Method and device for determining well type of multi-layer tight sandstone gas reservoir

Abstract

The invention relates to a method and a device for determining a well type of a multi-layer tight sandstone gas reservoir. The method comprises the following steps: evaluating the production capacity of a gas well in a research block of the tight sandstone gas reservoir to obtain a gas well production capacity evaluation result; based on the gas well productivity evaluation result, in combination with the geological characteristics and fracturing construction factors of the tight gas reservoir in the research area, single-factor and multi-factor productivity influence factor analysis is carried out, the gas well productivity main control geological factors are determined, and the main control geological factor analysis influencing the production effect of the gas well after fracturing is enhanced; the invention provides a convenient and quantifiable well type selection method. A series of well type optimization charts corresponding to the yield increase multiple ratios of different horizontal wells and vertical wells are established, the numerical value of the reserve concentration ratio is embodied on the well type selection charts for the first time, and multi-layer tight gas reservoir well type selection is facilitated. Quantification of well type selection indexes is achieved, a basis is provided for efficient and convenient well type selection, and the method has positive significance in improving the reserve utilization degree of tight gas reservoirs and improving development benefits.

Description

Technical Field

[0001] The invention relates to a method and a device for determining a well type of a multi-layer tight sandstone gas reservoir. Background Art

[0002] Tight gas reservoirs have poor reservoir properties, small sand bodies, strong heterogeneity, and are characterized by low permeability, low abundance, and low production. Tight gas reservoirs are widely distributed and have different geological conditions. Some tight gas reservoirs are on the edge of economic benefits or cannot be developed economically and effectively. If the well type is not selected properly, the reserve utilization and economic benefits will be further reduced. In order to obtain better development results, the selection of development well types is very important and has great significance for improving the development effect of gas reservoirs. Summary of the invention

[0003] In order to provide a method for determining the well type of a multi-layer tight sandstone gas reservoir, so that the gas well selection index can be quantified and the reserve production degree and gas reservoir development effect can be improved to the greatest extent, the present invention proposes a method and device for determining the well type of a multi-layer tight sandstone gas reservoir. The technical solution proposed by the present invention is as follows:

[0004] In a first aspect, the present invention provides a method for determining a well type of a multi-layer tight sandstone gas reservoir, comprising:

[0005] Based on the pre-determined evaluation parameters, the gas well production capacity evaluation is carried out in the study block of tight sandstone gas reservoir to obtain the gas well productivity evaluation results;

[0006] Based on the gas well productivity evaluation results, according to the geological characteristics of the tight gas reservoir in the study area and the fracturing construction factors, the main controlling geological factors affecting the gas well productivity are determined; the main controlling geological factors include the total effective thickness of the reservoir and the reservoir permeability;

[0007] According to the actual data of the gas field, a multi-layer tight gas reservoir numerical model is established;

[0008] Based on the multi-layer tight gas reservoir numerical model, the cumulative gas production of different well types under different combinations of main controlling geological factors and reserves concentration of different horizontal well production layers is calculated; wherein the well types include horizontal wells and vertical wells;

[0009] According to the cumulative production of horizontal wells and vertical wells, the production increase ratio under each combination of conditions is calculated;

[0010] For each of the predetermined different selected yield increase multiples:

[0011] According to the production increase ratio under each combination of conditions, the reservoir permeability corresponding to the selected production increase ratio under different combinations of total effective reservoir thickness and reserve concentration is calculated;

[0012] According to the reservoir permeability corresponding to the selected production increase ratio under the combination of different total effective thickness of the reservoir and the reserve concentration, the reservoir permeability corresponding to the selected reserve concentration under different total effective thickness of the reservoir is calculated, and a well type optimization chart is established;

[0013] According to the cost ratio of drilling horizontal wells and vertical wells in the planned drilling area, a corresponding target plate is selected from the well type optimization plates under all selected production increase ratios, and a target well type is determined according to the target plate.

[0014] In one or some embodiments, the calculation of the reservoir permeability corresponding to the selected production increase ratio under different combinations of total effective reservoir thickness and reserve concentration according to the production increase ratio under each combination of conditions includes:

[0015] For each combination of total effective thickness and reserve concentration of each reservoir in each combination of conditions:

[0016] According to the production increase multiples corresponding to different reservoir permeabilities under the combination of the total effective thickness of the reservoir and the reserve concentration, a second relationship between the reservoir permeability and the production increase multiples is obtained by fitting;

[0017] The reservoir permeability corresponding to the selected production increase ratio is calculated according to the second relationship.

[0018] In one or some embodiments, the second relationship between reservoir permeability and production increase ratio is obtained by fitting the production increase ratio corresponding to different reservoir permeabilities under the combination of the total effective thickness of the reservoir and the reserve concentration, including:

[0019] The production increase multiple data points corresponding to different reservoir permeabilities under the combination of the total effective thickness of the reservoir and the reserve concentration are selected, and trend line regression is performed on the data points using multiple methods. The trend line with the highest fitting degree is selected to obtain a second relationship between the reservoir permeability and the production increase multiple; wherein the multiple methods include: exponential regression, linear regression, logarithmic regression, polynomial regression and power function regression.

[0020] In one or some embodiments, the reservoir permeability corresponding to the selected reserve concentration under different total effective reservoir thicknesses is calculated in the following manner:

[0021] For each of the different combinations of total effective thickness of reservoirs and reserve concentrations, the total effective thickness of reservoirs is:

[0022] Selecting reservoir permeability data points corresponding to different reserve concentrations under the total effective thickness of the reservoir, performing trend line regression on the data points, selecting the trend line with the highest fitting degree, and obtaining a first relationship between reservoir permeability and reserve concentration;

[0023] The reservoir permeability corresponding to the selected reserve concentration is calculated according to the first relationship.

[0024] In one or some embodiments, selecting a corresponding target plate from the well type preferred plates under all selected production increase multiples according to the cost ratio of drilling horizontal wells and vertical wells in the planned drilling area, and determining the target well type according to the target plate includes:

[0025] According to the cost ratio of drilling horizontal wells and vertical wells in the planned drilling area, a corresponding target plate is selected from the well type optimization plates under all selected production increase ratios;

[0026] According to the obtained effective thickness and permeability of the reservoir in the planned drilling area, points are cast in the target map;

[0027] Based on the obtained target layer reserve concentration of the planned drilling area, determining a corresponding reserve concentration curve in the target plate;

[0028] The target well type is determined according to the position of the injection point relative to the reserve concentration curve.

[0029] In one or some embodiments, determining the target well type according to the position of the injection point relative to the reserve concentration curve includes:

[0030] If the injection point is below the reserve concentration curve, the target well type is a horizontal well; if the injection point is above the reserve concentration curve, the target well type is a vertical well.

[0031] In one or some embodiments, the method further comprises:

[0032] Obtaining the effective thickness of the reservoir in the planned drilling area, and determining whether the effective thickness of the reservoir in the planned drilling area meets the preset yield condition corresponding to the target well type;

[0033] If satisfied, the target well type is used as the final development well type.

[0034] In one or some embodiments, the multi-layer tight gas reservoir numerical simulation model is established by:

[0035] Obtaining gas field geological parameter data, gas reservoir fluid seepage related data and gas well production parameters from the actual data of the gas field; wherein the gas field geological parameter data include production layer distribution, gas reservoir porosity, permeability and gas saturation; the gas reservoir fluid seepage related data include gas density, water density, PVT data, gas-water relative permeability data and rock compression coefficient; the gas well production parameters include vertical well bore position, horizontal well bore position, vertical well production production data and horizontal well production production data;

[0036] Based on the gas field geological parameter data, the gas reservoir fluid seepage related data and the gas well production parameters, a multi-layer tight gas reservoir numerical simulation model is established;

[0037] By selecting different reservoir permeabilities, different total effective reservoir thicknesses, different horizontal well layer reserve concentrations, and different well type combinations, numerical simulation models of multi-layer tight gas reservoirs with different well types under different reservoir conditions were obtained.

[0038] In one or some embodiments, the evaluation parameters include dynamic reserves of gas wells: the gas well production capacity evaluation is carried out on the research block of tight sandstone gas reservoir based on the pre-acquired evaluation parameters to obtain the gas well productivity evaluation result, including:

[0039] According to the production characteristics of tight gas wells in the study area, based on the preset gas well dynamic reserves evaluation method, the dynamic reserves of gas wells in the study area are determined. The size of the dynamic reserves of the gas wells in a single well is used as an indicator to evaluate the long-term production capacity of the fracturing wells, and the gas well productivity evaluation results are obtained.

