Unconventional natural gas reservoir fracturing development dessert area screening method and related device

Abstract

The invention discloses an unconventional natural gas reservoir fracturing development dessert area screening method and a related device, and the method comprises the steps: obtaining rock mechanical parameters, ground stress parameters and rock strength characteristic parameters of a development well through logging data; establishing three-dimensional geomechanical models of different main control parameters by utilizing a three-dimensional geologic model of the target reservoir and the parameters; according to the reserves of the three-dimensional geologic models of the different layers of the target reservoir and the distribution interval of the main control parameters of the three-dimensional geomechanical model, the distribution frequency is utilized, and the distribution standard of the reserves and the main control parameters is determined at each layer; according to the production data, determining a high-yield well division standard, and according to the high-yield well division standard, screening high-yield wells at different layers in the target block; calculating the distribution probability of the high-yield well on the two-dimensional distribution graph of the reserves and the main control parameters by using a distribution standard; according to the distribution probability, determining a screening criterion of fracturing development dessert areas at different layers of the target block; and determining the site selection of the fracturing development wells at different layers according to the screening criterion.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of petroleum engineering, and particularly relates to a method for screening a sweet spot area of a fractured unconventional natural gas reservoir and a related device. BACKGROUND

[0002] Developing unconventional natural gas reservoirs is of great significance to energy security and natural gas supply and demand balance. Conventional natural gas resources are very limited, while unconventional natural gas resources such as shale gas, coalbed methane and tight sandstone gas are very abundant and have great development potential. Through technological innovation and large-scale development, unconventional natural gas can significantly increase domestic natural gas supply, reduce dependence on foreign countries and enhance energy self-control capability. At the same time, as a clean and low-carbon energy source, increasing production of natural gas helps to optimize the energy structure. Under the current energy situation, accelerating the development of unconventional natural gas is an important strategic measure to ensure energy security and meet the growing demand for natural gas.

[0003] Unconventional natural gas reservoirs have the characteristics of low porosity and low permeability, and can only be economically developed with the help of hydraulic fracturing technology. In order to achieve better fracturing results, the sweet spot area of the reservoir must be evaluated before fracturing, so as to ensure high production after fracturing. Precise positioning of the sweet spot area of the reservoir is not only beneficial to the formation of complex fracture networks by hydraulic fracturing, but also can reduce the cost of reservoir development.

[0004] However, due to the strong heterogeneity of unconventional natural gas reservoirs, there are great differences in geomechanical properties, porosity and permeability properties, and rock mechanical properties between different layers, which brings great challenges to the screening of the sweet spot area of the reservoir for fracturing development. How to accurately locate the position of the sweet spot area for fracturing development of different layers is a major technical bottleneck problem currently faced by the development of unconventional natural gas reservoirs. SUMMARY

[0005] In order to solve the technical bottleneck problem faced by the development of unconventional natural gas reservoirs, the present application proposes a method for screening a sweet spot area of a fractured unconventional natural gas reservoir and a related device, which can accurately locate the position of the sweet spot area for fracturing development of different layers in a block, ensure the effect of subsequent fracturing development, and achieve economic and efficient development of different layers of the target reservoir.

[0006] In order to achieve the above purpose, the technical scheme of the present application is as follows:

[0007] A method for screening a sweet spot area of a fractured unconventional natural gas reservoir, comprising the following steps:

[0008] Using the obtained well logging data of the development wells in the target reservoir block, the rock mechanical parameters, the ground stress parameters and the rock strength characteristic parameters of the development wells are obtained;

[0009] On the basis of the established target reservoir three-dimensional geological model, combined with the rock mechanics parameters, the ground stress parameters, the rock strength characteristic parameters, a three-dimensional geomechanical model of different main control parameters is established;

[0010] According to the distribution interval of the reserves of the three-dimensional geological model of different horizons of the target reservoir and the three-dimensional geomechanical model of the main control parameters, the distribution standard of the reserves and the main control parameters is determined at each horizon based on the distribution frequency;

[0011] According to the obtained production data of the development wells in the target reservoir block, a high-yield well division standard is determined, and high-yield wells of different horizons in the target block are screened according to the high-yield well division standard;

[0012] The distribution probability of the high-yield wells on the two-dimensional distribution graph of the reserves and the main control parameters is calculated by using the distribution standard;

[0013] According to the distribution probability, a screening criterion of the fracturing development sweet spot area of different horizons of the target block is determined;

[0014] The site selection of the fracturing development wells of different horizons is determined according to the screening criterion.

[0015] Preferably, the logging data includes acoustic logging data, gamma logging data and density logging data; the acoustic logging data includes shear wave logging data and longitudinal wave logging data;

[0016] When the acoustic logging data only contains shear wave logging data, the shear wave logging data is inverted from the longitudinal wave logging data according to the following formula according to the reservoir characteristics, and the specific mode is as follows:

[0017] For tight sandstone reservoir: V s = 0.8V P - 1.17

[0018] For coal rock gas reservoir: V s = V P / 2.45

[0019] For shale gas reservoir: V s = V P / 2.15

[0020] Wherein, V s is the shear wave velocity, and V p is the longitudinal wave velocity.

