Multi-layer sandstone oil field water drive layer series recombination method

Abstract

The invention relates to the technical field of petroleum engineering, and discloses a multi-layer sandstone oil field water-drive layer series recombination method which comprises the following steps: S1, drilling a foundation well pattern to exploit an oil layer in a successive densification development mode; s2, drilling a dense well pattern in stages and batches to exploit a medium-low permeability layer and a thin-difference oil layer; and S3, after oil field development enters the extra-high water cut period, injection-production system adjustment is carried out. The step S1 specifically comprises the following steps: S101, geological survey and evaluation: carrying out detailed geological survey and evaluation, and knowing conditions such as distribution, properties and reserves of an oil layer; through subdivision and recombination of an existing complex water drive well pattern, the purposes of clear series of strata, independent well pattern, perfect injection and production and easy adjustment are achieved, an ultra-high water cut stage series of strata well pattern adjustment mode is established, meanwhile, the development scheme of an oil field can be optimized, the number of producing wells is reduced, the number of injection wells is increased, and therefore the oil-water well number ratio is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of petroleum engineering, and specifically to a method for reorganizing water drive layer systems in multi-layer sandstone oilfields. Background Art

[0002] When the wells were drilled and developed in Daqing Oilfield, a step-by-step infill development method was adopted. First, the basic well pattern was drilled to exploit the good oil layers, and then the infill well pattern was drilled in batches to exploit the medium and low permeability layers and the thin and poor oil layers. After the oilfield development entered the extra-high water cut period, the main method for adjusting the water drive layer system well pattern was to implement the adjustment of the injection-production system and to implement the conversion of single old oil wells to injection wells, so as to reduce the ratio of oil wells to water wells. The disadvantages of this method are as follows: First, the span of the adjusted layer system is large, the adjusted well section is long, and the perforated well section of the Putaohua oil layer reaches 253 m, which intensifies the interlayer contradiction. Through the fine adjustment of injection wells, the interlayer contradiction under multi-layer combined production cannot be fundamentally solved. Second, the exploited layer systems between well patterns are staggered, and the injection-production relationship is complex. Several well patterns in the same development layer system are exploited simultaneously, and one injection well needs to coordinate the connection relationship with 10-12 surrounding production wells, which brings great difficulties to dynamic analysis and adjustment. Therefore, those skilled in the art have proposed a method for reorganizing the water drive layer system in multi-layer sandstone oilfields to solve the above problems. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the present invention provides a method for reorganizing the water drive layer system in multi-layer sandstone oilfields, which solves the problem that the interlayer contradiction under multi-layer combined production cannot be fundamentally solved through the fine adjustment of injection wells in the prior art.

[0004] To achieve the above objectives, the present invention is realized through the following technical solutions: A method for reorganizing the water drive layer system in multi-layer sandstone oilfields, including the following steps: S1. Adopt a step-by-step infill development method, first drill the basic well pattern to exploit the good oil layers; S2. Drill the infill well pattern in batches to exploit the medium and low permeability layers and the thin and poor oil layers; S3. After the oilfield development enters the extra-high water cut period, implement the adjustment of the injection-production system.

[0005] Preferably, the S1 step specifically includes the following steps: S101. Geological investigation and evaluation: Conduct a detailed geological investigation and evaluation to understand the distribution, properties, reserves, etc. of the oil layers; S102. Basic well pattern design: According to the geological investigation results, design the layout plan of the basic well pattern; determine the positions of the main production wells and injection wells, taking into account factors such as the thickness, dip angle, and permeability of the oil layers; S103. Drilling and completion: According to the basic well pattern design plan, carry out the drilling operation, first drill and complete the production wells of the basic well pattern to achieve the initial exploitation of the oil layers; S104, Production Testing and Evaluation: After a new well is drilled, conduct production testing and evaluation to assess its productivity and effectiveness, and based on the evaluation results, carry out further optimization and adjustment; S105, Infill Well Pattern Design: After the basic well pattern has exploited the oil reservoir, according to the oilfield development plan, design the layout scheme of the infill well pattern, and determine the positions of production wells and injection wells for further exploitation of medium-low permeability layers and thin and poor oil layers; S106, Drilling and Completion: According to the infill well pattern design scheme, carry out drilling operations to drill and complete the production wells and injection wells of the infill well pattern for further exploitation of medium-low permeability layers and thin and poor oil layers; S107, Production Testing and Evaluation: After a new well is drilled, conduct production testing and evaluation to assess its productivity and effectiveness, and based on the evaluation results, carry out further optimization and adjustment; S108, According to the oilfield development plan, cycle through the steps of infill well pattern design, drilling and completion, and production testing and evaluation to gradually exploit medium-low permeability layers and thin and poor oil layers, and achieve the comprehensive development of the oilfield.

