A method for constructing a spatial structure well pattern for injection and production in fracture-cavity oil reservoirs

Abstract

The present invention discloses a method for constructing a spatial structure well network for injection and production in a fracture-cavity oil reservoir, the method comprising: using a geophysical method to identify and characterize the fracture-cavity structure; based on the fracture-cavity structure identification and characterization, performing fracture-cavity structure division and connectivity analysis inside the fracture-cavity unit; performing reserve classification analysis based on the fracture-cavity structure division and connectivity analysis results inside the fracture-cavity unit; analyzing the current degree of perfection of the injection-production well network based on the fracture-cavity structure identification and characterization results, the fracture-cavity structure division and connectivity analysis results inside the fracture-cavity unit, and the reserve classification analysis results; constructing an injection-production well network perfection plan based on the injection-production well network perfection analysis results. According to the method of the present invention, the injection-production well network optimization configuration for carbonate fracture-cavity oil reservoirs can be achieved, thereby greatly improving the development efficiency and economic benefits of carbonate fracture-cavity oil reservoirs.

Description

Technical Field

[0001] The invention relates to the field of geological exploration and development, and in particular to a method for constructing a well network with a spatial structure for injection and production in a fracture-cavity oil reservoir. Background Art

[0002] Under the existing technical environment, oil and gas development is usually carried out using injection-production well networks. A perfect injection-production well network is the key to improving water drive control, production degree and recovery rate. Establishing an injection-production well network that adapts to the geological characteristics of the reservoir is of great significance for the effective control of water drive reserves, efficient production and improvement of water drive recovery rate. In the existing technology, clastic rock reservoirs have formed a relatively mature idea and method for constructing injection-production well networks, and there are three main types of well network deployment: row well network, area well network and irregular well network.

[0003] With the advancement of geological exploration and development technology, carbonate fracture-vuggy reservoirs have gradually become the main target of current oil and gas development. However, in the existing technical environment, the injection-production well network construction method suitable for carbonate fracture-vuggy reservoirs has not been formed. The current injection-production well network of carbonate fracture-vuggy reservoirs uses the basic well network of the capacity construction period to establish local injection-production well groups. However, due to the differences in geological structures, the injection-production well network architecture used in clastic reservoirs in the existing technology cannot be well applied to carbonate fracture-vuggy reservoirs. Therefore, the extraction efficiency of the injection-production well network currently used in carbonate fracture-vuggy reservoirs is not ideal. Summary of the invention

[0004] The present invention provides a method for constructing a spatial structure well pattern for injection and production in a fracture-cavity oil reservoir, the method comprising:

[0005] Use geophysical methods to identify and characterize fracture-cavity structures;

[0006] Based on the identification and characterization of the fracture-hole structure, the fracture-hole structure division and connectivity analysis within the fracture-hole unit are carried out;

[0007] Based on the fracture-cavity structure division and connectivity analysis results within the fracture-cavity unit, reserve classification analysis is carried out;

[0008] The current degree of perfection of the injection-production well network is analyzed based on the identification and characterization results of the fracture-cavity structure, the division of the fracture-cavity structure and the connectivity analysis results within the fracture-cavity unit, and the reserve classification analysis results;

[0009] According to the analysis results of the injection-production well network perfection, a plan for improving the injection-production well network is constructed.

[0010] In one embodiment, the identification and characterization of the crack hole structure includes:

[0011] Identify and characterize the seismic cave phase for caves;

[0012] Identify and characterize seismic fracture phases for fracture reservoirs;

[0013] The karst seismic phase analysis technology with multi-attribute fusion is used to classify seismic responses of similar characteristics, reducing the ambiguity in the interpretation of geological characteristics.

[0014] In one embodiment, the division and connectivity analysis of the fracture hole structure inside the fracture hole unit includes:

[0015] Track statically connected cracks and holes to realize the division of the connected structure association relationship inside the crack and hole unit;

[0016] Dynamic connectivity verification is performed in combination with development dynamic information within the fracture-cavity unit, wherein the development dynamic information includes well-to-well interference, production characteristic similarity, flooding characteristics, and tracer monitoring information;

[0017] and / or,

[0018] According to the material balance principle, the fluid flow relationship between inter-well fractures and caves is expressed by two parameters: comprehensive conductivity and control volume, and the degree of inter-well connectivity is quantitatively analyzed.

