Method for evaluating development potential of regional thermal reservoir

Abstract

The application provides a method for evaluating development potential of a regional thermal reservoir, which is used for guiding comprehensive development of the regional thermal reservoir by combining historical geothermal well data with thermal reservoir analysis; the method is used for improving overall development benefit of the geothermal field and realizing efficient and low-cost development mode of the regional sandstone thermal reservoir geothermal resource by means of reservoir logging evaluation method and application technology research of the sandstone thermal reservoir; the research result is used for guiding comprehensive development of the regional thermal reservoir and is beneficial to large-scale development and utilization of the widely distributed sandstone thermal reservoir geothermal resource.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of geothermal development, and particularly relates to a regional geothermal reservoir development potential evaluation method. BACKGROUND

[0002] Geothermal resources are important energy minerals, high-temperature geothermal resources can be used for power generation, and medium and low-temperature geothermal resources can be directly utilized, and only a small amount of greenhouse gases is discharged in the development and utilization process. Therefore, reasonable development and utilization of geothermal resources have important significance for relieving energy constraints and environmental pressure, promoting energy structure adjustment and optimization, and improving the quality of economic growth.

[0003] In order to actively respond to the call of national energy saving and emission reduction, based on historical projects, the company has formed geothermal development and utilization technologies such as cascade utilization, comprehensive utilization, tail water purification and recharge, and shallow geothermal energy development. In Shaanxi sandstone geothermal tail water same layer recharge and large section test water development, a significant breakthrough has been made, and a single well exploitation and single well all recharge technical development mode has been built. After the geothermal water is used to transfer heat, it is all recharged underground, and the geothermal water quantity, pressure and flow direction are not changed, which effectively breaks through the bottleneck of sustainable development of geothermal resources.

[0004] The sandstone geothermal reservoir area in the Guanzhong Basin in Shaanxi is in the traditional forced heating area in China as a whole. With the development of regional economy, the demand for heating is increasing. Therefore, it is necessary to study the geothermal development potential. However, the traditional method only evaluates the potential of single well development. For example, the public number is: “CN115130795A” discloses a method for evaluating the development potential of single well geothermal reservoir, which is characterized in that it comprises the following steps: obtaining a plurality of evaluation parameters of the geothermal reservoir associated with the exploration stage and the numerical values thereof; determining the weight coefficient of each evaluation parameter according to the correlation degree between each evaluation parameter and the development potential of the geothermal reservoir; determining the development potential evaluation index of the geothermal reservoir according to the parameter value and the weight coefficient of each evaluation parameter; and determining the good or bad grade of the geothermal reservoir according to the evaluation index.

[0005] Due to the flowability of geothermal fluid itself and geological characteristics, the geothermal energy in the region is related to each other. If only single well is evaluated, it may cause chaos in the whole regional geothermal exploitation, so that the geothermal distribution is divided and flowed due to uneven exploitation and recharge problems, and the later exploitation is increased. SUMMARY

[0006] Therefore, the main purpose of the present application is to provide a regional geothermal reservoir development potential evaluation method.

[0007] The technical scheme adopted by the present application is as follows:

[0008] The application provides a regional thermal reservoir development potential evaluation method, which is used for guiding regional geothermal comprehensive development by combining historical geothermal well data with thermal reservoir analysis; and comprises the following steps:

[0009] Regional geological data are acquired, and the distribution regions of rough thermal insulation layers and heat conduction layers are obtained based on the analysis of the regional geological data;

[0010] A plurality of historical development geothermal wells are selected as standard wells in the rough distribution regions of the thermal insulation layers and the heat conduction layers, a regional thermal reservoir distribution comprehensive columnar section is established, and standard well sandstone aquifer characteristic data and geothermal fluid property data are obtained based on the historical data of the standard wells;

[0011] The standard wells are drilled to obtain core samples, so that the lithological data of different strata are analyzed, the standard well sandstone aquifer characteristic data and the geothermal fluid property data obtained based on the historical data are corrected based on the lithological data, sandstone aquifer characteristic correction data and geothermal fluid property correction data are obtained,

[0012] The sandstone aquifer characteristic correction data and the geothermal fluid property correction data are marked in the regional thermal reservoir distribution comprehensive columnar section;

[0013] The marker layers, stratum convolute sedimentary convolute characteristics and lithological thickness variation rules are used to divide small layer boundaries and sandstone correlation lines in the regional thermal reservoir distribution comprehensive columnar section, regional thermal reservoir distribution characteristics are obtained, and stratum division is compared to form a stratum layering data table and a small layer data table;

[0014] The sand bodies of the recharging wells and the production wells in the region are analyzed by using the regional thermal reservoir distribution characteristics and the stratum layering data table and the small layer data table, an analysis file is obtained, and the analysis file is used to determine the geothermal reservoir characteristics of different production layers in different well areas;

[0015] The regional thermal reservoir characteristics are divided based on the geothermal reservoir characteristics of different production layers in different well areas, and the regional geothermal comprehensive development is guided based on the regional thermal reservoir characteristics;

[0016] The marker layer is a marker with stable stratum plane distribution, obvious logging curve characteristics and easy-to-distinguish upper and lower strata;

[0017] The determination of the geothermal reservoir characteristics of different production layers in different well areas refers to different stratum porosities, permeabilities, porosity-permeability parameters and porosity-permeability properties of different marker wells.