[0006] Preferably, step S2 specifically includes the following steps: S201, Conduct detailed geological surveys and evaluations to understand the distribution, properties, and reserves of medium-low permeability layers and thin and poor oil layers, and based on the geological survey results, design the layout scheme of the infill well pattern and determine the positions of production wells and injection wells for medium-low permeability layers and thin and poor oil layers; S202, According to the infill well pattern design scheme, carry out drilling operations, first drill and complete the production wells for medium-low permeability layers and thin and poor oil layers to achieve preliminary exploitation of these formations; S203, After a new well is drilled, conduct production testing and evaluation to assess its productivity and effectiveness, based on the evaluation results, carry out further optimization and adjustment, and select a suitable location around the completed production wells to drill and complete injection wells to ensure a reasonable injection-production relationship between the injection wells and production wells; S204, Conduct joint commissioning of the newly drilled injection wells and surrounding production wells to ensure the normal operation of the injection-production system and achieve the expected oil production increase effect. Then, conduct production monitoring of the infill well pattern, collect production data, and conduct analysis and evaluation, and based on the monitoring results, carry out adjustment and optimization to improve the exploitation efficiency of medium-low permeability layers and thin and poor oil layers.

[0007] Preferably, in step S3, implementing the adjustment of the injection-production system includes the following steps: S301, Adjust the layer interval, control the length of the adjusted well section within a reasonable range, and solve the interlayer contradiction under multi-layer combined production; S302, Coordinate the connectivity of 10 - 12 surrounding production wells to ensure good connection between the injection well and surrounding production wells; S303. Conduct dynamic analysis and adjustment on the situation where the exploited layer series intersects between well patterns to optimize the complexity of injection-production relationship.

[0008] Preferably, the specific process in the S301 step is as follows: According to the analysis of interlayer contradictions, solve the interlayer contradictions by adjusting the well section length. The well section length can be increased or decreased to balance the productivity and injection of different layer series, and determine a reasonable range of well section lengths according to the characteristics of the oilfield and the development plan.

[0009] Preferably, the specific process in the S302 step is as follows: According to the geological survey results and the positions of injection wells, select 10 - 12 production wells around to ensure that there is a suitable positional relationship between these production wells and the injection wells, and design the connection relationship according to the positional relationship, including determining the positions and wellbore directions of the connected wells. Then, carry out the drilling and completion operations of the connected wells to ensure a good connection between the injection wells and the surrounding production wells. Finally, after the drilling and completion of the connected wells, conduct injection-production joint commissioning to ensure the normal operation of the injection-production system and achieve the expected oil production increase effect.

[0010] Preferably, the adjustment of the injection-production system in the S3 step further includes the following steps: Step 1. Utilize dynamic analysis technology to monitor the exploitation situation of the oilfield in real time for adjustment and optimization; Step 2. Based on data analysis and prediction models, formulate the best injection-production strategy to improve the exploitation efficiency; Step 3. Based on the analysis of injection-production data and production data, conduct dynamic adjustment and optimization of the well pattern; Step 4. Utilize modern information technology and data processing methods to realize intelligent management of the injection-production system.

[0011] Preferably, the adjustment of the injection-production system in the S4 step further includes: Based on the geological model and fluid dynamics simulation, conduct optimized design of the injection-production system, and use the simulation and optimization results to guide the actual adjustment and operation of the injection-production system.