[0019] In one embodiment, a reserve classification analysis is performed, wherein the controlled reserves and the producing reserves are calculated and indicated.

[0020] In one embodiment, a reserve classification analysis is performed, wherein the reserves are divided into uncontrolled reserves, well-controlled unused reserves, connected difficult-to-produce reserves, and connected easy-to-produce reserves.

[0021] In one embodiment, the current degree of perfection of the injection-production well pattern is analyzed, including:

[0022] Considering the fracture-cavity structure and connectivity, a well network perfection evaluation index with the characteristics of fracture-cavity reservoirs is established, wherein the well network perfection evaluation index includes fracture-cavity control degree, injection-production correspondence rate, injection-production well number ratio, water drive reserve control degree and water drive reserve production degree;

[0023] The degree of perfection of the injection and production well network is quantitatively calculated and analyzed based on the well network perfection evaluation index.

[0024] In one embodiment, the method further comprises:

[0025] The water injection effect analysis of the current injection-production well network is carried out according to the water drive effect, including:

[0026] Determine water injection effect analysis indicators that meet the characteristics of water flooding development of fracture-cavity oil reservoirs, wherein the water injection effect analysis indicators include four aspects: development level, well network improvement, injection-production balance and effect and benefit;

[0027] Establishing water injection effect evaluation standards according to the water injection effect analysis indicators;

[0028] The injection-production well network improvement plan is optimized based on the water injection effect analysis results.

[0029] In one embodiment, water injection effect analysis indicators that meet the characteristics of water drive development of fracture-cavity oil reservoirs are determined, wherein the water injection effect analysis indicators include natural decline rate, water cut rise rate, water drive reserve control degree, water drive reserve utilization degree, oil well dual multi-directional benefit rate, cumulative injection-production ratio, energy retention degree, enhanced recovery and water-to-oil ratio.

[0030] In one embodiment, a water injection effect evaluation standard is established for the water injection effect analysis index, wherein the water injection effect evaluation standard is established respectively according to different geological backgrounds, water-containing stages and index weights.

[0031] In one embodiment, the method further comprises:

[0032] Conducting a benefit analysis on the injection-production well network improvement plan, and optimizing the injection-production well network improvement plan based on the benefit analysis results, including:

[0033] When additional injection and production wells are needed to improve the control of fractures and holes and the injection and production well pattern, the additional drilling costs should be analyzed;

[0034] and / or,

[0035] When it is necessary to adjust the injection-production structure, well pattern parameters and / or injection-production relationship, analyze the cost of the adjustment measures.

[0036] According to the method of the present invention, the injection and production well pattern optimization configuration for carbonate fracture-vuggy oil reservoirs can be achieved, thereby greatly improving the development efficiency and economic benefits of carbonate fracture-vuggy oil reservoirs.

[0037] Other features or advantages of the present invention will be described in the following description. Moreover, some features or advantages of the present invention will become apparent through the description, or will be understood through the implementation of the present invention. The purpose and some advantages of the present invention can be achieved or obtained through the steps specifically pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0039] Figure 1 as well as Figure 2 is a flow chart of a method according to an embodiment of the present invention;

[0040] Figure 3is a schematic diagram of the recognition and characterization results of the crack hole structure according to an embodiment of the present invention;

[0041] Figure 4 is a schematic diagram of an associated well group according to an embodiment of the present invention;

[0042] Figure 5 is a schematic diagram of connectivity analysis results according to an embodiment of the present invention;

[0043] Figure 6 is a schematic diagram of reserve classification analysis results according to an embodiment of the present invention;

[0044] Figure 7 is a schematic diagram of a well pattern perfection analysis result according to an embodiment of the present invention;

[0045] Figure 8 is a schematic diagram of a well pattern improvement solution according to an embodiment of the present invention;

[0046] Fig. 9 It is a schematic diagram of the distribution effect after the well pattern is improved according to an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The following will describe the implementation methods of the present invention in detail in conjunction with the accompanying drawings and embodiments, so that the implementers of the present invention can fully understand how the present invention applies technical means to solve technical problems and achieve the implementation process of technical effects and implement the present invention specifically according to the above implementation process. It should be noted that as long as there is no conflict, the various embodiments of the present invention and the various features in the embodiments can be combined with each other, and the technical solutions formed are all within the protection scope of the present invention.

