GB/T 11615-2026Geological exploration standard for geothermal resources (English PDF)

4.1 Purpose

The main objectives of geothermal resource geological exploration include.

a) Based on the investigation of the geothermal geological background, determine the areas where geothermal resources can be developed and utilized, and the reasonable depth for development and utilization;

b) Determine the lithology, spatial distribution, effective porosity, permeability, productivity, and correlation with fault structures of the geothermal reservoir;

c) Investigate the lithology, thickness variation, sealing effect on the geothermal reservoir, and geothermal warming rate of the caprock;

d) Determine the temperature, occurrence state, physical properties, and chemical composition of the geothermal fluid, and evaluate its potential utilization.

e) Investigate the characteristics of the geothermal hydrodynamic field, recharge and discharge conditions, calculate and evaluate geothermal resource reserves, and propose sustainable development and utilization strategies for geothermal resources. Recommendations;

f) Conduct research and dynamic monitoring of geothermal water reinjection;

g) To provide data on geothermal resources, including reserves and exploitable quantities, as well as the necessary geological information, for the development and protection of geothermal resources, in order to reduce the burden of development. risk.

4.2 Basic Requirements

4.2.1 Geothermal resource exploration work shall be carried out in stages according to the principle of gradual progress, and shall be divided into general survey, detailed survey and exploration according to the level of work from low to high.

Three stages; for geothermal fields or regions that have already been exploited on a large scale, exploitation evaluation work should be carried out in light of the problems that have arisen during exploitation and the needs of resource management.

4.2.2 Geothermal resource assessment should estimate geothermal resource reserves and exploitable quantities. Geothermal resource reserves are not classified, and exploitable quantities are... The corresponding geothermal exploration stages (general survey, detailed survey, exploration) are divided into three levels from low to high. inferred (Level D), controlled (Level C), and proven (Level B).

The recoverable quantity corresponds to the verification accuracy (Level A) in the exploitation evaluation stage. The classification of geothermal resource reserves and the accuracy grading of recoverable quantities should conform to... Table A.1 in Appendix A.

4.2.3 Before commencing exploration work, comprehensive geological, geothermal, drilling, geophysical, and geochemical data should be collected and analyzed, and an exploration implementation plan should be prepared. plan.

4.2.4 Exploration boreholes should be laid out based on geological surveys, geophysical and geochemical explorations, and the boreholes should preferably be laid out according to the principle of "integration of exploration and extraction".

Then design. Drilling operations should be carried out according to the design technical requirements, obtaining complete and accurate geological and geothermal parameter data, and completing geological logging;

If conditions permit, wells should be drilled in accordance with the technical requirements for geothermal production wells.

4.2.5 For geothermal extraction areas that have reached a certain scale of extraction, exploration data should be summarized and analyzed in a timely manner to assess geothermal resource reserves.

The calculation and evaluation process yields a corresponding geothermal resource exploration and evaluation report, providing a basis for the scientific formulation of geothermal resource development and utilization plans or schemes.

4.2.6 For geothermal concentrated extraction areas that have already been put into large-scale extraction, their exploitable volume should be verified and assessed every 5 years based on dynamic monitoring data.

The price provides a basis for resource management and protection, and for ensuring the sustainable use of resources.

4.2.7 The results of different exploration stages should meet the requirements of the corresponding design stages. The basis for large-scale development and utilization of geothermal resources should... For the proven recoverable quantities submitted during the exploration phase, with a precision level of B or higher; for medium-sized or small-sized geothermal fields with simple geothermal geological conditions.

For individual geothermal well exploration, the exploration stages can be simplified or combined according to the actual situation. The basis for development and utilization should be a control accuracy of (Level C) or above. Other recoverable reserves.

5.1 Geothermal resource temperature classification and reservoir type

5.1.1 Geothermal resource temperatures are divided into three levels. high temperature, medium temperature, and low temperature (see Table 1).

5.2 Research Content

5.2.1 Geological Research

5.2.1.1 Study the stratigraphy, structure, magmatic (volcanic) activity, and geothermal displays of the geothermal field to determine the reservoir, caprock, heat-controlling structures, and reservoir type. Types, geothermal water sources, etc.

