Optimal design method for well expansion in complex fault blocks with multiple layers and faults

Abstract

The present invention discloses a method for optimizing the design of well expansion in complex fault blocks with multiple layers and multiple faults. The method includes: conducting a regional stratum comparative analysis based on the regional stratigraphic stratification model to obtain the target stratum for well location deployment; obtaining the stratum for oil layer groups, sandstone groups, and single sand bodies based on the sedimentary cycles of the target stratum in combination with the "214" comparison method; finely calibrating seismic and geological horizons; establishing an isochronous stratigraphic framework; finely identifying the boundary faults and internal inter-well small faults of the complex fault block; and simultaneously obtaining the structural ups and downs of the target reservoir; obtaining the development of target sand bodies in unknown areas, and then obtaining the distribution characteristics of the sand bodies in the target reservoir of the complex fault block; optimizing the design of well locations in the reservoir based on the obtained complex fault block reservoir data; and ground planning of slave well platforms, i.e., drilling three to five wells on one platform. This method can determine the most effective well location, ensure the efficient development of complex fault blocks, and improve the success rate of reservoir drilling and the utilization rate of new wells.

Description

Technical Field

[0001] The present invention relates to the technical field of well expansion optimization, and in particular to an optimization design method for well expansion in a complex fault block with multiple layers and multiple faults. Background Art

[0002] In recent years, due to various factors such as the high degree of exploration in old areas, complete well network, high recovery rate, severe water flooding, and difficulty in economic evaluation, well site deployment has become difficult. As a result, production capacity construction can only be implemented in complex blocks with many faults, complex structures, multiple layers of development, and incomplete understanding of geological bodies.

[0003] Conventional reservoirs, with a complete understanding of the geology, have relatively simple well placement plans, typically selecting locations with structurally high points and thick oil reservoirs. However, the existing fault system is complex, with numerous interpreted faults and complex structures. Furthermore, the wellbore area is influenced by sedimentation, resulting in rapid reservoir changes and ineffective implementation of oil-water distribution patterns. Therefore, conventional well placement methods are no longer suitable for complex fault blocks characterized by frequent pinch-outs of sand bodies. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for optimizing the design of expansion wells in complex fault blocks with multiple layers and multiple faults. The method can determine the most effective well location and ensure the efficient development of complex fault blocks; utilize high-angle, dual or multi-target geological design to connect multiple reservoirs, thereby improving the success rate of reservoir drilling and the utilization rate of new wells.

[0005] To achieve the above objectives, the technical solution of this application is: an optimization design method for well expansion in complex fault blocks with multiple layers and multiple faults, including:

[0006] Based on the regional stratigraphic stratification model, a comparative analysis of the entire region was conducted to determine the target strata for well placement. Based on the sedimentary cycles of the target strata, the "214" comparison method was used to determine the stratification standards for oil layer groups, sandstone groups, and single sand bodies. Each single sand body layer was finely divided. At the same time, synthetic seismic records and VSP tests were performed on old wells to form a grid-like, high-precision seismic profile. This compensated for the insufficient resolution of 3D seismic data, extracted accurate velocity parameters, finely calibrated seismic and geological horizons, and established an isochronous stratigraphic framework. This provided reliable basic data for seismic interpretation and reservoir inversion, enabled fine tracking of single sand bodies, and provided a more reasonable description of oil-water relationships.

[0007] Finely identify boundary faults of complex fault blocks and internal inter-well small faults, and simultaneously obtain the current status of the target reservoir structure ups and downs;

[0008] Obtain the development of target sand bodies in unknown areas, and then obtain the distribution characteristics of target reservoir sand bodies in complex fault blocks;

[0009] Based on the obtained complex fault-block reservoir data, optimize the design of well locations in the reservoir;

[0010] Furthermore, it also includes full consideration of factors such as economic benefits, geological requirements, ground environment, and construction difficulty. Ground planning starts from the well platform, that is, one platform is used to drill 3 to 5 wells. This can effectively reduce the time and costs of ground land acquisition, well site expansion, road paving, drilling rig relocation, production pipeline installation, and centralized management of oil wells. Under limited ground conditions, more geological reservoirs can be utilized to ensure the smooth implementation and production of new wells, thereby achieving efficient reserve and production increases in oil reservoirs.