[0048] Under the existing technical environment, oil and gas development is usually carried out using injection-production well networks. A perfect injection-production well network is the key to improving water drive control, production degree and recovery rate. Establishing an injection-production well network that adapts to the geological characteristics of the reservoir is of great significance for the effective control of water drive reserves, efficient production and improvement of water drive recovery rate. In the existing technology, clastic rock reservoirs have formed a relatively mature idea and method for constructing injection-production well networks, and there are three main types of well network deployment: row well network, area well network and irregular well network.

[0049] With the advancement of geological exploration and development technology, carbonate fracture-vuggy reservoirs have gradually become the main target of current oil and gas development. However, in the existing technical environment, the injection-production well network construction method suitable for carbonate fracture-vuggy reservoirs has not been formed. The current injection-production well network of carbonate fracture-vuggy reservoirs uses the basic well network of the capacity construction period to establish local injection-production well groups. However, due to the differences in geological structures, the injection-production well network architecture used in clastic reservoirs in the existing technology cannot be well applied to carbonate fracture-vuggy reservoirs. Therefore, the extraction efficiency of the injection-production well network currently used in carbonate fracture-vuggy reservoirs is not ideal.

[0050] In view of the above problems, the present invention proposes a method for constructing a spatial structure well pattern for injection and production in a fracture-vuggy oil reservoir.

[0051] The reservoirs of carbonate fracture-cave reservoirs are mainly composed of structural fractures caused by structural deformation and holes, caves and fractures formed by karstification. Among them, large caves are the main reservoir space, and fractures are both the main reservoir space and the main connecting channels. The carbonate matrix basically has no reservoir-permeability significance. The reservoir space has various shapes, large and small differences, uneven distribution, and strong heterogeneity. It is different from carbonate fracture-type reservoirs, carbonate fracture-pore-cave reservoirs, and even more different from conventional porous sandstone reservoirs.

[0052] Under the existing technical environment, the regular well pattern (row well pattern, area well pattern) of conventional clastic reservoirs requires a relatively complete oil layer structure, relatively stable oil layer distribution, clear oil-bearing boundary position, good internal and external connectivity, and high flow coefficient. In addition, the row well pattern is not suitable for reservoirs with severe heterogeneity, which can easily lead to uneven waterline advancement; in the area well pattern, the planar geometric relationship between oil and water wells has a great influence on the sweep coefficient of water injection, requiring a regular well pattern. Due to the strong heterogeneity of carbonate fracture-cave reservoirs, the construction method and well pattern of regular well patterns are difficult to implement and have poor applicability.

[0053] Furthermore, in the prior art, the deployment ideas and methods of irregular well networks have not been studied in depth. The deployment of irregular well networks is mainly aimed at small oil fields with irregular oil layer distribution, and irregular point water injection methods are used when it is difficult to arrange regular water injection well networks. However, for highly heterogeneous fracture-cavity reservoirs, there are no mature ideas and methods for reference on how to consider different reservoir space types, fracture-cavity structures, and injection-production relationship characteristics, and how to optimize water injection methods and well network forms.

[0054] The distribution plane of fracture-cavity reservoirs is extremely irregular, with multiple sets of vertical stacking. The spatial combination of fracture-cavity structures is extremely complex. Improving the recovery rate requires considering the control and use of spatial reserves. The current injection-production well network of carbonate fracture-cavity reservoirs uses the basic well network of the capacity construction period to establish local injection-production well groups. At present, the basic well network mainly uses large caves, and the control degree of small-scale fractures and caves is low. After entering the water injection development, it leads to the main unidirectional displacement on the plane and the low injection-production correspondence rate; the vertical direction is mainly shallow injection and production, and the control degree of sub-sets is low. In addition, the current deployment of local injection-production well groups only starts from the relationship between plane water injection wells and oil wells, without systematically considering the three-dimensional injection and production in the plane and the vertical direction, the comprehensive control of multi-directional and multi-section, the injection-production relationship characteristics of reservoir space type and high and low positions, and has not yet formed an adaptive, complete and feasible method for constructing injection-production well networks.