[0040] In a second aspect, the present invention provides a device for determining a well type of a multi-layer tight sandstone gas reservoir, comprising:

[0041] An evaluation module is used to evaluate the gas well production capacity of the research block of the tight sandstone gas reservoir based on predetermined evaluation parameters to obtain a gas well production capacity evaluation result;

[0042] An analysis module is used to determine the main controlling geological factors affecting the gas well productivity based on the gas well productivity evaluation results, according to the geological characteristics of the tight gas reservoir in the study area and the fracturing construction factors; the main controlling geological factors include the total effective thickness of the reservoir and the reservoir permeability;

[0043] Modeling module, used to establish a multi-layer tight gas reservoir numerical model based on the actual data of the gas field;

[0044] The first calculation module is used to calculate the cumulative gas production of different well types under different combinations of main controlling geological factors under different horizontal well production layer reserve concentrations based on the multi-layer tight gas reservoir numerical model; wherein the well types include horizontal wells and vertical wells;

[0045] The second calculation module is used to calculate the production increase ratio under each combination of conditions based on the cumulative production of horizontal wells and the cumulative gas production of vertical wells;

[0046] A chart establishment module is used for calculating, for each selected production increase ratio in different predetermined selected production increase ratios: according to the production increase ratio under each combination of conditions, the reservoir permeability corresponding to the selected production increase ratio under different combinations of total effective reservoir thickness and reserve concentration; according to the reservoir permeability corresponding to the selected production increase ratio under different combinations of total effective reservoir thickness and reserve concentration, the reservoir permeability corresponding to the selected reserve concentration under different total effective reservoir thickness is calculated, and a well type optimization chart is established;

[0047] The target well type determination module is used to select a corresponding target plate from all well type optimization plates under all selected production increase ratios according to the cost ratio of drilling horizontal wells and vertical wells in the planned drilling area, and determine the target well type according to the target plate.

[0048] In a third aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for determining a well type of a multi-layer tight sandstone gas reservoir as described in the first aspect.

[0049] In a fourth aspect, the present invention provides an electronic device, comprising a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus;

[0050] Memory, used to store computer programs;

[0051] The processor is used to implement the method for determining the well type of a multi-layer tight sandstone gas reservoir as described in the first aspect when executing the program stored in the memory.

[0052] Based on the above technical solution, the beneficial effects of the present invention compared with the prior art are as follows:

[0053] The method for determining the well type of a multi-layer tight sandstone gas reservoir provided by the present invention is to evaluate the gas well production capacity of the research block of the tight sandstone gas reservoir based on the predetermined evaluation parameters to obtain the gas well production capacity evaluation result; then based on the gas well production capacity evaluation result, combined with the geological characteristics of the tight gas reservoir in the research area and the fracturing construction factors, single factor and multi-factor production capacity influencing factor analysis are carried out to determine the main controlling geological factors of the gas well production capacity, strengthen the analysis of the main controlling geological factors affecting the production effect after the gas well fracturing, provide a convenient and quantifiable well type selection method, and make up for the shortcomings of the existing methods. A series of well type optimization plates corresponding to different horizontal well and vertical well production increase ratios are established, and the numerical value of the reserve concentration is reflected on the well type selection plate for the first time, which is convenient for the selection of well types in multi-layer tight gas reservoirs. Using the well type optimization plate, the suitable well type can be determined according to the reservoir permeability, total effective thickness of the reservoir and the reserve concentration of the known formation, and the quantification of the well type selection index is realized, which provides a basis for the efficient and convenient selection of well types, and has positive significance for improving the reserve utilization degree and development efficiency of tight gas reservoirs.

[0054] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0055] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0057] Figure 1 It is a schematic diagram of the process of determining the well type of multi-layer tight sandstone gas reservoir;

[0058] Figure 2 It is a schematic diagram of the extremely poor results of various factors affecting the effect of fracturing horizontal wells;

[0059] Figure 3 It is a schematic diagram of the extremely poor results of various factors affecting the effect of fracturing vertical wells;

[0060] Figure 4 It is a schematic diagram of the model of fractured vertical well and fractured horizontal well in multi-layer tight gas reservoir;

[0061] Figure 5 This is the relationship curve between reservoir permeability and production increase ratio (total effective reservoir thickness is 12m, reserve concentration is 50%);

[0062] Figure 6 It is the relationship curve between reservoir permeability and reserve concentration (total effective reservoir thickness is 12m);

[0063] Figure 7 It is the optimal chart for well types under different reserve concentrations (the cost of horizontal wells is 2.5 times that of vertical wells);

[0064] Figure 8 It is the optimal chart for well types under different reserve concentrations (the cost of horizontal wells is 2.8 times that of vertical wells);

[0065] Fig. 9 It is a diagram of a preferred example of the well type W1-W4;

[0066] Fig.10 It is another schematic diagram of the process of determining the well type of a multi-layer tight sandstone gas reservoir;

[0067] Fig.11 It is a schematic diagram of the structure of a device for determining the well type of a multi-layer tight sandstone gas reservoir;

[0068] Fig.12 It is a structural diagram of an electronic device. DETAILED DESCRIPTION

[0069] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0070] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0071] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0072] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0073] At present, there are mainly the following methods for selecting well types: First, production capacity is calculated based on theoretical research and mathematical models, and the well type is selected from the perspective of maximum production capacity; second, a research area is selected, an actual geological model is established, numerical simulation is carried out, and the gas well indicators of different simulated well types are compared and analyzed to determine the well type; third, well type adaptability analysis is carried out from the perspective of development geology to determine the appropriate well type; fourth, gas well economic evaluation is carried out from the perspective of gas well controlled reserves and production costs to select the well type.

[0074] The inventor found in his work that the current method has some limitations. The theoretical calculation model is complex, with many parameters, which are difficult to obtain accurately and inconvenient to use on site. The well type adaptability analysis from the geological perspective is often based on qualitative analysis, and quantitative evaluation is insufficient. The modeling process is complex and the workload is large. The economic evaluation method lacks convenient quantitative indicators in well type selection. The existing methods are not convenient and fast enough when selecting well types. Secondly, they are based on qualitative analysis, and quantitative analysis is insufficient. There is a lack of quantifiable parameter indicators for well type selection, which cannot meet the inventor's expectations. After further research and development, the inventor made the present invention.

[0075] In order to overcome the shortcomings of the existing technology, make the gas well selection indicators quantifiable, conveniently select the well type through specific parameters, and maximize the reserve utilization and gas reservoir development effect, the present invention proposes a method and device for determining the well type of multi-layer tight sandstone gas reservoir.

[0076] Embodiment 1

[0077] The embodiment of the present invention provides a method for determining the well type of a multi-layer tight sandstone gas reservoir, referring to Figure 1 As shown, including:

[0078] S101. Based on the pre-determined evaluation parameters, a gas well production capacity evaluation is performed on the research block of the tight sandstone gas reservoir to obtain a gas well productivity evaluation result;

[0079] Carry out gas well production capacity evaluation, which refers to the uncertainty of the initial production of the current fracturing gas wells, replacing the open flow rate with the dynamic reserves that can better reflect the long-term production capacity of the fracturing wells as the key evaluation parameter, conduct post-fracturing production capacity evaluation, carry out production forecasts throughout the life cycle of the gas well, and understand the long-term production status of the gas well from the time of opening to abandonment.

[0080] S102, based on the gas well productivity evaluation results, according to the geological characteristics of the tight gas reservoir in the study area and the fracturing construction factors, determine the main controlling geological factors affecting the gas well productivity; the main controlling geological factors include the total effective thickness of the reservoir and the reservoir permeability;

[0081] Determining the main controlling geological factors of gas well productivity means that in the selection of evaluation parameters, the focus is on selecting parameters that have a significant impact on fracturing gas wells and are independent of each other, and selecting as few factors as possible to cover more attributes. The geological factors mainly include porosity, reservoir permeability, gas saturation, total effective reservoir thickness, reservoir length, effective reservoir length, formation anisotropy, etc. The analysis of single-factor productivity influencing factors is carried out based on actual data, and the numerical model of typical tight gas reservoir fracturing vertical wells and fracturing horizontal wells is established based on gas well and reservoir parameters. Through single-factor actual data analysis and multi-factor orthogonal test analysis, it is determined that the main geological factors affecting gas well productivity are reservoir permeability and total effective reservoir thickness.

