Karst gas reservoir development favorable area optimization method and device based on strike-slip fracture

Abstract

The invention relates to the technical field of oil and gas field development, and discloses a strike-slip fracture-based karst gas reservoir development favorable area optimization method and device.According to the method, firstly, a breaking control karst area is divided into different fracture control areas, and then according to the divided fracture control areas, in combination with the karst water flow direction, the karst gas reservoir development favorable area is optimized; dividing the fracture control area into different fracture control karst reservoir development mode areas on a plane, finally evaluating the stable production capacity of the gas well in the fracture control karst reservoir development mode areas, and finally determining a favorable gas reservoir development area. According to the method, on the basis of strike-slip fracture, deposition, karst and gas well stable production capability evaluation are integrated, a new gas well deployed through the method is formed, high yield is tested, high yield and stable yield of the gas well can be achieved, and the overall development effect of a gas reservoir can be effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development, in particular to karst gas reservoir development, and in particular to a method and device for selecting a favorable area for karst gas reservoir development based on strike-slip faults. Background Art

[0002] The Sinian gas reservoir in the Sichuan Basin is a typical karst gas reservoir at home and abroad. The development potential of this gas reservoir is huge, but 80% of the natural gas reserves of the gas reservoir are stored in ultra-low porosity reservoirs with a porosity of less than 5%. In addition, affected by multiple factors such as sedimentation and karstification, the reservoir is highly heterogeneous, and it is extremely difficult to find favorable development areas. Through years of exploration, a method for optimizing favorable development areas with hills and beaches controlling the presence or absence and karst controlling the quality has been established. Although the gas wells deployed in the favorable development areas selected by this method can basically achieve high production, more than 30% of the gas wells are difficult to achieve high and stable production. Therefore, the production effect is not very ideal, which will affect the overall development effect of the gas reservoir.

[0003] The invention patent with publication number CN113513311A and publication date October 19, 2021 discloses "a method and device for dividing the internal structure of a carbonate strike-slip fault and broken zone". Its specific technical solution is as follows: the method and device for dividing the internal structure of a carbonate strike-slip fault and broken zone provided by the present invention relate to the technical field of oil and gas reservoir development. The division method includes obtaining the characteristics of a carbonate strike-slip fault and broken zone; the characteristics include cracks, holes and caves; and the carbonate strike-slip fault and broken zone is divided into a first type, a second type and a third type according to the characteristics. The method and device for dividing the internal structure of a carbonate strike-slip fault and broken zone provided by the present invention can be used to guide the design of drilling trajectories and the adjustment and optimization during the drilling process by dividing the carbonate strike-slip fault and broken zone into a first type, a second type and a third type, while optimizing the drilling fluid, realizing early prediction of complex working conditions, and ensuring well control safety.

[0004] Although the above-mentioned prior art mentions the concept of strike-slip faults and divides strike-slip fault fracture zones into three types, this technology is mainly used to identify strike-slip fault zones, classify faults, and guide the implementation of well location targets, but does not clearly guide the selection of favorable development areas. Summary of the invention

[0005] In order to solve the problems and shortcomings existing in the above-mentioned prior art, the present invention proposes a method and device for optimizing favorable areas for karst gas reservoir development based on strike-slip faults. The gas wells deployed by this method can not only achieve high production, but also achieve stable production of the gas wells, which can effectively improve the overall development effect of the gas reservoir.

[0006] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows:

[0007] A method for selecting favorable areas for karst gas reservoir development based on strike-slip faults, comprising:

[0008] According to the fault development direction and geometric position between faults in the gas reservoir block, the fault-controlled karst area is divided into different fault-controlled areas;

[0009] According to the divided fault-controlled areas and the direction of karst water flow, the fault-controlled areas are divided into different fault-controlled karst reservoir development pattern areas on the plane;

[0010] The stable production capacity of gas wells in the fault-controlled karst reservoir development pattern area is evaluated, and the favorable area for gas reservoir development is finally determined.

[0011] Preferably, the fault-controlled karst area is divided into different fault-controlled areas according to the fault development direction and the geometric position between the faults in the gas reservoir block, including:

[0012] Based on seismic, well logging and core data, the karst paleo-geomorphology of the gas reservoir is obtained by using the impression method or residual thickness method;

[0013] According to the karst development period and the formation period and development characteristics of the faults, the first-level or second-level large faults formed before the karst period were selected, and the karst paleo-geomorphology and faults were superimposed using geological image and text processing software;

[0014] Determine the main direction of karst water flow based on the distribution characteristics of karst paleo-geomorphology;

[0015] According to the fault development direction and geometric position between faults in the gas reservoir block, the block is divided into different fault-controlled areas.

[0016] Preferably, the fault-controlled karst reservoir development pattern area includes three types in total, among which:

[0017] In the first type of area, algal mounds are developed and located in the residual mounds or slope break zones of ancient landforms. The direction of karst water flow is parallel to the direction of fault development. The areas on both sides of the fault are fault-controlled parallel areas.