[0012] The present invention provides a method for reorganizing waterflood layer series in a multi-layer sandstone oilfield. It has the following beneficial effects: Through the subdivision and reorganization of the current complex waterflood well pattern, the present invention achieves the purpose of "clear layer series, independent well pattern, optimized well spacing, perfect injection-production, and conducive to adjustment", establishes an adjustment mode for layer series and well pattern in the extra-high water cut period, with an average daily oil production increase of 1.0 t per production well, controlling the water cut rise by 1.6%, and annually slowing down the natural decline by 2.35 percentage points.

[0013] Through the layer system reorganization, the present invention can adjust the distribution of the injected water, making it enter each layer system more evenly, avoiding the problem of over-exploitation of high-permeability layer systems and under-exploitation of low-permeability layer systems, improving the water flooding effect, and at the same time optimizing the oilfield development plan, reducing the number of production wells and increasing the number of injection wells, thereby reducing the ratio of oil wells to water wells. This can reduce production costs, improve the economic benefits of the oilfield, and reduce the consumption of underground water resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a flow chart of the method for reorganizing water flooding layer systems in a multi-layer sandstone oilfield according to Embodiment 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Embodiment 1

[0016] As Figure 1 shown, the embodiment of the present invention provides a method for reorganizing water flooding layer systems in a multi-layer sandstone oilfield, including the following steps: S1. A development method of successive densification, first drilling a basic well pattern to exploit the good oil layers; The specific steps in step S1 include the following steps: S101. Geological survey and evaluation: Conduct a detailed geological survey and evaluation to understand the distribution, properties, reserves, etc. of the oil layers; Specifically, during the geological survey and evaluation process, we need to understand the distribution of the oil layers in detail, evaluate their properties and reserves to ensure the smooth progress of subsequent exploitation. These oil layers may be located deep underground and require precise exploration and detailed evaluation to determine their distribution and reserves.

[0017] S102. Design of the basic well pattern: According to the geological survey results, design the layout plan of the basic well pattern; determine the positions of the main production wells and injection wells, taking into account factors such as the thickness, dip angle, and permeability of the oil layers; Specifically, after completing the geological survey, we need to design the layout plan of the basic well pattern according to the geological survey results. The main factors to be considered in this process include the thickness, dip angle, and permeability of the oil layers. A reasonable design of the basic well pattern can maximize the exploitation efficiency and reduce waste at the same time.

[0018] S103. Drilling and completion: According to the basic well pattern design plan, carry out drilling operations, first drill and complete the production wells of the basic well pattern to achieve the initial exploitation of the oil layers; Specifically, the well is an important link in the oil extraction process. It is necessary to drill and complete the production wells of the basic well pattern first to achieve the initial exploitation of the oil reservoir. In this process, it is necessary to accurately control the direction and depth of drilling to ensure the accuracy and safety of exploitation.

[0019] S104. Production testing and evaluation: After the new well is drilled, conduct production testing and evaluation, evaluate its productivity and effectiveness, and based on the evaluation results, conduct further optimization and adjustment; Specifically, this link mainly evaluates the productivity and effectiveness of the new well and conducts further optimization and adjustment according to the evaluation results. If the productivity of the new well fails to meet the expectations, we need to re-evaluate the geological conditions and adjust the design plan.

[0020] S105. Infill well pattern design: After the basic well pattern has exploited the oil reservoir, according to the oilfield development plan, design the layout plan of the infill well pattern, and determine the positions of the production wells and injection wells for further exploitation of the medium and low permeability layers and thin and poor oil layers; S106. Drilling and well completion: According to the infill well pattern design plan, carry out drilling operations, drill and complete the production wells and injection wells of the infill well pattern to further exploit the medium and low permeability layers and thin and poor oil layers; S107. Production testing and evaluation: After the new well is drilled, conduct production testing and evaluation, evaluate its productivity and effectiveness, and based on the evaluation results, conduct further optimization and adjustment; S108. According to the oilfield development plan, cycle through the steps of infill well pattern design, drilling and well completion, and production testing and evaluation to gradually exploit the medium and low permeability layers and thin and poor oil layers and achieve the comprehensive development of the oilfield.