[0082] The key geological parameters that affect the long-term production capacity of gas wells are quantitatively determined mainly through multi-factor influencing factor analysis.

[0083] First, select the evaluation parameters.

[0084] The productivity of tight gas wells varies greatly, and there are many factors affecting productivity, and the relationships between them are complex. It is impractical to find all the influencing factors, which requires the use of reasonable methods to screen out suitable evaluation parameters, remove parameters with great correlation with each other, and determine the necessary key evaluation parameters. To select factors that have a greater impact on the productivity of fracturing wells from many characteristic factors, several principles should be followed: First, the parameters can reflect the characteristics of a certain aspect, such as permeability reflecting seepage capacity, and porosity reflecting reservoir space; second, the selected parameter set should reflect the main characteristics as much as possible. For example, for fracturing horizontal wells, in addition to geological factors, it should also include fracture parameters related to fracturing construction and parameters related to horizontal wells; third, the correlation between indicators is small and relatively independent; fourth, the parameters are easy to obtain and quantifiable.

[0085] Screening was carried out according to the above principles, focusing on selecting parameters that have a significant impact on fracturing gas wells and are independent of each other, and selecting as few factors as possible to cover more attributes. For the convenience of analysis, based on actual data, the factors affecting production capacity were divided into two categories: geological and engineering for analysis, so as to determine the main factors affecting production capacity. Geological factors mainly study porosity, reservoir permeability, gas saturation, total effective reservoir thickness, reservoir length, effective reservoir length, formation anisotropy, etc. Engineering factors mainly study horizontal section length, gas well skin coefficient, sand addition amount, fracture length, fracture conductivity, fracturing spacing (number of sections), fracturing fluid return rate, reservoir drilling rate, etc.

[0086] Secondly, we conduct single factor capacity influencing factor analysis, that is, we mainly analyze the correlation between each selected evaluation parameter and dynamic reserves, and see which parameters have relatively high correlation, so as to make a preliminary judgment. The correlation between evaluation parameters and dynamic reserves can be calculated by correlation function.

[0087] Finally, a multi-factor analysis of factors affecting gas well production capacity is carried out. In the actual production process of gas wells, geological factors and engineering factors often interact with each other at the same time. In order to study the main influencing factors of gas well production capacity under the simultaneous interaction of different single factors, a numerical model of fractured horizontal wells in typical tight gas reservoirs is established based on the actual data of the Sulige gas field, and an orthogonal experiment is designed to analyze the primary and secondary order of the influence of different factors on gas well production capacity.

[0088] The process of establishing the numerical model of typical tight gas reservoir fractured vertical wells and fractured horizontal wells is as follows. The Eclipse software, a commonly used numerical simulation software for oil and gas reservoirs in the oil and gas field development profession in the petroleum industry, is used to establish the model and simulate the calculation under different production parameters. When establishing the model, the numerical simulation grid parameters are 800m in the plane x direction, 1200m in the y direction, 20m in the longitudinal z direction, and the grid size is 20×20×1m.

[0089] For fractured horizontal wells, based on the main influencing factors selected in the previous single factor analysis, the reservoir permeability, total effective reservoir thickness, effective reservoir length, horizontal section length, number of fractures, and fracturing scale (fracture half-length) with relatively large influence were selected. At the same time, the fracture conductivity, horizontal well skin coefficient and formation anisotropy were considered, and a 9-factor 4-level orthogonal experiment was designed. The horizontal well orthogonal experiment factors and their level values ​​are shown in Table 1.

[0090]

[0091] Table 1

[0092] Determine the range of each influencing factor separately, refer to Figure 2As shown in Table 2, the range of various factors affecting the effect of fracturing horizontal wells is shown. According to the range size, the order of priority of the impact on the horizontal well production capacity is obtained. Refer to Table 2 for the results of the horizontal well range analysis.

[0093]

[0094] Table 2

[0095] The order of influence of various factors on the productivity of horizontal wells after fracturing is: reservoir permeability>number of fractures>fracture half-length>total effective reservoir thickness>Kv / Kh>effective reservoir length>horizontal section length>skin coefficient>conductivity.

[0096] For vertical wells, reservoir permeability, total effective reservoir thickness, fracture half-length, fracture conductivity, vertical well skin coefficient and formation anisotropy were selected to design a 6-factor 5-level orthogonal test. The vertical well orthogonal test factors and their level values ​​are shown in Table 3 below.

[0097]

[0098] Table 3

[0099] The range of each factor affecting the effect of fracturing vertical wells is calculated separately. The results are as follows Figure 3 According to the range size, the order of priority of the impact on vertical well productivity is obtained, and the vertical well range analysis result table is shown in Table 4 below.

[0100]

[0101] Table 4

[0102] The order of influence of various factors on the productivity of vertical wells after fracturing is: reservoir permeability>total effective reservoir thickness>fracture half-length>Kv / Kh>skin coefficient>conductivity.

[0103] From the above results, it can be seen that the geological factors that have the greatest impact on the productivity of fractured vertical wells and fractured horizontal wells in tight gas reservoirs are the total effective thickness of the reservoir and the reservoir permeability. Therefore, the main controlling geological factors are the total effective thickness of the reservoir and the reservoir permeability.

[0104] S103. Establish a multi-layer tight gas reservoir numerical model based on actual data of the gas field;

[0105] The multi-layer tight gas reservoir numerical model established by the present invention includes two types, the fracturing vertical well production model and the fracturing horizontal well production model. Among them, the vertical well runs through three layers, and each layer is perforated for production; the horizontal well is only produced in layer 3. Based on the analysis of factors affecting productivity and according to the actual data of the gas field, a multi-layer tight gas reservoir numerical model is established, and the influence of changes in different main controlling geological factors on the productivity of horizontal wells and vertical wells is compared and analyzed, so as to establish a well type optimization chart to optimize the well type.

[0106] S104, based on the multi-layer tight gas reservoir numerical model, calculating the cumulative gas production of different well types under different concentrations of reserves in production layers of horizontal wells and different combinations of main controlling geological factors; wherein the well types include horizontal wells and vertical wells;

[0107] The reserve concentration is the ratio of the geological reserves of a single layer to the total reserves of the reservoir. The production increase ratio is the ratio of the cumulative gas production of horizontal wells to the cumulative gas production of vertical wells.

[0108] Based on the multi-layer tight gas reservoir numerical simulation model, simulation is performed under different reservoir production conditions to obtain the corresponding cumulative gas production. The different reservoir production conditions are the above-mentioned different horizontal well production layer reserve concentration, the combination of total effective reservoir thickness and reservoir permeability. The numerical range of the horizontal well production layer reserve concentration is determined according to the statistical value of the reservoir reserve concentration actually encountered by the horizontal wells in the area. The specific numerical range of the total effective thickness of the reservoir and the reservoir permeability can be determined according to the main interval of the reservoir physical property distribution in the study area. The calculation of the cumulative gas production is obtained by simulating and calculating different multi-layer tight gas reservoir numerical simulation models through numerical simulation software. Based on the multi-layer tight gas reservoir numerical simulation model established in step S103, the different horizontal well production layer reserve concentrations, total effective thickness of the reservoir and reservoir permeability in step S104 are arranged and combined, and a corresponding number of models are established. Each model is simulated and calculated to obtain the cumulative gas production under different parameters.

[0109] S105, calculating the production increase ratio under each combination of conditions according to the cumulative production of the horizontal wells and the cumulative gas production of the vertical wells;

[0110] The ratio of the cumulative gas production of horizontal wells to the cumulative gas production of vertical wells is the production increase ratio. The above combination of conditions is the combination of different horizontal well production layer reserve concentration, total effective reservoir thickness and reservoir permeability.

