A method and system for predicting the number of development wells of a marine thick-thin alternating reservoir

Abstract

The present application relates to a kind of offshore thick-thin interactive reservoir development well number segmentation prediction method and system, it is characterized in that, the method includes: according to the sand body classification grading standard of offshore thick-thin interactive reservoir, sand body classification grading processing is carried out to target oilfield;According to the sand body classification grading processing result of target oilfield and the development well dimensionless oil increment prediction chart of different types, grade sand body established in advance, obtain the development well oil increment prediction result of target oilfield;Based on the development well oil increment prediction result of target oilfield, determine the injection-production well spacing and development well number of different development stages of target oilfield full life, the present application can be widely applied in petroleum and natural gas exploitation field.

Description

Technical Field

[0001] This invention relates to the field of oil and gas extraction, and in particular to a method and system for segmented prediction of the number of development wells in offshore thick-thin alternating reservoirs. Background Technology

[0002] Unlike onshore oilfield development, offshore oilfield development involves high investment costs, significant risks, and poor economic returns. Important facilities such as central platforms, wellhead platforms, and main pipelines generally need to be constructed and reserved in advance to maximize underground potential while ensuring economic benefits. This requires offshore oilfield managers to have an accurate understanding of the final scale of the oilfield and to design a full-lifecycle development plan in advance, including the basic well network development stage, primary, secondary, and tertiary infill development stages, and adjustment well development stages. This will enable reasonable medium- and long-term planning and deployment, guiding the integrated development investment and facility construction of offshore oilfields.

[0003] Shallow-water deltaic sedimentary oilfields are mainly distributed in the Bohai Sea region of China. They are an important reservoir type in China's offshore oilfields and a significant growth point for future production in China's nearshore waters. Influenced by sedimentary characteristics and hydrodynamic evolution, their reservoirs are characterized by typical thick-thin alternating reservoirs, featuring large vertical spans, numerous layered sand bodies, and significant differences in the planar distribution of sand bodies. This severe variation in reservoir quality makes it difficult to determine key indicators such as the appropriate injection-production well spacing and the number of development wells at different development stages, hindering the accurate control of the phased construction scale of the oilfield and making the design of a full-life-cycle development plan extremely challenging.

[0004] Therefore, there is an urgent need to develop a segmented prediction method and system for the number of development wells in offshore thick-thin inter-layer reservoirs. This system should be able to quickly determine the reasonable injection-production well spacing and number of development wells at different development stages throughout the entire development life of offshore thick-thin inter-layer reservoirs. This will guide the medium- and long-term rational planning and layout of offshore shallow-water deltaic sedimentary oilfields, improve the economic benefits of offshore oilfield development, and reduce development risks. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to provide a method and system for segmented prediction of the number of development wells in offshore thick-thin interactive reservoirs, which can quickly determine the reasonable injection-production well spacing and the number of development wells at different development stages throughout the entire development life of the offshore thick-thin interactive reservoir.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: Firstly, it provides a method for segmented prediction of the number of development wells in offshore thick-thin alternating reservoirs, comprising:

[0007] Based on the classification and grading standards for sand bodies in marine reservoirs with alternating thick and thin layers, the target oilfield is classified and graded according to its sand bodies.

[0008] Based on the results of sand body classification and treatment of the target oilfield and the pre-established dimensionless oil increase prediction charts for development wells of different types and grades of sand bodies, the prediction results of oil increase from development wells in the target oilfield are obtained.

[0009] Based on the predicted increase in oil production from development wells in the target oilfield, the injection-production well spacing and the number of development wells at different development stages throughout the entire lifespan of the target oilfield are determined.

[0010] Furthermore, the process of establishing the dimensionless oil production prediction charts for development wells of different types and grades of sand bodies includes:

[0011] By introducing the swept volume factor, oil displacement efficiency factor, and sand body distribution scale and injection-production well spacing matching factor, the traditional recovery rate model is modified, and a calculation model for the oil increase of offshore development wells throughout their entire life cycle is established.

[0012] Based on the calculation model of oil production increase of offshore development wells throughout their entire life cycle, and combined with the development characteristics of continuous thick sand bodies at sea, a dimensionless oil production increase evaluation chart for offshore development wells in continuous thick sand bodies is established.

[0013] Based on the calculation model of oil production increase of offshore development wells throughout their entire life cycle, and combined with the development characteristics of offshore strip-shaped thick sand bodies, an evaluation chart for oil production increase of offshore strip-shaped thick sand body development wells is established.

[0014] Based on the calculation model of oil production increase of offshore development wells throughout their entire life cycle, and combined with the development characteristics of thin sand bodies at sea, an evaluation chart of oil production increase of offshore thin sand body development wells is established.

[0015] The horizontal axis of the dimensionless oil production prediction chart for each development well is the distance between injection and production wells, D. t The vertical axis represents the dimensionless increase in oil production (n) of development wells. f .

[0016] Furthermore, the calculation model for the increased oil production of offshore development wells throughout their entire lifespan is as follows:

[0017]

[0018] Where, n t For development wells, G represents increased oil production; G represents recoverable reserves; A represents oil-bearing area; K represents increased oil production. e The effective permeability of the sand body; μ o D represents the viscosity of the formation crude oil. t L represents the distance between injection and production wells. m α represents the limit value of the sand body width; α, β, λ, and γ are all model parameters.

[0019] Furthermore, the prediction results of the increased oil production of development wells in the target oilfield, obtained based on the sand body classification and grading results of the target oilfield and the pre-established dimensionless oil production prediction charts for different types and grades of sand bodies, include:

[0020] Based on the differentiated characteristics of the target oilfield reserves and the principle of graded utilization of reserves, and according to the graded classification of sand bodies in the target oilfield, the proportion of recoverable reserves of different types and grades of sand bodies in the target oilfield is statistically analyzed.