5.2.1.2 Conduct targeted geological surveys and geophysical and geochemical explorations in the surrounding and related areas of the geothermal field to study the geothermal field morphology.

The geological background of the formation and the dynamic field, temperature field and circulation path of geothermal fluids.

5.2.1.3 Systematically investigate surface thermal indications and well (borehole) temperatures, determine the extent of geothermal anomaly zones, and analyze the causes and conditions of geothermal anomaly zones.

5.2.1.4 Determine the extent, reservoir, caprock, geothermal fluid channels, geothermal field, and boundary conditions of the geothermal field, and determine the geothermal field's geological characteristics. Thermal geological model.

5.2.1.5 Study the geological environmental conditions for the formation of geothermal resources, and the potential impacts of developing geothermal resources on the geological environment.

5.2.2 Geothermal Field Study

5.2.2.1 Investigate the geothermal variations at different depths and in different areas of the exploration zone, and determine the geothermal warming rate and thermal properties of the isothermal zone depth, reservoir, and caprock.

The temperature of the reservoir is studied to determine the characteristics of the geothermal field within the exploration area and to delineate the extent of the geothermal field.

5.2.2.2 Estimate the reservoir temperature using the geothermal warming rate or geochemical temperature scale (see Appendix B), and analyze the genesis, heat-controlling structures, and heat sources of the geothermal field. Make analyses and inferences.

5.2.3 Thermal Storage Research

The lithology, thickness, burial depth, distribution, interrelationships, and boundary conditions of each geothermal reservoir were investigated, and the porosity and effective porosity of each reservoir were determined.

Parameters such as elastic water release coefficient, permeability coefficient, pressure conduction coefficient, and pressure head height are used to study major thermal reservoirs or those with near-term development and utilization value. Value thermal storage permeability.

5.2.4 Geothermal Fluid Research

5.2.4.1 Determine the temperature, phase, steam-to-water ratio (steam dryness), and non-condensable gas composition of the geothermal fluid during discharge to facilitate the development of geothermal resources.

It provides a basis for development, utilization, and environmental impact assessment.

5.2.4.2 Determine the physical properties and chemical composition, microbial content, isotopic composition, useful components, and harmful components of geothermal fluids to evaluate their properties.

The possible uses of thermal fluids provide a basis for material selection in design.

5.2.4.3 Measure the pressure and production characteristics of geothermal fluids in various geothermal wells (holes), and study the relationship between geothermal fluids and atmospheric precipitation, ambient temperature groundwater, and different... The interrelationships of geothermal fluids in the geothermal reservoir are analyzed, including their sources, storage, migration, and discharge conditions.

5.2.4.4 Study the dynamic changes in temperature, pressure, yield and chemical composition of geothermal fluids.

5.3 Work Contents at Each Stage of Exploration

c) Conduct geothermal multi-well and multi-well depressurization (blowout) tests to understand inter-well interference and hydrodynamic field changes, in order to determine the appropriate... This provides a reliable basis for the rational layout of mining and production well groups;

d) Conduct single-hole or multi-hole reinjection test studies;

e) Improve dynamic monitoring practices and conduct continuous monitoring of geothermal fluid dynamics (injection and irrigation volume, head pressure, water temperature, and water quality) for more than two years. Research;

f) Based on the test results of multiple geothermal boreholes, annual dynamic monitoring data, and empirical parameters, use at least two methods to calculate, compare, and evaluate.

g) Five years after the completion of exploration, before large-scale development of exploration areas where the actual extraction volume is less than the recoverable volume of Grade B, geothermal fluid availability should be assessed.

5.3.1 Census

Conduct a general survey in areas with geothermal activity or where geothermal activity is planned for development.

a) Analyze existing geological, remote sensing interpretation, geophysical, geochemical, radioactive surveys, and other relevant geothermal resources in the study area. The survey area was determined based on the data;

b) Conduct a preliminary investigation of the stratigraphy, tectonics, and magmatic (volcanic) activity in the survey area, with a focus on geothermal outcrops (springs) and geothermal wells.

