An adaptive magma rock reservoir geothermal drilling simulation model construction method and system

Abstract

The application discloses a kind of simulation model construction methods of adapting magma rock reservoir geothermal drilling, specifically related to geothermal drilling simulation technical field, including collecting target well area lithology, fracture, temperature, rock mechanics and drilling response data, form basic feature information;Based on the basic feature information, a three-dimensional reservoir structure model is constructed to represent the lithology heterogeneity, fracture network and temperature-related physical properties, the heat-flow-solid coupling parameters and drilling boundary conditions are determined, the wellbore-reservoir coupling simulation model is established, and the measured drilling response information is used to correct the model.The method of the application can realize the information interaction between reservoir structure, wellbore state and multi-physical field, improve the adaptability and simulation accuracy of the simulation model to the actual geological conditions and drilling conditions of magma rock reservoir, and provide a reliable basis for drilling state prediction and parameter optimization.

Description

Technical Field

[0001] This invention relates to the field of geothermal drilling simulation technology, specifically to a method and system for constructing geothermal drilling simulation models adapted to magmatic reservoirs. Background Technology

[0002] Geothermal drilling is a crucial step in the development of deep geothermal resources. Igneous reservoirs typically exhibit characteristics such as lithological heterogeneity, well-developed natural fractures, and high formation temperatures. During drilling, wellbore pressure, drilling fluid temperature, and the state of the surrounding rock mass continuously change, thus requiring simulation models to analyze the drilling process.

[0003] Existing technologies typically establish reservoir models based on geological, logging, and rock property data, and use numerical simulation methods to calculate temperature, seepage, and stress fields. For fractured reservoirs, fluid migration and heat transfer processes can be characterized through fracture network models. Some methods further employ thermal-fluid-solid coupling or parameter inversion to improve model accuracy.

[0004] However, existing methods are still insufficient in comprehensively characterizing lithological differences, fracture spatial distribution, and temperature-related physical properties in magmatic reservoirs. Furthermore, they do not adequately consider the dynamic interactions of pressure, temperature, stress, and fracture conditions between the wellbore and reservoir during drilling, which can easily lead to discrepancies between simulation results and actual drilling responses. Therefore, a geothermal drilling simulation method that can be constructed and corrected by combining actual reservoir characteristics and measured drilling responses is needed. Summary of the Invention

[0005] To address the technical problems existing in the prior art, embodiments of the present invention provide a method and system for constructing a simulation model for geothermal drilling in magmatic rock reservoirs. The technical solution is as follows: A method for constructing a simulation model for geothermal drilling in magmatic rock reservoirs, comprising: Collect lithology, fracture, temperature, rock mechanics, and drilling response data of the target well area to form basic characteristic information; Based on the aforementioned basic feature information, a three-dimensional reservoir structure model is constructed to characterize lithological heterogeneity, fracture network, and temperature-related physical properties, thereby generating reservoir structure information. Based on the basic feature information and the reservoir structure information, the thermal-fluid-solid coupling parameters and drilling boundary conditions are determined to form model parameter information; A wellbore-reservoir coupled simulation model is established based on the reservoir structure information and the model parameter information. The wellbore-reservoir coupled simulation model is corrected using the measured drilling response information in the basic feature information to obtain a geothermal drilling simulation model adapted to the target well area.

[0006] As a further aspect of the present invention, the formation of basic feature information includes: Acquire geological interpretation data, logging data, core and rock test data, geothermal data, and drilling engineering data for the target well area; The data are correlated according to unified spatial coordinates, well depth benchmarks and time benchmarks, abnormal data are identified and missing data is supplemented; The lithology, fracture characteristics, temperature characteristics, rock mechanics characteristics, and drilling response characteristics are matched according to the corresponding well depth to form the basic feature information with well depth correspondence.

[0007] As a further aspect of the present invention, the construction of the three-dimensional reservoir structure model includes: Based on the aforementioned basic characteristic information, different igneous rock lithological zones, stratigraphic interfaces, and tectonic interfaces are identified, and a fracture network is constructed based on the spatial location, occurrence, scale, and development degree of the fractures. The lithological zones, stratigraphic interfaces, tectonic interfaces, and fracture networks are mapped to a unified three-dimensional space to form the three-dimensional reservoir structure model with lithological region identifiers and fracture region identifiers, and the corresponding reservoir structure information is generated.