[0021] Determine the initial oil production increase of development wells in different types and grades of sand bodies in the target oilfield;

[0022] Based on the dimensionless oil production prediction chart of development wells for different types and grades of sand bodies, combined with the initial oil production of development wells for different types and grades of sand bodies in the target oilfield, the oil production of development wells in the target oilfield is calculated by weighting the proportion of recoverable reserves of different types and grades of sand bodies in the target oilfield.

[0023] Plot the curves of the increase in oil production from development wells in the target oilfield as a function of the injection-production well spacing to obtain the predicted results of the increase in oil production from development wells in the target oilfield.

[0024] Furthermore, the calculation of the oil production increase of development wells in the target oilfield based on the dimensionless oil production increase prediction chart of different types and grades of sand bodies, combined with the initial oil production increase of development wells in different types and grades of sand bodies in the target oilfield, and weighted according to the proportion of recoverable reserves of different types and grades of sand bodies in the target oilfield, includes:

[0025] Based on the initial oil increase of development wells in different types and grades of sand bodies in the target oilfield, and according to the dimensionless oil increase prediction chart of development wells in different types and grades of sand bodies, the oil increase variation curves of development wells in different types and grades of sand bodies in the target oilfield are plotted to obtain the prediction results of oil increase of development wells in different types and grades of sand bodies in the target oilfield.

[0026] The oil production increase from development wells in the target oilfield is calculated by weighting the predicted oil production from different types and grades of sand bodies and the proportion of recoverable reserves of different types and grades of sand bodies in the target oilfield.

[0027] Furthermore, based on the predicted increase in oil production from development wells in the target oilfield, the injection-production well spacing and the number of development wells at different development stages throughout the target oilfield's lifespan are determined, including:

[0028] Based on the characteristics of the target oilfield, determine the oil production increase of development wells at different development stages;

[0029] By using the increased oil production of development wells at different development stages of the target oilfield, the curve of the increased oil production of development wells of the target oilfield as a function of injection-production well spacing is cut off, and the injection-production well spacing corresponding to the cutoff point is determined, which is the injection-production well spacing at different development stages throughout the life of the target oilfield.

[0030] Based on the oil-bearing area, well pattern and well type of the target oilfield, as well as the injection-production well spacing at different development stages throughout the life of the target oilfield, the number of development wells at different development stages throughout the life of the target oilfield is calculated.

[0031] Furthermore, the classification and grading standards for sand bodies in the offshore thick-thin alternating reservoir include categories A, B, and C, wherein:

[0032] Category A includes levels 1, 2, 3, and 4. All four levels consist of continuous, thick sand bodies. Level 1 sand bodies in Category A have a thickness >15m, a width >500m, and a coefficient of variation <0.6f; Level 2 sand bodies have a thickness of 10–15m, a width of 450–500m, and a coefficient of variation of 0.6–0.8f; Level 3 sand bodies have a thickness of 5–10m, a width of 400–450m, and a coefficient of variation of 0.8–1.0f; and Level 4 sand bodies have a thickness of 5–10m, a width of 350–400m, and a coefficient of variation >1.0f.

[0033] Category B includes Level 1 and Level 2. Both levels consist of banded thick sand bodies. Level 1 sand bodies in Category B have a thickness greater than 10m, a width of 300–350m, and a coefficient of variation of <1.0f. Level 2 sand bodies in Category B have a thickness of 5–10m, a width of 250–300m, and a coefficient of variation of >1.0f.

[0034] Category C includes levels 1, 2, and 3. All three levels consist of thin-layered sand bodies. Level 1 sand bodies in Category C have a thickness of <5m, a width of 200–250m, and a coefficient of variation of <0.8f. Level 2 sand bodies in Category C have a thickness of <5m, a width of 150–200m, and a coefficient of variation of 0.8–1.0f. Level 3 sand bodies in Category C have a thickness of <5m, a width of <150m, and a coefficient of variation of >1.0f.

[0035] Secondly, a segmented prediction system for the number of development wells in offshore thick-thin interactive reservoirs is provided, including:

[0036] The classification and grading module is used to classify and grade sand bodies in the target oilfield according to the classification and grading standards for sand bodies in offshore thick-thin alternating reservoirs.

[0037] The development well oil production prediction module is used to obtain the development well oil production prediction results of the target oilfield based on the sand body classification and processing results of the target oilfield and the pre-established dimensionless oil production prediction charts for different types and grades of sand bodies.

[0038] The module for determining injection-production well spacing and the number of development wells is used to determine the injection-production well spacing and the number of development wells at different development stages throughout the life cycle of a target oilfield, based on the predicted increase in oil production from development wells.

[0039] Thirdly, a processing device is provided, including computer program instructions, wherein when the computer program instructions are executed by the processing device, they are used to implement the steps corresponding to the above-mentioned method for segmented prediction of the number of development wells in offshore thick and thin interactive reservoirs.

[0040] Fourthly, a computer-readable storage medium is provided, on which computer program instructions are stored, wherein the computer program instructions, when executed by a processor, are used to implement the steps corresponding to the above-mentioned method for segmented prediction of the number of development wells in offshore thick and thin interactive reservoirs.

[0041] The present invention has the following advantages due to the adoption of the above technical solutions:

[0042] 1. This invention can solve the problems of high difficulty and low accuracy in the long-term planning of the number of wells for the phased development of offshore thick and thin alternating reservoirs throughout their entire life cycle. The invention has a clear principle, objective calculation results, and strong operability. It can effectively guide the design of phased development schemes for offshore water-drive oilfields throughout their entire life cycle. The application effect is good and the application prospects are broad.

