Search

CN-122020998-A - Geothermal resource quantity estimation and evaluation method

CN122020998ACN 122020998 ACN122020998 ACN 122020998ACN-122020998-A

Abstract

The invention relates to the technical field of geothermal exploration, and particularly discloses a geothermal resource quantity estimation and evaluation method, which comprises the following steps of S1, defining a target geothermal zone, and establishing a three-dimensional conceptual geological model of the target geothermal zone based on multi-source data fusion; S2, determining the spatial form and parameters of a target thermal reservoir according to the three-dimensional conceptual geologic model, wherein the parameters comprise thermal reservoir area, thickness, porosity, rock density and rock specific heat capacity, S3, calculating the thermal reservoir capacity of the target thermal reservoir by adopting a volumetric method based on the three-dimensional conceptual geologic model and geothermal gradient data or borehole temperature measurement data, and S4, estimating the geothermal fluid producibility of the target thermal reservoir based on hydrogeological test data, geochemical data and the three-dimensional conceptual geologic model. The geothermal resource quantity estimation and evaluation method constructs a three-dimensional entity model capable of accurately describing heat storage heterogeneity and a heat control-water guide structure, and fundamentally solves the problem of excessive simplification of the traditional model.

Inventors

  • CHE LINLIN
  • LI SHUAI

Assignees

  • 中国地质大学（武汉）

Dates

Publication Date
20260512
Application Date
20260119

Claims (10)