[0008] As a further aspect of the present invention, the generation of reservoir structure information further includes: The three-dimensional reservoir structure model is spatially discretized, and the density of discrete units is increased in the wellbore adjacent area, fracture development area, lithological change area, and area where the temperature change gradient is greater than a preset gradient threshold. Establish an attribute mapping relationship between discrete units and the basic feature information, so that each discrete unit has a corresponding lithological identifier, fracture identifier, spatial location and temperature attribute, and summarize the attribute mapping relationship into the reservoir structure information.

[0009] As a further aspect of the present invention, the model parameter information includes: Based on the basic characteristic information and the reservoir structure information, thermal parameters, seepage parameters and rock mechanical parameters are determined for different lithological regions and fracture regions respectively; Based on the correspondence between temperature and rock physical properties, the thermal parameters, seepage parameters, and rock mechanical parameters are corrected for temperature correlation, and the parameter mapping relationship between the model parameters and each discrete unit in the three-dimensional reservoir structure model is established, thereby forming the model parameter information.

[0010] As a further aspect of the present invention, the determination of the drilling boundary conditions includes: Based on the aforementioned basic feature information, well trajectory, drilling depth, drilling pressure, rotation speed, drilling fluid discharge, drilling fluid inlet temperature, wellbore pressure, and formation temperature information are obtained. The spatial correspondence between the wellbore and the three-dimensional reservoir structure model is determined based on the wellbore trajectory. The drilling fluid flow boundary, wellbore pressure boundary, wellbore temperature boundary, and drill bit action boundary are then loaded to their respective spatial positions to form drilling boundary information, which is part of the model parameter information.

[0011] As a further aspect of the present invention, the establishment of the wellbore-reservoir coupling simulation model includes: Based on the reservoir structure information and the model parameter information, the solution relationships for the temperature field, seepage field and stress field are established respectively, and the information interaction relationship between each field is established. The pressure information generated by the seepage field is transmitted to the stress field, and the temperature information generated by the temperature field is transmitted to both the seepage field and the stress field. The flow properties of the crack region are updated based on the deformation information generated by the stress field, so that the updated flow properties continue to participate in the calculation of the temperature field and the seepage field, forming a closed-loop interaction of thermal-fluid-solid information.

[0012] As a further aspect of the present invention, the wellbore-reservoir coupling simulation model also includes an interactive interface between the wellbore and the reservoir; Based on the interactive interface, the pressure and temperature information of the drilling fluid in the wellbore is transmitted to the corresponding reservoir boundary, and the state of the drilling fluid in the wellbore is updated according to the fluid exchange and heat exchange information generated by the reservoir boundary. Simultaneously, drill bit-rock interaction information is generated based on drilling pressure, rotation speed, and rock mechanics parameters at the corresponding position of the drill bit. This drill bit-rock interaction information, together with the wellbore state, is used to generate simulation response information for the drilling process.

[0013] As a further aspect of the present invention, the corrected wellbore-reservoir coupling simulation model includes: Measured drilling response information is extracted from the basic feature information, and the measured drilling response information is compared with the simulation response information generated by the wellbore-reservoir coupling simulation model to obtain response deviation information. Based on the response deviation information, determine the model parameters to be adjusted that meet the preset conditions for affecting the simulation response, and iteratively correct the model parameters to be adjusted until the response deviation information meets the preset correction conditions, thereby obtaining the corrected wellbore-reservoir coupling simulation model.

[0014] As a further aspect of the present invention, obtaining a geothermal drilling simulation model adapted to the target well area includes: The measured drilling response information corresponding to the well section that did not participate in the model parameter correction was selected as the verification information. The verification information was compared with the simulation response information generated by the corrected wellbore-reservoir coupling simulation model to obtain the model verification information. When the model verification information meets the preset verification conditions, the corrected wellbore-reservoir coupling simulation model is determined as the geothermal drilling simulation model. When the preset verification conditions are not met, the model parameter information is readjusted based on the model verification information and model correction is performed.