[0043] 2. This invention can quickly determine the reasonable injection-production well spacing and number of development wells at different development stages throughout the entire life cycle of offshore thick-thin alternating reservoirs. It provides a basis for key decision-making and deployment such as platform model selection, number of reserved well slots, and scale of fluid treatment. It can effectively guide the medium- and long-term rational planning and layout of offshore thick-thin alternating reservoirs and significantly improve the economic benefits of offshore oilfield development projects.

[0044] In summary, this invention can be widely applied in the field of oil and gas extraction. Attached Figure Description

[0045] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings:

[0046] Figure 1 This is a schematic diagram of a dimensionless oil production evaluation chart for development wells in contiguous thick sand bodies at sea, provided in an embodiment of the present invention.

[0047] Figure 2 This is a schematic diagram of a dimensionless oil production evaluation chart for offshore strip-shaped thick sand body development wells provided in an embodiment of the present invention;

[0048] Figure 3 This is a schematic diagram of a dimensionless oil production evaluation chart for offshore thin-layer sand body development wells provided in an embodiment of the present invention;

[0049] Figure 4This is a schematic diagram of the predicted oil production of development wells of different types and grades of sand bodies in the P oilfield, provided by an embodiment of the present invention.

[0050] Figure 5 This is a schematic diagram of the predicted oil production increase of development wells in the P oilfield provided in an embodiment of the present invention;

[0051] Figure 6 This is a schematic diagram of the predicted well spacing for injection and production at different development stages of the P oilfield, provided by an embodiment of the present invention. Detailed Implementation

[0052] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0053] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0054] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0055] The method and system for segmented prediction of the number of development wells in offshore thick-thin interactive reservoirs provided in this invention can solve the problems of high difficulty and low accuracy in the long-term planning of the number of development wells in the stages of the entire life cycle of offshore thick-thin interactive reservoirs. It can quickly determine the reasonable injection-production well spacing and the number of development wells at different development stages during the entire life cycle of offshore thick-thin interactive reservoirs, and guide the reasonable planning and layout of offshore thick-thin interactive reservoirs in the long term.

[0056] Example 1

[0057] This embodiment provides a method for segmented prediction of the number of development wells in offshore reservoirs with alternating thick and thin layers, including the following steps:

[0058] 1) Based on the classification and grading standards for sand bodies in offshore reservoirs with alternating thick and thin layers, the target oilfield is classified and graded as follows:

[0059] 1.1) Establish a classification and grading standard for sand bodies in offshore reservoirs with alternating thick and thin layers.

[0060] Specifically, the sedimentary genesis of marine thick-thin alternating reservoirs is complex, with a large vertical span. The planar distribution and continuity of thick / thin sand bodies from different depositional periods vary greatly, resulting in different matching with injection-production well networks and significant differences in the actual water drive control. Consequently, the development performance of different sand bodies varies greatly throughout their entire life cycle. Therefore, it is necessary to first conduct a detailed classification and grading of the sand bodies in marine thick-thin alternating reservoirs.

[0061] Drawing on the experience of dense well network tests in onshore oilfields, and considering the main controlling factors of water drive sweep effect in sand bodies, this study establishes a classification and grading standard for sand bodies in offshore thick-thin alternating reservoirs. This standard is developed by subdividing sequence layers to distinguish single-phase thin layers, well-controlled sand body directional and width determination, microfacies sculpting of individual thin sand bodies, and pattern combination identification of complexes. Taking into account sand body thickness, distribution range, and continuity, the standard classifies sand bodies in offshore thick-thin alternating reservoirs into three categories and nine levels, including categories A, B, and C.

[0062] Category A includes levels 1, 2, 3, and 4. All four levels consist of continuous, thick sand bodies. Level 1 sand bodies in Category A have a thickness >15m, a width >500m, and a coefficient of variation <0.6f; Level 2 sand bodies have a thickness of 10–15m, a width of 450–500m, and a coefficient of variation of 0.6–0.8f; Level 3 sand bodies have a thickness of 5–10m, a width of 400–450m, and a coefficient of variation of 0.8–1.0f; and Level 4 sand bodies have a thickness of 5–10m, a width of 350–400m, and a coefficient of variation >1.0f.

[0063] Category B includes Level 1 and Level 2. Both levels consist of banded thick sand bodies. Level 1 sand bodies in Category B have a thickness greater than 10m, a width of 300–350m, and a coefficient of variation of <1.0f. Level 2 sand bodies in Category B have a thickness of 5–10m, a width of 250–300m, and a coefficient of variation of >1.0f.

[0064] Category C includes levels 1, 2, and 3. All three levels consist of thin-layered sand bodies. Level 1 sand bodies in Category C have a thickness of <5m, a width of 200–250m, and a coefficient of variation of <0.8f; Level 2 sand bodies have a thickness of <5m, a width of 150–200m, and a coefficient of variation of 0.8–1.0f; Level 3 sand bodies have a thickness of <5m, a width of <150m, and a coefficient of variation of >1.0f, as shown in Table 1 below.

[0065] Table 1: Classification and Grading of Sand Bodies in Offshore Thick-Thin Interlacing Reservoirs

[0066]

[0067]

[0068] 1.2) Based on the classification and grading standards for sand bodies in offshore reservoirs with alternating thick and thin layers, the target oilfield is classified and graded.

[0069] 2) By introducing the swept volume factor, oil displacement efficiency factor, and the matching factor between sand body distribution scale and injection-production well spacing, the traditional recovery rate model is modified, and then a calculation model for the increased oil production of offshore development wells throughout their entire lifespan is derived and established, specifically:

[0070] 2.1) Introduce the swept volume factor, the oil displacement efficiency factor, and the matching factor between the sand body distribution scale and the injection-production well spacing.