[0018] Category II areas are areas where algal mounds are developed and located in paleo-geomorphological residual mounds or slope break zones, where the karst water flow direction intersects with the direction of fault development, and the water flow does not pass through the faults;

[0019] In the third type of area, algal hills are developed and located in ancient landform residual hills or slope break zones. The direction of karst water flow intersects with the direction of fault development, and the water flows through the fault area.

[0020] Preferably, the evaluation of the stable production capacity of gas wells in the fault-controlled karst reservoir development pattern area and the final determination of favorable areas for gas reservoir development include:

[0021] The four indices of open flow rate of gas wells in the fault-controlled karst reservoir development pattern area, gas production per unit pressure drop of gas wells, dynamic reserves of single gas wells and reservoir physical property parameters interpreted by well testing were calculated respectively. Based on the existing understanding of geological characteristics such as sedimentary facies, structure, lithology and karst landform, an evaluation chart for the stable production capacity of gas wells in different fault-controlled karst reservoir development pattern areas was established in combination with the calculation results, and finally the favorable areas for gas reservoir development were determined.

[0022] Preferably, the open flow rate of the gas well is calculated as follows:

[0023] Using the binomial productivity equation established by the productivity test of a few gas wells in the entire gas reservoir development area, according to the laminar coefficient and turbulent coefficient of the binomial productivity equation, the α coefficient of the gas well is obtained by the following calculation expression:

[0024]

[0025] Among them, q' AOF Indicates the open-flow rate of gas wells in the gas reservoir development area where production capacity testing has been carried out, in units of 10 4 m 3 / d; A is the laminar coefficient, dimensionless; B is the turbulent coefficient, dimensionless;

[0026] According to the α coefficient and the productivity coefficient KH of the gas well, a relationship curve is drawn, and the relationship between the α coefficient and the productivity coefficient KH value is obtained by regression.

[0027] α=0.0821ln(KH)-0.1 Formula (2);

[0028] Among them, K is the effective permeability of the formation, obtained from well logging interpretation, in mD; H is the effective thickness of the formation, obtained from well logging interpretation, in m;

[0029] Substituting formula (2) into the "one-point method" production capacity prediction calculation expression, the following modified "one-point method" gas well production capacity prediction calculation expression is obtained. For gas wells in the gas reservoir development area that have not been tested for production capacity, the open flow rate is calculated according to the following calculation expression:

[0030]

[0031] Among them, P R is the formation pressure, in MPa; P wf is the bottom hole flow pressure, in MPa; q g is the gas well test production, unit is 10 4 m 3 / d.

[0032] Preferably, the method for calculating the gas production per unit pressure drop of the gas well is as follows:

[0033] When the gas well reaches quasi-steady-state production and the production is basically stable, the gas reservoir pressure drop funnel is a set of parallel curves. The formation pressure drop value Δp of the gas well from time t1 to time t2 is obtained by the following calculation expression:

[0034]

[0035] Wherein, Δp is the drop in formation pressure from production at time t1 to time t2, in MPa; p e1 is the gas reservoir boundary pressure at time t1, in MPa; p e2 is the gas reservoir boundary pressure at time t2, in MPa; p wf1 is the bottom flow pressure of the gas well at time t1, in MPa; p wf2 is the bottom flow pressure of the gas well at time t2, in MPa; p t1 is the wellhead oil pressure at time t1, in MPa; p t2 is the wellhead oil pressure at time t2, in MPa, Δp tubing1 is the wellbore loss pressure at time t1, in MPa; Δp tubing2 is the wellhead oil pressure at time t2, in MPa;

[0036] During the stable production of a gas well, the wellbore pressure loss at different time points is basically the same, Δp tubing1 ≈Δp tubing2 , so formula (4) can be simplified to

[0037]

[0038] The gas production per unit pressure drop from production at time t1 to time t2 can be obtained by the following calculation expression

[0039]

[0040] Among them, J g is the gas production per unit pressure drop; q gi is the daily gas production of the i-th day when the gas well is in stable production.

[0041] Preferably, the calculation method of the single gas well dynamic reserves is as follows:

[0042] When the gas well enters the boundary control flow, the single well Blasingame curve is established using the production data and fitted with the theoretical characteristic curve. Any fitting point is selected and the actual fitting point (t ca ,q / Δp p ) M And the corresponding theoretical fitting point (t caDd ,q Dd ) M, calculate the dynamic reserves of the gas well according to the following calculation expression

[0043]

[0044] Where G represents the geological reserves of natural gas, in units of 10 8 m 3 ; C t Indicates the total compression coefficient of the formation, in MPa -1 ;t ca It represents the pseudo-time of material balance of gas well, in d; t caDd represents the dimensionless material balance pseudo-time of the Blasingame gas well, dimensionless; q represents the daily gas production of the gas well, unit is m 3 / d;Δp p represents the normalized pseudo-pressure difference, in MPa; q Dd It represents the dimensionless production of Blasingame gas well, dimensionless; S w It indicates the water saturation of gas reservoir, in %.

[0045] Preferably, the calculation method of the reservoir physical property parameters interpreted by the well test is as follows:

[0046] Based on the bottom hole pressure and production data of the gas well tested on site, the reservoir physical property parameters of the gas well are calculated using Pansystem or Saphir well test interpretation software.