[0015] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: In this invention, a three-dimensional reservoir model is constructed by integrating lithology, fractures, temperature, rock mechanics, and drilling response information of the target well area. This model considers lithological heterogeneity, fracture distribution, and temperature-related physical properties. A thermal-fluid-solid coupling relationship between the wellbore and the reservoir is established to achieve dynamic interaction of pressure, temperature, seepage, stress, and fracture status. At the same time, the model is corrected and verified by combining measured drilling responses, which improves the adaptability and simulation accuracy of the simulation model to the actual geological conditions and drilling conditions of magmatic reservoirs, and provides a reliable basis for drilling status prediction and parameter optimization. Attached Figure Description

[0016] Figure 1 This is an overall flowchart of a method for constructing a simulation model for geothermal drilling in magmatic reservoirs, provided in an embodiment of the present invention. Figure 2 This is a flowchart illustrating the construction process of the three-dimensional reservoir structure model and model parameter information provided in an embodiment of the present invention. Figure 3 The flowchart for wellbore-reservoir coupling simulation and model correction provided in the embodiments of the present invention is shown. Detailed Implementation

[0017] The following, in conjunction with the accompanying drawings and specific embodiments, further illustrates a method for constructing a simulation model for geothermal drilling in igneous rock reservoirs. This method is applicable to the construction of simulation models for the drilling process of geothermal wells in igneous rock reservoirs. It mainly considers the characteristics of igneous rock reservoirs, such as significant lithological heterogeneity, large differences in the degree of development of natural fractures, high temperatures in deep formations, and changes in rock properties with temperature. It unifies and correlates geological information, reservoir structure information, drilling engineering information, and actual drilling response information, and establishes a thermal-fluid-solid coupling relationship between the wellbore and the reservoir, thereby obtaining a geothermal drilling simulation model that can adapt to the actual geological conditions and drilling conditions of the target well area.

[0018] This method first collects lithology, fracture, temperature, rock mechanics, and drilling response data for the target well area, and processes data from different sources uniformly to form basic characteristic information. Then, using this basic characteristic information, a three-dimensional reservoir structure model characterizing lithological heterogeneity, fracture networks, and temperature-related properties is constructed to form reservoir structure information. Further, based on the basic characteristic information and the reservoir structure information, thermal parameters, seepage parameters, rock mechanics parameters, and drilling boundary conditions are determined to form model parameter information. On this basis, a wellbore-reservoir coupled simulation model is established, and the dynamic response of the wellbore and reservoir during actual drilling is simulated through information interaction between the temperature field, seepage field, and stress field. Finally, measured drilling response information is used to correct and verify the simulation results, thereby forming a geothermal drilling simulation model adapted to the target well area.

[0019] Example 1, please refer to Figure 1 This embodiment mainly illustrates the overall construction process of a geothermal drilling simulation model adapted to magmatic reservoirs and the formation process of basic characteristic information. Specifically, it includes: collecting lithology, fracture, temperature, rock mechanics, and drilling response data of the target well area to form basic characteristic information; constructing a three-dimensional reservoir structure model characterizing lithological heterogeneity, fracture network, and temperature-related properties based on the basic characteristic information to generate reservoir structure information; determining thermal-fluid-solid coupling parameters and drilling boundary conditions based on the basic characteristic information and the reservoir structure information to form model parameter information; establishing a wellbore-reservoir coupled simulation model based on the reservoir structure information and the model parameter information; and correcting the wellbore-reservoir coupled simulation model using the measured drilling response information in the basic characteristic information to obtain a geothermal drilling simulation model adapted to the target well area.

[0020] The above process constitutes the overall information transmission path of this method. Basic characteristic information serves both as the foundation for establishing the reservoir structure model and as the data source for determining model parameters and subsequent model calibration, ensuring consistent data sources across different stages. Reservoir structure information primarily describes the positional relationships of different lithological regions, fracture regions, and temperature distributions within the target well area in three-dimensional space; model parameter information describes the thermal, seepage, and rock mechanical properties corresponding to each spatial location, as well as the boundary conditions applied during drilling operations; the wellbore-reservoir coupled simulation model generates simulation response information based on the aforementioned information and ultimately compares it with the field-measured drilling response information.

[0021] During the formation of basic feature information, geological interpretation data, well logging data, core and rock experimental data, geothermal data, and drilling engineering data for the target well area are acquired. The geological interpretation data is used to determine the main lithological intervals, geological interfaces, and structural features; the well logging data is used to identify lithological variations at different depths, the development of natural fractures, and reservoir characteristics near the wellbore; the core and rock experimental data are used to determine the strength, elasticity, thermal, and permeability properties of different lithologies; the geothermal data is used to describe the original temperature and temperature variation trends at different locations in the reservoir; and the drilling engineering data reflects the working conditions during actual drilling, including drilling pressure, rotational speed, drilling fluid flow rate, drilling fluid temperature, wellbore pressure, and mechanical drilling speed.