[0071] Specifically, the ripple volume factor E V for:

[0072]

[0073] Oil displacement efficiency coefficient E D for:

[0074]

[0075] The matching coefficient T between sand body distribution size and injection-production well spacing S for:

[0076]

[0077] 2.2) Based on the swept volume factor, oil displacement efficiency factor, and the matching coefficient between sand body distribution scale and injection-production well spacing, the traditional recovery rate model is modified to obtain the modified recovery rate model:

[0078]

[0079] 2.3) Based on the modified recovery rate model, the cumulative oil production calculation model under different injection-production well spacing is obtained:

[0080]

[0081] 2.4) The independent variable D of injection-production well spacing in the cumulative oil production calculation model t After differential processing, the calculation model for the increased oil production of offshore development wells throughout their entire lifespan is obtained as follows:

[0082]

[0083] Among them, E R Recovery rate, in %; E V E is the sweep volume factor, dimensionless; D T is the oil displacement efficiency coefficient, dimensionless; s N is the matching coefficient between the sand body distribution scale and the injection-production well spacing, dimensionless; t Cumulative oil production, in units of 10,000 cubic meters; n t The unit for oil production from development wells is 10,000 cubic meters; G represents the recoverable reserves, also in 10,000 cubic meters; A represents the oil-bearing area, in km². 2 ;K e The effective permeability of the sand body is expressed in mD; K a The absolute permeability of the sand body is μ. o D represents the viscosity of the formation crude oil, expressed in MPa·s. t L represents the distance between injection and production wells, in km. m α represents the limit value of the sand body width, in km; α, β, λ, and γ are model parameters, as shown in Table 2 below:

[0084] Table 2: Model Parameter Values ​​for the Calculation Model of Increased Oil Production from Offshore Development Wells Throughout Their Lifespan

[0085]

[0086] It should be noted that the model calculates the increase in oil production from development wells, not the recoverable reserves, thus eliminating the problem of oil competition between new and old wells, avoiding double counting, and more accurately reflecting the development effect brought about by the commissioning of new wells.

[0087] 3) Based on the calculation model of increased oil production from offshore development wells throughout their entire lifespan, and combined with the development characteristics of continuous thick sand bodies at sea, a dimensionless evaluation chart for increased oil production from offshore development wells in continuous thick sand bodies is established, such as... Figure 1As shown, the horizontal axis of the evaluation chart for dimensionless oil production from development wells in contiguous thick sand bodies at sea represents the distance between injection and production wells, D. t The vertical axis represents the dimensionless increase in oil production n of the development well. f .

[0088] Specifically, offshore oilfields have high drilling and completion costs. To reduce development investment, the injection-production well spacing of the basic well network in offshore oilfields is generally large, averaging around 500m. Subsequently, based on the distribution of remaining oil, multiple rounds of densification and adjustment are carried out to continuously reduce the injection-production well spacing, thereby continuously improving the water drive sweepability, and ultimately achieving the maximum recovery rate that the oilfield can achieve within the economic threshold.

[0089] Considering the significant differences in static factors such as reservoir properties and fluid characteristics among different oilfields, the absolute values ​​of oil increase from development wells vary considerably. To more intuitively and accurately predict the variation patterns of oil increase from development wells in different offshore oilfields, this embodiment introduces the dimensionless oil increase n from development wells. f This parameter represents the increased oil production n of development wells under a certain injection-production well spacing condition in offshore oilfields. t The ratio of the oil production increase n0 of development wells in the same oilfield with a well spacing of 500m to the total oil production increase n0 represents, in physical terms, the degree of decrease in the oil production increase of development wells when infill drilling in offshore oilfields reaches a certain stage. f The larger the value, the greater the dimensionless increase in oil production of the development well.

[0090]

[0091] Where, n f n0 represents the dimensionless increase in oil production from the development well, where n is dimensionless; n0 represents the initial increase in oil production from the development well under the condition of a 500m distance between the injection and production wells, in units of 10,000 cubic meters.

[0092] 4) Based on the calculation model of increased oil production from offshore development wells throughout their entire lifespan, and combined with the development characteristics of offshore striped thick sand bodies, an evaluation chart for increased oil production from offshore development wells in striped thick sand bodies is established, such as... Figure 2 As shown, the horizontal axis of the evaluation chart for increased oil production from development wells in offshore strip-shaped thick sand bodies represents the distance between injection and production wells, D. t The vertical axis represents the dimensionless increase in oil production n of the development well. f .

[0093] 5) Based on the calculation model of increased oil production from offshore development wells throughout their entire lifespan, and combined with the development characteristics of thin-layered sand bodies at sea, an evaluation chart for increased oil production from offshore thin-layered sand body development wells is established, such as... Figure 3 As shown in the figure, the horizontal axis of the evaluation chart for increased oil production from development wells in offshore thin sand bodies represents the distance between injection and production wells, D. t The vertical axis represents the dimensionless increase in oil production n of the development well. f .

[0094] 6) Based on the sand body classification and treatment results of the target oilfield, the dimensionless oil increase evaluation charts for development wells in continuous thick sand bodies at sea, the oil increase evaluation charts for development wells in strip-shaped thick sand bodies at sea, and the oil increase evaluation charts for development wells in thin sand bodies at sea, the predicted oil increase results for development wells in the target oilfield are obtained, specifically as follows:

[0095] 6.1) Based on the differentiated characteristics of the target oilfield's reserves and the principle of graded reserve utilization, and according to the results of the graded classification of sand bodies in the target oilfield, the proportion of recoverable reserves for different types and grades of sand bodies in the target oilfield is statistically analyzed, as shown in Table 3 below:

[0096] Table 3: Proportion of Reserves for Different Types and Grades of Sand Bodies

[0097]

[0098] Specifically, the exploitable reserves of Class A contiguous thick sand bodies account for P Ax for:

[0099]

[0100] The proportion of recoverable reserves of Class B strip-shaped thick sand bodies in P By for:

[0101]

[0102] The recoverable reserves of Class C thin-layer sand bodies account for P Cz for:

[0103]

[0104] Among them, G 总 G represents the total utilized reserves, in ten thousand cubic meters; P represents the utilized reserves, in ten thousand cubic meters; subscripts A, B, and C represent the reserve types; subscripts x, y, and z represent the reserve grade numbers, where x = 1, 2, 3, 4, y = 1, 2, and z = 1, 2, 3.