[0111] S106, for each of the different predetermined selected production increase ratios:

[0112] According to the production increase ratio under each combination of conditions, the reservoir permeability corresponding to the selected production increase ratio under different combinations of total effective reservoir thickness and reserve concentration is calculated;

[0113] Based on the analysis of factors affecting productivity, according to the actual data of the gas field, a multi-layer tight gas reservoir numerical model is established, and the impact of changes in different controlling geological factors on the productivity of horizontal wells and vertical wells is compared and analyzed, so as to establish a well type optimization chart and select the well type. According to the reservoir permeability corresponding to the selected increase ratio under the combination of different total effective reservoir thickness and reserve concentration, the reservoir permeability corresponding to the selected reserve concentration under different total effective reservoir thickness is calculated, and a well type optimization chart is established;

[0114] When establishing a well type optimization map, calculate the reservoir permeability corresponding to a certain value of the increase ratio under different total effective reservoir thicknesses and reserve concentrations; determine the relationship between reservoir permeability and reserve concentration when the increase ratio is a certain value under different total effective reservoir thicknesses; based on the relationship between reservoir permeability and reserve concentration, determine the reservoir permeability corresponding to reserve concentrations in different intervals under different total effective reservoir thicknesses, draw a graph, and establish a well type optimization map. Change the increase ratio value to obtain a series of maps under different increase ratios. For each condition combination used to establish a well type optimization map, the horizontal well cost and the vertical well cost are known, that is, the horizontal well and vertical well cost ratio is known. For each condition combination, obtain the cost ratio under the condition combination, so as to correspond the cost ratio with the increase ratio, and obtain a series of maps under different horizontal well and vertical well cost ratios.

[0115] Reference Figure 7 to Figure 8 As shown in the figure, the well type optimization charts under different reserve concentrations when the selected production increase ratio is 2.5 and the selected production increase ratio is 2.8. The well type optimization chart has main parameters of total effective reservoir thickness, reservoir permeability and reserve concentration, which realizes the quantification of well type selection parameters. In addition, the reserve concentration change curve is applied to the well type optimization chart for the first time, which is convenient for well type selection in multi-layer tight gas reservoirs.

[0116] S107, according to the cost ratio of drilling horizontal wells and vertical wells in the planned drilling area, select a corresponding target plate from all well type optimization plates under the selected production increase ratio, and determine the target well type according to the target plate.

[0117] Judging the suitable well type means finding the corresponding point on the well type optimization chart based on the reservoir permeability and total effective thickness of the gas well point. When the reserve concentration value of the gas well is at the lower left of the corresponding reserve concentration curve on the chart, it is suitable for horizontal well development; when it is at the upper right of the curve, it is suitable for vertical well development.

[0118] In an optional embodiment, the method further includes:

[0119] S108, obtaining the effective thickness of the reservoir in the planned drilling area, and determining whether the effective thickness of the reservoir in the planned drilling area meets the preset yield condition corresponding to the target well type; if so, the target well type is used as the final development well type. If not, development is temporarily suspended.

[0120] The economic benefit judgment refers to the determination of the lower limit of the effective reservoir thickness corresponding to horizontal wells and vertical wells to achieve a certain rate of return based on the effective reservoir thickness encountered by the vertical wells and horizontal wells that have been put into production in this study area and the EUR statistics. It is judged by whether the effective reservoir thickness in the planned drilling area reaches the corresponding lower limit of the effective reservoir thickness. The economic benefit judgment is carried out to determine whether the development benefit meets the requirements and determine the final development well type of the gas reservoir based on the condition of meeting the preset rate of return of the gas reservoir development.

[0121] The present invention belongs to the field of oil and natural gas development, and particularly relates to a multi-layer system tight sandstone gas reservoir well type determination method that has important guiding significance for the selection of well types on the spot of gas fields. The method overcomes the shortcomings of the existing methods that are mainly based on qualitative analysis when selecting well types, are insufficient in quantitative analysis, and are not convenient and fast enough. For a research block of a certain tight sandstone gas reservoir, a gas well production capacity evaluation is carried out, the main controlling factors of gas well production capacity are determined, a multi-layer tight gas reservoir digital model is established, and single well indicators of vertical wells and horizontal wells are calculated and compared when different main controlling factors change. A series of well type optimization plates are established, and suitable plates are selected according to the cost multiple ratio of horizontal wells to vertical wells, and suitable well types are judged, and whether the economic benefits of the preferred well type meet the requirements is judged, and the final development well type is determined. The present invention provides a convenient and quantifiable well type selection method, which provides a basis for efficiently and conveniently selecting well types, and has positive significance for improving the reserve utilization degree and development benefits of tight gas reservoirs.

[0122] Specifically, the present invention evaluates the gas well production capacity of the research block of the tight sandstone gas reservoir based on the predetermined evaluation parameters to obtain the gas well production capacity evaluation results; then based on the gas well production capacity evaluation results, combined with the geological characteristics of the tight gas reservoir in the study area and the fracturing construction factors, single-factor and multi-factor production capacity influencing factor analysis is carried out to determine the main controlling geological factors of the gas well production capacity, strengthen the analysis of the main controlling geological factors affecting the production effect after gas well fracturing, and provide a convenient and quantifiable well type selection method, which makes up for the shortcomings of the existing methods. A series of well type optimization plates corresponding to different horizontal well and vertical well production increase ratios are established, and the numerical value of the reserve concentration is reflected on the well type selection plate for the first time, which is convenient for the selection of well types in multi-layer tight gas reservoirs. Using the well type optimization plate, the suitable well type can be determined according to the reservoir permeability, total effective thickness of the reservoir and the reserve concentration of the known formation, realizing the quantification of the well type selection index, providing a basis for the efficient and convenient selection of well types, and having positive significance for improving the reserve utilization degree and development efficiency of tight gas reservoirs.

[0123] In an optional embodiment, the evaluation parameters include dynamic reserves of gas wells: the gas well production capacity evaluation is carried out on the research block of tight sandstone gas reservoir based on the pre-acquired evaluation parameters to obtain the gas well productivity evaluation result, including:

[0124] According to the production characteristics of tight gas wells in the study area, based on the preset gas well dynamic reserves evaluation method, the dynamic reserves of gas wells in the study area are determined, and the size of the gas well dynamic reserves of a single well is used as an indicator to evaluate the long-term production capacity of the fracturing well, and the gas well productivity evaluation result is obtained.

[0125] The production capacity of gas wells is evaluated. For tight gas reservoirs, the open-flow rate varies greatly in different production stages. The single use of open-flow rate for comparison cannot accurately reflect the long-term production capacity of gas wells. By analyzing the dynamic reserves and the later production capacity of gas wells, the dynamic reserves can better reflect the long-term production capacity of gas wells. The single-well controlled dynamic reserves are introduced as the main indicator for evaluating the long-term production effect after gas well fracturing. On this basis, the factors affecting the production capacity of gas wells are analyzed and evaluated. The production characteristics of reservoirs and tight gas wells in the study area are as follows: (1) The reservoirs are low-permeability and dense, and the pressure recovery time is long. There is a big contradiction between shut-in pressure measurement and gas field production, and there is a lack of pressure test data; (2) The production of gas wells varies greatly, and the stable production capacity of most wells is poor; (3) The production system of gas wells is unstable and the number of wells is large, so it is difficult to fully apply conventional dynamic reserve evaluation methods. According to the production characteristics of tight gas wells in the study area and the applicability analysis of various methods, the modern production instability analysis method and the production decline method are selected as the main methods for evaluating the dynamic reserves of gas wells. The dynamic reserves of gas wells in the study area are determined, and the size of the dynamic reserves of the gas wells in a single well is used as an indicator for evaluating the long-term production capacity of fracturing wells. In the past, the production capacity of gas wells was often evaluated by open flow rate, but open flow rate cannot represent the long-term production capacity of gas wells. Gas wells with high open flow rate in the initial stage may not have high cumulative gas production in the later stage. The final cumulative gas production is still the measure of the long-term production capacity of gas wells. The dynamic reserves multiplied by the preset coefficient can get the cumulative gas production. Judging by the size, the larger the dynamic reserves of a single well, the stronger the long-term production capacity of the fracturing well.

[0126] In an optional embodiment, the above-mentioned multi-layer tight gas reservoir numerical simulation model is established by the following method:

[0127] S1031, obtaining gas field geological parameter data, gas reservoir fluid seepage related data and gas well production parameters from the actual data of the gas field; wherein the gas field geological parameter data include production layer distribution, gas reservoir porosity, permeability and gas saturation, the gas reservoir fluid seepage related data include gas density, water density, PVT data, gas-water relative permeability data and rock compression coefficient, and the gas well production parameters include vertical wellbore position, horizontal wellbore position, vertical well production production data and horizontal well production production data;

[0128] The average length of the horizontal section of all wells in the study area is calculated to obtain the horizontal section length of the above-mentioned horizontal wells.