[0055] Based on the above analysis of the characteristics of fracture-cavity oil reservoirs, combined with the current basic well network layout method for fracture-cavity oil reservoirs, the present invention proposes a method for constructing a well network with a spatial structure for injection and production in fracture-cavity oil reservoirs. In the method of the present invention, based on the fracture-cavity connectivity structure characteristics of fracture-cavity oil reservoirs, a construction concept of "injection-production spatial structure well network" is proposed. That is, based on the three-dimensional spatial distribution of fracture-cavity bodies, combined with information such as fracture-cavity types, scales, and connectivity structures, a vector configuration relationship between water injection wells and oil production wells is established to achieve an injection-production well network that maximizes control and mobilization of fractures and caves. The goal of constructing an injection-production spatial structure well network is to establish a well network form in which the well network vector and the fracture-cavity vector are coordinated through vector configuration, forming a multi-directional plane and multi-set vertical injection-production structure, and ultimately achieving the goals of effective control, efficient mobilization, and balanced displacement.

[0056] Next, the detailed process of the method according to the embodiment of the present invention is described in detail based on the accompanying drawings. The steps shown in the flowchart of the accompanying drawings can be executed in a computer system including a set of computer executable instructions. Although the logical order of each step is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0057] like Figure 1 As shown, in one embodiment, the method of the present invention includes the following process.

[0058] S110, using geophysical methods to identify and characterize fracture-cavity structures;

[0059] S120, based on the fracture-hole structure identification and characterization in step S110, performing fracture-hole structure division and connectivity analysis inside the fracture-hole unit;

[0060] S130, performing reserve classification analysis based on the fracture-cavity structure division and connectivity analysis results within the fracture-cavity unit in step S120;

[0061] S140, analyzing the perfection of the current injection-production well pattern based on the identification and characterization results of the fracture-cavity structure in steps S110 to S130, the fracture-cavity structure division and connectivity analysis results within the fracture-cavity unit, and the reserve classification analysis results;

[0062] S150, constructing an injection-production well network improvement plan based on the injection-production well network improvement degree analysis result.

[0063] Specifically, in one embodiment, in step S110, the cave structures and fracture reservoirs are identified and described respectively. Specifically, the steps include:

[0064] Identify and characterize the seismic cave phase for caves;

[0065] Identify and characterize seismic fracture phases for fracture reservoirs;

[0066] The karst seismic phase analysis technology with multi-attribute fusion is used to classify seismic responses of similar characteristics, reducing the ambiguity in the interpretation of geological characteristics.

[0067] Specifically, in one embodiment, in the process of identifying and characterizing the seismic cave phase for caves, the amplitude gradient attribute and instantaneous energy attribute are first used for contour recognition, and then the maximum curvature attribute and coherence attribute are combined to perform cluster analysis of the seismic cave phase, thereby forming the identification and characterization of the seismic cave phase.

[0068] Specifically, in one embodiment, in the process of identifying and characterizing seismic fracture phases for fracture reservoirs, the maximum curvature attribute is first used to identify large-scale fractures, and then the formation dip and coherence attributes are combined to identify and characterize the seismic fracture phases.

[0069] Furthermore, in one embodiment, in step S110, the recognition and characterization results are classified. Specifically, it also includes:

[0070] The karst seismic phase analysis technology with multi-attribute fusion is used to classify seismic responses of similar characteristics, reducing the ambiguity in the interpretation of geological characteristics.

[0071] In one embodiment, by respectively identifying, characterizing and classifying, fine characterization of fractures and caves of different scales is achieved, laying a solid foundation for the construction of injection and production well patterns.

[0072] Furthermore, in one embodiment, the division and connectivity analysis of the fracture-hole structure within the fracture-hole unit is performed, and the fracture-hole connectivity and combination relationship characteristics are further clarified by the division of the associated well group. Specifically, it includes:

[0073] Track statically connected cracks and holes to realize the division of the connected structure association relationship inside the crack and hole unit;

[0074] Dynamic connectivity verification is performed in combination with development dynamic information within the fracture-cavity unit, wherein the development dynamic information includes well-to-well interference, production characteristic similarity, flooding characteristics, and tracer monitoring information;

[0075] and / or,

[0076] According to the material balance principle, the fluid flow relationship between inter-well fractures and caves is expressed by two parameters: comprehensive conductivity and control volume, and the degree of inter-well connectivity is quantitatively analyzed.

[0077] Specifically, in one embodiment, the connection structure association relationship inside the crack and hole unit is first divided, and then the dynamic connectivity verification is performed.