[0105] 6.2) Determine the initial oil production increase n of development wells for different types and grades of sand bodies in the target oilfield. 0Ax n 0By n 0Cz .

[0106] 6.3) Based on the dimensionless oil production evaluation charts for development wells in contiguous thick sand bodies, strip-shaped thick sand bodies, and thin-layered sand bodies, and combined with the initial oil production of development wells in different types and grades of sand bodies in the target oilfield, the oil production of development wells in the target oilfield is calculated by weighting the proportion of recoverable reserves of different types and grades of sand bodies in the target oilfield:

[0107] 6.3.1) Based on the initial oil production of development wells in different types and grades of sand bodies in the target oilfield, and according to the evaluation charts of dimensionless oil production of development wells in continuous thick sand bodies, strip-shaped thick sand bodies, and thin sand bodies, the oil production variation curves of development wells in different types and grades of sand bodies in the target oilfield are plotted to obtain the predicted oil production results of development wells in different types and grades of sand bodies in the target oilfield.

[0108] 6.3.2) Based on the predicted oil production increase from development wells of different types and grades of sand bodies in the target oilfield and the proportion of recoverable reserves of different types and grades of sand bodies in the target oilfield, the weighted calculation of the oil production increase from development wells in the target oilfield is performed:

[0109]

[0110] Where, n 0Ax n 0By n 0Cz Initial oil production increase of development wells in different types and grades of sand bodies in the target oilfield; n fAx n fBy n fCz Dimensionless oil increase in development wells of different types and grades of sand bodies in the target oilfield.

[0111] 6.4) Plot the curve of the increase in oil production from development wells in the target oilfield as a function of the injection-production well spacing, and obtain the predicted results of the increase in oil production from development wells in the target oilfield.

[0112] 7) Based on the predicted increase in oil production from development wells in the target oilfield, plan and deploy the injection-production well spacing and the number of development wells for different development stages throughout the entire life cycle of the target oilfield.

[0113] Specifically, based on offshore development experience, the investment costs vary significantly across different development stages throughout the lifecycle of an offshore oilfield. Generally, the basic well network stage requires the construction of all surface facilities, incurring costs for the central processing platform, wellhead platform, main and branch pipelines, and drilling and completion. The primary infill drilling stage often relies on the existing central platform and main pipelines for processing and transportation, requiring costs for the wellhead platform, branch pipelines, and drilling and completion. The secondary and tertiary infill drilling stages utilize external platforms attached to the existing wellhead platform, incurring costs for the external platform and drilling and completion. The later adjustment stage utilizes pre-reserved or abandoned well slots on the existing platform for sidetracking, requiring only drilling and completion costs. Therefore, the average investment cost per well varies significantly across different development stages. To ensure good economic viability for development projects at different stages, the increased oil production of development wells at different stages must reach different economic thresholds. By utilizing the economic threshold values ​​for increased oil production from development wells at different development stages, the curves showing the change in increased oil production from development wells in a target oilfield as a function of injection-production well spacing are divided into stages. This allows for the prediction of reasonable injection-production well spacing and the number of development wells at different development stages, ensuring that development projects at each stage are economically viable. Simultaneously, it also supports the rational investment and construction of surface facilities and well slots. Therefore, this step includes:

[0114] 7.1) Based on the characteristics of the target oilfield (water depth, burial depth, development method, etc.), determine the economic threshold (i.e., the increase in oil production from development wells) for different development stages. t基础井 n t一次井 n t二次井 n t三次井 n t调整井 .

[0115] 7.2) The economic threshold n for increased oil production from development wells at different development stages of the target oilfield. t基础井 n t一次井 n t二次井 n t三次井 n t调整井 The curve of increased oil production from development wells in the target oilfield as a function of injection-production well spacing was cut off, and the injection-production well spacing D corresponding to the cutoff point was determined. t基础井 D t一次井 D t二次井 D t三次井 D t调整井 This refers to the injection-production well spacing at different development stages throughout the entire lifespan of the target oilfield.

[0116] 7.3) Based on the oil-bearing area, well pattern, and well type of the target oilfield, as well as the injection-production well spacing at different development stages throughout the target oilfield's lifespan, calculate the number of development wells W at different development stages throughout the target oilfield's lifespan. t基础井 W t一次井 W t二次井 W t三次井 Wt调整井 .

[0117] Specifically, the number of development wells W in the basic well network t基础井 for:

[0118]

[0119] Number of development wells W in a single encrypted well network t一次井 for:

[0120]

[0121] Number of development wells W in secondary densification well network t二次井 for:

[0122]

[0123] Number of development wells W in the three-stage infiltration well network t三次井 for:

[0124]

[0125] Adjust the number of development wells W in the well network t调整井 for:

[0126]

[0127] The following detailed embodiments illustrate the method for segmented prediction of the number of development wells in offshore thick-thin alternating reservoirs according to the present invention:

[0128] The P oilfield is located in the south-central part of a certain sea area, with an average water depth of 27–33 m, a reservoir burial depth of 900–1400 m, an average reservoir permeability of 1000–1500 mD, and an average crude oil viscosity of 20–30 mPa·s. It is a typical shallow-water delta oilfield developed using early water injection. The P oilfield reservoir has a vertical span of 500 m, divided into 47 layered sand bodies. The sand bodies are stably interbedded, exhibiting significant differences in development. The invention will be described in detail below using the P oilfield as an example.