[0021] Preferably, the logging data of the development wells in the target reservoir block is obtained, one-dimensional geomechanical parameter interpretation is carried out, and the rock mechanics parameters, the ground stress parameters and the rock strength characteristic parameters of the development wells are obtained;

[0022] The rock mechanics parameters include Young's modulus and Poisson's ratio.

[0023] The ground stress parameters include maximum horizontal principal stress and minimum horizontal principal stress.

[0024] The rock strength characteristic parameters include rock tensile strength parameter and compressive strength parameter.

[0025] Preferably, on the basis of the target reservoir three-dimensional geological model of the petrel software, the three-dimensional geomechanical model of different main control parameters is established in the Geomechanics module of the petrel software by combining the rock mechanics parameters, the ground stress parameters and the rock strength characteristic parameters.

[0026] The target reservoir three-dimensional geological model must meet the following conditions: having a sedimentary facies model and a structure model, having an attribute model including porosity, permeability and gas saturation, and having a three-dimensional reserve SD distribution model.

[0027] The specific steps of establishing the three-dimensional geomechanical model of different main control parameters in the Geomechanics module of the petrel software are as follows:

[0028] According to the rock mechanics parameters, the ground stress parameters and the rock strength characteristic parameters, the main control parameters of the three-dimensional geomechanical model are calculated, and the main control parameters include brittleness index, two-way stress difference and fracture toughness.

[0029] The main control parameters are imported into the three-dimensional geological model in the Geomechanics module of the petrel software, and attribute filling is used to map the main control parameters to the grid cells.

[0030] The discrete grid data is interpolated into continuous attribute grids by using the Kriging interpolation method, so as to finally establish the three-dimensional geomechanical model of different main control parameters.

[0031] For different types of unconventional natural gas reservoirs, the main control parameter brittleness index BI is calculated by using the normalized weighted average value method.

[0032]

[0033] wherein E BI is the normalized elastic modulus, v BI is the normalized Poisson's ratio; E Max and E Min are the maximum and minimum values of the core Young's modulus within the statistical range of the development well; v Max and v Min are the maximum and minimum values of the core Poisson's ratio within the statistical range of the development well.

[0034] For different types of unconventional natural gas reservoirs, the main control parameter two-way stress difference SE is calculated by using the following formula:

[0035] SE = D max - D min

[0036] For different types of unconventional natural gas reservoirs, the main control parameter is fracture toughness K IC The calculation formula is:

[0037] Tight sandstone reservoir: K IC = 0.005 + 0.125 * σ t - 0.0034 * σ f + 0.015 * E;

[0038] Coal rock gas reservoir: K IC = 0.0045 + 0.13 * σ t - 0.0028 * σ f + 0.013 * E;

[0039] Shale gas reservoir: K IC = 0.0035 + 0.165 * σ t - 0.0018 * σ f + 0.021 * E;

[0040] Where σ t is the tensile strength parameter of the rock, σ f is the compressive strength parameter, and E is the Young's modulus.

[0041] Preferably, according to the reserves of the three-dimensional geological model of different layers of the target reservoir and the distribution interval of the main control parameter of the three-dimensional geomechanical model, the distribution standard of the reserves and the main control parameter is determined at each layer based on the distribution frequency, which specifically includes the following steps:

[0042] The three-dimensional geomechanical model and the three-dimensional reserve SD distribution model of different layers and different main control parameters are converted into two-dimensional distribution graphs;

[0043] The distribution frequency of each main control parameter in the two-dimensional distribution graph is counted;

[0044] According to the distribution frequency of each main control parameter, each main control parameter is divided into low, medium and high intervals, and the range of parameter values in each interval is taken as the distribution standard of the reserves and the main control parameter determined at each layer;

[0045] Wherein, the calculation formula for converting the three-dimensional geomechanical model and the three-dimensional reserve SD distribution model of different main control parameters into two-dimensional distribution graphs is as follows:

[0046]

[0047] Where H iP is the distribution thickness of the parameter value on the three-dimensional model i Z represents the parameter value to be converted, and P represents the distribution value of the parameter value after conversion on the two-dimensional graph.

[0048] Preferably, the distribution probability of the high-yield well on the two-dimensional distribution graph of the reserves and the main control parameter is calculated using the distribution standard, and specifically includes the following steps:

[0049] Mark all high-yield wells on the two-dimensional distribution graph of the reserves and the main control parameter at different horizons;

[0050] According to the distribution standard, the number of times x of the occurrence of the high-yield well in the high-reserve interval, the high-fragility index interval, the low two-way stress difference interval, and the low fracture toughness interval at different horizons is counted. i ;

[0051] According to the number of times of the occurrence of the high-yield well in the high-reserve interval, the high-fragility index interval, the low two-way stress difference interval, and the low fracture toughness interval at different horizons, the distribution probability P of the high-yield well is calculated, P = x / the total number of high-yield wells. i i i