Thermal indicators are used to conduct field surveys and tests to infer the geothermal reservoir, caprock, water-conducting and heat-controlling structures, heat source, and water source in geothermal anomaly zones.

The scope of geothermal anomalies was delineated, and a conceptual model of geothermal reservoirs was proposed.

c) In areas with geothermal indications, determine the natural discharge and chemical composition of geothermal fluids, and estimate the reservoir temperature in geothermal anomaly zones. Geothermal resource reserves;

d) Establish dynamic monitoring points in areas with geothermal activity and conduct dynamic monitoring.

e) Estimate geothermal resource reserves, submit the recoverable reserves with an inference accuracy of D, assess the development and utilization prospects of geothermal anomaly areas, and prepare for detailed exploration. Provide a basis for the work.

5.3.2 Detailed Investigation

Based on the census work, detailed survey areas are determined. The following work should be carried out in the detailed survey areas.

a) To basically ascertain the lithology, thickness, and burial distribution of strata and igneous rocks in the area, and to identify faults and their occurrence, as well as the pore size of strata and igneous rocks.

The degree of development of fissures, cracks, karst and hydrothermal alteration, geothermal changes and geothermal gradients, and the classification of thermal reservoirs, caprocks, water-conducting and heat-controlling structures;

b) The basic lithology, thickness, and burial depth of the geothermal reservoir, the temperature, pressure, and production of geothermal fluids, and the effective porosity and permeability of the reservoir were determined. Identify the water and heat sources;

c) Conduct depressurization (venting) tests to obtain parameters and delineate areas rich in geothermal fluids;

d) Select representative locations to deploy exploration boreholes for drilling to verify the lithology, thickness, and burial depth of the geothermal reservoir, as well as the temperature and pressure of the geothermal fluids. Power, production capacity;

e) Conduct single-well reinjection test research;

f) Establish a preliminary numerical model of the geothermal reservoir and improve dynamic monitoring of geothermal fluid dynamics (production and irrigation volume, head pressure, water temperature, and water quality). Conduct monitoring and research to understand the annual dynamic characteristics;

g) Calculate geothermal resource reserves and submit recoverable quantities with control accuracy (Level C) to support exploration work and the planning of geothermal resource development and utilization. The overall plan provides the basis.

5.3.3 Exploration

The proposed mining area selected from the detailed geothermal survey is designated as the exploration area. The following work should be carried out in the exploration area.

a) Determine the stratigraphic structure, magmatic rock distribution, main heat-controlling structures, and water-conducting structures of the exploration area; as well as the lithology, thickness, and distribution of each geothermal reservoir. Burial conditions and their interrelationships;

b) Conduct geothermal drilling or combined exploration and production drilling projects to determine the geothermal warming rate of each reservoir and caprock, and the main characteristics of the reservoir (permeability).

Geothermal fluid properties, effective porosity, etc.; temperature, pressure, production, and chemical composition, etc.

Geothermal resource reserves, and submit the exploitable amount with proven accuracy (Level B), to provide a basis for the design scheme of geothermal resource development and utilization;

The amount of mining and its environmental impact will be reassessed.

5.4 Key Points of Exploration for Different Types of Thermal Reservoirs

5.4.1 Strip thermal reservoir

5.4.1.1 Based on geological surveys, and combined with geophysical and geochemical exploration, geothermal temperature measurements, geothermal anomaly zones or geothermal... The boundary of the field.

5.4.1.2 The morphology, scale, occurrence, mechanical properties and combination relationships of the main fault structures that control or influence the distribution of geothermal resources should be studied.

5.4.1.3 Geothermal wells should be drilled to penetrate the fault along the direction of its extension at fault intersections and on the hanging wall of major heat-controlling fault structures.

By identifying the geological fault zones, determining the geothermal fluid occurrence conditions, and obtaining parameters through depressurization tests, the exploitable amount of geothermal fluid in the geothermal field can be calculated and evaluated.

5.4.1.4 For natural hot springs controlled by fault structures, their exploitable volume is calculated and evaluated based on multi-year flow dynamic monitoring data.

5.4.2 Layered thermal reservoir

5.4.2.1 It is advisable to conduct geological surveys (mainly deep well temperature measurement surveys) to understand possible geothermal anomaly zones.