[0022] Because the aforementioned data come from different sources, their original recording formats, well depth benchmarks, spatial coordinate benchmarks, and acquisition times may differ. Therefore, it is necessary to correlate the data according to a unified spatial coordinate, well depth, and time benchmark. Specifically, different data are converted to a unified well depth system and a unified spatial coordinate system for the target well, and data correlations are established according to corresponding well depths or spatial locations, so that lithological data, fracture data, temperature data, rock mechanics data, and drilling response data from the same location can be accessed together.

[0023] For data exhibiting significant anomalies, identification is performed based on the changing trends of adjacent well sections, the continuity relationship between similar measuring points, or corresponding geological conditions, and the anomaly data is then corrected. For locally missing data, it is supplemented based on adjacent locations, the same lithological intervals, or continuous variation patterns. Through the above processing, the direct impact of a single anomaly measuring point or missing data on subsequent 3D reservoir models and coupled simulation results is avoided.

[0024] After unified data processing, lithology, fracture characteristics, temperature characteristics, rock mechanics characteristics, and drilling response characteristics are matched according to the corresponding well depth to form the basic feature information with well depth correspondence. The lithology category indicates the type of igneous rock at the current location; the fracture characteristics indicate the location, direction, dip angle, size, spacing, aperture, and development degree of fractures; the temperature characteristics indicate the formation temperature and temperature variation trend at different spatial locations; the rock mechanics characteristics describe the elasticity, strength, and thermal deformation characteristics of the corresponding lithology; and the drilling response characteristics describe the wellbore pressure, drilling fluid temperature, mechanical drilling rate, and other response information reflecting the drilling status during actual drilling operations.

[0025] Of the drilling response information, a portion is used as subsequent model calibration data, while the other portion serves as independent validation data. The data used for model calibration participates in model parameter adjustment, while the data used for independent validation does not participate in parameter adjustment; it is only used to determine whether the calibrated model can accurately reflect the actual drilling response of the well sections not included in the calibration. This approach avoids a model that only has a high fit to the calibrated well sections while lacking adaptability to other well sections.

[0026] The basic feature information formed by the above processing includes at least spatial location, well depth, lithological identifier, fracture identifier, temperature attribute, rock mechanical attribute, and drilling response attribute, so that the spatial location of any subsequent model can be traced back to the corresponding field or experimental data, and provides a unified data foundation for reservoir structure construction, parameter determination, and model calibration.

[0027] Example 2, please refer to Figure 2 This embodiment, based on the basic feature information formed in Embodiment 1, further constructs a three-dimensional reservoir structure model and determines the model parameter information and drilling boundary conditions corresponding to the reservoir spatial location. Specifically, it includes: identifying different igneous rock lithological zones, stratigraphic interfaces, and tectonic interfaces based on the basic feature information, and constructing a fracture network based on the spatial location, occurrence, scale, and development degree of fractures; mapping the lithological zones, stratigraphic interfaces, tectonic interfaces, and fracture networks to a unified three-dimensional space to form the three-dimensional reservoir structure model with lithological region identifiers and fracture region identifiers, and generating the corresponding reservoir structure information.

[0028] In the specific implementation process, the spatial distribution range of different igneous rock lithologies is determined based on the geological interpretation results and well logging results of the target well area. Different lithological regions are assigned corresponding lithological region identifiers. When the lithology changes, a corresponding lithological interface is established in the three-dimensional model, enabling the model to identify changes in reservoir properties when the drill bit moves from one type of igneous rock to another.

[0029] Further analysis of natural fracture logging results and core observations reveals the spatial location, orientation, dip angle, size, aperture, and development degree of fractures, which are then used to construct a fracture network. For fractures whose spatial locations have been clearly identified through logging data, fracture structures are established according to their actual locations. For reservoir areas far from the wellbore and lacking direct logging coverage, the fracture network is spatially extended based on the predominant fracture orientation, fracture spacing, fracture size, and development characteristics of different fracture groups already determined in the target well area.