[0129] S1032, establishing a multi-layer tight gas reservoir numerical simulation model based on the gas field geological parameter data, the gas reservoir fluid seepage related data and the gas well production parameters;

[0130] S1033. Select different reservoir permeabilities, different total effective reservoir thicknesses, different horizontal well layer reserve concentrations, and different well type combinations to obtain a numerical simulation model of a multi-layer tight gas reservoir with different well types under different reservoir conditions.

[0131] In an optional embodiment, the above step S106 calculates the reservoir permeability corresponding to the selected increase ratio under different combinations of total effective thickness and reserve concentration according to the increase ratio under each combination of conditions, including:

[0132] For each combination of total effective thickness and reserve concentration of each reservoir in each combination of conditions:

[0133] S1061, fitting a second relational expression between reservoir permeability and production increase ratio according to the production increase ratio corresponding to different reservoir permeabilities under the combination of the total effective thickness of the reservoir and the reserve concentration;

[0134] For example, when the total effective thickness of the reservoir is 12 m and the reserve concentration is 50%, the data points of the increase in production ratio corresponding to different reservoir permeabilities when the total effective thickness of the reservoir is 12 m and the reserve concentration is 50% in step S104 are selected for fitting to obtain the second relationship between the reservoir permeability and the increase in production ratio.

[0135] S1062. Calculate the reservoir permeability corresponding to the selected production increase ratio according to the second relationship.

[0136] The reservoir permeability calculation refers to selecting existing production increase multiple data points corresponding to different permeabilities, performing trend line regression on the data points (selecting the trend line with the highest fitting degree, and selecting the power function regression with the highest fitting degree in this case), and calculating through the regression relationship to obtain the permeability when the production increase multiple is a certain value. Specifically, substituting the selected production increase multiple into the second relationship can obtain the corresponding reservoir permeability.

[0137] In an optional embodiment, the second relationship between reservoir permeability and production increase ratio is obtained by fitting the production increase ratio corresponding to different reservoir permeabilities under the combination of the total effective thickness of the reservoir and the reserve concentration, including:

[0138] Select the data points of the production increase ratio corresponding to different reservoir permeabilities under the combination of the total effective thickness of the reservoir and the reserve concentration, use multiple methods to perform trend line regression on the data points, select the trend line with the highest fitting degree, and obtain the second relationship between reservoir permeability and production increase ratio. Among them, the multiple methods include: exponential regression, linear regression, logarithmic regression, polynomial regression and power function regression. Figure 6 As shown, it is the relationship curve between reservoir permeability and reserve concentration when the total effective thickness of the reservoir is 12m and the reserve concentration is 50%.

[0139] The reservoir permeability corresponding to the selected reserve concentration under the different total effective thickness of the reservoir in the above step S106 is calculated in the following way:

[0140] For each of the different combinations of total effective thickness of reservoirs and reserve concentrations, the total effective thickness of reservoirs is:

[0141] S201. Select reservoir permeability data points corresponding to different reserve concentrations under the total effective thickness of the reservoir, perform trend line regression on the data points, select the trend line with the highest fitting degree, and obtain a first relationship between reservoir permeability and reserve concentration.

[0142] The relationship between reservoir permeability and reserve concentration refers to selecting permeability data points corresponding to different existing reserve concentrations under different total reservoir effective thicknesses, performing trend line regression on the data points (selecting the trend line with the highest degree of fit, and this time selecting the power function regression with the highest degree of fit), and obtaining a regression equation, which is the relationship between reservoir permeability and reserve concentration.

[0143] The above step S1061 determines the reservoir permeability corresponding to the selected increase ratio under each combination of total effective thickness of the reservoir and the reserve concentration. From the data set, for each total effective thickness of the reservoir, the reservoir permeability data points corresponding to different reserve concentrations under the total effective thickness of the reservoir are selected, and the first relationship between the reservoir permeability and the reserve concentration under the total effective thickness of the reservoir is obtained by fitting. Figure 5 As shown, it is the relationship curve between reservoir permeability and reserve concentration when the total effective thickness of the reservoir is 12m. The present invention adopts multiple fitting methods to perform trend line regression on the selected data points respectively, selects the trend line with the highest fitting degree, and obtains the regression relationship, which is the relationship between reservoir permeability and reserve concentration. The fitting methods can include exponential regression, linear regression, logarithmic regression, polynomial regression and power function regression.

[0144] S202. Calculate the reservoir permeability corresponding to the selected reserve concentration according to the first relationship.

[0145] Substituting the selected production increase times into the second relational equation, the corresponding reservoir permeability can be obtained by selecting the reserve concentration. According to the reservoir permeability corresponding to the selected reserve concentration under the total effective thickness of each reservoir, the corresponding well type optimization chart is established. Figure 8 As shown in the figure, it is the optimal well type chart under different reserve concentration when the production increase ratio is selected to be 2.5.

[0146] In an optional embodiment, the above step S107, according to the cost ratio of drilling horizontal wells and vertical wells in the planned drilling area, selects a corresponding target plate from the well type preferred plates under all selected production increase ratios, and determines the target well type according to the target plate, including:

[0147] S1071, selecting a corresponding target plate from among all well type optimization plates under the selected production increase ratio according to the cost ratio of drilling horizontal wells to drilling vertical wells in the planned drilling area;

[0148] The horizontal well cost and vertical well cost of each condition combination used to establish the well type optimization map are known, that is, the horizontal well and vertical well cost ratio is known. For each condition combination, the cost ratio under the condition combination is obtained, so as to correspond the cost ratio with the selected production increase ratio. When selecting the target map of the proposed drilling area, the well type optimization maps corresponding to drilling horizontal wells and drilling vertical wells in the proposed drilling area are screened from all the well type optimization maps under the selected production increase ratio to obtain the target map. Figure 7 and Figure 8 As shown, they are the optimization diagrams of well types under different reserve concentrations when the selected production increase ratio is 2.5 and the selected production increase ratio is 2.8.

[0149] S1072, projecting points in the target map according to the acquired effective reservoir thickness and reservoir permeability of the planned drilling area;

[0150] S1073, based on the obtained reserve concentration of the target layer in the planned drilling area, determining a corresponding reserve concentration curve in the target plate;

[0151] S1074. Determine the target well type according to the position of the investment point relative to the reserve concentration curve.

[0152] In an optional embodiment, determining the target well type according to the position of the injection point relative to the reserve concentration curve includes:

[0153] If the injection point is below the reserve concentration curve, the target well type is a horizontal well; if the injection point is above the reserve concentration curve, the target well type is a vertical well.

[0154] Embodiment 2

[0155] In order to make a clearer description of the well type determination method for a multi-layer tight sandstone gas reservoir provided by the embodiment of the present invention and verify the accuracy of the method, this embodiment will further illustrate the present invention with reference to four gas wells W1, W2, W3 and W4 in a multi-layer tight sandstone gas reservoir. Fig.10 described.

[0156] Step S301, conduct gas well production capacity evaluation. For tight gas reservoirs, the open-flow rate varies greatly in different production stages. The single use of open-flow rate for comparison cannot accurately reflect the long-term production capacity of the gas well. By analyzing the dynamic reserves and the later production capacity of the gas well, the dynamic reserves can better reflect the long-term production capacity of the gas well. The single-well controlled dynamic reserves are introduced as the main indicator for evaluating the long-term production effect after gas well fracturing. On this basis, the factors affecting the gas well production capacity are analyzed and evaluated. The production characteristics of reservoirs and tight gas wells in the study area are as follows: (1) The reservoir is low-permeability and tight, the pressure recovery time is long, the contradiction between shut-in pressure measurement and gas field production is large, and there is a lack of pressure test data; (2) The gas well production varies greatly, and the stable production capacity of most wells is poor; (3) The gas well production system is unstable and the number of wells is large, so it is difficult to fully apply the conventional dynamic reserve evaluation method. According to the production characteristics of tight gas wells in the study area and the applicability analysis of various methods, modern production instability analysis method and production decline method are selected as the main methods for evaluating the dynamic reserves of gas wells in the study area. The dynamic reserves of gas wells in the study area are determined, and the size of the dynamic reserves of a single well is used as an indicator for evaluating the long-term production capacity of fracturing wells.