[0052] Preferably, according to the distribution probability, the screening criteria of the fracturing development sweet spot area of different horizons in the target block are determined, and specifically include the following steps:

[0053] According to the distribution probability, the four parameters of reserves, fragility index, two-way stress difference and fracture toughness are sorted from high to low;

[0054] According to the order of the parameters obtained by sorting, the sweet spot area screening criteria of the priority order of the four parameters of the reserves, the fragility index, the two-way stress difference and the fracture toughness of the different horizons in the target block are determined according to the distribution standard; wherein the high-reserve distribution interval is selected as the screening criterion for the reserves parameter, the high-fragility index distribution interval is selected as the screening criterion for the fragility index parameter, the low two-way stress difference interval is selected as the screening criterion for the two-way stress difference parameter, and the low fracture toughness distribution interval is selected as the screening criterion for the fracture toughness parameter.

[0055] The application also provides a system for screening a sweet spot area of a fracturing development of an unconventional natural gas reservoir, which is used to realize the method for screening a sweet spot area of a fracturing development of an unconventional natural gas reservoir.

[0056] The parameter calculation module is used to obtain the rock mechanics parameters, the ground stress parameters and the rock strength characteristic parameters of the development well by using the obtained logging data of the development well in the target reservoir block.

[0057] ​​​The three-dimensional geomechanical model establishment module is used for establishing a three-dimensional geomechanical model of different main control parameters on the basis of the established three-dimensional geologic model of the target reservoir, in combination with the rock mechanics parameters, the ground stress parameters and the rock strength characteristic parameters.

[0058] The distribution standard determination module is used for determining the distribution standard of reserves and main control parameters according to the distribution interval of the reserves of the three-dimensional geologic model and the main control parameters of the three-dimensional geomechanical model of different horizons of the target reservoir, and according to the distribution frequency.

[0059] The high-yield well screening module is used for determining a high-yield well division standard according to the production data of the development wells in the target reservoir block, and screening the high-yield wells of different horizons in the target block according to the high-yield well division standard.

[0060] The distribution probability calculation module is used for calculating the distribution probability of the high-yield wells on the two-dimensional distribution graph of the reserves and the main control parameters by using the distribution standard.

[0061] The screening criterion determination module is used for determining the screening criterion of the fractured development sweet spot area of different horizons of the target block according to the distribution probability.

[0062] The site selection module is used for determining the site selection of the fractured development wells of different horizons according to the screening criterion.

[0063] The application further provides an electronic device, comprising:

[0064] One or more processors;

[0065] A storage device having one or more programs stored thereon;

[0066] When the one or more programs are executed by the one or more processors, the one or more processors implement the unconventional natural gas reservoir fractured development sweet spot area screening method as described above.

[0067] The application further provides a storage medium having a computer program stored thereon, wherein the computer program is executed by a processor to implement the unconventional natural gas reservoir fractured development sweet spot area screening method as described above.

[0068] The application has the following beneficial effects:

[0069] The unconventional natural gas reservoir fractured development sweet spot area screening method can quickly identify the main control factors affecting the fractured development effect of the target reservoir, and promote the priority order of the high-yield fractured wells. In addition, the screening criterion of the fractured development sweet spot area can be customized and accurately designed for different types of unconventional natural gas reservoirs. The sweet spot area screening criterion established by the application can efficiently and quickly select the site of the fractured wells of different horizons. BRIEF DESCRIPTION OF DRAWINGS

[0070] Figure 1 The shear wave slowness inversion result of J129 well in the embodiment of the present application;

[0071] Figure 2 The ground stress interpretation result of J129 well in the embodiment of the present application;

[0072] Figure 3 The three-dimensional geological model of the Upper Paleozoic gas reservoir in a certain gas field in the embodiment of the present application;

[0073] Figure 4 The three-dimensional geomechanical model (brittleness index) of the He8 horizon in the embodiment of the present application;

[0074] Figure 5(a) is a two-dimensional distribution graph of the brittleness index of the He8 horizon in the embodiment of the present application; Figure 5(b) is a brittleness index distribution frequency graph of the He8 horizon in the embodiment of the present application;

[0075] Figure 6 The distribution graph of high-yield wells and low-yield wells of the He8 horizon in the embodiment of the present application (red for high-yield, black for low-yield)

[0076] Figure 7 The distribution of high-yield wells of the Shan 1 group in the high brittleness index area in the embodiment of the present application. DETAILED DESCRIPTION

[0077] The present application will be described in detail below in conjunction with the drawings and embodiments of the present application. The described embodiments are only a part of the embodiments of the present application, and are not all the embodiments.

[0078] The unconventional natural gas reservoir fracturing development sweet spot screening method of the present application comprises the following steps:

[0079] Step (1), collecting the logging data and production data of the development wells in the target reservoir block; wherein the logging data to be collected includes: acoustic logging data, gamma logging data, and density logging data. The acoustic logging data includes two kinds of shear wave logging data and longitudinal wave logging data. When there is no shear wave logging data in the acoustic logging data, the shear wave logging data is inverted from the longitudinal wave logging data according to the following formula according to the reservoir characteristics: for tight sandstone reservoirs: V s = 0.8V P - 1.17; for coal rock gas reservoirs: V s = V P / 2.45; for shale gas reservoirs: V s = V P / 2.15; wherein V S is the shear wave velocity, and V p is the longitudinal wave velocity.