[0011] Furthermore, the “214” comparison method is characterized by equal deposition time, equal thickness of adjacent wells, and unified well-seismic data, which is consistent with structural interpretation, sedimentary laws, reservoir characteristics, and production dynamics.

[0012] Furthermore, the boundary faults of complex fault blocks and the internal inter-well small faults are finely identified, and the current status of the target reservoir structure ups and downs is obtained. The specific method is as follows:

[0013] Using Geoeast seismic software, single sand body layer data, accurate velocity parameters, and grid-networked high-precision seismic profiles, an integrated structural interpretation of the overlying and underlying target reservoirs was performed. By combining seismic interpretation and stratigraphic correlation with drilling, mud logging, and other interpretation conclusions and production and development dynamic data, the fine identification of complex block boundary faults and internal inter-well small faults was achieved, and the current structural ups and downs of the target reservoir were determined.

[0014] Furthermore, an integrated structural interpretation of the overlying and underlying target reservoirs is performed according to the step size of the seismic 2 traces.

[0015] Furthermore, the development of target sand bodies in unknown areas can be obtained, and the distribution characteristics of target reservoir sand bodies in complex fault blocks can be obtained. The specific methods are as follows:

[0016] By comparing the results and parameters of stratification and structural interpretation, the geological data are closely integrated with the seismic data, and the display of the target sand body in the seismic data is accurately calibrated and identified. The seismic iso-axis is accurately tracked using seismic data interpretation, and the development of the target sand body in the unknown area is inferred by analogy from the reflection of the completed drilling target layer in the seismic. The distribution characteristics of the sand body in the target reservoir of the complex fault block are then obtained, which solves the problem of unclear understanding of the phase changes between the various layers or single sand bodies in the complex fault block.

[0017] Furthermore, the design scheme for optimizing the well location in the reservoir is specifically designed by adopting a high-angle, dual or multi-target oil well design scheme to make the oil well trajectory close to the cross-section and accurately tap the remaining oil at the edge of the fault.

[0018] Furthermore, high-angle, dual or multi-target oil well design plans are adopted to deepen the overlying reservoir while taking into account the underlying reservoir, or to drill and explore the underlying reservoir while taking into account the overlying reservoir when there are risks, so as to improve the reservoir drilling rate of a single well and avoid the risk of a single well not drilling a reservoir or the risk of a drilled reservoir not being able to achieve economic development.

[0019] Furthermore, when the overlying and underlying reservoir systems of a small fault-block reservoir have large plane displacements, conventional thinking requires only the implementation of new wells for each. However, the design of high-angle, dual- or multi-target wells can ensure the thickness of the new well oil layer while accurately tapping the potential of the remaining oil in the two sets of reservoir systems, thereby improving the utilization rate of the reservoir reserves.

[0020] Due to the adoption of the above technical solutions, the present invention can achieve the following technical effects: The optimization design method of the multi-layer system, multi-fault complex block expansion wells of the present application can meet the needs of overall re-evaluation and development of oil reservoir geological bodies with such characteristics as complex fault systems, rapid reservoir phase changes, complex oil-water relationships, and small reserve areas. The design of personalized high-angle, dual or multi-target oil wells can ensure the thickness of the new well oil layer while accurately tapping the potential of the remaining oil at the edge of the fault, improve the single well reservoir drilling rate and the degree of oil reservoir reserve utilization, and avoid the risk of a single well not encountering a reservoir or the drilled reservoir not being able to achieve economic development. Planning the slave well platform can effectively realize the waiting time and investment costs of the oil well in various time periods such as deployment, pre-drilling, drilling, production, and post-management, improve the production time rate of the oil well, mobilize more geological reservoirs under limited ground conditions, ensure the smooth implementation and production management of the new well, and achieve efficient reserve and production increase in the oil reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings in the specification, which constitute a part of this application, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0022] Figure 1 This is the principle diagram of the optimization design method for the expansion wells in this multi-layer system with multiple faults and complex blocks.

[0023] Figure 2 This is a schematic diagram of the grid-type high-precision seismic profile in this design method.

[0024] Figure 3 This is a schematic diagram of structural interpretation based on the step size of 2 seismic traces in this design method.

[0025] Figure 4 This is a schematic diagram of the design method for accurately tracking earthquake co-axial lines using seismic data interpretation.