[0030] The resulting fracture network can represent the directional differences, spatial intersections, and local developmental differences between different fracture groups, avoiding the simplistic treatment of the entire magmatic reservoir as a continuous medium with uniform permeability. Since natural fractures often constitute the main fluid migration channels in deep magmatic geothermal reservoirs, preserving the spatial distribution characteristics of fractures is beneficial to improving the accuracy of subsequent reservoir seepage calculations and well-reservoir fluid exchange calculations.

[0031] After mapping the lithological regions, lithological interfaces, structural interfaces, and fracture networks onto the same three-dimensional space, a three-dimensional reservoir structure model is formed. Different locations within this model correspond to lithological region identifiers and fracture region identifiers, allowing the model to determine its lithology and whether it is within a fracture-affected area based on its current location during operation.

[0032] Furthermore, the three-dimensional reservoir structure model is spatially discretized, and the density of discrete units is increased in the wellbore adjacent area, fracture development area, lithological variation area, and area where the temperature change gradient is greater than a preset gradient threshold; an attribute mapping relationship between discrete units and the basic feature information is established, so that each discrete unit has a corresponding lithological identifier, fracture identifier, spatial location and temperature attribute, and the attribute mapping relationship is summarized into the reservoir structure information.

[0033] In this context, areas far from the wellbore where lithology, temperature, and fracture conditions change relatively little can use relatively large discrete elements to reduce the overall computational load. Around the wellbore, where temperature, pressure, and stress change significantly due to drilling disturbances, the discretization accuracy is increased. Near natural fractures, where fluid flow and stress states may undergo local abrupt changes, the discretization accuracy is also increased. Interfaces between different lithologies and areas with rapid temperature changes also employ higher discretization accuracy, thus balancing model computational efficiency with simulation accuracy in key areas.

[0034] After discretization, each discrete unit establishes a mapping relationship with the basic feature information and at least saves its spatial location, lithological region identifier, fracture region identifier, and temperature attribute. Thus, data originally existing in the form of well logging curves, core experiment results, and geothermal records are transformed into spatial attributes that can be directly assigned to the three-dimensional computational unit.

[0035] Lithological heterogeneity refers to the fact that different spatial locations do not use exactly the same rock parameters. When the computational unit is located in different lithological regions, the model calls the physical property parameters of the corresponding lithology; when the computational unit is located in a fractured region, it is also necessary to further call the fracture-related seepage properties on the basis of the matrix properties. This enables the model to simulate the changes in drilling response that occur when the drill bit passes through different types of magmatic rocks and different fracture development regions.

[0036] After generating reservoir structure information, based on the basic feature information and the reservoir structure information, thermal parameters, seepage parameters, and rock mechanical parameters are determined for different lithological regions and fracture regions respectively. The thermal parameters, seepage parameters, and rock mechanical parameters are then corrected for temperature-related factors according to the correspondence between temperature and rock properties. A parameter mapping relationship between the model parameters and each discrete unit in the three-dimensional reservoir structure model is established, thereby forming the model parameter information.

[0037] Among them, thermal parameters are used to describe the thermal conductivity and heat storage capacity of rocks and fluids; seepage parameters are used to describe the fluid transport capacity in the rock matrix and natural fractures; rock mechanics parameters are used to describe the ability of rocks to deform and undergo stress changes under the combined effects of wellbore pressure, formation pressure, geostress and temperature changes.

[0038] Considering that the target formation temperature in geothermal drilling is typically significantly higher than that under ambient temperature experimental conditions, the rock physical properties obtained from indoor ambient temperature experiments cannot be directly used as fixed parameters for the entire deep reservoir. This implementation method performs temperature-related corrections on the corresponding thermal parameters, seepage parameters, and rock mechanical parameters based on the temperature attributes in the basic characteristic information, enabling the same lithology to have different actual calculation parameters when located in different temperature regions.

[0039] Specifically, when the temperature of a discrete element increases, its thermal conductivity, elastic characteristics, strength characteristics, or flow properties can be modified based on the pre-established correspondence between rock parameters and temperature. The modified parameters are directly associated with the corresponding discrete element and used as model parameters for subsequent thermo-fluid-solid coupling calculations.

[0040] Further determine the drilling boundary conditions. Based on the basic feature information, obtain the well trajectory, drilling depth, drilling pressure, rotational speed, drilling fluid discharge, drilling fluid inlet temperature, wellbore pressure, and formation temperature information; determine the spatial correspondence between the wellbore and the three-dimensional reservoir structure model based on the well trajectory, and load the drilling fluid flow boundary, wellbore pressure boundary, wellbore temperature boundary, and drill bit action boundary to the corresponding spatial positions to form the drilling boundary information as part of the model parameter information.