  1. 1. The geothermal resource quantity estimation and evaluation method is characterized by comprising the following steps of: S1, defining a target geothermal zone, and establishing a three-dimensional conceptual geological model of the target geothermal zone based on multi-source data fusion; S2, determining the space morphology and parameters of the target thermal storage according to the three-dimensional conceptual geologic model, wherein the parameters comprise thermal storage area, thickness, porosity, rock density and rock specific heat capacity; s3, calculating the heat storage capacity of the target heat storage by adopting a volumetric method based on the three-dimensional conceptual geologic model and the geothermal gradient data or the borehole temperature measurement data; s4, estimating the geothermal fluid producibility of the target thermal reservoir based on hydrogeologic experimental data, geochemical data and the three-dimensional conceptual geologic model; s5, coupling the heat storage capacity and the geothermal fluid producible capacity, establishing a heat storage numerical model of the target geothermal zone by adopting a numerical simulation method, and correcting and verifying the model; and S6, setting different exploitation schemes based on the corrected thermal storage numerical model, and simulating and predicting the temperature field and pressure field change of thermal storage and the geothermal resource quantity dynamic change under the long-term exploitation condition to finish resource quantity estimation and sustainability evaluation.
  2. 2. The geothermal resource quantity estimation and evaluation method according to claim 1, wherein the process of establishing a three-dimensional conceptual geological model in step S1 specifically comprises: S1.1, collecting and interpreting data, namely collecting a geological map of a target geothermal area and a surrounding area, a borehole lithology log, geophysical exploration data, seismic reflection section interpretation results, magnetotelluric sounding data, geothermal field measurement data and remote sensing image linear construction interpretation results; S1.2, identifying key interfaces and elements, namely identifying and determining key geological interfaces and key geological elements for controlling a geothermal system structure based on the data of the step S1.1, wherein the key geological interfaces comprise a top plate and a bottom plate of a main thermal reservoir, a bottom boundary of a regional heat insulation cover layer and a top boundary of a deep heat source; S1.3, constructing a three-dimensional entity model under the constraint of multi-source data; And S1.4, assigning model geological properties, namely assigning initial geological properties to the model units according to lithology, construction position and geophysical inversion parameters on the basis of the three-dimensional entity model constructed in the step S1.3, wherein the initial geological properties comprise lithology type, initial porosity, initial permeability anisotropy and initial thermal conductivity.
  3. 3. The geothermal resource quantity estimation and evaluation method according to claim 1, wherein the step S1.3 specifically comprises the following sub-steps: S1.3.1, establishing a hierarchical structure framework, namely dividing a modeling area into a plurality of secondary structure blocks by taking the main heat control-water guide structure identified in the step S1.2 as a boundary, wherein primary water guide fractures penetrating through a cover layer and communicating a deep heat source and a shallow heat reservoir are used as primary boundaries for controlling vertical migration of fluid, and secondary fractures or lithology change zones for controlling lateral flow of fluid in the heat reservoir are used as secondary boundaries; S1.3.2, layer interface deterministic modeling, namely, for a key geological interface with continuous space spread and multiple data control points, adopting a deterministic interpolation algorithm to respectively generate triangular mesh curved surfaces of a thermal storage top plate, a thermal storage bottom plate and a thermal storage cover bottom boundary based on borehole uncovering data and seismic interpretation layer data; S1.3.3, construction-lithology cooperative random modeling, namely, for a region which is cut strongly by fracture or has severe lithology variation, adopting a random simulation method based on targets, firstly randomly generating fracture zone three-dimensional entities conforming to geological laws in a construction framework according to fracture occurrence and geophysical attribute bodies, and secondly, simulating spatial distribution of different lithology bodies in each block body separated by the fracture zone by using a sequential indication simulation method; S1.3.4, model fusion and three-dimensional entity generation, namely fusing the layered interface curved surface generated in the step S1.3.2 with the structure-lithology random implementation generated in the step S1.3.3, namely cutting the lithology body which is randomly simulated by taking the layered curved surface as constraint to ensure the correct sequence relation of stratum layers, and simultaneously embedding a primary water-guiding fracture entity model as an independent unit to form a final unified three-dimensional entity model, wherein the model is composed of three-dimensional body units with definite boundaries and respectively represents a cover layer, a thermal reservoir, a substrate, a water-guiding fracture zone unit serving as the independent modeling unit and different lithology bodies.
  4. 4. The method of claim 1, wherein in step S1.3.3, the target-based stochastic simulation method is constrained by dip, length, and density distribution functions of the fracture, and lithologic probability volumes generated by log data and seismic inversion data in conjunction with Kriging interpolation.
  5. 5. A geothermal resource quantity estimation and evaluation method according to claim 3, wherein in step S1.3.4, the initial permeability imparted to the water-conducting fracture zone unit is set to be highest in the direction parallel to the fracture strike, to be next highest in the direction perpendicular to the fracture face, and to be lowest in the other directions to characterize the strong anisotropy of its permeability.
  6. 6. The method for estimating and evaluating geothermal resource amount according to claim 1, wherein in step S1.2, the method for identifying major fracture or fracture zone comprises performing fault interpretation of the seismic reflection profile, and performing multi-evidence superposition analysis and three-dimensional visualization in combination with low-resistance anomaly zones in magnetotelluric sounding data and linear structures in remote sensing images to determine the position, occurrence, extension and intersection relationship with thermal reservoirs.
  7. 7. The method of estimating and evaluating geothermal resource amount according to claim 1, wherein in step S2, the determining spatial morphology and parameters of the target thermal storage specifically includes: Directly extracting the three-dimensional space shape, the distribution area and the thickness of the target thermal reservoir by utilizing the three-dimensional conceptual geological model; based on core experimental data, logging interpretation data or regional experience values, and in combination with lithology partitions in the model, porosity, rock density and rock specific heat capacity parameter values are given to the thermal storage units in the three-dimensional conceptual geological model.
  8. 8. The geothermal resource quantity estimation and evaluation method according to claim 1, wherein in step S3, the formula for calculating the thermal storage quantity by using the volumetric method is as follows: Wherein, the For the thermal storage capacity, n is the total number of the body units divided by the thermal storage three-dimensional solid model, For the volume of the i-th individual unit, For the density of the rock thereof, For the specific heat capacity of the rock thereof, For the purpose of its average temperature, the temperature of the material, As a result of the reference temperature, For its effective thermal storage coefficient.
  9. 9. The geothermal resource quantity estimation and evaluation method according to claim 1, wherein in step S4, the geothermal fluid producible quantity of the target thermal reservoir specifically comprises calculating permeability coefficient, water storage coefficient and water guide coefficient of the thermal reservoir based on pumping test data, and taking the permeability coefficient, water storage coefficient and water guide coefficient as a basis for carrying out partition correction on permeability and water storage rate attributes of corresponding body units in the three-dimensional conceptual geological model; Analyzing the cause, the supply source and the circulation path of the geothermal fluid by combining the deep heat storage temperature estimated by the geochemical temperature scale and the chemical composition of the geothermal fluid; And taking the three-dimensional conceptual geologic model and the initial geologic attribute thereof as a basic hydrogeologic structure model, adopting a numerical simulation method, and determining the geothermal fluid producible amount of the target thermal storage through trial-and-error optimization under the conditions of setting allowable water level deep and planning mining years.
  10. 10. The geothermal resource quantity estimation evaluation method according to claim 1, wherein in step S5, the correcting and verifying the model specifically comprises: using historical geothermal fluid water level dynamic, wellhead temperature and water chemistry observation data or short-term exploitation test data as constraint conditions for model dynamic correction; The permeability, the water storage rate and the boundary flow parameters of a fracture zone and lithology units in the model are adjusted through an automatic history fitting algorithm, so that the water level and temperature dynamic curves obtained through simulation are matched with the observed data within a set error range; And predicting and verifying the fitted model by adopting an independent observation data group which does not participate in history fitting, and confirming the reliability of the model.