[0018] Further, the logging curve characteristics are one or a combination of resistivity logging curve and natural gamma ray logging curve.

[0019] Further, the sandstone aquifer characteristic data includes: volume density, viscosity, compressibility and heat enthalpy of geothermal water; and storage coefficient, hydraulic conductivity coefficient, heat conduction coefficient and specific heat parameter of the aquifer.

[0020] Further, the geothermal fluid property data is a migration mode of the geothermal fluid, including a heat energy conduction migration mode and a migration mode with substance participation.

[0021] The present application improves the overall development benefit of the geothermal field by developing the reservoir logging evaluation method and application technology of the sandstone thermal reservoir, and realizes the efficient and low-cost development mode of the regional sandstone thermal reservoir geothermal resources. BRIEF DESCRIPTION OF DRAWINGS

[0022] The following drawings only schematically illustrate and explain the present application, and are not used to limit the scope of the present application, in which:

[0023] Figure 1 The method flowchart of the present application is shown in the figure;

[0024] Figure 2 The porosity distribution histogram of Xianyang region is shown in the figure;

[0025] Figure 3 The permeability distribution histogram of Xianyang region is shown in the figure;

[0026] Figure 4 The porosity distribution histogram of Wugong, Xingping and Zhouzhi regions is shown in the figure;

[0027] Figure 5 The permeability distribution histogram of Xingping, Wugong and Zhouzhi regions is shown in the figure;

[0028] Figure 6 The porosity distribution histogram of Xi'an region is shown in the figure;

[0029] Figure 7 The permeability distribution histogram of Xi'an region is shown in the figure. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme, design method and advantages of the present application more clear and explicit, the present application is further described in detail below in combination with examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0031] Referring to Figure 1 The present application provides a regional thermal reservoir development potential evaluation method, which is used for guiding the regional geothermal comprehensive development by using historical geothermal well data in combination with thermal reservoir analysis; and includes the following steps:

[0032] Obtaining regional geological data, and analyzing the regional geological data to obtain a rough distribution area of a thermal insulation layer and a thermal conduction layer;

[0033] Selecting a plurality of historical geothermal development wells as standard wells in the rough distribution area of the regional thermal insulation layer and the thermal conduction layer, establishing a regional thermal reservoir distribution comprehensive columnar section, and obtaining standard well sandstone aquifer characteristic data and geothermal fluid property data based on historical data of the standard wells;

[0034] Drilling and coring the standard wells to analyze lithological data of different strata, correcting the standard well sandstone aquifer characteristic data and the geothermal fluid property data based on the lithological data, to obtain corrected sandstone aquifer characteristic data and corrected geothermal fluid property data,

[0035] Marking marker beds in the regional thermal reservoir distribution comprehensive columnar section based on the corrected sandstone aquifer characteristic data and the corrected geothermal fluid property data;

[0036] Dividing small layer boundaries and sandstone correlation lines in the regional thermal reservoir distribution comprehensive columnar section by using the marker beds, stratum cyclothem rotation characteristics, and lithological thickness variation rules, obtaining regional thermal reservoir distribution characteristics, and comparing the stratum division to form a stratum layering data table and a small layer data table;

[0037] Analyzing sand bodies of injection wells and production wells in the region by using the regional thermal reservoir distribution characteristics and the stratum layering data table and the small layer data table, obtaining an analysis file, and determining different well area and different production layer geothermal reservoir characteristics by using the analysis file;

[0038] Dividing regional thermal reservoir characteristics based on the different well area and different production layer geothermal reservoir characteristics, and guiding regional geothermal comprehensive development based on the regional thermal reservoir characteristics.

[0039] Further, the marker bed is a marker bed with stable stratum plane distribution, obvious logging curve characteristics, and easy distinction from upper and lower strata.

[0040] Further, the logging curve characteristics are one or a combination of resistivity logging curve characteristics and natural gamma ray logging curve characteristics.

[0041] Further, the sandstone aquifer characteristic data include volume density, viscosity, compressibility, and heat enthalpy of geothermal water, and storage coefficient, water conductivity coefficient, heat conduction coefficient, and specific heat parameter of the aquifer.

[0042] Further, the geothermal fluid property data is a migration mode of geothermal fluid, including a heat energy conduction migration mode and a migration mode with material participation.

[0043] Further, the determining the geothermal reservoir characteristics of different production layers in different well zones refers to the porosity, permeability values, porosity-permeability parameters and porosity-permeability properties of different strata of different marker wells.