[0041] The wellbore trajectory is used to determine the actual spatial position of the wellbore in the three-dimensional reservoir structure model, so that each well depth corresponds to a specific discrete reservoir unit. Drilling pressure and rotational speed are used to describe the mechanical action exerted by the drill bit on the bottom rock, drilling fluid discharge rate is used to determine the flow state inside the wellbore, drilling fluid inlet temperature is used to determine the initial thermal state entering the wellbore, wellbore pressure boundary is used to define the drilling fluid pressure state inside the wellbore, and formation temperature serves as the initial condition for the heat exchange process between the wellbore and the reservoir.

[0042] By loading the aforementioned boundary conditions onto the corresponding spatial locations, model parameter information with characteristics of actual drilling conditions is formed. Thus, as the drill bit moves continuously along the well trajectory, the model can read the corresponding lithology identifier, fracture identifier, temperature attributes, and temperature-corrected model parameters based on the drill bit's current spatial location. Simultaneously, it can call upon the drilling pressure, rotation speed, and drilling fluid parameters corresponding to the current drilling conditions, achieving a unified mapping between the geological environment and drilling conditions.

[0043] Example 3, please refer to Figure 3 This embodiment, based on the reservoir structure information and model parameter information formed in Embodiment 2, further establishes a wellbore-reservoir coupled simulation model to realize information interaction between temperature, seepage, stress, and fracture state. The wellbore-reservoir coupled simulation model is then corrected and verified using field-measured drilling response information. Specifically, this includes: establishing the solution relationships for the temperature field, seepage field, and stress field based on the reservoir structure information and model parameter information, and establishing information interaction relationships between these fields; transferring the pressure information generated by the seepage field to the stress field, and the temperature information generated by the temperature field to both the seepage field and the stress field; updating the flow properties of the fracture region based on the deformation information generated by the stress field, so that the updated flow properties continue to participate in the calculation of the temperature field and seepage field, forming a closed-loop interaction of thermal-fluid-solid information.

[0044] The temperature field describes the changes in wellbore and surrounding reservoir temperature over time and space following heat exchange between the drilling fluid and the high-temperature rock mass. After the drilling fluid enters the deep wellbore from the surface, its temperature is typically lower than that of the deep reservoir. Therefore, heat from the reservoir is transferred to the drilling fluid in the wellbore, raising its temperature while simultaneously lowering the temperature of the wellbore and surrounding reservoir. These temperature changes further affect the thermal deformation characteristics of the rock, fluid properties, and local reservoir seepage conditions.

[0045] The seepage field is used to describe the flow state of reservoir fluids under the combined effects of formation pressure, wellbore pressure, and fracture permeability. Intact magmatic matrix typically has low fluid transport capacity, while natural fractures can form the main flow channels. Therefore, the model calls the corresponding seepage parameters according to the fracture identifier of different discrete units, so that fractured regions and intact matrix regions have different flow responses.

[0046] The stress field is used to describe the stress and deformation state of the rock mass around the well under the combined effects of original geostress, formation pressure, wellbore pressure, and temperature changes. Pressure information generated by the seepage field is transferred to the stress field to determine the changes in the effective stress state of the rock mass after changes in pore pressure; temperature information generated by the temperature field is also transferred to the stress field to calculate the thermal deformation and thermal stress changes caused by cooling or heating of the rock mass.

[0047] After calculating the rock mass deformation at the fracture location using stress field calculations, the flow properties of the fracture region are further updated based on this deformation information. When changes in wellbore stress cause the fracture to open, the fracture flow capacity increases accordingly; when the fracture is compressed, the fracture flow capacity decreases accordingly. The updated fracture flow properties are re-input into the seepage field, further influencing reservoir pressure changes and the fluid exchange state between the wellbore and the reservoir.

[0048] Since changes in reservoir flow state further alter the fluid heat-carrying process, the updated fracture flow properties also participate in temperature field calculations. The new temperature field calculation results are then transmitted to the stress field, forming a continuous cyclical information exchange between temperature, pressure, rock mass deformation, and fracture flow properties. This approach establishes a thermal-fluid-solid closed loop, rather than calculating the temperature field, seepage field, and stress field independently.