[0080] Step (2), one-dimensional geomechanical parameter interpretation is performed by using logging data to obtain rock mechanics parameters, geostress parameters and rock strength characteristic parameters of the development well; wherein the rock mechanics parameters include Young's modulus E and Poisson's ratio v; the geostress parameters include maximum horizontal principal stress D max and minimum horizontal principal stress D min ; and the rock strength characteristic parameters include rock tensile strength parameter s t and compressive strength parameter s f ;

[0081] Step (3), on the basis of the target reservoir three-dimensional geology model of petrel software, the three-dimensional geomechanical model of different main control parameters is established in the Geomechanics module of petrel software by combining the parameters (i.e. rock mechanics parameters, geostress parameters and rock strength characteristic parameters) obtained in step (2); wherein the target reservoir three-dimensional geology model must meet the following conditions: (1) having a sedimentary facies model and a structure model; (2) having an attribute model including porosity, permeability and gas saturation; (3) having a three-dimensional reserve SD distribution model.

[0082] The specific establishment process of the above-mentioned three-dimensional geomechanical model of different main control parameters includes the following steps:

[0083] Firstly, the main control parameters of the three-dimensional geomechanical model, i.e. brittleness index BI, two-way stress difference SE and fracture toughness K IC , are calculated according to the parameters obtained in step (2); then the main control parameters are imported into the three-dimensional geology model in the Geomechanics module of petrel software, and attribute filling is used to map the main control parameters to the grid cells; finally, the discrete grid data is interpolated into continuous attribute grids by using Kriging interpolation method, so as to finally establish the three-dimensional geomechanical model of different main control parameters.

[0084] Among them, for different types of unconventional natural gas reservoirs, the brittleness index BI of the main control parameter is calculated by using the normalized weighted average method, which is specifically as follows:

[0085]

[0086] Among them, E BI is the normalized elastic modulus, v BI is the normalized Poisson's ratio; E Max and E Min are respectively the maximum and minimum values of the core Young's modulus within the statistical range of the development well; v Max and v Min are respectively the maximum and minimum values of the core Poisson's ratio within the statistical range of the development well.

[0087] For different types of unconventional natural gas reservoirs, the main control parameter two-way stress difference SE calculation formula is:

[0088] SE = D max - D min

[0089] For different types of unconventional natural gas reservoirs, the main control parameter fracture toughness K IC The calculation formula is:

[0090] Tight sandstone reservoir: K IC = 0.005 + 0.125 * σ t - 0.0034 * σ f + 0.015 * E

[0091] Coal rock gas reservoir: K IC = 0.0045 + 0.13 * σ t - 0.0028 * σ f + 0.013 * E

[0092] Shale gas reservoir: K IC = 0.0035 + 0.165 * σ t - 0.0018 * σ f + 0.021 * E

[0093] Step (4), analyze the distribution interval of reserves and main control parameters of three-dimensional geological model of different layers of target reservoir and three-dimensional geomechanical model, and establish distribution standards of reserves and main control parameters in each layer according to distribution frequency;

[0094] The specific process of this step is as follows:

[0095] Firstly, the three-dimensional geomechanical model and the three-dimensional reserve SD distribution model of different layers and different main control parameters (brittleness index BI, two-way stress difference SE and fracture toughness K IC ) are converted into two-dimensional distribution graphs;

[0096] Then, the distribution frequency of four parameters (BI, SE, K IC , SD) in the two-dimensional distribution graph is counted;

[0097] Finally, according to the distribution frequency of each parameter, each parameter is divided into low, medium and high three intervals, and the range of parameter value in each interval is the distribution standard of reserves and main control parameters in each layer.

[0098] Among them, the calculation formula of converting the three-dimensional geomechanical model and the three-dimensional reserve SD distribution model of different main control parameters into two-dimensional distribution graphs is as follows:

[0099]

[0100] wherein H i is the distribution thickness of the parameter value on the three-dimensional model, P i represents the parameter value to be converted, and Z is the distribution value of the parameter value after conversion on the two-dimensional graph.

[0101] Step (5), analyze the open flow production data of the development wells in the target block, formulate the high-yield well division standard, and screen the high-yield wells of different horizons in the target block; the specific steps of this step are as follows:

[0102] First, collect and analyze the open flow data of all development wells in different horizons in the target block;

[0103] Then, count the distribution frequency of the open flow of the development wells in different horizons;

[0104] Finally, define the top quarter of the wells in the distribution frequency as high-yield wells.