[0047] Preferably, based on the existing understanding of the characteristics of sedimentary facies, structure, lithology, and karst landform, a gas well stable production capacity evaluation chart for different fault-controlled karst reservoir development patterns is established in combination with calculation results, and finally the favorable area for gas reservoir development is determined, which means that according to the established gas well stable production capacity evaluation chart, the area with better results of four indicator parameters of gas well stable production capacity is selected as the favorable area for gas reservoir development.

[0048] A device for selecting favorable areas for karst gas reservoir development based on strike-slip faults, comprising:

[0049] The fault-controlled karst area division module is used to divide the fault-controlled karst area into different fault-controlled areas according to the fault development direction and the geometric position between the faults in the gas reservoir block;

[0050] The fault control area division module is used to divide the fault control area into different fault-controlled karst reservoir development pattern areas on the plane according to the divided fault control area and the karst water flow direction;

[0051] The evaluation module is used to evaluate the stable production capacity of gas wells in the fault-controlled karst reservoir development pattern area and ultimately determine the favorable area for gas reservoir development.

[0052] A computer device comprises a memory, a processor and a computer program stored in the memory and executable in the processor. When the processor executes the computer program, the above-mentioned method for selecting favorable areas for karst gas reservoir development based on strike-slip faults is implemented.

[0053] A computer-readable storage medium stores a computer program, which, when executed in a computer processor, implements the above-mentioned method for selecting favorable areas for karst gas reservoir development based on strike-slip faults.

[0054] Beneficial effects of the present invention:

[0055] The traditional method of selecting favorable development areas based on the presence or absence of hills and beaches and the quality of karsts is that the gas wells deployed in the selected favorable development areas can basically achieve high production, but more than 30% of the gas wells are difficult to achieve high and stable production, and the production effect is poor, which affects the overall development effect of the gas reservoir. The previous method mainly sought high production in the test of gas wells, while this method, based on the strike-slip fault, comprehensively evaluates the sedimentation, karst and stable production capacity of gas wells, and forms a new method for selecting favorable areas. Practice has proved that the gas wells deployed by this method not only have high production in the test, but also can achieve high and stable production of gas wells, which can effectively improve the overall development effect of the gas reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The foregoing and following detailed description of the present invention will become more apparent when read in conjunction with the following drawings, in which:

[0057] Figure 1 is a flow chart of the method of the present invention;

[0058] Figure 2 It is a structural diagram of the device of the present invention;

[0059] Figure 3 It is a schematic diagram of the superposition of karst and fault landforms of the present invention;

[0060] Figure 4 It is the relationship curve diagram of the α coefficient and the capacity coefficient KH of the present invention;

[0061] Figure 5 It is a schematic diagram of pressure distribution when the gas well of the present invention enters a quasi-steady-state flow;

[0062] Figure 6 The gas well production performance curve of the present invention;

[0063] Figure 7 This is a gas well stable production capacity chart of the present invention;

[0064] Figure 8 This is the well location deployment diagram of Example 2 of the present invention. DETAILED DESCRIPTION

[0065] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions for achieving the purpose of the present invention will be further described below through several specific embodiments. It should be noted that the technical solutions claimed for protection in the present invention include but are not limited to the following embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work shall fall within the scope of protection of the present invention.

[0066] Karst oil and gas reservoirs are also called karst oil and gas reservoirs. They are oil and gas reservoirs that gather in the traps formed by the carbonate rock strata covered by impermeable rock layers in ancient karst (caves, holes, crystal caves, etc.). Karst oil and gas reservoirs belong to stratigraphic denudation oil and gas reservoirs, which are often closely related to ancient weathering surfaces, ancient buried hills, and ancient landform protrusions. Karst oil and gas reservoirs often form huge reserves, high pressure, and high yield oil and gas reservoirs when the oil source is abundant.

[0067] Karst gas reservoirs have great development potential, but 80% of the natural gas reserves in gas reservoirs are stored in ultra-low-porosity reservoirs with a porosity of less than 5%. In addition, affected by various factors such as sedimentation and karstification, the reservoirs are highly heterogeneous, and it is extremely difficult to find favorable development areas. Through years of exploration, a method for optimizing favorable development areas has been established, where the presence of hills and beaches and the quality of karst are controlled. Although the gas wells deployed in the favorable development areas selected by this method can basically achieve high production, more than 30% of the gas wells are difficult to achieve high and stable production. Therefore, the production effect is not very ideal, which will affect the overall development effect of the gas reservoir.

[0068] Based on this, this embodiment provides a method for optimizing favorable areas for karst gas reservoir development based on strike-slip faults. On the basis of strike-slip faults, this method comprehensively evaluates sedimentation, karstity and gas well stable production capacity to form a new method for optimizing favorable areas. Practice has proved that the gas wells deployed by this method not only test high production, but also achieve high and stable production of the gas wells, which can effectively improve the overall development effect of the gas reservoir.

[0069] In order to facilitate the understanding of this embodiment, firstly, a method for selecting favorable areas for karst gas reservoir development based on strike-slip faults disclosed in an embodiment of the present invention is introduced in detail.

[0070] First, the professional terms involved in the embodiments of the present invention are explained:

[0071] Fault-controlled karst: Fault-controlled karst refers to dissolution and expansion with the fault fracture zone as the core.