[0026] Figure 5 It is a cross-sectional schematic diagram of a high-angle dual-target oil well in this design method.

[0027] Figure 6 This is a schematic diagram of a slave-type well platform.

[0028] Among them: A—fault, B—high-angle oil well, C, D—target points, E—co-axis, F—vertical well, a, b, c—oil layers. DETAILED DESCRIPTION

[0029] In order to help those skilled in the art better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] This example is the Dalinghe oil reservoir in the Shahejie Formation Sha3 section of a certain oil field block. The Dalinghe reservoir of this oil reservoir has three sets of oil layer groups, two of which have a history of oil production and are the target layers of this study. The vertical burial depth difference between the two sets of oil layer groups exceeds 500 meters. In addition, the overall fault system of the oil reservoir is complex, with many interpreted faults, deep-water turbidity deposits, rapid reservoir phase change, many single sand bodies, and unclear understanding of the oil and water distribution law. Since the oil reservoir was put into development, it has been mainly based on measures to tap potential, and lacks an overall understanding and evaluation of the geological body of the oil reservoir. By implementing the multi-layer multi-fault complex block expansion well optimization design method on the two sets of reservoir blocks developed in the reservoir, preliminary development results have been achieved; such as Figure 1-6 As shown, the design method specifically includes:

[0031] Step 1. Based on the regional stratigraphic stratification model, a comparative analysis of the entire area was conducted, and the area was identified as the Dalinghe oil reservoir in the third member of the Shahejie Formation. According to the sedimentary cycle of the Dalinghe oil reservoir, combined with the "214" comparison method, the stratification standards for oil layer groups, sandstone groups, and single sand bodies were obtained. The reservoir was divided into three oil layer groups and five sandstone groups. At the same time, synthetic seismic records and VSP tests were prepared from selected old wells to extract accurate velocity parameters, finely calibrate seismic and geological horizons, establish an isochronous stratigraphic framework, achieve fine tracking of single sand bodies, and determine the oil-water interface of each reservoir, thereby making the oil-water relationship more reasonable.

[0032] Step 2. Using Geoeast seismic software and the data from Step 1, we performed an integrated structural interpretation of the overlying and underlying target reservoirs within the seismic data, using a two-channel step size. By integrating seismic interpretation and stratigraphic correlation, along with drilling, well logging, and other interpretations and production and development data, we achieved detailed identification of the overlying and underlying block boundary faults and internal interwell faults within the reservoir. Based on the original understanding, we eliminated three faults, added four, and revised three, refining the fault inheritance and occurrence within the block.

[0033] Step 3. Utilize the layered data obtained in step 1 and the structural interpretation conclusions obtained in step 2, combine them closely, utilize the display of the target layer of the completed drilling in the area in the seismic data, and track the same-direction axis through seismic to realize the distribution characteristics of the target reservoir sand body in the location area, and solve the problem of unclear understanding of the phase changes between the various layers or single sand bodies in the well area.

[0034] Step 4. Utilizing the layered data obtained in Step 1, the structural interpretation conclusions from Step 2, and the sand body distribution characteristics from Step 3, well placement was performed to optimize the new well trajectory design. A customized high-angle, dual- or multi-target well design strategy was employed to ensure that the well trajectory closely adhered to the fault plane and precisely tapped the remaining oil at the fault edge. This design involved drilling one control well, targeting the underlying reservoir while also considering the overburden. Four development wells were also designed, targeting the overburden while deepening and also considering the underlying reservoir, for a total of five wells. This resulted in precise drilling of 10 targets, increasing the reservoir penetration rate per well and mitigating the risk of a single well failing to encounter a reservoir or failing to economically develop the encountered reservoir. Furthermore, because the horizontal displacement of the overburden and underlying strata exceeded 500 meters, this strategy saved five drilling wells compared to conventional vertical well single-target designs. This strategy ensured the new well's reservoir thickness while precisely tapping the remaining oil in both reservoirs, thereby increasing the utilization rate of the reservoir reserves.

[0035] Step 5. Taking into full consideration factors such as economic benefits, geological requirements, ground environment, and construction difficulty, the ground planning is carried out from the well platform. In the new well design, two old platforms are selected to implement the new well. The waiting time and investment costs of the oil well in various time periods such as deployment, pre-drilling, drilling, production, and post-management are realized, the oil well production rate is improved, and more geological reservoirs are mobilized under limited ground conditions to ensure the smooth implementation and production management of the new well, thereby achieving efficient reserve and production increase of the oil reservoir.