5.4.2.2 Based on geophysical exploration methods such as gravity, magnetics, electrical resistivity, and seismic surveys, determine the sedimentary thickness of loose strata or the burial of concealed bedrock.

Depth and distribution of major fault structures determine the scope of geothermal resource exploration.

5.4.2.3 Through deep geophysical exploration on the profile, we can gain a detailed understanding of the deep stratigraphic structure and the burial depth of the main thermal reservoirs.

5.4.2.4 Based on the results of geothermal well drilling and new insights, conduct exploration in peripheral areas and gradually expand the exploration scope.

5.4.2.5 Calculate and evaluate the exploitable amount of geothermal fluid based on extraction and irrigation test data and dynamic monitoring data of extraction.

5.4.2.6 A detailed study should be conducted on the stratigraphic structure and the variation of geothermal gradient with depth and strata to classify the reservoir and caprock. Emphasis should be placed on studying the rocks within each reservoir.

The influence of properties, thickness, distribution, thermal conductivity, and important fracture structures on the connectivity of geothermal reservoirs and the controlling effect on geothermal fluid temperature was investigated to identify the main geothermal reservoirs. Delineate geothermal fluid enrichment zones (belts).

6.1 Geological Survey

The accuracy requirements for geothermal geological surveys should conform to Table A.2, and the main requirements are as follows.

a) During the geothermal resource general survey phase, the geological survey scale for geothermal resources shall be no less than 1/200,000;

b) The working scale for the detailed investigation phase shall be no less than 1/100,000;

c) The working scale during the exploration phase shall be no less than 1/50,000;

d) The working scale for the mining evaluation stage shall be no less than 1/50,000.

6.2 Geophysical Exploration

6.2.1 The geothermal resource survey stage mainly focuses on collecting regional geophysical exploration data.

6.2.2 The detailed investigation and exploration phases primarily utilize area geophysical exploration. The exploration area should be equal to or slightly larger than the geological survey area, and the geophysical exploration lines should be perpendicular to the ground.

The main structural trend and the detailed profile should be determined by the location of the proposed geothermal well, and the exploration depth should be greater than the depth of the proposed geothermal well.

6.2.3 During the exploitation evaluation stage, geophysical exploration can be conducted at pre-set borehole locations and in directions perpendicular to the geological structure, according to the needs of well placement for geothermal resource exploitation. Examine the cross-section and conduct supplementary exploration.

6.2.4 The workload should meet the requirements of geophysical accuracy and exploration depth for the corresponding scale.

6.3 Geochemical Exploration

6.3.1 Select representative geothermal fluid samples from hot springs and other existing deep wells with geothermal indications in the exploration area for complete chemical analysis and isotopic analysis. Element test.

6.3.2 Representative rock samples were collected from surface travertine terraces and well core samples for complete petrochemical analysis and inductively coupled plasma spectroscopy and mass spectrometry.

Analytical or semi-quantitative spectral analysis. Sampling density and testing items should be increased as the exploration progresses.

6.3.3 The above chemical analysis results of water and rocks should be geochemically classified and calculated, including. fluid type, characteristic components, and component ratios.

In terms of rate, geochemical temperature scale, water-rock balance, isotope geochemistry, etc.

6.4 Geothermal Drilling

6.4.1 The deployment requirements for geothermal drilling projects are as follows.

a) Based on a thorough collection and analysis of existing geological, geophysical, and geochemical exploration data, select areas for geothermal resource exploration and development. Geothermal drilling projects will be deployed in representative locations.

b) To ascertain the type, distribution, burial conditions, and permeability of major geothermal reservoirs; the quality, temperature, and pressure of geothermal fluids; and the productive capacity of geothermal wells. The focus is on strength.

c) Exploration depth can be determined based on the main geothermal reservoir type, burial depth, current extraction technology and economic conditions, and market demand.

For exposed linear geothermal reservoirs, the exploration depth is generally controlled within 1,000 m; for concealed basin-type layered geothermal reservoirs, the exploration depth... Generally not exceeding 5,000 m.

d) Geothermal exploration should adhere to the principle of "integration of exploration and extraction." Where geothermal geological exploration boreholes have the potential for exploitation, well completion techniques should be followed.