Description

Geothermal resource quantity estimation and evaluation method Technical Field The invention relates to the technical field of geothermal exploration, in particular to a geothermal resource quantity estimation and evaluation method. Background The conventional volumetric method is simple and simplified, complex heat Chu Gai is converted into a homogeneous model, experimental parameters are relied on, only static storage capacity can be estimated, sustainable mining potential cannot be estimated, but the dynamic method based on numerical simulation can simulate the mining process, but reliability is severely limited by the precision of an initial conceptual model, the conventional modeling means is difficult to fully utilize multi-source exploration data to finely describe a heat storage three-dimensional structure, non-uniformity and key control water-guiding structure, so that actual deviation between the model and geology is large, correction is difficult, and uncertainty of a prediction result is high. The existing method has fundamental contradiction between the roughness of static estimation and the high requirement of dynamic simulation on a basic model, and a new method capable of deeply fusing geological geophysical data, constructing a high-precision three-dimensional geological model and realizing integrated accurate evaluation from static reserves to dynamic sustainability is needed. Disclosure of Invention In order to solve the technical problems, the invention provides a geothermal resource quantity estimation and evaluation method, which comprises the following steps: S1, defining a target geothermal zone, and establishing a three-dimensional conceptual geological model of the target geothermal zone based on multi-source data fusion; S2, determining the space morphology and parameters of the target thermal storage according to the three-dimensional conceptual geologic model, wherein the parameters comprise thermal storage area, thickness, porosity, rock density and rock specific heat capacity; s3, calculating the heat storage capacity of the target heat storage by adopting a volumetric method based on the three-dimensional conceptual geologic model and the geothermal gradient data or the borehole temperature measurement data; s4, estimating the geothermal fluid producibility of the target thermal reservoir based on hydrogeologic experimental data, geochemical data and the three-dimensional conceptual geologic model; s5, coupling the heat storage capacity and the geothermal fluid producible capacity, establishing a heat storage numerical model of the target geothermal zone by adopting a numerical simulation method, and correcting and verifying the model; and S6, setting different exploitation schemes based on the corrected thermal storage numerical model, and simulating and predicting the temperature field and pressure field change of thermal storage and the geothermal resource quantity dynamic change under the long-term exploitation condition to finish resource quantity estimation and sustainability evaluation. Preferably, the process of establishing the three-dimensional conceptual geological model in the step S1 specifically includes: S1.1, collecting and interpreting data, namely collecting a geological map of a target geothermal area and a surrounding area, a borehole lithology log, geophysical exploration data, seismic reflection section interpretation results, magnetotelluric sounding data, geothermal field measurement data and remote sensing image linear construction interpretation results; S1.2, identifying key interfaces and elements, namely identifying and determining key geological interfaces and key geological elements for controlling a geothermal system structure based on the data of the step S1.1, wherein the key geological interfaces comprise a top plate and a bottom plate of a main thermal reservoir, a bottom boundary of a regional heat insulation cover layer and a top boundary of a deep heat source; S1.3, constructing a three-dimensional entity model under the constraint of multi-source data; And S1.4, assigning model geological properties, namely assigning initial geological properties to the model units according to lithology, construction position and geophysical inversion parameters on the basis of the three-dimensional entity model constructed in the step S1.3, wherein the initial geological properties comprise lithology type, initial porosity, initial permeability anisotropy and initial thermal conductivity. Preferably, the step S1.3 specifically includes the following substeps: S1.3.1, establishing a hierarchical structure framework, namely dividing a modeling area into a plurality of secondary structure blocks by taking the main heat control-water guide structure identified in the step S1.2 as a boundary, wherein primary water guide fractures penetrating through a cover layer and communicating a deep heat source and a shallow heat reservoir are used as primary boundarie