[0072] Bottom hole flow pressure: Bottom hole flow pressure is the abbreviation of bottom hole flow pressure, which is the bottom hole pressure during oil and gas well production. It indicates the remaining pressure after oil and gas flow from the formation to the bottom of the well. For a self-flowing well, it is also the starting pressure for oil and gas to flow from the bottom of the well to the ground.

[0073] Production capacity coefficient: The product KH of the effective permeability K of the formation and the effective thickness H of the formation is called the production capacity coefficient, which is a parameter that indicates the production capacity of oil and gas wells.

[0074] The embodiment of the present invention discloses a method for selecting favorable areas for karst gas reservoir development based on strike-slip faults. Figure 1 , the method specifically comprises the following steps:

[0075] Step S101: Divide the fault-controlled karst area into different fault-controlled areas.

[0076] First, based on seismic, well logging, core and other data, the karst paleo-geomorphology of the gas reservoir is obtained by using the impression method or residual thickness method, and the karst development period and fault formation period and development characteristics are clarified, and the first-level or second-level large faults formed before the karst period are selected;

[0077] Then, the karst paleo-geomorphology and faults are superimposed by geological image processing software (such as Shiwen, GeoMap, etc.) (refer to the attached manual). Figure 3 ), according to the distribution characteristics of karst landforms and the natural law of water flowing from high to low, the main direction of karst water flow is determined. Figure 3 The middle karst paleo-geomorphology is characterized by being high in the east and low in the west, so the direction of karst water flow is from east to west;

[0078] Finally, different fault control areas are divided according to the fault development direction and the geometric position between faults in the block (such as Figure 3 in the partitions).

[0079] In this embodiment, it should be noted that the use of the impression method or the residual thickness method to obtain the karst paleo-geomorphology of the gas reservoir is a conventional means known to those skilled in the art, and is not an invention of the present invention.

[0080] In this embodiment, it should also be noted that the superposition of the karst paleo-landform and the fault is a superposition on a two-dimensional plane.

[0081] Step S102: According to the divided fault-controlled areas and in combination with the direction of karst water flow, the fault-controlled areas are divided into different fault-controlled karst reservoir development pattern areas on the plane.

[0082] According to the fault-controlled areas divided in the previous article, the karstification caused by karst water flow, combined with the direction of karst water flow, the fault-controlled areas are divided into three types of fault-controlled karst reservoir development pattern areas on the superimposed two-dimensional plane map, including type I area, type II area and type III area, among which:

[0083] Type I area: Algal mounds are developed and located in ancient landform residual hills or slope break zones. The direction of karst water flow is parallel to the direction of fault development. The areas on both sides of the fault are fault-controlled parallel areas (i.e. Figure 3 Zone I in the

[0084] Category II: Algal mounds are developed and located in ancient landform residual hills or slope break zones. The direction of karst water flow intersects with the development direction of the fault, and the water flow does not pass through the fault area ( Figure 3 Zones III and IV in the

[0085] Category III: Algal mounds are developed and located in ancient landform residual mounds or slope break zones. The direction of karst water flow intersects with the development direction of the fault. The water flows through the fault area ( Figure 3 II and V in the .

[0086] Step S103: Evaluate the stable production capacity of gas wells in the fault-controlled karst reservoir development pattern area, and finally determine the favorable area for gas reservoir development.

[0087] The four indices of open flow rate of gas wells in the fault-controlled karst reservoir development pattern area, gas production per unit pressure drop of gas wells, dynamic reserves of single gas wells and reservoir physical property parameters interpreted by well testing were calculated respectively. Based on the existing understanding of geological characteristics such as sedimentary facies, structure, lithology and karst landform, an evaluation chart of the stable production capacity of gas wells in different fault-controlled karst reservoir development patterns was established in combination with the calculation results of the four indicator parameters. According to the established evaluation chart, the areas with better results of the four indicator parameters representing the gas well production capacity were selected as the final favorable areas for gas reservoir development.

[0088] In this embodiment, four index parameters characterizing the gas well productivity are the open flow rate of the gas well, the gas production per unit pressure drop of the gas well, the dynamic reserves of the single gas well, and the reservoir physical property parameters interpreted by the well test.

[0089] In this embodiment, the calculation method of the open flow rate of the gas well is as follows:

[0090] For deep and highly heterogeneous karst gas reservoirs, the reservoir heterogeneity is strong and the burial depth is generally deep. The production capacity test is not only time-consuming and costly, but also difficult to carry out on a large scale. It is difficult to directly obtain the stable production capacity of gas wells that have not been tested for interpretation. Therefore, using the binomial production capacity equation established by the few gas wells in the entire gas reservoir development area that have been tested for production capacity, according to the laminar coefficient and turbulent coefficient of the binomial production capacity equation, the α coefficient of the gas well can be obtained through the following calculation expression

[0091]

[0092] Among them, q' AOF Indicates the open-flow rate of gas wells in the gas reservoir development area where production capacity testing has been carried out, in units of 10 4 m 3 / d; A is the laminar coefficient, dimensionless; B is the turbulent coefficient, dimensionless; α is the dimensionless coefficient;