[0044] Example verification:

[0045] Taking the current well completion in the Lantian Bahe Group in Shaanxi, the Zhouzhi, Lintong region, Xianyang region as a reference, based on historical logging, geological, water testing, core analysis and test data, through the dissection of typical sandstone geothermal reservoirs in Shaanxi, combined with the idea of geology theory guiding logging evaluation, the research work of geothermal reservoir characteristics analysis, geothermal reservoir evaluation, productivity prediction, geothermal reservoir favorable area optimization and geothermal well pumping efficiency evaluation was carried out. Realize the optimization of geothermal reservoir single well sweet spot (geothermal enrichment area) and regional favorable area, and then realize the geothermal reservoir evaluation from point to plane, and realize the economic benefit development of geothermal field.

[0046] Figure 2 The porosity distribution histogram of Xianyang region is shown in the figure, Figure 3 The permeability distribution histogram of Xianyang region is shown in the figure; according to the statistical results of porosity and permeability distribution histogram, the porosity value of geothermal well in Xianyang region is mostly distributed in 20-25%, and part is greater than 25%, and the porosity is good; the permeability value is mostly distributed in 200-400 md, accounting for 60%.

[0047] Figure 4 The porosity distribution histogram of Wu Gong, Xingping and Zhouzhi region is shown in the figure, Figure 5 The permeability distribution histogram of Xingping, Wugong and Zhouzhi region is shown in the figure; according to the porosity and permeability parameters of the target layer of the existing geothermal well in Xingping, Wugong and Zhouzhi region, the porosity and permeability distribution histogram is drawn. The results show that the porosity value is mostly distributed in 15-20% in the three regions, and Wugong and Zhouzhi are slightly worse than Xingping; the permeability value is mostly distributed in <200 md, which is slightly worse than Xianyang region.

[0048] Figure 6 The porosity distribution histogram of Xi'an region is shown in the figure, Figure 7 The permeability distribution histogram of Xi'an region is shown in the figure, and the porosity and permeability distribution histogram is drawn according to the porosity and permeability parameters of the target layer of the existing geothermal well in Zhouzhi and Lintong region. The results show that the porosity of Xi'an and Lintong region is about 20%, and the porosity value of Lintong region is mostly distributed in 20-25%, and the permeability is mostly distributed in 200-300 md, and the overall physical property parameter is better than that of Xi'an region.

[0049] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for evaluating the development potential of regional thermal reservoirs, characterized in that, The method described above utilizes historical geothermal well data combined with reservoir analysis to guide the comprehensive development of regional geothermal resources; it includes the following steps: Obtain regional geological data, and analyze the data to obtain a rough distribution area of ​​the insulation and heat-conducting layers; In the rough distribution area of ​​the regional insulation and heat conduction layers, multiple historically developed geothermal wells were selected as standard wells to establish a comprehensive columnar profile of the regional thermal reservoir distribution. Based on the historical data of the standard wells, the characteristic data of the sandstone aquifer and the geothermal fluid properties of the standard wells were obtained. Standard wells are drilled and cored to analyze lithological data from different formations. Based on this lithological data, historical data on sandstone aquifer characteristics and geothermal fluid properties from the standard wells are corrected to obtain corrected sandstone aquifer characteristic data and corrected geothermal fluid property data. Based on the corrected data of sandstone aquifer characteristics and geothermal fluid properties, marker layers are marked in the comprehensive columnar profile of regional geothermal reservoir distribution. By utilizing marker layers, stratigraphic cyclic depositional cyclic characteristics, and lithological thickness variation patterns, sub-layer boundaries and sandstone correlation lines are delineated in the comprehensive columnar profile of regional geothermal reservoir distribution to obtain the regional geothermal reservoir distribution characteristics. The stratigraphic divisions are then compared to form stratigraphic stratification data tables and sub-layer data tables. The sand bodies of reinjection wells and production wells in the region are analyzed using regional geothermal reservoir distribution characteristics, stratigraphic stratification data tables, and sub-layer data tables to obtain analysis files. The analysis files are then used to determine the characteristics of geothermal reservoirs of different producing layers in different well areas. Regional geothermal reservoir characteristics are defined based on the characteristics of different producing layers in different well areas, and the regional geothermal comprehensive development is guided based on these regional geothermal reservoir characteristics; the marker layer is characterized by stable formation plane distribution, obvious logging curve characteristics, and easy differentiation from the upper and lower formations. Determining the characteristics of geothermal reservoirs in different well areas and producing layers refers to the porosity, permeability, porosity-permeability parameters, and porosity-permeability properties of different formations in different marker wells.

2. The method for evaluating the development potential of regional thermal reservoirs according to claim 1, characterized in that, The logging curve is characterized by one or a combination of resistivity logging curves and natural gamma logging curves.

3. The method for evaluating the development potential of regional thermal reservoirs according to claim 1, characterized in that, The characteristic data of the sandstone aquifer include: the bulk density, viscosity, compressibility and enthalpy of the geothermal water; as well as the aquifer's water storage coefficient, hydraulic conductivity, thermal conductivity and specific heat parameters.

4. The method for evaluating the development potential of regional thermal reservoirs according to claim 1, characterized in that, The geothermal fluid property data refers to the transport modes of geothermal fluids, including transport modes by heat conduction and transport modes involving matter.

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