[0078] Specifically, in one embodiment, ant body tracking technology is used to track statically connected fractures and holes, so as to realize the division of the connected structure association relationship within the fracture and hole unit. An associated well group represents a fracture and hole structure with a static connected relationship.

[0079] Furthermore, in one embodiment, in step S130, the controlled reserves and produced reserves are calculated and marked. Specifically, in one embodiment, the controlled reserves are the geological reserves of the static associated well group, and the produced reserves are the geological reserves of the injection-production connected well group. Since the fracture-cavity reservoir uses fractures and caves as the reservoir space and the combination relationship is complex, by calibrating the controlled reserve range of the oil well, the distribution of the remaining uncontrolled reserves is clarified, providing a basis for the deployment of injection-production wells. Reserve classification analysis can clarify the reserve production type and the distribution of the remaining reserve potential.

[0080] Specifically, in one embodiment, during the process of performing reserve classification analysis, the reserves are divided into uncontrolled reserves, well-controlled unused reserves, connected difficult-to-recover reserves, and connected easy-to-recover reserves.

[0081] Furthermore, in one embodiment, a method of quantitative calculation of indicators is used to analyze the perfection of the injection-production well pattern. Specifically, it includes:

[0082] Considering the fracture-cavity structure and connectivity, an evaluation index for the degree of perfection of the well pattern with the characteristics of fracture-cavity reservoirs is established;

[0083] The degree of perfection of the injection-production well network is quantitatively calculated and analyzed based on the well network perfection evaluation index.

[0084] Specifically, in one embodiment, the evaluation index of the well network perfection degree includes the fracture-cavity control degree, the injection-production correspondence rate, the injection-production well number ratio, the water drive reserve control degree and the water drive reserve utilization degree.

[0085] Specifically, in one embodiment, a neural network method and a fuzzy comprehensive evaluation method are used to quantitatively calculate and analyze the degree of perfection of the injection and production well network.

[0086] Furthermore, in one embodiment, in step S140, by carrying out the analysis of the degree of perfection of the injection-production well network, the low injection-production well control area is identified, thereby indicating the direction of improvement of the injection-production well network. Specifically, in one embodiment, after the well network perfection analysis, the high, medium and low well control areas can be identified, so that in the subsequent improvement plan, the density of water injection wells in the low well control area can be focused.

[0087] Furthermore, in one embodiment, in step S140, by carrying out the analysis of the perfection of the injection-production well network, the control status of the well network and the well network utilization status are clarified. In step S150, for well networks with insufficient control, new injection-production improvement wells are added to improve the control of fractures and holes and the injection-production well network; for well networks with insufficient utilization, the injection-production structure, well network parameters, injection-production relationship and other measures are adjusted to optimize the well network deployment and adjustment potential to maximize the water drive utilization.

[0088] Furthermore, in order to further improve the production efficiency of the injection-production well network, in one embodiment, the injection-production well network improvement plan is also optimized based on the water drive effect analysis. Through the comprehensive evaluation of the unit water injection effect, the differences in the water injection effects of different well groups are reflected, and the areas with low water drive control and utilization are clarified to evaluate the displacement effect and clarify the utilization potential. Specifically, the unit water injection effect analysis results can reflect the good, medium, and poor water injection effects of each well group. Single indicator effect analysis is performed on the well group with poor water injection effect, so as to formulate corresponding treatment plans.

[0089] Specifically, in one embodiment, the method further includes:

[0090] Analyze the water injection effect of the current injection-production well network based on the water drive effect;

[0091] The injection-production well network improvement plan is optimized based on the water injection effect analysis results.

[0092] Specifically, in one embodiment, the water injection effect analysis is performed on the current injection-production well pattern according to the water flooding effect, including:

[0093] Determine the water injection effect analysis indicators that meet the characteristics of water flooding development of fracture-cavity oil reservoirs. The water injection effect analysis indicators include four aspects: development level, well network improvement, injection-production balance and effect and benefit;

[0094] Establish water injection effect evaluation standards based on water injection effect analysis indicators;

[0095] The water injection effect analysis is carried out according to the water injection effect evaluation standard.

[0096] Specifically, in one embodiment, the water injection effect analysis indicators include natural decline rate, water cut rise rate, water drive reserve control degree, water drive reserve utilization degree, oil well dual multi-directional benefit rate, cumulative injection-production ratio, energy retention degree, enhanced recovery factor and water-to-oil ratio.