[0157] Step S302, conduct an analysis of the main controlling geological factors of gas well productivity and determine the key geological parameters that affect the long-term production capacity of the gas well. Select parameters that have a significant impact on the fracturing gas well and are independent of each other as evaluation parameters, conduct single-factor productivity influencing factor analysis based on actual data, establish a typical tight gas reservoir fracturing vertical well and fracturing horizontal well numerical model based on gas well and reservoir parameters, and conduct multi-factor productivity influencing factor analysis through orthogonal experiments. The results show that the geological factors that have the greatest impact on gas well productivity are the total effective thickness of the reservoir and the permeability of the reservoir. The process of determining the main controlling geological factors can refer to the description in S102 above, which will not be repeated here.

[0158] Step S303, based on the analysis of factors affecting productivity and according to the actual data of the gas field, a multi-layer tight gas reservoir numerical model is established. The established model has three layers, including two types, a fractured vertical well production model and a fractured horizontal well production model. The vertical well runs through three layers, and each layer is perforated for production. The horizontal well is only produced in layer 3 (refer to Figure 4 shown).

[0159] Eclipse software, a commonly used numerical simulation software for oil and gas reservoirs in the oil and gas field development profession in the petroleum industry, was selected for model establishment and simulation. This model was established based on the relevant parameters of the Mizhi gas field, a typical tight gas reservoir in multiple layers. The Mizhi gas field has developed multiple gas-bearing strata, with the main strata being the Box 8 Group, the Shan 2 Group, and the Taiyuan Group. The model established for the gas field also corresponds to three strata, divided into two situations: fracturing vertical well production and fracturing horizontal well production. The actual production vertical wells penetrate the three strata, and each stratum is perforated for production. The horizontal wells are only produced in one of the strata. The established model also corresponds to three strata, of which the vertical wells penetrate the three strata, and each stratum is perforated for production. The horizontal wells are only produced in stratum 3. There are 18 horizontal wells in production in the gas field study area, with an average horizontal section length of about 1,100 meters and an average fracturing of seven sections. The horizontal well length of the established model is 1,100 meters and seven fracturing sections. Select different reservoir permeability (6 data points between 0.05-1mD), different total effective thickness of reservoir (5 data points between 4-20m), different horizontal well layer reserve concentration (4 data points between 25-100%), different well types (fractured vertical well, horizontal well) combination, establish 6×5×4×2=240 models, and obtain horizontal well and vertical well production data under different reservoir conditions. When establishing the model, the numerical simulation grid parameters are 700m in the plane x direction, 2100m in the y direction, 50m in the longitudinal z direction, and the grid size is 20×20×1m.

[0160] Step S304, calculate the reservoir permeability 0.05-1mD, the total effective thickness of the reservoir 4-20m (the specific numerical range can be determined according to the main range of reservoir physical property distribution in the study area), the horizontal well production layer reserve concentration 25%-100%, and the single well cumulative gas production when different main controlling geological factors change (reservoir permeability, total effective thickness of the reservoir). For example, the values ​​calculated in this example are shown in the following table (Table 5). According to the cumulative gas production of horizontal wells and vertical wells, calculate the production increase ratio under each combination of conditions.

[0161] Effective reservoir permeability (md) 0.05、0.2、0.4、0.6、0.8、1 Total effective thickness of reservoir (m) 4、8、12、16、20 Horizontal well layer reserve concentration (%) 25、50、75、100 Well Type Fracturing vertical wells, fracturing horizontal wells

[0162] Table 5

[0163] The calculation of the cumulative gas production is obtained by simulating different models using numerical simulation software. Based on the multi-layer tight gas reservoir numerical simulation model established in step S103, the parameters in Table 5 in step S304 are arranged and combined, the reservoir permeability includes 6 different values, the total effective thickness of the reservoir includes 5 different values, the reserve concentration includes 4 values, and there are 2 well types. A total of 6×5×4×2=240 models are established, and each model is simulated and calculated to obtain the cumulative gas production under different parameters.

[0164] Step S305, the cost of horizontal wells in the study area is 2.5 times that of vertical wells. Calculate the corresponding reservoir permeability when the production increase ratio is 2.5 under different total effective reservoir thicknesses and reserve concentrations. The production increase ratio value is selected based on the cost ratio of horizontal wells to vertical wells in the study area. For example, when the total effective thickness of the reservoir is 12m and the reserve concentration is 50%, select the production increase ratio data points corresponding to different reservoir permeabilities when the total effective thickness of the reservoir is 12m and the reserve concentration is 50% in step S304 (see Table 6), perform trend line regression on the data points, and select the trend line with the highest degree of fit. The trend line with the highest degree of fit this time is the power function regression (see Figure 5 The correlation coefficient reaches 0.9854. The power function trend line regression formula is used to calculate the corresponding reservoir permeability of 0.102mD when the production increase ratio is 2.5. In the same way, the total effective thickness and reserve concentration of other reservoirs are calculated, and the corresponding reservoir permeability when the production increase ratio is 2.5. Thus, the total effective thickness and reserve concentration of each reservoir are obtained, and the corresponding reservoir permeability when the production increase ratio is 2.5 is obtained.

[0165] In step S304, the total effective thickness of the reservoir in Table 1 has five values ​​of 4, 8, 12, 16, and 20, and the horizontal well stratum reserve concentration has four different values. There are 5×4=20 combinations of different total effective thickness of the reservoir and the horizontal well stratum reserve concentration. Each data combination corresponds to a reservoir permeability calculation formula, and there are 20 calculation formulas in total. One of the 20 combinations is selected here as an example for explanation, that is, the reservoir permeability calculation when the total effective thickness of the reservoir is 12m and the reserve concentration is 50%. Through the explanation in the example, the power function regression is obtained, referring to Figure 5 As shown, Figure 5 The power function formula of the regression is the reservoir permeability calculation formula. Substitute the value of the production increase ratio as x into the formula, and the calculated y value is the reservoir permeability corresponding to the production increase ratio. Similarly, for each combination, regressing the data points will obtain a power function formula, which are the reservoir permeability calculation formulas for other cases.

[0166]

[0167] Table 6

[0168] Step S306, calculating the reservoir permeability corresponding to the reserve concentration when the production increase ratio is 2.5 under different effective reservoir thicknesses.

[0169] First, determine the relationship between reservoir permeability and reserve concentration when the production increase ratio is 2.5 under different effective reservoir thicknesses. Select the reservoir permeability data points corresponding to the different reserve concentrations obtained in step S305 under different total effective reservoir thicknesses, and obtain them by performing trend line regression on the data points. For example, when the total effective reservoir thickness is 12m, select the reservoir permeability data points when the production increase ratio is 2.5 corresponding to the different reserve concentrations obtained in step S305 (Table 7), perform trend line regression on the data points, and select the trend line with the highest degree of fit. The trend line with the highest degree of fit this time is the power function regression (refer to Figure 6 As shown in Figure 2, the correlation coefficient reaches 0.9993. This power function regression relationship is the relationship between reservoir permeability and reserve concentration. The corresponding reservoir permeability is calculated by this formula when the total effective thickness of the reservoir is 12m and the reserve concentration ranges from 5% to 100%. Similarly, when regressing the total effective thickness of other reservoirs, the relationship curve between reserve concentration and reservoir permeability can be obtained, and the corresponding reservoir permeability can be obtained when the reserve concentration ranges from 5% to 100% when the total effective thickness of other reservoirs is 12m.

[0170]

[0171] Table 7

[0172] Graphs were drawn using the office software Excel, and trend lines were added to the data points. The trend line options included exponential, linear, logarithmic, polynomial, and power. Each regression method was tried, and the R-squared values ​​of the correlation coefficients of various regressions were compared. The power function regression had the highest correlation coefficient.

[0173] Step S307, plotting and establishing a chart based on the data points of reservoir permeability and reserve concentration under different total effective thickness of reservoirs obtained in step S306. Figure 7 As shown, this is the well type selection chart when the cost of a horizontal well is 2.5 times that of a vertical well (i.e., the production increase multiple).

[0174] Step S308, changing the production increase multiple value, and obtaining a series of charts under different horizontal well and vertical well cost multiples. For example, changing the production increase multiple value from 2.1, 2.2, and gradually increasing to 3.0, and obtaining a well type selection chart in which the horizontal well is 2.1, 2.2, and up to 3.0 times the vertical well cost. Figure 8 Well type selection chart for when the cost of a horizontal well is 2.8 times that of a vertical well.