[0105] Step (6), statistically analyze the distribution probability of the high-yield wells screened out in step (5) on the two-dimensional distribution graph of reserves and main control parameters, which specifically includes the following steps:

[0106] First, mark all high-yield wells on the two-dimensional distribution graph of reserves and three main control parameters of different horizons;

[0107] Then, according to the standard formulated in step 4, count the number of times x i of the occurrence of high-yield wells in different high-reserve intervals, high brittleness index intervals, low two-way stress difference intervals, and low fracture toughness intervals.

[0108] Finally, calculate the distribution probability P i of the occurrence of high-yield wells = x i / total number of high-yield wells.

[0109] Step (7), based on the statistical analysis results of step (6), formulate the screening criteria for the sweet spot area of fracturing development of different horizons in the target block, which specifically includes the following steps:

[0110] First, according to the distribution probability obtained by step (6), sort the reserves, brittleness index, two-way stress difference and fracture toughness in descending order;

[0111] Then, according to the order of the parameters obtained by sorting, and according to the distribution standard of different parameters in step (4), formulate the sweet spot area screening criteria of different horizons in the target block containing the priority order of the four parameters; wherein the reserve parameter selects the high-reserve distribution interval as the screening criterion, the brittleness index parameter selects the high-brittleness index distribution interval as the screening criterion, the two-way stress difference parameter selects the low two-way stress difference interval as the screening criterion, and the fracture toughness parameter selects the low fracture toughness distribution interval as the screening criterion.

[0112] Step (8), the dessert area screening criteria formulated according to step (7) is used to guide the location of different layer position fracturing development wells.

[0113] In the above calculation formula of the present application, the symbol "*" represents the multiplication sign "×".

[0114] The principle of the above scheme of the present application is as follows:

[0115] When the unconventional natural gas reservoir is developed by fracturing, the high or low of the target layer reserves and whether the complex fracture network can be formed by fracturing operation are the two most critical factors affecting the production effect after fracturing. The two-way stress difference, brittleness index and fracture toughness are three key geomechanical parameters affecting whether the fracture network can be formed by hydraulic fracturing. Based on this, the Petrel software is creatively used to construct a three-dimensional geomechanical model, to identify the distribution probability of the three-dimensional geomechanical model and the three-dimensional reserve model of the high-yield well in the oilfield which has been fractured, so as to statistically analyze the potential main controlling factors affecting the high yield of the fracturing well, and to prioritize the four key parameters of reserves, brittleness index, two-way stress difference and fracture toughness, and finally to customize the fracturing development dessert area screening criteria of different layers according to the priority order of the main controlling factors.

[0116] Embodiment

[0117] The Upper Paleozoic gas reservoir of a certain gas field belongs to unconventional tight sandstone gas reservoir, with an average porosity of less than 7% and a permeability of less than 1 mD, which needs to use hydraulic fracturing technology to realize the economic benefit development demand. In order to ensure the fracturing development effect, the method of the present application is used by the oilfield to formulate the fracturing development dessert area screening criteria of the two main layers of He 8 and Shan 1 groups. The specific implementation steps are as follows:

[0118] Step (1), first, the logging data and production data of a total of 566 wells of the two main layers of He 8 and Shan 1 groups of the Upper Paleozoic gas reservoir of the gas field which have been fractured are collected, among which 456 wells lack shear wave logging data, therefore, the shear wave logging data is obtained by inverting the longitudinal wave data by using the empirical formula V s = 0.8V P -1.17. Taking well J129 as an example, the shear wave inversion result is shown in Figure 1

[0119] Step (2), on the basis of step (1), the logging data is used to perform one-dimensional geomechanical parameter interpretation to obtain the rock mechanics parameters (Young's modulus E, Poisson's ratio v) of the development well, the geostress parameters (the maximum horizontal principal stress D max , the minimum horizontal principal stress D min ), and the rock strength characteristic parameters (the rock tensile strength parameter s t , the compressive strength parameter s f ​); wherein the in-situ stress interpretation results of J129 well are shown in Figure 2

[0120] Step (3), based on the 3D geological model of the gas reservoir in the Upper Paleozoic of the gas field, the brittle index BI, the difference of two-way stress SE and the fracture toughness KIC of the two main horizons of He8 and Shan1 were established in the Geomechanics module of the petrel software combined with the parameters obtained in step (2). IC The 3D geomechanical model. The 3D geological model of the gas reservoir in the Upper Paleozoic of the gas field is shown in Figure 3 The 3D geomechanical model (brittle index) of He8 horizon is shown in Figure 4

[0121] Step (4), the 3D geomechanical models of He8 and Shan1 with different main control parameters (brittle index BI, difference of two-way stress SE and fracture toughness KIC) and the 3D reserves SD distribution model were converted into two-dimensional distribution graphs (for example, the two-dimensional distribution graph of the brittle index of He8 horizon is shown in Fig. 5(a)); then the distribution frequencies of the four parameters (BI, SE, KIC, SD) in the two-dimensional distribution graphs were counted (for example, the distribution frequency graph of the brittle index of He8 horizon is shown in Fig. 5(b)); finally, according to the distribution frequencies of each parameter, each parameter was divided into low, medium and high three intervals, and the distribution standards of reserves and main control parameters of He8 and Shan1 were determined according to the range of parameter values in each interval, as shown in Tables 1 and 2, wherein Table 1 is the distribution standard of reserves and main control parameters of He8 horizon, and Table 2 is the distribution standard of reserves and main control parameters of Shan1 horizon.