Request for implementation; drilling geological logging, well logging, well completion testing, and geological data collection and processing for geothermal extraction wells, in addition to meeting well completion technical requirements.

In addition to implementation, all geothermal geological data should be collected accurately and completely in accordance with geological exploration requirements.

6.4.2 The drilling engineering control requirements shall be selected according to Table A.2, and there shall be at least one control well for each geological structural unit.

6.5 Geothermal reinjection

6.5.1 The deployment requirements for geothermal reinjection projects are as follows.

a) In geothermal exploration projects that primarily utilize thermal energy, geothermal reinjection tests should be conducted; single-well or multi-well tests should be completed during the exploration phase.

Recharge tests are conducted in multiple wells during the mining evaluation phase.

b) Geothermal reinjection uses geothermal raw water. If geothermal raw water is unavailable, other clean water sources can be used for reinjection. Reinjection should not damage the geothermal storage. It causes pollution.

c) Geothermal fields or geothermal extraction areas with high geothermal fluid salinity, declining geothermal head, and existing natural reinjection conditions should... Actively promote reinjection and implement a balanced extraction model that combines extraction and recharge, encompassing water, heat (energy), and chemical components.

6.5.2 The control requirements for the recharge project are as follows.

a) The depth and structure of the reinjection well and the production well should preferably be the same. A same-layer reinjection mode should be adopted to maintain the pressure of the exploited thermal reservoir.

b) Reinjection water should not enter the production well before it has reached the warming target in the reservoir.

c) Analyze the impact of geological structure, geothermal reservoir properties, reinjection volume, and temperature difference between extraction and reinjection water on reinjection.

d) The layout of geothermal reinjection wells should be integrated with the geothermal extraction wells, based on the results of reinjection tests, the reinjection capacity of the wells, and the need to maintain the extraction area.

The number of recharge wells needs to be determined to achieve irrigation balance.

7.1 Remote Sensing Interpretation

7.1.1 Remote sensing interpretation is mainly used to determine the following geothermal geological issues.

a) Basic outline of landforms, strata, geological structures, and concealed structures in geothermal areas;

b) Surface springs, spring clusters, geothermal overflow zones, and locations of surface heat signatures;

c) Distribution range of surface hydrothermal alteration zones;

d) Spatial distribution of deep temperature field and high temperature anomalies.

7.1.2 Remote sensing interpretation should precede geological surveys, primarily using aerial photograph interpretation, supplemented by aerial infrared measurements or satellite imagery when necessary.

Like interpretation. All interpretation results should be verified on-site along major stratigraphic boundaries and fault structures, or combined with ground geological and geophysical exploration work. The two sides will proceed together.

7.1.3 Perform comprehensive interpretation using remote sensing images from different times and bands. Pay attention to image quality and collect spectral characteristics of different geological bodies.

Establish direct and indirect interpretation markers for geological and geothermal geology. Utilize computer image processing.

7.1.4 Use large-scale aerial photographs, interpret them with an aerial stereoscope using a computer, and generate images using a stereoscopic plotter.

7.1.5 Submit interpretive maps and text descriptions at the appropriate scale.

7.2 Geological Survey

7.2.1 Geological surveys should be conducted based on full utilization of remote sensing interpretation and regional geological survey data. Their main tasks are.

a) Field verification of the difficulties in remote sensing interpretation;

b) Investigate the stratigraphic and lithological characteristics, geological structure, magmatic and neotectonic activity of the geothermal field, and understand the geological conditions of its formation. Geological background and structural conditions;

c) Determine the type, distribution, and scale of surface heat displays, and the relationship between geothermal anomaly zones (areas) and geological structures;

d) Analyze the recharge, runoff, and conditions of geothermal fluids.

7.2.2 The scope of the geological survey should include the relevant tectonic units. For zoned geothermal reservoirs, this should include geothermal anomaly zones (areas) and potential heat-controlling elements within the geothermal field.

Structural boundaries; layered geothermal reservoirs should be appropriately expanded according to the possible exploitation range, including areas with close relationships.