[0097] Specifically, in one embodiment, water injection effect evaluation standards are established according to different geological backgrounds, water-bearing stages, and index weights.

[0098] Furthermore, in order to improve the executability of the injection-production well network improvement plan, in one embodiment, a benefit analysis is also performed on the injection-production well network improvement plan, and the injection-production well network improvement plan is optimized based on the benefit analysis results. Specifically, in one embodiment, it includes:

[0099] When additional injection and production wells are needed to improve the control of fractures and holes and the injection and production well pattern, the additional drilling costs should be analyzed;

[0100] and / or,

[0101] When it is necessary to adjust the injection-production structure, well pattern parameters and / or injection-production relationship, analyze the cost of the adjustment measures.

[0102] Through benefit analysis and solution optimization, the maximum cumulative oil production or benefits can be achieved.

[0103] Further, such as Figure 2 As shown, in one embodiment, the method includes the following process.

[0104] S211, identification and characterization of seismic cave facies for caves;

[0105] S212, identification and characterization of seismic fracture phases for fracture reservoirs;

[0106] S213, classifying seismic responses of similar features to reduce the ambiguity of interpretation of geological features;

[0107] S221, tracking statically connected cracks and holes to achieve the division of the connected structure association relationship inside the crack and hole unit;

[0108] S222, dynamic connectivity verification is performed in combination with the development dynamic information inside the fracture-hole unit;

[0109] S223, the fluid flow relationship between the fractures and caves between wells is expressed by two parameters: comprehensive conductivity and control volume, and the degree of connectivity between wells is quantitatively analyzed;

[0110] S230, performing reserve classification analysis, and calculating and marking controlled reserves and produced reserves;

[0111] S241, establish the evaluation index of well pattern perfection with characteristics of fracture-vuggy reservoirs;

[0112] S242, based on the well network perfection evaluation index, quantitative calculation and analysis of the current injection and production well network perfection is performed according to the identification and characterization results of the fracture-cavity structure, the division and connectivity analysis results of the fracture-cavity structure within the fracture-cavity unit, and the reserve classification analysis results;

[0113] S250, constructing a preliminary injection-production well network improvement plan based on the injection-production well network improvement degree analysis result;

[0114] S261, determine the water injection effect analysis index that meets the characteristics of water flooding development of fracture-cavity oil reservoirs;

[0115] S262, establishing water injection effect evaluation standards based on water injection effect analysis indicators;

[0116] S263, analyzing the water injection effect according to the water injection effect evaluation standard;

[0117] S264, optimizing the injection-production well pattern improvement plan based on the water injection effect analysis result;

[0118] S271, conduct a benefit analysis on the injection and production well network improvement plan;

[0119] S272, optimize the injection and production well network improvement plan based on the benefit analysis results.

[0120] The present invention, through the establishment of a method for constructing a well network with a spatial structure for injection and production in fracture-cavity oil reservoirs, embodies the construction ideas from static characterization to dynamic optimization, from plane deployment to three-dimensional construction, from unidirectional injection and production to multi-directional displacement, and from technical optimization to benefit maximization in fracture-cavity oil reservoirs with extremely strong heterogeneity. The present invention can provide a set of suitable ideas and methods for constructing a well network with a spatial structure for injection and production for fracture-cavity oil reservoirs. It can realize the well network deployment design for units without water injection development, and optimize and adjust the injection and production well network for units with water injection development, effectively guiding the well network construction work of fracture-cavity oil reservoirs.

[0121] Next, the execution effect of the embodiment of the present invention is described in detail based on a specific application scenario. Taking a certain fracture-cavity unit as an example, the method for constructing a spatial structure well pattern for injection and production of a fracture-cavity oil reservoir according to an embodiment of the present invention is described. The method includes the following steps.

[0122] (1) Step 1: Detailed carving of the seam holes

[0123] The TH12402 fracture-cave unit is a typical composite karst background unit. The developed shallow underground rivers and cracks make the fracture-cave connection structure extremely complex. Geophysical methods are used to identify and characterize the fracture-cave structure. The identification and characterization results are shown in the figure. Figure 3 shown.

[0124] (2) Step 2: Connectivity Characterization

[0125] Based on the detailed identification and characterization of fractures and caves, the fracture-cavity structure of the TH12402 unit was divided and the connectivity was evaluated. Five associated well groups were divided within the unit, and the connectivity between the wells was generally good. Figure 4 The connectivity analysis results are shown in Figure 5 shown.