[0129] According to the sand body classification and grading standards in Table 1, the 47 layered sand bodies in the P oilfield were classified and graded, as shown in Table 4 below:

[0130] Table 4: Classification Results of Sand Bodies in Oilfield P

[0131]

[0132] Based on the classification results of sand bodies in the P oilfield, the proportion of recoverable reserves for different types and grades of sand bodies in the P oilfield is shown in Table 5 below:

[0133] Table 5: Parameter values ​​for the calculation model of increased oil production from development wells in different grades of sand bodies in Oilfield P

[0134]

[0135] The initial oil production increase of development wells for different types and grades of sand bodies in oilfield P is determined as shown in Table 6 below:

[0136] Table 6: Initial Oil Gain from Development Wells in Oilfield with Different Types and Grades of Sand Bodies

[0137]

[0138]

[0139] Based on the evaluation charts for dimensionless oil production increase from development wells in contiguous thick sand bodies, strip-shaped thick sand bodies, and thin-layered sand bodies, and combined with the initial oil production increase from development wells in different types and grades of sand bodies in the P oilfield, the oil production increase from development wells in the target oilfield was calculated weighted according to the proportion of recoverable reserves of different types and grades of sand bodies in the P oilfield. A curve showing the variation of oil production increase from development wells in the P oilfield with the injection-production well spacing was then plotted. Figure 4 As shown.

[0140] By combining the curves of increased oil production from development wells in the P oilfield with the variation of injection-production well spacing and the proportion of recoverable reserves of different types and grades of sand bodies in the P oilfield (Table 5), an evaluation curve of increased oil production from development wells in the P oilfield was plotted. Figure 5 As shown, the predicted increase in oil production from development wells is obtained.

[0141] Based on the predicted increase in oil production from development wells in the P oilfield, the injection-production well spacing and the number of development wells for different development stages throughout the P oilfield's lifespan are planned and deployed:

[0142] Based on the characteristics of the P oilfield (water depth, burial depth, development method, etc.) and by analogy with the development experience of similar oilfields, the economic threshold n for increased oil production from development wells at different development stages is preliminarily determined. t基础井 =150,000 cubic meters, n t一次井 =120,000 cubic meters, n t二次井 =90,000 cubic meters, n t三次井 =70,000 cubic meters, n t调整井 =40,000 cubic meters.

[0143] The economic threshold n for increased oil production from development wells at different development stages in the P oilfield. t基础井 n t一次井 n t二次井 n t三次井 n t调整井 The curve showing the change in oil production from development wells in the P oilfield as a function of injection-production well spacing ( ) Figure 5 Determine the injection-production well distance D corresponding to the cutoff point. t基础井=370m, D t一次井 =320m, D t二次井 =290m, D t三次井 =270m, D t调整井 =230m, which is the injection-production well spacing at different development stages throughout the life of the P oilfield, such as Figure 6 As shown.

[0144] The oil-bearing area of ​​oil field P is A = 3.5 km². 2 The design of directional well network for water injection development, combined with the traditional formulas for calculating well density and injection-production well spacing, yields the number of development wells W at different development stages throughout the lifespan of the P oilfield. t基础井 =26 ports, W t一次井 =9 port, W t二次井 =7 port, W t三次井 =6 ports, W t调整井 =18 mouths.

[0145] This invention has been verified and applied in the field production of the P oilfield, a typical shallow-water deltaic oilfield. Horizontally, it is divided into 22 development blocks, and vertically into 47 layered sand bodies. Most development blocks have already undergone the basic well network development stage and have entered the high water-cut stage. Under the current well network conditions, subsurface contradictions are prominent, with significant differences in horizontal and vertical development effects, serious local enrichment of remaining oil, and a severe production situation, necessitating infill drilling and adjustment. Considering the development investment costs of the P oilfield, the methods and ideas of this invention have been adopted to plan and deploy 145 infill wells and 310 adjustment wells in the 22 development blocks of the P oilfield, and a medium- and long-term implementation plan has been formulated. Currently, in-depth research work on primary and secondary projects has been carried out in the five main development blocks of the P oilfield according to the formulated plan. The final design of the number of development wells matches the prediction results of this invention by up to 90%. Furthermore, the method of this invention can also provide strong technical support for the design of full-life-cycle development schemes for newly discovered offshore oilfields awaiting production, with broad application prospects.

[0146] Example 2

[0147] This embodiment provides a segmented prediction system for the number of development wells in offshore thick and thin interactive reservoirs, including:

[0148] The classification and grading module is used to classify and grade sand bodies in target oilfields according to the classification and grading standards for sand bodies in offshore reservoirs with alternating thick and thin layers.

[0149] The development well oil production prediction module is used to obtain the oil production prediction results of development wells in the target oilfield based on the sand body classification and processing results of the target oilfield and the pre-established dimensionless oil production prediction charts for different types and grades of sand bodies.

[0150] The module for determining injection-production well spacing and the number of development wells is used to determine the injection-production well spacing and the number of development wells at different development stages throughout the life cycle of a target oilfield, based on the predicted increase in oil production from development wells.

[0151] The system provided in this embodiment is used to execute the above-described method embodiments. For specific processes and details, please refer to the above embodiments, which will not be repeated here.