[0049] Furthermore, the wellbore-reservoir coupled simulation model also includes an interactive interface between the wellbore and the reservoir; based on the interactive interface, the pressure and temperature information of the drilling fluid in the wellbore is transmitted to the corresponding reservoir boundary, and the state of the drilling fluid in the wellbore is updated according to the fluid exchange and heat exchange information generated by the reservoir boundary; at the same time, drill bit-rock interaction information is formed according to the drilling pressure, rotation speed and rock mechanics parameters at the corresponding position of the drill bit, and the drill bit-rock interaction information and the wellbore state are used together to generate simulation response information of the drilling process.

[0050] The wellbore-reservoir interaction interface is located at the wellbore wall and is used to realize information exchange between the wellbore computation domain and the reservoir computation domain. The wellbore computation domain first determines the flow state of the drilling fluid in the wellbore based on the drilling fluid discharge rate, inlet temperature, wellbore structure, and pressure conditions, and then transmits the pressure and temperature information corresponding to the wellbore wall location to the reservoir computation domain.

[0051] After receiving wellbore pressure information, the reservoir computational domain further calculates the possible fluid exchange between the wellbore and the reservoir; after receiving wellbore temperature information, it further calculates the heat exchange between the wellbore and the high-temperature rock mass. The fluid exchange and heat exchange information obtained from the reservoir calculations are fed back to the wellbore computational domain, thereby updating the drilling fluid pressure, flow rate, and temperature status.

[0052] Through the aforementioned two-way interaction, the wellbore condition is not solely determined by the drilling fluid inlet conditions, but is continuously affected by reservoir pressure, fracture development, and formation temperature; the reservoir condition is also affected by drilling fluid cooling, wellbore pressure, and drilling disturbances.

[0053] At the drill bit location, the model further reads the current drilling pressure, rotational speed, and rock mechanics parameters corresponding to the reservoir unit where the drill bit is located, and forms drill bit-rock interaction information. This drill bit-rock interaction information is used to describe the process of rock fracturing under corresponding strength, elastic characteristics, and fracture conditions after the drill bit applies axial load and rotational action to the rock.

[0054] When the drill bit is located in different lithological regions, the model calls upon different rock mechanics parameters; when the drill bit enters a fractured region, the interaction state between the drill bit and the rock is adjusted based on the corresponding fracture markers. This allows drilling responses, such as the rate of penetration, to change accordingly with variations in lithology, fractures, and temperature conditions.

[0055] After cyclic calculations of wellbore flow, temperature field, seepage field, stress field, and drill bit-rock interaction, the model generates bottom hole circulating pressure, drilling fluid return temperature, mechanical drilling rate, wellbore temperature state, reservoir pressure state, stress state, and fracture flow state, and summarizes the above information to form simulation response information.

[0056] Further, measured drilling response information is extracted from the basic feature information, and the measured drilling response information is compared with the simulation response information generated by the wellbore-reservoir coupling simulation model to obtain response deviation information. Based on the response deviation information, the model parameters to be adjusted that affect the simulation response and meet the preset conditions are determined, and the model parameters to be adjusted are iteratively corrected until the response deviation information meets the preset correction conditions to obtain the corrected wellbore-reservoir coupling simulation model.

[0057] During model calibration, the simulated bottom hole circulation pressure, drilling fluid return temperature, and mechanical drilling rate are compared with the measured drilling response information corresponding to the same well section to determine the current model's ability to describe the actual drilling process in the target well area. When there is a significant deviation between a certain type of simulated response and the measured response, the model parameters to be adjusted are determined based on the degree of influence of different model parameters on this type of simulated response.

[0058] Among these factors, reservoir fracture flow properties primarily affect fluid exchange between the wellbore and the reservoir, as well as local pressure response; thermal parameters mainly influence the heat exchange process between the wellbore and the reservoir, and the drilling fluid temperature response; while rock mechanics parameters and drill bit-rock interaction parameters primarily affect the rock fragmentation state and mechanical drilling rate. Therefore, the corresponding model parameters can be selected and adjusted according to different response deviations.