[0126] (3) Step 3: Reserve classification analysis

[0127] Based on the analysis of the connectivity structure of the fracture-cavity reservoir, the controlled reserves and produced reserves of the TH12402 unit were calculated and marked. The uncontrolled reserves are mainly distributed in the western part of the unit, and the well-controlled unproduced reserves are mainly distributed in the middle part of the unit, which is the main direction of potential development in the lower part. The results of the reserve classification analysis are as follows: Figure 6 shown.

[0128] (4) Step 4: Well pattern perfection analysis

[0129] Through the evaluation of the degree of perfection of the injection-production well network, it was found that the degree of perfection of the well network of TH12402 unit was only 49%, and it was clear that the low injection-production well control area was mainly in the northwest and northeastern edges of the unit, which was the main direction for the improvement of the injection-production well network. Figure 7 shown.

[0130] (5) Step 5: Comprehensive analysis of water flooding effect

[0131] The TH12402 unit was evaluated for its natural decline rate, water cut rise rate, water drive reserve control degree, water drive reserve utilization degree, oil well dual multi-directional benefit rate, cumulative injection-production ratio, energy retention degree, enhanced recovery factor, and water-to-oil ratio. After comprehensive evaluation, it was considered that the unit water drive development effect was medium. The comprehensive analysis results of water drive effect are shown in Table 1.

[0132]

[0133] Table 1

[0134] (6) Step 6: Optimizing the efficient well pattern

[0135] According to the characteristics of the injection-production well network in the early stage of the unit, the method of constructing the injection-production spatial structure well network was adopted, with the goal of establishing multi-directional injection and production, and constructing a "surface well network" form. The injection-production well network was improved by considering the distribution of uncontrolled and produced reserves, connectivity, injection-production relationship and other characteristics.

[0136] TH12402 unit is expected to add 7 wells, including 3 injection and production wells (oil production first, then water injection), 4 low-yield and low-efficiency wells will be gradually converted to injection wells, and 13 new injection and production well pairs are expected to be added. The injection and production well ratio will increase from the current 1:5.4 to 1:1.7, the injection and production correspondence rate will increase from the current 34% to 91%, and the water drive control degree will be increased from the current 53% to 85%. Through the optimization and improvement of the well network, the water drive control degree will be greatly improved, and the improvement of the injection and production well network will be increased from 49% to 78%. The well network improvement plan for TH12402 unit is as follows: Figure 8 As shown, the distribution effect after improvement is as follows Fig. 9 shown.

[0137] The method of the present invention aims at the extremely strong geological heterogeneity of fracture-vuggy oil reservoirs. The design of the injection-production spatial structure well network takes into account the well network construction ideas from static characterization to dynamic optimization, from plane deployment to three-dimensional construction, from unidirectional injection and production to multi-directional displacement, and from technology to benefit optimization.

[0138] The present invention avoids the inapplicability of conventional injection-production well pattern construction methods in carbonate fracture-cavity reservoirs, and the established construction method and analysis steps can reasonably and comprehensively characterize the fracture-cavity connectivity structural characteristics of fracture-cavity reservoirs. At the same time, the method is highly targeted and involves a large amount of information, but has good adaptability to field applications. It is a systematic and applicable construction method, which is of great significance for the efficient water injection development of fracture-cavity reservoirs with extremely strong heterogeneity.

[0139] According to the method of the present invention, the injection and production well pattern optimization configuration for carbonate fracture-vuggy oil reservoirs can be achieved, thereby greatly improving the development efficiency and economic benefits of carbonate fracture-vuggy oil reservoirs.

[0140] It should be understood that the embodiments disclosed in the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should be extended to equivalent substitutions of these features understood by ordinary technicians in the relevant field. It should also be understood that the terms used herein are only used for the purpose of describing specific embodiments and are not meant to be limiting.

[0141] The "one embodiment" mentioned in the specification means that the specific features, structures or characteristics described in conjunction with the embodiment are included in at least one embodiment of the present invention. Therefore, the phrase "one embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0142] Although the embodiments disclosed in the present invention are as above, the contents described are only embodiments adopted for facilitating understanding of the present invention and are not intended to limit the present invention. The method according to the present invention may also have other various embodiments. Without departing from the essence of the present invention, those skilled in the art may make various corresponding changes or deformations according to the present invention, but these corresponding changes or deformations shall all belong to the protection scope of the claims of the present invention.