[0152] Example 3

[0153] This embodiment provides a processing device corresponding to the segmented prediction method for the number of development wells in offshore thick and thin interactive reservoirs provided in Embodiment 1. The processing device can be applied to client processing devices, such as mobile phones, laptops, tablets, desktop computers, etc., to execute the method of Embodiment 1.

[0154] The processing device includes a processor, a memory, a communication interface, and a bus. The processor, memory, and communication interface are connected via the bus to enable communication between them. The memory stores computer programs that can run on the processing device. When the processing device runs the computer programs, it executes the offshore thick-thin interactive reservoir development well number segmentation prediction method provided in Embodiment 1.

[0155] In some implementations, the memory may be high-speed random access memory (RAM), and may also include non-volatile memory, such as at least one disk storage device.

[0156] In other implementations, the processor can be any type of general-purpose processor, such as a central processing unit (CPU) or a digital signal processor (DSP), and there is no limitation here.

[0157] Furthermore, the logical instructions in the aforementioned memory can be implemented as software functional units and sold or used as independent products, and can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0158] Those skilled in the art will understand that the structure of the above-described computing device is only a partial structure related to the solution of this application and does not constitute a limitation on the computing device to which the solution of this application is applied. A specific computing device may include more or fewer components, or combine certain components, or have different component arrangements.

[0159] Example 4

[0160] This embodiment provides a computer program product corresponding to the offshore thick-thin interactive reservoir development well number segmentation prediction method provided in Embodiment 1. The computer program product may include a computer-readable storage medium on which computer-readable program instructions are loaded for executing the offshore thick-thin interactive reservoir development well number segmentation prediction method described in Embodiment 1.

[0161] A computer-readable storage medium can be a tangible device that holds and stores instructions for use by an instruction execution device. A computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any combination thereof.

[0162] The computer-readable storage medium provided in the above embodiments has a similar implementation principle and technical effect to the above method embodiments, and will not be described again here.

[0163] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0164] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0165] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0166] The above embodiments are only used to illustrate the present invention. The structure, connection method and manufacturing process of each component can be varied. All equivalent transformations and improvements made on the basis of the technical solution of the present invention should not be excluded from the protection scope of the present invention.

Claims

1. A method for segmented prediction of the number of development wells in offshore reservoirs with alternating thick and thin layers, characterized in that, include: Based on the classification and grading standards for sand bodies in marine reservoirs with alternating thick and thin layers, the target oilfield is classified and graded according to its sand bodies. Based on the results of sand body classification and treatment of the target oilfield and the pre-established dimensionless oil increase prediction charts for development wells of different types and grades of sand bodies, the prediction results of oil increase from development wells in the target oilfield are obtained. Based on the predicted increase in oil production from development wells in the target oilfield, the injection-production well spacing and the number of development wells at different development stages throughout the entire life cycle of the target oilfield are determined. The process of establishing the dimensionless oil production prediction charts for development wells of different types and grades of sand bodies includes: By introducing the swept volume factor, oil displacement efficiency factor, and sand body distribution scale and injection-production well spacing matching factor, the traditional recovery rate model is modified, and a calculation model for the oil increase of offshore development wells throughout their entire life cycle is established. Based on the calculation model of oil production increase of offshore development wells throughout their entire life cycle, and combined with the development characteristics of continuous thick sand bodies at sea, a dimensionless oil production increase evaluation chart for offshore development wells in continuous thick sand bodies is established. Based on the calculation model of oil production increase of offshore development wells throughout their entire life cycle, and combined with the development characteristics of offshore strip-shaped thick sand bodies, an evaluation chart for oil production increase of offshore strip-shaped thick sand body development wells is established. Based on the calculation model of oil production increase of offshore development wells throughout their entire life cycle, and combined with the development characteristics of thin sand bodies at sea, an evaluation chart of oil production increase of offshore thin sand body development wells is established. The horizontal axis of the dimensionless oil production prediction charts for each development well is the distance between injection and production wells. The vertical axis represents the dimensionless increase in oil production from development wells. ; The calculation model for increased oil production from offshore development wells throughout their entire lifespan is as follows: in, To increase oil production in development wells; To utilize reserves; The oil-bearing area; The effective permeability of the sand body; The viscosity of the formation crude oil; This refers to the distance between injection and production wells; This represents the limit value for the width of the sand body; , , 、 All of these are model parameters.

2. The method for segmented prediction of the number of development wells in offshore thick-thin alternating reservoirs as described in claim 1, characterized in that, The method, based on the sand body classification and grading results of the target oilfield and the pre-established dimensionless oil production prediction charts for different types and grades of sand bodies, yields the predicted oil production increase of development wells in the target oilfield, including: Based on the differentiated characteristics of the target oilfield reserves and the principle of graded utilization of reserves, and according to the graded classification of sand bodies in the target oilfield, the proportion of recoverable reserves of different types and grades of sand bodies in the target oilfield is statistically analyzed. Determine the initial oil production increase of development wells in different types and grades of sand bodies in the target oilfield; Based on the dimensionless oil production prediction chart of development wells for different types and grades of sand bodies, combined with the initial oil production of development wells for different types and grades of sand bodies in the target oilfield, the oil production of development wells in the target oilfield is calculated by weighting the proportion of recoverable reserves of different types and grades of sand bodies in the target oilfield. Plot the curves of the increase in oil production from development wells in the target oilfield as a function of the injection-production well spacing to obtain the predicted results of the increase in oil production from development wells in the target oilfield.

