorable area of the target layer of the carbonate gas reservoir based on the lower limit of the reservoir parameters for the development of the carbonate gas reservoir. The final target layer favorable area of carbonate gas reservoir is determined based on the reserve parameters of the favorable area of the target layer in the preliminary carbonate gas reservoir. The well placement method is determined based on the reservoir properties of the favorable area of the final target layer of the carbonate gas reservoir.
2. The method according to claim 1, characterized in that, Obtain reservoir parameters of the target layer of carbonate gas reservoir, and determine the favorable area of the target layer of carbonate gas reservoir based on the lower limit of the reservoir parameters for the development of carbonate gas reservoir. This includes obtaining the thickness of the high-quality reservoir, the thickness of the hill and shoal body, the relative elevation of the karst paleogeography, the thickness of the karst zone, and the fracture density of the target layer of carbonate gas reservoir. In the target layer of carbonate gas reservoirs, the blocks in which the thickness of high-quality reservoirs, the thickness of hills and shoals, the relative elevation of karst paleomorphology, the thickness of karst zones, and the lower limit of fracture density are all greater than those of high-quality reservoirs, hills and shoals, relative elevation of karst paleomorphology, the thickness of karst zones, and the lower limit of fracture density are used for the exploitation of carbonate gas reservoirs are identified as the preliminary favorable areas for the target layer of carbonate gas reservoirs.
3. The method according to claim 2, characterized in that, The final target layer favorable area of the carbonate gas reservoir is determined based on the reserve parameters of the target layer favorable area of the preliminary carbonate gas reservoir. This includes determining the reserves of the target layer favorable area of the preliminary carbonate gas reservoir based on the area, average effective thickness, average effective porosity, average gas saturation and volume coefficient of the target layer favorable area of the preliminary carbonate gas reservoir. The favorable area of the preliminary target layer of carbonate gas reservoir with reserves greater than the lower limit of dynamic reserves is identified as the favorable area of the final target layer of carbonate gas reservoir.
4. The method according to any one of claims 1 to 3, characterized in that, The well placement method is determined based on the reservoir properties of the favorable area of the final carbonate gas reservoir target layer. This includes analyzing the development pattern and geological characteristics of the high-quality reservoir in the favorable area of the final carbonate gas reservoir target layer, and determining the effective well pattern by combining seismic profile reflection. The effective well pattern includes horizontal wells and deviated wells.
5. A method for selecting favorable development areas of carbonate gas reservoirs and its well placement device, characterized in that, The device includes a reservoir parameter unit, used to determine the lower limit of dynamic reserves for carbonate gas reservoir development based on economic benefits, and to determine the lower limit of reservoir parameters for carbonate gas reservoir development based on the lower limit of dynamic reserves for carbonate gas reservoir development. The reservoir parameter unit includes a dynamic reserve lower limit module and a parameter lower limit module; the dynamic reserve lower limit module is used to take the dynamic reserves of the carbonate gas reservoir when the internal rate of return is the lower limit of the profit internal rate of return during the exploitation of the carbonate gas reservoir as the dynamic reserve lower limit of the carbonate gas reservoir. The parameter lower limit module is used to determine the lower limits of high-quality reservoir thickness, hill and shoal body thickness, relative elevation of karst paleogeography, karst zone thickness, and fracture density for carbonate gas reservoir development based on the lower limit of dynamic reserves. This includes: establishing the relationship between high-quality reservoir thickness and dynamic reserves for carbonate gas reservoir development; and determining the lower limit of high-quality reservoir thickness for carbonate gas reservoir development based on the relationship between the lower limit of dynamic reserves and the relationship between high-quality reservoir thickness and dynamic reserves. The relationship between the thickness of the high-quality reservoir for carbonate gas reservoir development and the thickness of the hill and shoal body, the relative elevation of the karst paleomorphology, the thickness of the karst zone, and the fracture density is established. The lower limit of the thickness of the high-quality reservoir for carbonate gas reservoir development is determined based on the lower limit of the thickness of the high-quality reservoir. The first determining unit is used to obtain the reservoir parameters of the target layer of the carbonate gas reservoir and to determine the favorable area of the target layer of the carbonate gas reservoir based on the lower limit of the reservoir parameters for the development of the carbonate gas reservoir. The second determining unit is used to determine the final target layer favorable area of the carbonate gas reservoir based on the reserve parameters of the target layer favorable area of the preliminary carbonate gas reservoir. The well placement determination unit is used to determine the well placement method based on the reservoir properties of the favorable area of the final target layer of the carbonate gas reservoir.
6. The apparatus according to claim 5, characterized in that, The first determining unit includes an acquisition module and a preliminary advantageous area module; The acquisition module is used to obtain the thickness of high-quality reservoirs, hill and shoal bodies, relative elevation of karst paleogeography, thickness of karst zones, and fracture density of the target layer in carbonate gas reservoirs. The preliminary favorable area module is used to identify blocks in the target carbonate gas reservoir where the thickness of the high-quality reservoir, the thickness of the hill-shoal body, the relative elevation of the karst paleomorphology, the thickness of the karst zone, and the fracture density are all greater than the lower limit of the thickness of the high-quality reservoir, the thickness of the hill-shoal body, the relative elevation of the karst paleomorphology, the thickness of the karst zone, and the fracture density for carbonate gas reservoir development.
7. The apparatus according to claim 6, characterized in that, The second determining unit includes a reserve module and a final favorable area module; The reserves module is used to determine the reserves of the favorable area of the target layer of the preliminary carbonate gas reservoir based on the area, average effective thickness, average effective porosity, average gas saturation and volume factor of the favorable area of the target layer. The final favorable area module is used to identify the favorable areas of the preliminary target layer of carbonate gas reservoirs with reserves greater than the lower limit of dynamic reserves as the final favorable areas of the target layer of carbonate gas reservoirs.