[0122] Table 1

[0123]

[0124] Table 2

[0125]

[0126] Step (5), the open flow capacity data of 566 development wells in the two different horizons of He8 and Shan1 were collected and analyzed; then the distribution frequencies of the open flow capacity of the development wells in the two main horizons were counted; finally, the top quarter of the wells in the distribution frequency were defined as high-yield wells, and the distribution graph of high-yield wells and low-yield wells in He8 horizon is shown in Figure 6

[0127] ​​​Step (6), mark all high-yield wells on the two-dimensional distribution map of the three main control parameters of the Box 8 and Shan 1 groups; then, according to the standards established in step (4), the number of times of occurrence of high-yield wells in the high-reserve interval, the high-fragility index interval, the low two-way stress difference interval and the low fracture toughness interval of the two main layers of the Box 8 and Shan 1 groups is respectively counted, and the distribution probability of the high-yield wells is calculated, and the results are shown in Table 3. For example, the distribution of high-yield wells in the high-fragility index area of the Shan 1 group is shown in Table 3. Figure 7

[0128] Table 3

[0129]

[0130]

[0131] Step (7), according to the distribution probability obtained by step (6), the priority order of the four parameters affecting whether the fractured well is high-yield for the Box 8 layer is: fragility index > fracture toughness > reserve > two-way stress difference; and the priority order of the four parameters affecting whether the fractured well is high-yield for the Shan 1 group is: reserve > fragility index > two-way stress difference > fracture toughness. According to the statistical results, the screening criteria for the sweet spot area of the fractured development of the two main layers of the Box 8 and Shan 1 groups are successfully established, as shown in Table 4 and Table 5. Table 4 is the screening criteria for the sweet spot area of the fractured development of the Box 8 layer, and Table 5 is the screening criteria for the sweet spot area of the fractured development of the Shan 1 group.

[0132] Table 4

[0133] Screening priority Specific parameter range First class Brittleness index distribution interval 0.568-0.982 Second class Fracture toughness distribution interval 0.19-0.24 Third class Reserves distribution interval 0.0095-0.125 Fourth class Two-way stress difference distribution interval 4-8

[0134] Table 5

[0135] Screening priority Specific parameter range First class Reserves distribution interval 0.87-1.42 Second class Brittleness index distribution interval 0.56-0.92 Third class Two-way stress difference distribution interval 4-9 Fourth class Fracture toughness distribution interval 0.12-0.35

[0136] Step (8), according to the screening criteria for the sweet spot area of the fractured development of the Box 8 and Shan 1 groups, the oil field engineers guide the location of 2 fractured development wells in the Box 8 layer and the Shan 1 layer, including wJ-8 well and HN-6 well. The open flow capacities of the two new wells after fracturing are all more than 45,000 cubic meters per day, which is more than 20% higher than the effect of the adjacent wells after fracturing, and the overall economic benefit is significant.

[0137] In addition, the embodiment of the present application also provides a system for implementing the unconventional natural gas reservoir fracturing development sweet spot screening method, and the system comprises:

[0138] The parameter calculation module is used for acquiring the rock mechanics parameters, the ground stress parameters and the rock strength characteristic parameters of the development well by using the logging data of the development well in the target reservoir block.

[0139] ​The three-dimensional geomechanical model establishing module is used for establishing a three-dimensional geomechanical model of different main control parameters on the basis of the established three-dimensional geologic model of the target reservoir, in combination with the rock mechanics parameters, the ground stress parameters and the rock strength characteristic parameters.

[0140] The distribution standard determining module is used for determining the distribution standard of reserves and main control parameters according to the distribution interval of the reserves of the three-dimensional geologic model and the main control parameters of the three-dimensional geomechanical model of different horizons of the target reservoir, and taking the distribution frequency as the basis.

[0141] The high-yield well screening module is used for determining a high-yield well division standard according to the production data of the development wells in the target reservoir block, and screening the high-yield wells of different horizons in the target block according to the high-yield well division standard.

[0142] The distribution probability calculating module is used for calculating the distribution probability of the high-yield wells on the two-dimensional distribution graph of the reserves and the main control parameters by using the distribution standard.

[0143] The screening criterion determining module is used for determining the screening criterion of the fractured development sweet spot area of different horizons of the target block according to the distribution probability.

[0144] The site selection module is used for determining the site selection of the fractured development wells of different horizons according to the screening criterion.

[0145] The embodiment of the application further provides a corresponding electronic device and a computer readable storage medium, which are used for implementing the scheme provided by the embodiment of the application.

[0146] The electronic device comprises a storage device and one or more processors, the storage device is used for storing instructions or codes, and the processor is used for executing the instructions or codes, so that the device executes the unconventional natural gas reservoir fractured development sweet spot area screening method described in any embodiment of the application.