3. The method for segmented prediction of the number of development wells in offshore thick-thin alternating reservoirs as described in claim 2, characterized in that, The method of predicting the dimensionless increase in oil production from development wells based on different types and grades of sand bodies, combined with the initial increase in oil production from development wells of different types and grades of sand bodies in the target oilfield, and weighted according to the proportion of recoverable reserves of different types and grades of sand bodies in the target oilfield, includes: Based on the initial oil increase of development wells in different types and grades of sand bodies in the target oilfield, and according to the dimensionless oil increase prediction chart of development wells in different types and grades of sand bodies, the oil increase variation curves of development wells in different types and grades of sand bodies in the target oilfield are plotted to obtain the prediction results of oil increase of development wells in different types and grades of sand bodies in the target oilfield. The oil production increase from development wells in the target oilfield is calculated by weighting the predicted oil production from different types and grades of sand bodies and the proportion of recoverable reserves of different types and grades of sand bodies in the target oilfield.

4. The method for segmented prediction of the number of development wells in offshore thick-thin alternating reservoirs as described in claim 1, characterized in that, Based on the predicted increase in oil production from development wells in the target oilfield, the injection-production well spacing and the number of development wells at different development stages throughout the target oilfield's lifespan are determined, including: Based on the characteristics of the target oilfield, determine the oil production increase of development wells at different development stages; By using the increased oil production of development wells at different development stages of the target oilfield, the curve of the increased oil production of development wells of the target oilfield as a function of injection-production well spacing is cut off, and the injection-production well spacing corresponding to the cutoff point is determined, which is the injection-production well spacing at different development stages throughout the life of the target oilfield. Based on the oil-bearing area, well pattern and well type of the target oilfield, as well as the injection-production well spacing at different development stages throughout the life of the target oilfield, the number of development wells at different development stages throughout the life of the target oilfield is calculated.

5. The method for segmented prediction of the number of development wells in offshore thick-thin alternating reservoirs as described in claim 1, characterized in that, The classification and grading standards for sand bodies in offshore reservoirs with alternating thick and thin layers include categories A, B, and C, among which: Category A includes levels 1, 2, 3, and 4. All four levels consist of continuous, thick sand bodies. Level 1 sand bodies in Category A have a thickness >15m, a width >500m, and a coefficient of variation <0.6f; Level 2 sand bodies have a thickness of 10–15m, a width of 450–500m, and a coefficient of variation of 0.6–0.8f; Level 3 sand bodies have a thickness of 5–10m, a width of 400–450m, and a coefficient of variation of 0.8–1.0f; and Level 4 sand bodies have a thickness of 5–10m, a width of 350–400m, and a coefficient of variation >1.0f. Category B includes Level 1 and Level 2. Both levels consist of banded thick sand bodies. Level 1 sand bodies in Category B have a thickness >10m, a width of 300–350m, and a coefficient of variation <1.0f. Level 2 sand bodies in Category B have a thickness of 5–10m, a width of 250–300m, and a coefficient of variation >1.0f. Category C includes levels 1, 2, and 3. All three levels consist of thin-layered sand bodies. Level 1 sand bodies in Category C have a thickness of <5m, a width of 200–250m, and a coefficient of variation of <0.8f. Level 2 sand bodies in Category C have a thickness of <5m, a width of 150–200m, and a coefficient of variation of 0.8–1.0f. Level 3 sand bodies in Category C have a thickness of <5m, a width of <150m, and a coefficient of variation of >1.0f.

6. A segmented prediction system for the number of development wells in offshore thick-thin interactive reservoirs, characterized in that, include: The classification and grading module is used to classify and grade sand bodies in the target oilfield according to the classification and grading standards for sand bodies in offshore thick-thin alternating reservoirs. The development well oil production prediction module is used to obtain the development well oil production prediction results of the target oilfield based on the sand body classification and processing results of the target oilfield and the pre-established dimensionless oil production prediction charts for different types and grades of sand bodies. The module for determining injection-production well spacing and number of development wells is used to determine the injection-production well spacing and number of development wells at different development stages throughout the life cycle of a target oilfield based on the predicted increase in oil production from development wells. The process of establishing the dimensionless oil production prediction charts for development wells of different types and grades of sand bodies includes: By introducing the swept volume factor, oil displacement efficiency factor, and sand body distribution scale and injection-production well spacing matching factor, the traditional recovery rate model is modified, and a calculation model for the oil increase of offshore development wells throughout their entire life cycle is established. Based on the calculation model of oil production increase of offshore development wells throughout their entire life cycle, and combined with the development characteristics of continuous thick sand bodies at sea, a dimensionless oil production increase evaluation chart for offshore development wells in continuous thick sand bodies is established. Based on the calculation model of oil production increase of offshore development wells throughout their entire life cycle, and combined with the development characteristics of offshore strip-shaped thick sand bodies, an evaluation chart for oil production increase of offshore strip-shaped thick sand body development wells is established. Based on the calculation model of oil production increase of offshore development wells throughout their entire life cycle, and combined with the development characteristics of thin sand bodies at sea, an evaluation chart of oil production increase of offshore thin sand body development wells is established. The horizontal axis of the dimensionless oil production prediction charts for each development well is the distance between injection and production wells. The vertical axis represents the dimensionless increase in oil production from development wells. ; The calculation model for increased oil production from offshore development wells throughout their entire lifespan is as follows: in, To increase oil production in development wells; To utilize reserves; The oil-bearing area; The effective permeability of the sand body; The viscosity of the formation crude oil; This refers to the distance between injection and production wells; This represents the limit value for the width of the sand body; , , 、 All of these are model parameters.

7. A processing device, characterized in that, It includes computer program instructions, wherein when the computer program instructions are executed by a processing device, they are used to implement the steps corresponding to the method for segmented prediction of the number of development wells in offshore thick and thin interactive reservoirs as described in any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer program instructions, wherein when executed by a processor, the computer program instructions are used to implement the steps corresponding to the offshore thick-thin interactive reservoir development well number segmentation prediction method according to any one of claims 1-5.

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