[0021] S2. Drill the infill well pattern in batches to exploit the medium and low permeability layers and thin and poor oil layers; The specific steps in S2 are as follows: S201. Conduct a detailed geological survey and evaluation to understand the distribution, properties, reserves, etc. of the medium and low permeability layers and thin and poor oil layers, and based on the geological survey results, design the layout plan of the infill well pattern and determine the positions of the production wells and injection wells for the medium and low permeability layers and thin and poor oil layers; Specifically, according to these geological survey results, design the layout plan of the infill well pattern and determine the positions of the production wells and injection wells for the medium and low permeability layers and thin and poor oil layers. These steps are crucial because they can provide an accurate basis for subsequent drilling operations.

[0022] S202. According to the infill well pattern design plan, carry out drilling operations, first drill and complete the production wells of the medium and low permeability layers and thin and poor oil layers to achieve the initial exploitation of these formations; Specifically, once we have a complete encrypted well pattern design plan, we will start the drilling operation. First, we will drill and complete the production wells in the medium and low permeability layers and the thin and poor oil layers to achieve the initial exploitation of these formations. These production wells will be the main sources for us to obtain crude oil. Therefore, their locations and quantities will be strictly considered and calculated.

[0023] S203. After the completion of the new well drilling, conduct production testing and evaluation to assess its productivity and effectiveness. According to the evaluation results, carry out further optimization and adjustment, and select appropriate locations around the drilled production wells to drill and complete the injection wells to ensure a reasonable injection-production relationship between the injection wells and the production wells. S204. Conduct joint commissioning of the newly drilled injection wells and the surrounding production wells to ensure the normal operation of the injection-production system and achieve the expected oil production increase effect. After that, conduct production monitoring on the encrypted well pattern, collect production data, and conduct analysis and evaluation. According to the monitoring results, make adjustments and optimizations to improve the exploitation efficiency of the medium and low permeability layers and the thin and poor oil layers.

[0024] S3. After the oilfield development enters the extra-high water cut stage, implement the adjustment of the injection-production system. In this step, implementing the adjustment of the injection-production system includes the following steps: S301. Adjust the formation interval, control the length of the adjusted well section within a reasonable range, and solve the interlayer contradiction under multi-layer combined production. The specific process in step S301 is as follows: According to the analysis of the interlayer contradiction, solve the interlayer contradiction by adjusting the well section length. The well section length can be increased or decreased to balance the productivity and injection of different formations, and determine a reasonable well section length range according to the characteristics and development plan of the oilfield. S302. Coordinate the connection relationship of 10 - 12 surrounding oil production wells to ensure a good connection between the injection well and the surrounding oil production wells. The specific process in step S302 is as follows: According to the geological survey results and the location of the injection well, select 10 - 12 surrounding oil production wells to ensure a suitable positional relationship between these oil production wells and the injection well. Design the connection relationship according to the positional relationship, including determining the locations and wellbore directions of the connected wells. After that, conduct the drilling and completion operations of the connected wells to ensure a good connection between the injection well and the surrounding oil production wells. Finally, after the drilling and completion of the connected wells, conduct injection-production joint commissioning to ensure the normal operation of the injection-production system and achieve the expected oil production increase effect. S303. Conduct dynamic analysis and adjustment of the situation where the exploited formations in the well pattern are staggered to optimize the complexity of the injection-production relationship. The adjustment of the injection-production system in step S3 also includes the following steps: Step 1. Use dynamic analysis technology to monitor the exploitation situation of the oilfield in real time and conduct adjustments and optimizations. Specifically, scientific methods are used to conduct in-depth research on the reservoir characteristics, fluid properties, pressure distribution, etc. of the oil field, and combined with the results of the prediction model, the best injection and production strategy is formulated to improve production efficiency.

[0025] Step 2: Based on data analysis and prediction models, formulate the best injection and production strategy to improve mining efficiency; Specifically, scientific methods are used to conduct in-depth research on the reservoir characteristics, fluid properties, pressure distribution, etc. of the oil field, and combined with the results of the prediction model, the best injection and production strategy is formulated to improve production efficiency.