Claims

1. A method for constructing a spatial structure well pattern for injection and production in a fracture-cavity oil reservoir, characterized in that: The method comprises: Use geophysical methods to identify and characterize fracture-cavity structures; Based on the identification and characterization of the fracture-hole structure, the fracture-hole structure division and connectivity analysis within the fracture-hole unit are carried out; Based on the fracture-cavity structure division and connectivity analysis results within the fracture-cavity unit, reserve classification analysis is carried out; The current degree of perfection of the injection-production well network is analyzed based on the identification and characterization results of the fracture-cavity structure, the division of the fracture-cavity structure and the connectivity analysis results within the fracture-cavity unit, and the reserve classification analysis results; Construct an injection-production well network improvement plan based on the analysis results of the injection-production well network improvement degree; Analyze the current degree of perfection of the injection-production well network, including: considering the fracture-cavity structure and connectivity, establishing a well network perfection evaluation index with the characteristics of fracture-cavity oil reservoirs, the well network perfection evaluation index includes fracture-cavity control degree, injection-production correspondence rate, injection-production well number ratio, water drive reserve control degree and water drive reserve utilization degree; quantitatively calculate and analyze the degree of perfection of the injection-production well network based on the well network perfection evaluation index; The method further includes: performing water injection effect analysis on the current injection-production well network according to the water drive effect, including: determining water injection effect analysis indicators that meet the characteristics of water drive development of fracture-cavity oil reservoirs, wherein the water injection effect analysis indicators include four aspects: development level, well network improvement, injection-production balance and effect and benefit; establishing water injection effect evaluation standards according to the water injection effect analysis indicators; and optimizing the injection-production well network improvement plan based on the water injection effect analysis results.

2. The method according to claim 1, characterized in that Identify and characterize the fracture and hole structure, including: Identify and characterize the seismic cave phase for caves; Identify and characterize seismic fracture phases for fracture reservoirs; The karst seismic phase analysis technology with multi-attribute fusion is used to classify seismic responses of similar characteristics, reducing the ambiguity in the interpretation of geological characteristics.

3. The method according to claim 1, characterized in that The division and connectivity analysis of the fracture-hole structure inside the fracture-hole unit are carried out, including: Track statically connected cracks and holes to realize the division of the connected structure association relationship inside the crack and hole unit; Dynamic connectivity verification is performed in combination with development dynamic information within the fracture-cavity unit, wherein the development dynamic information includes well-to-well interference, production characteristic similarity, flooding characteristics, and tracer monitoring information; and / or, According to the material balance principle, the fluid flow relationship between inter-well fractures and caves is expressed by two parameters: comprehensive conductivity and control volume, and the degree of inter-well connectivity is quantitatively analyzed.

4. The method according to claim 1, characterized in that: Conduct reserve classification analysis, including calculation and indication of controlled reserves and producing reserves.

5. The method according to claim 1, characterized in that Conduct reserve classification analysis, in which reserves are divided into uncontrolled reserves, well-controlled unused reserves, connected difficult-to-recover reserves, and connected easy-to-recover reserves.

6. The method according to claim 1, characterized in that Determine water injection effect analysis indicators that are in line with the characteristics of water drive development of fracture-cavity oil reservoirs, wherein the water injection effect analysis indicators include natural decline rate, water cut rise rate, water drive reserve control degree, water drive reserve utilization degree, oil well dual multi-directional benefit rate, cumulative injection-production ratio, energy retention degree, enhanced recovery factor and water-to-oil ratio.

7. The method according to claim 1, characterized in that A water injection effect evaluation standard is established for the water injection effect analysis index, wherein the water injection effect evaluation standard is established respectively according to different geological backgrounds, water-containing stages and index weights.

8. The method according to any one of claims 1 to 7, characterized in that: The method further comprises: Conducting a benefit analysis on the injection-production well network improvement plan, and optimizing the injection-production well network improvement plan based on the benefit analysis results, including: When additional injection and production wells are needed to improve the control of fractures and holes and the injection and production well pattern, the additional drilling costs should be analyzed; and / or, When it is necessary to adjust the injection-production structure, well pattern parameters and / or injection-production relationship, analyze the cost of the adjustment measures.

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