[0093] According to the α coefficient and productivity coefficient KH of the gas well, draw a relationship curve (refer to the attached Figure 4 ), the relationship between the α coefficient and the capacity coefficient KH value is obtained by semi-logarithmic regression

[0094] α=0.0821ln(KH)-0.1 Formula (2);

[0095] Among them, K is the effective permeability of the formation, obtained from well logging interpretation, in mD; H is the effective thickness of the formation, obtained from well logging interpretation, in m;

[0096] Substitute equation (2) into the following "one-point method" capacity prediction calculation expression:

[0097]

[0098] The following modified “one-point method” gas well productivity prediction calculation expression can be obtained. For gas wells in the gas reservoir development area that have not been tested for productivity, their open-flow rate is calculated according to the following calculation expression:

[0099]

[0100] Among them, P R is the formation pressure, in MPa; P wf is the bottom hole flow pressure, in MPa; q g is the gas well test production, unit is 10 4 m 3 / d.

[0101] In this embodiment, it should be noted that the gas well binomial productivity calculation expression is a productivity equation group known to those skilled in the art.

[0102] In this embodiment, it should also be noted that the open flow rate is a parameter and index used to evaluate the gas production capacity of a gas well.

[0103] In this embodiment, it is necessary to further explain that the relationship between the α coefficient and the capacity coefficient KH value obtained by regression is obtained by semi-logarithmic regression, and the specific calculation method is a conventional means known to technicians in the field.

[0104] In this embodiment, the calculation method of the gas production per unit pressure drop of the gas well is as follows:

[0105] The traditional method of calculating the gas production per unit pressure drop requires multiple well tests or long-term well shut-in point pressure measurement, which is not only costly, but also affects the normal production of the gas well. The data error is greatly affected by the operation, and it is difficult to implement on a large scale during the development of gas reservoirs. Therefore, this embodiment can calculate the gas production per unit pressure drop of the gas well by selecting the ecological dynamic data during the quasi-steady-state production of the gas well.

[0106] Refer to the instruction manual Figure 5 and Figure 6 When the gas well reaches quasi-steady-state production and the production is basically stable, the gas reservoir pressure drop funnel is a set of parallel curves. The formation pressure drop value Δp of the gas well from time t1 to time t2 is obtained by the following calculation expression:

[0107]

[0108] Wherein, Δp is the drop in formation pressure from production at time t1 to time t2, in MPa; p e1 is the gas reservoir boundary pressure at time t1, in MPa; p e2 is the gas reservoir boundary pressure at time t2, in MPa; p wf1 is the bottom flow pressure of the gas well at time t1, in MPa; p wf2 is the bottom flow pressure of the gas well at time t2, in MPa; p t1 is the wellhead oil pressure at time t1, in MPa; p t2 is the wellhead oil pressure at time t2, in MPa; Δp tubing1 is the wellbore loss pressure at time t1, in MPa; Δp tubing2 is the wellhead oil pressure at time t2, in MPa;

[0109] During the stable production of a gas well, the wellbore pressure loss at different time points is basically the same, so Δp tubing1 ≈Δp tubing2 , so formula (4) can be simplified to

[0110]

[0111] Therefore, the gas production per unit pressure drop from time t1 to time t2 can be calculated by the following expression:

[0112]

[0113] Among them, J g is the gas production per unit pressure drop; q gi is the daily gas production of the i-th day when the gas well is in stable production.

[0114] In this embodiment, it should be noted that the daily gas production data of the i-th day when the gas well is in stable production can be obtained through the on-site flow meter.

[0115] In this embodiment, the calculation method of the single well dynamic reserves of the gas well is as follows:

[0116] When the gas well enters the boundary control flow, the single well Blasingame curve is established using the production data and fitted with the theoretical characteristic curve. Any fitting point is selected and the actual fitting point (t ca ,q / Δp p ) M And the corresponding theoretical fitting point (t caDd ,q Dd ) M , calculate the dynamic reserves of the gas well according to the following calculation expression

[0117]

[0118] Where G represents the geological reserves of natural gas, in units of 10 8 m 3 ; C t Indicates the total compression coefficient of the formation, in MPa -1 ;t ca It represents the pseudo-time of material balance of gas well, in d; t caDd represents the dimensionless material balance pseudo-time of the Blasingame gas well, dimensionless; q represents the daily gas production of the gas well, unit is m 3 / d;Δp p represents the normalized pseudo-pressure difference, in MPa; q Dd It represents the dimensionless production of Blasingame gas well, dimensionless; S w It indicates the water saturation of gas reservoir, in %.

[0119] In this embodiment, it should be noted that the daily gas production data of the gas well can be obtained through a flow meter on site. In the calculation of this embodiment, several fitting points can be obtained.

[0120] In this embodiment, the calculation method of the reservoir physical property parameters interpreted by the well test is specifically as follows:

[0121] By using the bottom hole pressure and production data of gas wells tested on site and using well test interpretation software such as Pansystem and Saphir, the reservoir physical property parameters of the gas well can be calculated.

[0122] In this embodiment, it should be noted that the reservoir physical property parameter refers to the average permeability of the reservoir.