[0026] Step 3: Based on the analysis of injection and production data, dynamically adjust and optimize the well pattern; Specifically, by analyzing historical injection and production data, we can identify existing problems and optimization space in the well network, make dynamic adjustments and optimizations in a timely manner, and improve the production effect of the oil field. Step 4: Use modern information technology and data processing methods to achieve intelligent injection and production system management.

[0027] Specifically, by introducing advanced information technology and data processing methods, the injection and production system of the oil field is managed intelligently, automatic and intelligent monitoring and management are achieved, and the extraction efficiency and production benefits of the oil field are improved.

[0028] The injection-production system adjustment in step S3 also includes: optimizing the design of the injection-production system based on the geological model and fluid dynamics simulation, and using the simulation and optimization results to guide the actual injection-production system adjustment and operation.

[0029] This embodiment was implemented in the Beierdong Block of the Third Oil Production Plant of Daqing Oilfield. 104 wells (58 injection and 46 production) were deployed in the test area, including 28 newly drilled wells and 28 transferred injection wells. After production, the average daily oil production of a single well increased from 2.3t to 3.2t, slowing down the natural decline by 2.35 percentage points per year, and controlling the water cut to rise by 1.57 percentage points. Numerical simulation predicted that the water drive recovery rate could be increased by 2.55 percentage points, and the recoverable reserves could be increased by 18.6×104t. The orderly connection from field test to regional promotion was successfully achieved. From 2013 to 2014, 235 new wells were drilled in the Beierdong Block, 93 wells were transferred, and a production capacity of 123,000 tons was built. It is expected to increase the water drive recovery rate by 2.39 percentage points. From 2015 to 2016, 145 new wells were drilled in the Beisandong Block, 27 wells were transferred, and a production capacity of 59,400 tons was built. It is expected to increase the water drive recovery rate by 2.2 percentage points. The total recoverable reserves in the adjusted area increased by 1.6615 million tons.

[0030] In the adjustment technology for oilfield development in this embodiment, the original staggered complex layer system is reorganized into four sets of independent layer system well patterns for exploitation, namely the Saertu basic layer, the Saertu secondary layer, the Puta II - Gaol 9 layer, and the Gaol 10 - Gaol III layer. The injection-production well spacing is optimized for different types of oil layers. For the relatively well-developed Puta II and Gaol 1 - 9 oil layers, a well spacing of 250 m is adopted, and for the thin and poor layers below Gaol 10, a well spacing of 175 m is used for exploitation. At the same time, a supporting tracking adjustment technology is formed. Combining the re-understanding of geological characteristics after the completion of new wells and the change characteristics of dynamic indicators after layer system reorganization, three tracking adjustments are carried out: "optimizing the supporting measures for oil production and injection wells, matching the water injection relationship between new and old wells, and optimizing the fine division of injection wells". This invention technology effectively solves the development contradictions under the conditions of multi-layer systems and multi-well patterns in the extra-high water cut period. Embodiment 2