[0147] The storage medium stores a computer program, and when the computer program is executed by the processor, the unconventional natural gas reservoir fractured development sweet spot area screening method described in any embodiment of the application is realized.

[0148] Obviously, the described embodiments are only part of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the application.

[0149] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application but not to limit it. Although the present application has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the specific embodiments of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and any modification or equivalent replacement without departing from the spirit and scope of the present application should be covered in the protection scope of the claims of the present application.

Claims

1. A method for screening sweet spots in unconventional natural gas reservoir fracturing development, characterized in that, Includes the following steps: Using the logging data of development wells in the target reservoir block, obtain the rock mechanics parameters, geostress parameters, and rock strength characteristic parameters of the development wells; Based on the established three-dimensional geological model of the target reservoir, and in combination with the rock mechanics parameters, geostress parameters, and rock strength characteristic parameters, three-dimensional geomechanical models with different main control parameters are established. Based on the distribution range of the reserves in the three-dimensional geological model and the main control parameters of the three-dimensional geomechanical model at different layers of the target reservoir, the distribution standards of reserves and main control parameters are determined at each layer according to the distribution frequency. Based on the production data of development wells in the target reservoir block that have been obtained, determine the criteria for classifying high-yield wells, and screen high-yield wells in different layers within the target block according to the criteria for classifying high-yield wells. Using the aforementioned distribution standard, the distribution probability of the high-yield well on the two-dimensional distribution graph of reserves and main control parameters is calculated; Based on the aforementioned probability distribution, the selection criteria for sweet spots in fracturing development at different strata within the target block are determined; The site selection of fracturing development wells in different formations is determined based on the screening criteria.

2. The method for screening sweet spots in unconventional natural gas reservoir fracturing development according to claim 1, characterized in that, The logging data includes sonic logging data, gamma logging data, and density logging data; the sonic logging data includes shear wave logging data and longitudinal wave logging data. When the acoustic logging data only contains shear wave logging data, the shear wave logging data is inverted from the P-wave logging data according to the following formula based on the reservoir characteristics. The specific method is as follows: Tight sandstone reservoir: V s =0.8V P -1.17 Coal-rock gas reservoir: V s =V P / 2.45 Shale gas reservoirs: V s =V P / 2.15 Among them, V s It is the transverse wave velocity, V p It is the longitudinal wave velocity.

3. The method for screening sweet spots in unconventional natural gas reservoir fracturing development according to claim 1, characterized in that, Using the logging data of development wells in the target reservoir block, one-dimensional geomechanical parameters are interpreted to obtain the rock mechanics parameters, geostress parameters and rock strength characteristic parameters of the development wells; The rock mechanical parameters include Young's modulus and Poisson's ratio; The geostress parameters include: the maximum horizontal principal stress and the minimum horizontal principal stress; Rock strength characteristic parameters include: rock tensile strength parameters and rock compressive strength parameters.

4. The method for screening sweet spots in unconventional natural gas reservoir fracturing development according to claim 1, characterized in that, Based on the three-dimensional geological model of the target reservoir in Petrel software, and combined with the rock mechanics parameters, geostress parameters and rock strength characteristic parameters, a three-dimensional geomechanical model with different main control parameters is established in the Geomechanics module of Petrel software. The target reservoir's three-dimensional geological model must meet the following conditions: it must have a sedimentary facies model and a structural model, an attribute model including porosity, permeability and gas saturation, and a three-dimensional reservoir SD distribution model. The specific steps for establishing three-dimensional geomechanical models with different master control parameters in the Geomechanics module of Petrel software are as follows: Based on the rock mechanics parameters, geostress parameters, and rock strength characteristic parameters, the main control parameters of the three-dimensional geomechanical model are calculated. The main control parameters include the brittleness index, biaxial stress difference, and fracture toughness. In the Geomechanics module of the Petrel software, the master control parameters are imported into the three-dimensional geological model, and attribute filling is used to map the master control parameters onto the mesh cells. Kriging interpolation is used to interpolate discrete grid data into a continuous attribute grid, thereby ultimately establishing a three-dimensional geomechanical model with different master control parameters; For different types of unconventional natural gas reservoirs, the brittleness index BI, a key control parameter, was calculated using a normalized weighted average method. Among them, E BI For the normalized elastic modulus, ν BI E is the normalized Poisson's ratio. Max and E Min These represent the maximum and minimum values ​​of Young's modulus of core samples within the statistical range of the development well; ν Max and ν Min These represent the maximum and minimum Poisson's ratio values ​​for core samples within the statistical scope of the development wells, respectively. For different types of unconventional natural gas reservoirs, the formula for calculating the biaxial stress difference (SE) of the master control parameter is as follows: SE=D max -D min For different types of unconventional natural gas reservoirs, the main control parameter, fracture toughness K... IC The calculation formula is: Tight sandstone reservoir: K IC =0.005 + 0.125 * σ t -0.0034*σ f +0.015*E; Coal-rock gas reservoir: K IC =0.0045+0.13*σ t -0.0028*σ f +0.013*E; Shale gas reservoirs: K IC =0.0035 + 0.165 * σ t -0.0018*σ f +0.021*E; Where, σ t σ is the tensile strength parameter of the rock. f Here, E is the compressive strength parameter, and E is Young's modulus.