[0123] Refer to the instruction manual Figure 7 There are obvious differences in the stable production capacity of gas wells in the fault-controlled karst zone, including:

[0124] Category I area: mainly developed fracture-cavity reservoirs, with an average open-flow rate of 151.18×10 4 m 3 / d, average gas production per unit pressure drop 1991.41×10 4 m 3 / MPa, dynamic reserve 15.87×10 8 m 3 , the well test interpretation shows that the average reservoir permeability is 0.4mD, mainly in Zone I;

[0125] Category II area: mainly developed porous reservoirs, with an average open flow rate of 125.81×10 4 m 3 / d, average gas production per unit pressure drop, average dynamic reserves 12.70×10 8 m 3 , the well test interpretation shows that the average reservoir permeability is 0.15mD, mainly in Zone III and Zone IV;

[0126] Category III area: mainly porous reservoirs, with an average open flow rate of 76.76×10 4 m 3 / d, the average gas production per unit pressure drop is 151.37×10 4 m 3 / MPa, average dynamic reserve 3.3×10 8 m 3 The well test interpretation shows that the average reservoir permeability is 0.05mD, mainly in Zone II and Zone V.

[0127] Based on the fault-controlled karst zoning formed by the above-mentioned fault-controlled karst mode, the stable production capacity of gas wells was evaluated. The hydrodynamic conditions in Class I and Class II areas are relatively strong, the gas wells have high open flow, large gas production per unit pressure drop, large dynamic reserves, and good stable production capacity. The hydrodynamic conditions in Class III areas are relatively weak, and the gas well tests can obtain high production, but the reservoir properties in the far well area are poor, the fluid replenishment energy to the near well area is weak, the gas production per unit pressure drop and dynamic reserves are small, and the stable production capacity of gas wells is poor. Therefore, Class I and Class II areas are favorable development areas.

[0128] In this embodiment, by comparing four index parameters of the gas well, namely, the open flow rate of the gas well, the gas production per unit pressure drop of the gas well, the dynamic reserves of the single gas well, and the reservoir physical property parameters interpreted by the well test, the favorable area for gas reservoir development can be basically determined; further, based on the obtained favorable area for gas reservoir development, the established gas well stable production capacity evaluation chart can be used to reversely infer what the geological characteristics of the favorable area for gas reservoir development are.

[0129] The core of this technology is to form a new method for selecting favorable areas based on the distribution characteristics of strike-slip faults, comprehensive evaluation of sedimentation, karst and gas well stable production capacity, and its core is to guide the selection of favorable areas for development, thereby improving the overall development level of gas reservoirs.

[0130] Further, based on the same inventive concept, an embodiment of the present invention also provides a device for optimizing favorable areas for karst gas reservoir development based on strike-slip faults, as described in the following embodiments. As used below, the term "unit" or "module" can be a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable. For details, refer to the attached manual. Figure 2 The device may include: a fault-controlled karst area division module 201, a fault-controlled area division module 202 and an evaluation module 203.

[0131] The structure is described in detail below.

[0132] The fault-controlled karst area division module 201 is used to divide the fault-controlled karst area into different fault-controlled areas according to the fault development direction and the geometric position between the faults in the gas reservoir block;

[0133] The fault control area division module 202 is used to divide the fault control area into different fault-controlled karst reservoir development mode areas on the plane according to the divided fault control area and the direction of karst water flow;

[0134] The evaluation module 203 is used to evaluate the stable production capacity of gas wells in the fault-controlled karst reservoir development pattern area and ultimately determine the favorable area for gas reservoir development.

[0135] It should be noted that the systems, devices, models or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. For the convenience of description, in this specification, the above devices are described in various units according to their functions. Of course, when implementing the present invention, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0136] Furthermore, in the present specification, adjectives such as first and second may be used merely to distinguish one element or action from another, without necessarily or implying any actual such relationship or order.

[0137] From the above description, it can be seen that the embodiment of the present invention provides a method for optimizing favorable areas for karst gas reservoir development based on strike-slip faults. Based on strike-slip faults, a new method for optimizing favorable areas is formed by comprehensively evaluating the sedimentation, karstity and stable production capacity of gas wells. Practice has proved that the gas wells deployed by this method not only test high production, but also achieve high and stable production of gas wells, which can effectively improve the overall development effect of the gas reservoir.

[0138] Furthermore, an embodiment of the present invention also provides a computer device, which includes a memory, a processor, and a computer program stored in the memory and executable in the processor, and when the processor executes the computer program, the steps of any of the above methods are implemented.

[0139] Furthermore, an embodiment of the present invention also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed in a computer processor, the steps of any of the above methods are implemented.

[0140] The computer device may be a computing device such as a desktop computer, a notebook, a PDA, a cloud server, etc. The computer device may include, but is not limited to, a processor and a memory. For example, the computer device may also include an input and output device, a network access device, a bus, etc.

[0141] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc. The memory may be an internal storage unit of the electronic device, such as a hard disk or memory of a terminal device. The memory may also be an external storage device of the electronic device, such as a plug-in hard disk, a smart memory card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the electronic device. Further, the memory may include both an internal storage unit and an external storage device of the electronic device. The memory is used to store the computer program and other programs and data required by the electronic device. The memory may also be used to temporarily store data that has been output or is to be output.