7.2.3 The accuracy of geothermal geological surveys shall be in accordance with the requirements of geological survey specifications of the same scale, based on the availability of a geological base map of the corresponding scale.

Geothermal geological surveys should be conducted, with a relatively relaxed density of survey points. Emphasis should be placed on surface thermal indications and deep drilling geological surveys.

7.3 Geophysical Exploration

7.3.1 Geophysical exploration should preferably be conducted during the detailed investigation and exploration phase of geothermal resources. The exploration scope should include relevant tectonic units and be combined with geothermal data. The well location has been determined.

7.3.2 Preliminary geophysical exploration has identified the following geothermal geological issues.

a) Delineate the extent of geothermal anomalies, the spatial distribution of geothermal reservoirs, and the boundaries of geothermal fields;

b) Delineate concealed magmatic rocks and their alteration zones;

c) Determine the spatial distribution of basement undulations and hidden faults;

d) Determine the stratigraphic structure, burial depth of the geothermal reservoir, and potential enrichment zones of geothermal fluids in the exploration area.

7.3.3 Geophysical exploration methods are selected based on the geological conditions of the geothermal field and the physical properties of the object being explored. In addition to using conventional electrical methods... In addition to methods such as seismic, magnetic, and gravity methods, artificial seismic and electromagnetic sounding methods (such as magnetotelluric sounding) with higher resolution or greater detection depth can also be selected.

Controlled-source audio magnetotelluric sounding, continuous magnetotelluric profiling, transient electromagnetic method, time-frequency electromagnetic method, artificial seismic sounding, and micro-motion sounding, etc. The specific method is determined according to Table A.2.

7.3.4 Use geothermal measurements to delineate geothermal anomaly zones; use gravity and magnetic methods to explore and detect the basement, fault structures, and distribution of igneous rocks in sedimentary basins. etc.; Controlled-source audio-frequency magnetotellurics (CSAMT) and wide-area electromagnetic methods (WFEM) were used to determine the lithology of concealed bedrock and the location of water-rich faults.

Determine the location of exploration boreholes; use micro-motion exploration (MSM) to probe deep low-velocity layers; use soil mercury and radon gas measurements to determine shallowly buried active deposits.

Dynamic fault structures; seismic exploration is used to accurately delineate stratigraphic structure, reservoir depth, and fault location and attitude. Exploration depth in tectonic uplift areas.

For buried conductive geothermal resources, a combination of CSAMT, WFEM, MSM, gravity, and magnetic methods is recommended; while for shallow convective geothermal resources, a more advanced method is preferred.

Using a combination of CSAMT, thermometry, and radon measurement, conductive porous geothermal resources were explored in sedimentary basin areas. This involved employing CSAMT, large-gap electrical sounding, and... Micro-motion combination; in the uplift and depression fault zone, explore composite geothermal resources by using CSAMT, MSM, and high-precision gravity combination.

7.3.5 Geophysical exploration shall be carried out in accordance with the specifications for various geophysical exploration work.

7.3.6 The interpretation and inference of geophysical exploration data should follow the principles of "from known to unknown, from qualitative to quantitative, and comprehensive interpretation and inversion interpretation".

Therefore, information technology should be used to improve the quality of geological interpretation.

7.4 Geochemical Exploration

7.4.1 Geochemical exploration should be conducted at each stage of geothermal resource exploration, employing a variety of geochemical exploration methods, including special geothermal fluid groups.

The investigation and analysis of [fluorine (F), silicon dioxide (SiO2), boron (B), hydrogen sulfide (H2S), etc.] and radon gas measurement were used to determine the distribution range of geothermal anomalies.

7.4.2 For representative geothermal fluids, geochemical samples should be collected, and appropriate samples of ambient-temperature groundwater, surface water, and atmospheric precipitation should also be taken.

The samples were used as controls to analyze their differences and relationships. Sample collection methods and requirements are detailed in Appendix C.

7.4.3 Determine stable and radioactive isotopes in representative geothermal fluids, ambient-temperature groundwater, surface water, and atmospheric precipitation to infer geothermal energy. The origin and age of fluids.