5. The method for screening sweet spots in unconventional natural gas reservoir fracturing development according to claim 4, characterized in that, Based on the distribution range of reserves and master control parameters of the three-dimensional geological model of different layers of the target reservoir and the three-dimensional geomechanical model, the distribution standards of reserves and master control parameters are determined for each layer according to the distribution frequency. The specific steps include the following: The three-dimensional geomechanical models with different master control parameters at different strata and the three-dimensional SD reserve distribution model are converted into two-dimensional distribution graphics. The distribution frequency of each main control parameter in the two-dimensional display pattern is statistically analyzed; Based on the distribution frequency of each main control parameter, each main control parameter is divided into three intervals: low, medium, and high. The range of parameter values ​​in each interval serves as the standard for determining the reserves and distribution of the main control parameters in each stratum. The calculation formulas for converting the three-dimensional geomechanical model and the three-dimensional reserve SD distribution model with different main control parameters into two-dimensional distribution graphics are as follows: Among them, H i P represents the thickness of the parameter values ​​distributed on the 3D model. i Z represents the parameter value to be converted, and Z is the distribution value of the converted parameter value on the two-dimensional graph.

6. The method for screening sweet spots in unconventional natural gas reservoir fracturing development according to claim 1, characterized in that, Using the aforementioned distribution standard, the distribution probability of the high-yield well on the two-dimensional distribution graph of reserves and main control parameters is calculated, specifically including the following steps: All high-yield wells were marked on a two-dimensional plot of reserves and various key control parameters at different stratigraphic levels; Based on the aforementioned distribution criteria, the frequency (x) of high-yield wells occurring in different stratigraphic intervals, including high-reserve intervals, high-brittleness index intervals, low biaxial stress difference intervals, and low fracture toughness intervals, was statistically analyzed. i ; The probability distribution P of high-yield wells is calculated based on the frequency of occurrence in high-reserve intervals, high-brittleness index intervals, low biaxial stress difference intervals, and low fracture toughness intervals at different stratigraphic levels. i P i =x i / Total number of high-yield wells.

7. The method for screening sweet spots in unconventional natural gas reservoir fracturing development according to claim 1, characterized in that, Based on the aforementioned probability distribution, the selection criteria for sweet spots in fracturing development at different strata within the target block are determined, specifically including the following steps: Based on the aforementioned probability distribution, the four parameters—reserve quantity, brittleness index, biaxial stress difference, and fracture toughness—are ranked from high to low. Based on the order of the parameters obtained from the sorting, and according to the distribution criteria, the sweet spot selection criteria for different strata of the target block are determined according to the priority order of four parameters: reserves, brittleness index, biaxial stress difference, and fracture toughness. Among them, the high reserve distribution range is selected as the selection criterion for the reserve parameter, the high brittleness index distribution range is selected as the selection criterion for the brittleness index parameter, the low biaxial stress difference range is selected as the selection criterion for the biaxial stress difference parameter, and the low fracture toughness distribution range is selected as the selection criterion for the fracture toughness parameter.

8. A sweet spot screening system for unconventional natural gas reservoir fracturing development, characterized in that, include: Parameter calculation module: used to obtain rock mechanics parameters, geostress parameters, and rock strength characteristic parameters of development wells using the well logging data of development wells in the target reservoir block; Three-dimensional geomechanical model establishment module: Based on the established three-dimensional geological model of the target reservoir, and combined with the rock mechanics parameters, geostress parameters, and rock strength characteristic parameters, a three-dimensional geomechanical model with different main control parameters is established. Distribution standard determination module: Based on the distribution range of the reserves in the three-dimensional geological model and the main control parameters of the three-dimensional geomechanical model of different layers of the target reservoir, the distribution standard of reserves and main control parameters is determined in each layer according to the distribution frequency. High-yield well screening module: This module is used to determine the criteria for classifying high-yield wells based on the production data of development wells in the target reservoir block, and to screen high-yield wells in different layers within the target block according to the criteria for classifying high-yield wells. Distribution probability calculation module: used to calculate the distribution probability of the high-yield well on the two-dimensional distribution graph of reserves and main control parameters using the distribution standard; Screening Criteria Determination Module: Used to determine the screening criteria for fracturing sweet spots in different layers of the target block based on the distribution probability; Site selection module: used to determine the site selection of fracturing development wells in different formations according to the screening criteria.

9. An electronic device, characterized in that, include: One or more processors; A storage device on which one or more programs are stored; When the one or more programs are executed by the one or more processors, the one or more processors implement the unconventional natural gas reservoir fracturing development sweet spot screening method as described in any one of claims 1 to 7.

10. A storage medium, characterized in that, It stores a computer program, wherein the computer program, when executed by a processor, implements the method for screening sweet spots in unconventional natural gas reservoir fracturing development as described in any one of claims 1-7.

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