[0142] The devices or modules described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. For the convenience of description, the above devices are described separately by dividing them into various modules according to their functions. Of course, when implementing the present invention, the functions of each module can be implemented in the same or more software and / or hardware, or the modules that implement the same function can be implemented by a combination of multiple sub-modules. The device embodiments described above are only schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0143] Those skilled in the art also know that, in addition to implementing the controller in a purely computer-readable program code, the controller can be made to implement the same function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, such a controller can be considered as a hardware component, and the devices for implementing various functions included therein can also be considered as structures within the hardware component. Or even, the devices for implementing various functions can be considered as both software modules for implementing the method and structures within the hardware component.

[0144] Example 2

[0145] This embodiment takes the well location deployment of a certain project as an example to further illustrate the solution of the present invention.

[0146] Under the condition that reservoir sedimentary properties, karst landforms and other conditions are basically similar, two development wells are deployed on both sides of the fault. Well W1 deployed in the second-class area is located in the area where water flow does not pass through the fault, with a good degree of karstity and an open-flow rate of 106.24×10 4 m3 / d, daily gas production is 24×10 4 m 3 、Gas production per unit pressure drop reaches 2200×10 4 m 3 / MPa, dynamic reserves are 17.18×10 8 m 3 The permeability is 0.172mD and the drilling thickness is 180m. The W2 well deployed in the third category area is a water flow through the fracture area, the karst degree is poor, and the open flow rate of the gas well is 96.24×10 4 m 3 / d, daily gas production is 11.45×10 4 m 3 , gas production per unit pressure drop reaches 520×10 4 m 3 / MPa, dynamic reserves are 5.02×108 m 3 The permeability is 0.032mD and the drilled thickness is 147.20m.

[0147] By comparing the two wells, we can see that the gas wells deployed in the two areas have relatively favorable sedimentary environments and paleo-geomorphological locations, and the gas well test production is comparable. However, due to the influence of faults, the production effect of Well W1 is significantly better than that of Well W2. Therefore, the Class II area is a favorable development area.

[0148] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for selecting favorable areas for karst gas reservoir development based on strike-slip faults, characterized in that: include: According to the fault development direction and geometric position between faults in the gas reservoir block, the fault-controlled karst area is divided into different fault-controlled areas; According to the divided fault-controlled areas and the direction of karst water flow, the fault-controlled areas are divided into different fault-controlled karst reservoir development pattern areas on the plane; The stable production capacity of gas wells in the fault-controlled karst reservoir development pattern area is evaluated, and the favorable area for gas reservoir development is finally determined.

2. The method for selecting favorable areas for karst gas reservoir development based on strike-slip faults according to claim 1, characterized in that: According to the fault development direction and the geometric position between the faults in the gas reservoir block, the fault-controlled karst area is divided into different fault-controlled areas, including: Based on seismic, well logging and core data, the karst paleo-geomorphology of the gas reservoir is obtained by using the impression method or residual thickness method; According to the karst development period and the formation period and development characteristics of the faults, the first-level or second-level large faults formed before the karst period were selected, and the karst paleo-geomorphology and faults were superimposed using geological image and text processing software; Determine the main direction of karst water flow based on the distribution characteristics of karst paleo-geomorphology; According to the fault development direction and geometric position between faults in the gas reservoir block, the block is divided into different fault-controlled areas.

3. The method for selecting favorable areas for karst gas reservoir development based on strike-slip faults according to claim 1, characterized in that: The fault-controlled karst reservoir development pattern area includes three types in total, among which: In the first type of area, algal mounds are developed and located in the residual mounds or slope break zones of ancient landforms. The direction of karst water flow is parallel to the direction of fault development. The areas on both sides of the fault are fault-controlled parallel areas. Category II areas are areas where algal mounds are developed and located in paleo-geomorphological residual mounds or slope break zones, where the karst water flow direction intersects with the direction of fault development, and the water flow does not pass through the faults; In the third type of area, algal hills are developed and located in ancient landform residual hills or slope break zones. The direction of karst water flow intersects with the direction of fault development, and the water flows through the fault area.

4. The method for selecting favorable areas for karst gas reservoir development based on strike-slip faults according to claim 1, characterized in that: The stable production capacity of gas wells in the fault-controlled karst reservoir development pattern area is evaluated, and favorable areas for gas reservoir development are finally determined, including: The four index parameters of the open flow rate of gas wells in the fault-controlled karst reservoir development pattern area, the gas production per unit pressure drop of gas wells, the dynamic reserves of single gas wells and the reservoir physical property parameters interpreted by well testing were calculated respectively. Based on the existing understanding of the geological characteristics of sedimentary facies, structure, lithology and karst landform, an evaluation chart of the stable production capacity of gas wells in different fault-controlled karst reservoir development patterns was established in combination with the calculation results of the four index parameters, and finally the favorable areas for gas reservoir development were determined.