[0031] Another method for reorganizing water drive layer systems in multi-layer sandstone oilfields provided by an embodiment of the present invention includes the following steps: S11. Clearly define the development characteristics of oil layers, and conduct a detailed analysis of the sedimentary facies characteristics, oil layer development conditions (thickness, permeability, etc.), oil layer heterogeneity, and interlayer development conditions of different layer systems in the block, as the geological basis for layer system combination; S12. Clearly define the current situation of oilfield development. Based on the current dynamic development data of the oilfield, determine the remaining oil situation of each set of oil layers. Mainly based on the water cut level of the production well patterns of each set of layer systems at present, dynamic monitoring data (production fluid profile, water absorption profile, etc.), water flooding interpretation results of new wells, core well interpretation results, numerical simulation results, etc., comprehensively evaluate the remaining oil of each set of oil layers at present, identify the main remaining oil enrichment areas, and clarify the types of remaining oil distribution; S13. Evaluate the current situation of the layer system well pattern. The well pattern layer systems deployed in the initial stage are not clearly divided, the exploited layer systems between well patterns are staggered, and the injection-production relationship is complex and not conducive to adjustment. At the same time, the production well section is too long, and the interlayer interference is relatively large; S14. Carry out layer system reorganization work. Subdivide and reorganize the well pattern with too long perforation intervals and prominent interlayer contradictions. On the premise of meeting the requirements of injection-production well spacing, partially block some oil layers of the old wells in the original well pattern in sections to reduce the development well section. At the same time, supplement and drill new wells to improve the injection-production relationship. Combine new and old wells, make full use of old wells to reduce investment, and complete the optimization of well spacing and the independence of the well pattern; S15. Optimize the well pattern deployment method. The commonly used well pattern deployment methods in the current oilfield include linear well patterns, five-spot area well patterns, reverse nine-spot area well patterns, row-column injection well patterns, etc. When designing the well pattern method after layer system reorganization, it is necessary to fully consider the current situation of the existing well pattern, make good connection with the existing well pattern, and at the same time meet the development well spacing requirements of different layer systems, customize the injection-production well spacing design, and the well positions should be as regular as possible; S16. After the formation series recombination, perforation needs to fully consider the perforation situation of the existing well pattern. For the infill wells mainly aiming at improving the injection-production relationship of thin and poor oil layers, the inter-well connectivity needs to be fully considered, and the perforation intervals should be optimized by combining the water flooding status of the new wells to control the initial water cut of the oil wells. For some thick oil layers that have been highly water flooded, consider taking the method of staged perforation and adjusting the perforation density to mitigate the inter-layer contradiction and control the rising speed of water cut.

[0032] In this way, while implementing the formation series recombination, a supporting tracking and adjustment technology is formed. Combining the re-understanding of the geological characteristics after the completion of the new wells and the change characteristics of the dynamic indicators after the formation series recombination, three tracking and adjustments of "optimizing the supporting measures for oil and water wells, matching the injection-water relationship between new and old wells, and optimizing the fine division of injection wells" are carried out. The invention technology effectively solves the development contradictions under the conditions of multi-formation series and multi-well pattern in the ultra-high water cut period.

[0033] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for reorganizing water flooding layer systems in a multi-layer sandstone oilfield, characterized in that, It includes the following steps: S1. Sequential encryption development method: First, drill the basic well pattern to develop the good oil layers; S2. Drill the infill well pattern in batches to develop the medium-low permeability layers and thin and poor oil layers; S3. After the oilfield development enters the extra-high water cut stage, implement the adjustment of the injection-production system.

2. The method for reorganizing water flooding layer systems in a multi-layer sandstone oilfield according to claim 1, characterized in that, The specific steps in step S1 include the following steps: S101. Geological survey and evaluation: Conduct a detailed geological survey and evaluation to understand the distribution, properties, reserves, etc. of the oil layers; S102. Basic well pattern design: According to the results of the geological survey, design the layout plan of the basic well pattern; determine the positions of the main production wells and injection wells, considering factors such as the thickness, dip angle, and permeability of the oil layers; S103. Drilling and completion: According to the basic well pattern design plan, carry out the drilling operation, first drill and complete the production wells of the basic well pattern to achieve the initial exploitation of the oil layers; S104. Production testing and evaluation: After the new wells are drilled, conduct production testing and evaluation, evaluate their productivity and effects, and according to the evaluation results, carry out further optimization and adjustment; S105. Infill well pattern design: After the basic well pattern has developed the good oil layers, according to the oilfield development plan, design the layout plan of the infill well pattern, and determine the positions of the production wells and injection wells for further exploitation of the medium-low permeability layers and thin and poor oil layers; S106. Drilling and completion: According to the infill well pattern design plan, carry out the drilling operation, drill and complete the production wells and injection wells of the infill well pattern to further exploit the medium-low permeability layers and thin and poor oil layers; S107. Production testing and evaluation: After the new wells are drilled, conduct production testing and evaluation, evaluate their productivity and effects, and according to the evaluation results, carry out further optimization and adjustment; S108. According to the oilfield development plan, cycle through the steps of infill well pattern design, drilling and completion, and production testing and evaluation to gradually exploit the medium-low permeability layers and thin and poor oil layers and achieve the comprehensive development of the oilfield.