[0175] Step S309, select a suitable chart according to the horizontal well to vertical well cost ratio, and determine the suitable well type. According to the reservoir permeability and total effective reservoir thickness of the gas well, find the corresponding point on the chart. When the reserve concentration value of the gas well is at the lower left of the corresponding reserve concentration curve on the chart, it is suitable for horizontal well development; when it is at the upper right of the curve, it is suitable for vertical well development. The parameters of W1-W4 wells are shown in Table 8. Mark W1-W4 wells on the chart according to the total effective reservoir thickness and reservoir permeability values ​​(refer to Fig. 9 As shown in the figure, Well W1 plans to deploy horizontal wells with a stratum reserve concentration of 57%. The data point of Well W1 is located in the upper right of the 57% reserve concentration line. From the figure, it can be judged that Well W1 is suitable for deploying vertical wells. Similarly, Well W2 plans to deploy horizontal wells with a stratum reserve concentration of 48%. The data point of Well W2 is located in the upper right of the 48% reserve concentration line. From the figure, it can be judged that Well W2 is suitable for deploying vertical wells. Well W3 plans to deploy horizontal wells with a stratum reserve concentration of 59%. The data point of Well W3 is located in the lower left of the 59% reserve concentration line. From the figure, it can be judged that Well W3 is suitable for deploying horizontal wells. Well W4 plans to deploy horizontal wells with a stratum reserve concentration of 73%. The data point of Well W4 is located in the lower left of the 73% reserve concentration line. From the figure, it can be judged that Well W4 is suitable for deploying horizontal wells.

[0176]

[0177] Table 8

[0178] Step S310, economic benefit judgment. Determine whether the well type determined according to the map can meet a certain preset yield condition, and determine whether to adopt this well type for development. According to the effective thickness of the reservoirs encountered by the vertical wells and horizontal wells that have been put into production in this study area and the EUR statistics, a 6% yield is achieved, and the effective thickness of the reservoirs corresponding to the horizontal wells is generally above 8m, and the effective thickness of the reservoirs corresponding to the vertical wells is generally above 12m. The total effective thickness of the reservoir of the W1 well is 7m, which is less than 12m, and does not meet the preset yield condition. The development benefit does not meet the requirements and is suitable for postponing development; the total effective thickness of the reservoir of the W2 well is 15.8m, which is greater than 12m, and meets the preset yield condition, which is suitable for vertical well development; the effective thickness of the reservoir in the horizontal well layer to be deployed in the W3 well is 7.85m, which is less than 8m, and does not meet the preset yield condition. The development benefit does not meet the requirements and is suitable for postponing development; the effective thickness of the reservoir in the horizontal well layer to be deployed in the W4 well is 14.45m, which is greater than 8m, and meets the internal rate of return condition, which is suitable for horizontal well development.

[0179] Embodiment 3

[0180] The embodiment of the present invention provides a device for determining the well type of a multi-layer tight sandstone gas reservoir, referring to Fig.11 As shown, including:

[0181] An evaluation module 401 is used to evaluate the gas well production capacity of a research block of a tight sandstone gas reservoir based on predetermined evaluation parameters to obtain a gas well production capacity evaluation result;

[0182] The analysis module 402 is used to determine the main controlling geological factors affecting the gas well productivity based on the gas well productivity evaluation result, according to the geological characteristics of the tight gas reservoir in the study area and the fracturing construction factors; the main controlling geological factors include the total effective thickness of the reservoir and the reservoir permeability;

[0183] Modeling module 403, used to establish a multi-layer tight gas reservoir numerical model based on actual data of the gas field;

[0184] The first calculation module 404 is used to calculate the cumulative gas production of different well types under different combinations of main controlling geological factors under different horizontal well production layer reserve concentrations based on the multi-layer tight gas reservoir numerical model; wherein the well types include horizontal wells and vertical wells;

[0185] The second calculation module 405 is used to calculate the production increase ratio under each condition combination according to the cumulative production of the horizontal well and the cumulative gas production of the vertical well;

[0186] The chart establishment module 406 is used for calculating, for each selected production increase ratio in the different selected production increase ratios determined in advance: the reservoir permeability corresponding to the selected production increase ratio under different combinations of total effective reservoir thickness and reserve concentration according to the production increase ratio under each combination of conditions; the reservoir permeability corresponding to the selected production increase ratio under different combinations of total effective reservoir thickness and reserve concentration according to the reservoir permeability corresponding to the selected production increase ratio, calculating the reservoir permeability corresponding to the selected reserve concentration under different total effective reservoir thickness, and establishing a well type optimization chart;

[0187] The target well type determination module 407 is used to select a corresponding target plate from all well type optimization plates under all selected production increase ratios according to the cost ratio of drilling horizontal wells and vertical wells in the planned drilling area, and determine the target well type according to the target plate.

[0188] In an optional embodiment, the device further comprises:

[0189] The judgment module 408 is used to obtain the effective thickness of the reservoir in the planned drilling area, and judge whether the effective thickness of the reservoir in the planned drilling area meets the preset yield condition corresponding to the target well type; if so, the target well type is used as the final development well type.

[0190] The implementation principle and technical effect of the device for determining the well type of a multi-layer tight sandstone gas reservoir provided in the embodiment of the present invention are similar to those of any of the aforementioned method embodiments, and will not be repeated here.

[0191] Embodiment 4

[0192] An embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the method for determining a well type of a multi-layer tight sandstone gas reservoir as described in any one of the aforementioned method embodiments is implemented.

[0193] The computer-readable storage medium may be included in the device / apparatus described in the above embodiment; or it may exist independently without being assembled into the device / apparatus. The above computer-readable storage medium carries one or more programs, and when the above one or more programs are executed, the method according to the embodiment of the present invention is implemented.

[0194] According to an embodiment of the present invention, the computer-readable storage medium may be a non-volatile computer-readable storage medium, for example, may include but is not limited to: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present invention, the computer-readable storage medium may be any tangible medium containing or storing a program, which may be used by or in combination with an instruction execution system, apparatus, or device.

[0195] Embodiment 5

[0196] An embodiment of the present invention provides an electronic device, referring to Fig.12 As shown, it includes a processor 111, a communication interface 112, a memory 113 and a communication bus 114, wherein the processor 111, the communication interface 112 and the memory 113 communicate with each other through the communication bus 114.

[0197] Memory 113, used for storing computer programs;

[0198] The processor 111 is used to implement the method for determining the well type of a multi-layer tight sandstone gas reservoir described in any one of the above method embodiments when executing the program stored in the memory 113.

[0199] The implementation principle and technical effect of the electronic device provided by the embodiment of the present invention are similar to those of any of the aforementioned method embodiments, and will not be repeated here.

[0200] The above-mentioned memory 113 can be an electronic memory such as a flash memory, an EEPROM (electrically erasable programmable read-only memory), an EPROM, a hard disk or a ROM. The memory 113 has a storage space for program codes for executing any method steps in the above-mentioned method. For example, the storage space for program codes may include various program codes for implementing various steps in the above method respectively. These program codes can be read from or written into one or more computer program products. These computer program products include program code carriers such as hard disks, compact disks (CDs), memory cards or floppy disks. Such computer program products are usually portable or fixed storage units. The storage unit may have a storage segment or storage space arranged similarly to the memory 113 in the above-mentioned electronic device. The program code can be compressed, for example, in an appropriate form. Generally, the storage unit includes a program for executing the method steps according to an embodiment of the present invention, that is, a code that can be read by, for example, a processor 111, and when these codes are run by an electronic device, the electronic device performs the various steps in the method described above.

[0201] In this document, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. The orientation or position relationship indicated by the terms "upper", "lower", etc. is based on the orientation or position relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0202] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict. The present invention is not limited to any single aspect, any single embodiment, or any combination and / or permutation of these aspects and / or embodiments. Each aspect and / or embodiment of the present invention can be used alone, or in combination with one or more other aspects and / or other embodiments.