5. The method for selecting favorable areas for karst gas reservoir development based on strike-slip faults according to claim 4, characterized in that: The open flow rate calculation method of the gas well is as follows: Using the binomial productivity equation established by the productivity test of a few gas wells in the entire gas reservoir development area, according to the laminar coefficient and turbulent coefficient of the binomial productivity equation, the α coefficient of the gas well is obtained by the following calculation expression: Among them, q' AOF It represents the open-flow rate of gas wells in the gas reservoir development area where production capacity testing has been carried out; A is the laminar coefficient, dimensionless; B is the turbulent coefficient, dimensionless; According to the α coefficient and the productivity coefficient KH of the gas well, a relationship curve is drawn, and the relationship between the α coefficient and the productivity coefficient KH value is obtained by regression. α=0.0821ln(KH)-0.1 Formula (2); Among them, K is the effective permeability of the formation, which is obtained from well logging interpretation; H is the effective thickness of the formation, which is obtained from well logging interpretation; Substituting formula (2) into the "one-point method" production capacity prediction calculation expression, the following modified "one-point method" gas well production capacity prediction calculation expression is obtained. For gas wells in the gas reservoir development area that have not been tested for production capacity, their open flow rate is calculated according to the following calculation expression: Among them, P R is the formation pressure; P wf is the bottom hole flowing pressure; q g Testing production of gas wells.

6. The method for selecting favorable areas for karst gas reservoir development based on strike-slip faults according to claim 4, characterized in that: The specific method for calculating the gas production per unit pressure drop of the gas well is as follows: When the gas well reaches quasi-steady-state production and the production is basically stable, the gas reservoir pressure drop funnel is a set of parallel curves. The formation pressure drop value Δp of the gas well from time t1 to time t2 is obtained by the following calculation expression: Wherein, Δp is the drop in formation pressure from production at time t1 to time t2; p e1 is the gas reservoir boundary pressure at time t1; p e2 is the gas reservoir boundary pressure at time t2; p wf1 is the bottom hole flowing pressure of the gas well at time t1; p wf2 is the bottom hole flow pressure of the gas well at time t2; p t1 is the wellhead oil pressure at time t1; p t2 is the wellhead oil pressure at time t2; Δp tubing1 is the wellbore loss pressure at time t1; Δp tubing2 is the wellhead oil pressure at time t2; During the stable production of a gas well, the wellbore pressure loss at different time points is basically the same, Δp tubing1 ≈Δp tubing2 , so formula (4) can be simplified to The gas production per unit pressure drop from production at time t1 to time t2 can be obtained by the following calculation expression Among them, J g is the gas production per unit pressure drop; q gi is the daily gas production of the i-th day when the gas well is in stable production.

7. The method for selecting favorable areas for karst gas reservoir development based on strike-slip faults according to claim 4, characterized in that: The specific calculation method of the single gas well dynamic reserves is as follows: When the gas well enters the boundary control flow, the single well Blasingame curve is established using the production data and fitted with the theoretical characteristic curve. Any fitting point is selected and the actual fitting point (t ca ,q / Δp p ) M And the corresponding theoretical fitting point (t caDd ,q Dd ) M , calculate the dynamic reserves of the gas well according to the following calculation expression Where G represents the geological reserves of natural gas; C t Indicates the total compression coefficient of the formation; t ca represents the pseudo-time of material balance of gas well; t caDd represents the dimensionless material balance pseudo-time of the Blasingame gas well; q represents the daily gas production of the gas well; Δp p represents the normalized pseudo-pressure difference; q Dd represents the dimensionless production of Blasingame gas well; S w Indicates the water saturation of the gas reservoir.

8. The method for selecting favorable areas for karst gas reservoir development based on strike-slip faults according to claim 4, characterized in that: The calculation method of the reservoir physical property parameters interpreted by the well test is as follows: Based on the bottom hole pressure and production data of the gas well tested on site, the reservoir physical property parameters of the gas well are calculated using Pansystem or Saphir well test interpretation software.

9. The device for selecting favorable areas for karst gas reservoir development based on strike-slip faults according to claim 4, characterized in that: The method of establishing a gas well stable production capacity evaluation chart for different fault-controlled karst reservoir development pattern areas based on the existing understanding of the characteristics of sedimentary facies, structure, lithology, and karst landform and combining the calculation results of four index parameters to finally determine the favorable area for gas reservoir development means selecting areas with better results of the four index parameters of gas well stable production capacity as favorable areas for gas reservoir development based on the established gas well stable production capacity evaluation chart.

10. A device for selecting favorable areas for karst gas reservoir development based on strike-slip faults, characterized in that: include: The fault-controlled karst area division module is used to divide the fault-controlled karst area into different fault-controlled areas according to the fault development direction and the geometric position between the faults in the gas reservoir block; The fault control area division module is used to divide the fault control area into different fault-controlled karst reservoir development pattern areas on the plane according to the divided fault control area and the karst water flow direction; The evaluation module is used to evaluate the stable production capacity of gas wells in the fault-controlled karst reservoir development pattern area and ultimately determine the favorable area for gas reservoir development.

11. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable in the processor, characterized in that: When the processor executes the computer program, the method described in any one of claims 1 to 9 is implemented.

12. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed in a computer processor, the method according to any one of claims 1 to 9 is implemented.

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