3. The method for reorganizing water flooding layer systems in a multi-layer sandstone oilfield according to claim 1, characterized in that, The specific steps in step S2 include the following steps: S201. Conduct a detailed geological survey and evaluation to understand the distribution, properties, reserves, etc. of the medium-low permeability layers and thin and poor oil layers, and according to the results of the geological survey, design the layout plan of the infill well pattern, and determine the positions of the production wells and injection wells for the medium-low permeability layers and thin and poor oil layers; S202. According to the infill well pattern design plan, carry out the drilling operation, first drill and complete the production wells of the medium-low permeability layers and thin and poor oil layers to achieve the initial exploitation of these formations; S203. After the new wells are drilled, conduct production testing and evaluation, evaluate their productivity and effects, according to the evaluation results, carry out further optimization and adjustment, and select suitable positions around the drilled production wells to drill and complete the injection wells to ensure a reasonable injection-production relationship between the injection wells and the production wells; S204. Conduct joint commissioning of the newly drilled injection wells and the surrounding production wells to ensure the normal operation of the injection-production system and achieve the expected oil production increase effect. Then, conduct production monitoring of the infill well pattern, collect production data, and conduct analysis and evaluation, and according to the monitoring results, carry out adjustment and optimization to improve the exploitation efficiency of the medium-low permeability layers and thin and poor oil layers.

4. The method for reorganizing water flooding layer systems in a multi-layer sandstone oilfield according to claim 1, characterized in that, In step S3, the implementation of the injection-production system adjustment includes the following steps: S301. Adjust the layer series span, control the length of the adjusted well section within a reasonable range, and solve the interlayer contradiction under multi-layer combined production; S302. Coordinate the connection relationship of 10 - 12 surrounding oil production wells to ensure a good connection between the injection well and the surrounding oil production wells; S303. Conduct dynamic analysis and adjustment of the situation where the exploited layer series intersects between well patterns to optimize the complexity of the injection-production relationship.

5. The method for reorganizing water flooding layer systems in a multi-layer sandstone oilfield according to claim 4, characterized in that, The specific process in step S301 is as follows: According to the analysis of interlayer contradictions, solve the interlayer contradictions by adjusting the well section length. The well section length can be increased or decreased to balance the productivity and injection of different layer series, and determine a reasonable well section length range according to the characteristics and development plan of the oilfield.

6. The method for reorganizing water flooding layer systems in a multi-layer sandstone oilfield according to claim 1, characterized in that, The specific process in step S302 is as follows: According to the geological survey results and the location of the injection well, select 10 - 12 surrounding oil production wells to ensure that there is a suitable positional relationship between these oil production wells and the injection well, and design the connection relationship according to the positional relationship, including determining the location and wellbore direction of the connected wells, and then conduct the drilling and completion operations of the connected wells to ensure a good connection between the injection well and the surrounding oil production wells. Finally, after the drilling and completion of the connected wells, conduct injection-production joint commissioning to ensure the normal operation of the injection-production system and achieve the expected oil production increase effect.

7. The method for reorganizing water flooding layer systems in a multi-layer sandstone oilfield according to claim 1, characterized in that, The adjustment of the injection-production system in step S3 also includes the following steps: Step 1. Use dynamic analysis technology to monitor the exploitation situation of the oilfield in real time for adjustment and optimization; Step 2. Based on data analysis and prediction models, formulate the best injection-production strategy to improve the exploitation efficiency; Step 3. Based on the analysis of injection-production data and production data, conduct dynamic adjustment and optimization of the well pattern; Step 4. Use modern information technology and data processing methods to realize intelligent management of the injection-production system.

8. The method for restructuring water flooding layer series of multi-layer sandstone oilfield according to claim 1, characterized in that The adjustment of the injection-production system in step S3 also includes: Based on the geological model and fluid dynamics simulation, conduct optimized design of the injection-production system, and use the simulation and optimization results to guide the actual adjustment and operation of the injection-production system.

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