[0203] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for determining the well type of a multi-layer tight sandstone gas reservoir, characterized in that: include: Based on the pre-determined evaluation parameters, the gas well production capacity evaluation is carried out in the study block of tight sandstone gas reservoir to obtain the gas well productivity evaluation results; Based on the gas well productivity evaluation results, according to the geological characteristics of the tight gas reservoir in the study area and the fracturing construction factors, the main controlling geological factors affecting the gas well productivity are determined; the main controlling geological factors include the total effective thickness of the reservoir and the reservoir permeability; According to the actual data of the gas field, a multi-layer tight gas reservoir numerical model is established; Based on the multi-layer tight gas reservoir numerical model, the cumulative gas production of different well types under different combinations of main controlling geological factors and reserves concentration of different horizontal well production layers is calculated; wherein the well types include horizontal wells and vertical wells; According to the cumulative production of horizontal wells and vertical wells, the production increase ratio under each combination of conditions is calculated; For each of the predetermined different selected yield increase multiples: According to the production increase ratio under each combination of conditions, the reservoir permeability corresponding to the selected production increase ratio under different combinations of total effective reservoir thickness and reserve concentration is calculated; According to the reservoir permeability corresponding to the selected production increase ratio under the combination of different total effective thickness of the reservoir and the reserve concentration, the reservoir permeability corresponding to the selected reserve concentration under different total effective thickness of the reservoir is calculated, and a well type optimization chart is established; According to the cost ratio of drilling horizontal wells and vertical wells in the planned drilling area, a corresponding target plate is selected from the well type optimization plates under all selected production increase ratios, and a target well type is determined according to the target plate.

2. The method for determining the well type of a multi-layer tight sandstone gas reservoir according to claim 1, characterized in that: The method of calculating the reservoir permeability corresponding to the selected production increase ratio under different combinations of total effective reservoir thickness and reserve concentration according to the production increase ratio under each combination of conditions includes: For each combination of total effective thickness and reserve concentration of each reservoir in each combination of conditions: According to the production increase multiples corresponding to different reservoir permeabilities under the combination of the total effective thickness of the reservoir and the reserve concentration, a second relationship between the reservoir permeability and the production increase multiples is obtained by fitting; The reservoir permeability corresponding to the selected production increase ratio is calculated according to the second relationship.

3. The method for determining the well type of a multi-layer tight sandstone gas reservoir according to claim 2, characterized in that: The second relationship between reservoir permeability and production increase ratio is obtained by fitting the production increase ratio corresponding to different reservoir permeabilities under the combination of the total effective thickness of the reservoir and the reserve concentration, including: The production increase multiple data points corresponding to different reservoir permeabilities under the combination of the total effective thickness of the reservoir and the reserve concentration are selected, and trend line regression is performed on the data points using multiple methods. The trend line with the highest fitting degree is selected to obtain a second relationship between the reservoir permeability and the production increase multiple; wherein the multiple methods include: exponential regression, linear regression, logarithmic regression, polynomial regression and power function regression.

4. The method for determining the well type of a multi-layer tight sandstone gas reservoir according to claim 1, characterized in that: Under the different total effective thicknesses of the reservoirs, the reservoir permeability corresponding to the selected reserve concentration is calculated in the following way: For each of the different combinations of total effective thickness of reservoirs and reserve concentrations, the total effective thickness of reservoirs is: Selecting reservoir permeability data points corresponding to different reserve concentrations under the total effective thickness of the reservoir, performing trend line regression on the data points, selecting the trend line with the highest fitting degree, and obtaining a first relationship between reservoir permeability and reserve concentration; The reservoir permeability corresponding to the selected reserve concentration is calculated according to the first relationship.

5. The method for determining the well type of a multi-layer tight sandstone gas reservoir according to claim 1, characterized in that: The method of selecting a corresponding target plate from the well type optimization plates under all selected production increase ratios according to the cost ratio of drilling horizontal wells and vertical wells in the planned drilling area, and determining the target well type according to the target plate includes: According to the cost ratio of drilling horizontal wells and vertical wells in the planned drilling area, a corresponding target plate is selected from the well type optimization plates under all selected production increase ratios; According to the obtained effective thickness and permeability of the reservoir in the planned drilling area, points are cast in the target map; Based on the obtained target layer reserve concentration of the planned drilling area, determining a corresponding reserve concentration curve in the target plate; The target well type is determined according to the position of the injection point relative to the reserve concentration curve.

6. The method for determining the well type of a multi-layer tight sandstone gas reservoir according to claim 5, characterized in that: Determining the target well type according to the position of the injection point relative to the reserve concentration curve includes: If the injection point is below the reserve concentration curve, the target well type is a horizontal well; if the injection point is above the reserve concentration curve, the target well type is a vertical well.

7. The method for determining the well type of a multi-layer tight sandstone gas reservoir according to claim 1, characterized in that: The method further comprises: Obtaining the effective thickness of the reservoir in the planned drilling area, and determining whether the effective thickness of the reservoir in the planned drilling area meets the preset yield condition corresponding to the target well type; If satisfied, the target well type is used as the final development well type.

8. The method for determining the well type of a multi-layer tight sandstone gas reservoir according to claim 1, characterized in that: The multi-layer tight gas reservoir numerical simulation model is established in the following way: Obtaining gas field geological parameter data, gas reservoir fluid seepage related data and gas well production parameters from the actual data of the gas field; wherein the gas field geological parameter data include production layer distribution, gas reservoir porosity, permeability and gas saturation; the gas reservoir fluid seepage related data include gas density, water density, PVT data, gas-water relative permeability data and rock compression coefficient; the gas well production parameters include vertical well bore position, horizontal well bore position, vertical well production production data and horizontal well production production data; Based on the gas field geological parameter data, the gas reservoir fluid seepage related data and the gas well production parameters, a multi-layer tight gas reservoir numerical simulation model is established; By selecting different reservoir permeabilities, different total effective reservoir thicknesses, different horizontal well layer reserve concentrations, and different well type combinations, numerical simulation models of multi-layer tight gas reservoirs with different well types under different reservoir conditions were obtained.

9. The method for determining the well type of a multi-layer tight sandstone gas reservoir according to claim 8, characterized in that: The evaluation parameters include the dynamic reserves of the gas well: the gas well production capacity evaluation is carried out on the research block of the tight sandstone gas reservoir based on the pre-acquired evaluation parameters to obtain the gas well productivity evaluation results, including: According to the production characteristics of tight gas wells in the study area, based on the preset gas well dynamic reserves evaluation method, the dynamic reserves of gas wells in the study area are determined, and the size of the gas well dynamic reserves of a single well is used as an indicator to evaluate the long-term production capacity of the fracturing well, and the gas well productivity evaluation result is obtained.

10. A device for determining well type of multi-layer tight sandstone gas reservoir, characterized in that: include: An evaluation module is used to evaluate the gas well production capacity of the research block of the tight sandstone gas reservoir based on predetermined evaluation parameters to obtain a gas well production capacity evaluation result; An analysis module is used to determine the main controlling geological factors affecting the gas well productivity based on the gas well productivity evaluation results, according to the geological characteristics of the tight gas reservoir in the study area and the fracturing construction factors; the main controlling geological factors include the total effective thickness of the reservoir and the reservoir permeability; Modeling module, used to establish a multi-layer tight gas reservoir numerical model based on the actual data of the gas field; The first calculation module is used to calculate the cumulative gas production of different well types under different combinations of main controlling geological factors under different horizontal well production layer reserve concentrations based on the multi-layer tight gas reservoir numerical model; wherein the well types include horizontal wells and vertical wells; The second calculation module is used to calculate the production increase ratio under each combination of conditions based on the cumulative production of horizontal wells and the cumulative gas production of vertical wells; A chart establishment module is used for calculating, for each selected production increase ratio in different predetermined selected production increase ratios: according to the production increase ratio under each combination of conditions, the reservoir permeability corresponding to the selected production increase ratio under different combinations of total effective reservoir thickness and reserve concentration; according to the reservoir permeability corresponding to the selected production increase ratio under different combinations of total effective reservoir thickness and reserve concentration, the reservoir permeability corresponding to the selected reserve concentration under different total effective reservoir thickness is calculated, and a well type optimization chart is established; The target well type determination module is used to select a corresponding target plate from all well type optimization plates under all selected production increase ratios according to the cost ratio of drilling horizontal wells and vertical wells in the planned drilling area, and determine the target well type according to the target plate.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method for determining the well type of a multi-layer tight sandstone gas reservoir as described in any one of claims 1 to 9 is implemented.

12. An electronic device, characterized in that: It includes a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus; Memory, used to store computer programs; The processor is used to implement the method for determining the well type of a multi-layer tight sandstone gas reservoir as described in any one of claims 1 to 9 when executing the program stored in the memory.

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