7.4.4 Calculate the geochemical temperature scale. Calculate the sodium/potassium (Na/K), chlorine/boron (Cl/B), chlorine/fluorine (Cl/F), and chlorine/silica ratios in geothermal fluids.

The ratio of components such as (Cl/SiO2) was determined, and water-rock balance calculations were performed to analyze the source of minerals in geothermal fluids and their formation conditions.

7.4.5 Sample and identify hydrothermal alteration minerals from surface rocks and geothermal well cores to analyze and infer the characteristics and evolution of geothermal activity. history.

7.4.6 The scale of geochemical exploration maps should be consistent with the scale of geological surveys.

7.5 Geothermal Drilling

7.5.1 The design, construction, geological logging during drilling, and various well completion tests of exploration wells should meet the requirements for determining the stratigraphic structure and geological features of the geothermal field.

Geological features, lithology, geothermal variations, reservoir permeability, geothermal fluid pressure and its physical and chemical properties were analyzed to obtain representative calculation parameters. need.

7.5.2 For exploration wells intended for development and utilization, the surface casing and technical casing of the well should be cemented. The depth and diameter of the surface casing should be specified.

The cementing should meet the requirements of the outer diameter of the pump and the long-term operation of the geothermal well; the cementing cement should be returned to the wellhead; the lower technical casing should be lowered to a certain depth in the geothermal reservoir.

Within a certain range, the cementing should fill the annular gap between the casing and the borehole wall to maintain casing stability and seal the aquifer above the thermal reservoir, preventing different... Contamination can occur due to cross-contamination between water reservoir layers. For medium- and low-temperature geothermal wells with casing exceeding 1000 m and relatively stable formations, cementing is necessary.

The height of the cement return can be less than the length of the technical sleeve, but the height should be greater than 500 m, and more cement needs to be pressed into the top of it, with a vertical thickness of [missing information].

The casing of a high-temperature geothermal well should be at least 100 m long. The casing of the well should be designed to accommodate blowout preventers, and the surface casing and technical casing should be cemented throughout the entire well section.

7.6.2 Capacity Testing

7.6.2.1 After well washing meets the requirements, a productivity test should be conducted, including a pressure reduction (blowout) test in the exploration well and a geothermal reinjection test. The results obtained through these tests should be used to determine the productivity of the well.

Parameters such as geothermal fluid pressure, production, temperature, extraction-to-injection ratio, and reservoir permeability. The purpose and requirements of productivity testing at each exploration stage. The specific procedures are as shown in Table 3.

8.1 Green Exploration

8.1.1 Basic Requirements

8.1.1.1 The requirements of green development and ecological environmental protection should be integrated into the entire process of geothermal resource geological exploration, and environmental impact should be minimized. control.

8.1.1.2 We should rely on scientific and technological and management innovation to minimize or mitigate the disturbance, pollution and damage to the ecological environment caused by exploration activities.

8.1.1.3 A sound green exploration management system and job responsibilities should be established, and the implementation plan for geothermal resource geological exploration should include relevant green exploration provisions. Content and requirements.

8.1.2 Exploration and Design

8.1.2.1 Before conducting the exploration and design, a field survey should be carried out to make a preliminary judgment on the potential ecological and environmental impacts and their extent.

8.1.2.2 In the exploration design, the relationship between the exploration objectives and tasks and ecological environmental protection should be taken into account, and appropriate exploration methods and techniques should be adopted.

The survey work should be rationally planned, taking into account the sections, equipment, processes, and new materials, and should also cover site selection, road alignment, material storage, waste disposal, and various other aspects.

Clear business and technical arrangements have been made for green exploration work in all aspects of the exploration activities, including engineering construction, and clear prevention and control measures and organizational structures have been formulated. Management measures.

8.1.2.3 Waste oil collection bins should be set up at the drilling site, and waste oil should be recycled or professionally disposed of; noise generated during construction should be... It meets the requirements of GB 3096.

8.1.2.4 Waste generated in the work area shall be disposed of in accordance with requirements. Garbage in the living quarters shall be collected separately, and hazardous waste shall be disposed of at designated locations.

The waste should be sent to a designated waste disposal site for treatment; […]