[0036] This example deploys one control well and four development wells in the fault block, drilling all planned targets into the reservoir. The new wells have encountered a cumulative reservoir depth of 406.0 meters, with an average per-well depth of 81.2 meters. Five new wells have been put into production, producing over 100 tons per day. Cumulative oil production has exceeded 20,000 tons and gas production has exceeded 10 million cubic meters. This demonstrates efficient development results and is suitable for replication in major oil fields.

[0037] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0038] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An optimization design method for well expansion in complex fault blocks with multiple layers and multiple faults, characterized by: include: Based on the regional stratigraphic stratification model, a regional-wide comparative analysis of the stratigraphic layers was conducted to determine the target layers for well placement. Based on the sedimentary cycles of the target layers, the "214" comparison method was used to determine the stratification standards for oil layer groups, sandstone groups, and individual sand bodies. Each individual sand body layer was finely divided. Synthetic seismic records and VSP tests were performed on old wells to form a grid-like, high-precision seismic profile. Accurate velocity parameters were extracted, and seismic and geological horizons were finely calibrated to establish an isochronous stratigraphic framework. Finely identify boundary faults of complex fault blocks and internal inter-well small faults, and simultaneously obtain the current status of the target reservoir structure ups and downs; Obtain the development of target sand bodies in unknown areas, and then obtain the distribution characteristics of target reservoir sand bodies in complex fault blocks; Based on the obtained complex fault-block reservoir data, optimize the design of well locations in the reservoir; Finely identify boundary faults of complex fault blocks and internal inter-well small faults, and simultaneously obtain the structural ups and downs of the target reservoir. The specific methods are as follows: Using Geoeast seismic software, we leveraged single sand body layer data, accurate velocity parameters, and grid-based high-precision seismic profiles to conduct an integrated structural interpretation of the overlying and underlying target reservoirs. By combining seismic interpretation and stratigraphic correlation with drilling, mud logging, and well logging interpretation conclusions and production and development dynamics data, we achieved precise identification of complex block boundary faults and internal inter-well small faults, while also determining the structural ups and downs of the target reservoir. Conduct an integrated structural interpretation of the overlying and underlying target reservoirs according to the step length of seismic trace 2; Obtain the development of target sand bodies in unknown areas, and then obtain the distribution characteristics of target reservoir sand bodies in complex fault blocks. The specific methods are as follows: By comparing the results and parameters of layering and structural interpretation, geological data and seismic data are closely integrated to accurately calibrate and identify the appearance of target sand bodies in seismic data. Seismic data interpretation is used to accurately track the seismic isotropic axis. The development of target sand bodies in unknown areas is inferred by analogy based on the seismic reflection of the target layer in the completed well, thereby obtaining the distribution characteristics of sand bodies in the target reservoir of complex fault blocks. The above-mentioned design scheme for optimizing well locations in the reservoir is specifically designed by: adopting a high-angle, dual or multi-target oil well design scheme to make the oil well trajectory closely follow the fault surface and accurately tap the remaining oil at the edge of the fault; The "214" correlation method is characterized by equal deposition time, equal thickness of adjacent wells, and unified well-seismic data, which is consistent with structural interpretation, sedimentary laws, reservoir formation characteristics, and production dynamics.

2. The optimization design method for multi-layer multi-fault complex block well expansion according to claim 1 is characterized in that: It also includes planning a slave well platform on the ground, that is, one platform can drill 3 to 5 wells.

3. The optimization design method for multi-layer, multi-fault, complex fault block well expansion according to claim 1 is characterized in that: The design of high-angle, dual or multi-target oil wells is used to deepen the overlying reservoir while taking into account the underlying reservoir, or to drill and explore the underlying reservoir while taking into account the overlying reservoir when there are risks.

4. The optimization design method for multi-layer multi-fault complex fault block well expansion according to claim 1 is characterized in that: When the overlying and underlying reservoirs of a small fault block reservoir have large displacements in the plane, a high-angle, dual or multi-target oil well design is adopted to accurately tap the remaining oil in the two reservoirs while ensuring the thickness of the new well oil layer.

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