[0059] After adjusting the model parameters, the wellbore-reservoir coupling calculation is re-executed, and simulation response information is generated again. The new simulation response information is then compared with the measured drilling response information. If the response deviation information still does not meet the preset correction conditions, the model parameters to be adjusted are adjusted again, and the simulation process is repeated. When the response deviation information meets the preset correction conditions, parameter adjustment is stopped, and the corrected wellbore-reservoir coupling simulation model is obtained.

[0060] Furthermore, measured drilling response information corresponding to well sections that did not participate in model parameter correction is selected as verification information. The verification information is compared with the simulation response information generated by the corrected wellbore-reservoir coupled simulation model to obtain model verification information. When the model verification information meets the preset verification conditions, the corrected wellbore-reservoir coupled simulation model is determined as the geothermal drilling simulation model. When the preset verification conditions are not met, the model parameter information is readjusted according to the model verification information and model correction is performed.

[0061] The purpose of using uncalibrated well sections for verification is to determine whether the model only achieves good matching results for calibrated well sections, or whether it can further reflect the actual drilling conditions of other well sections in the target well area. During the verification process, the measured response of the well section is not used to modify the model parameters. Instead, the calibrated wellbore-reservoir coupled simulation model is used directly for calculation, and the calculation results are compared with the corresponding field measurement results for that well section.

[0062] When the deviations between the simulated responses (bottom hole circulation pressure, drilling fluid return temperature, and mechanical drilling rate) and the verification information generated by the model are all within the preset allowable range, it indicates that the current model can well characterize the drilling process in the magmatic reservoir of the target well area. Therefore, the corrected wellbore-reservoir coupled simulation model is determined as the geothermal drilling simulation model suitable for the target well area. When the verification results do not meet the preset requirements, the model parameters that need to be adjusted are re-determined based on the model verification information generated during the verification process, and the model is corrected and verified again.

[0063] During final model execution, the current lithological and fracture regions are identified from the reservoir structure information based on the current drill bit position, and the corresponding model parameter information is retrieved. The drilling operation status is determined based on the current drilling pressure, rotation speed, drilling fluid discharge rate, and drilling fluid inlet temperature. The wellbore calculation domain generates drilling fluid pressure and temperature information, which is then transmitted to the reservoir calculation domain through the wellbore-reservoir interface. The reservoir flow field calculates the reservoir flow state based on the pressure information, the temperature field calculates the heat exchange state based on the temperature difference between the wellbore and the reservoir, and the stress field calculates the stress and deformation state of the surrounding rock mass based on the pressure and temperature information. The fracture flow properties are then updated based on the deformation state, and the updated fracture flow properties are fed back to the temperature and flow fields.

[0064] Once the information interaction between the various fields reaches a preset stable state, the simulation response information corresponding to the current drilling position is output. As the drill bit continues to move along the well trajectory, the model reacquires new reservoir structure information, model parameter information, and drilling boundary information, and repeatedly performs calculations on wellbore flow, reservoir heat transfer, seepage, stress, and drill bit-rock interaction. This continuously simulates the changes in drilling response that occur when the drill bit moves from one lithology to another, from intact rock mass to fractured areas, and from lower-temperature areas to higher-temperature areas, thus achieving dynamic simulation of the entire process of geothermal drilling in magmatic reservoirs.

[0065] Through the above three embodiments, this method forms a complete technical link in which basic characteristic information, reservoir structure information, model parameter information, simulation response information, and model correction information are transmitted step by step. This allows lithological heterogeneity, natural fractures, high geothermal temperature, temperature-related rock properties, drilling fluid circulation, and drill bit-rock interaction to all enter the same simulation system. Furthermore, through bidirectional information interaction between the wellbore and the reservoir, as well as thermal-fluid-solid multi-field feedback, the adaptability of the geothermal drilling simulation model to the actual drilling environment of the target magmatic reservoir is improved.

[0066] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for constructing a simulation model for geothermal drilling in igneous rock reservoirs, characterized in that, include: Collect lithology, fracture, temperature, rock mechanics, and drilling response data of the target well area to form basic characteristic information; Based on the aforementioned basic feature information, a three-dimensional reservoir structure model is constructed to characterize lithological heterogeneity, fracture network, and temperature-related physical properties, thereby generating reservoir structure information. Based on the basic feature information and the reservoir structure information, the thermal-fluid-solid coupling parameters and drilling boundary conditions are determined to form model parameter information; A wellbore-reservoir coupled simulation model is established based on the reservoir structure information and the model parameter information. The wellbore-reservoir coupled simulation model is corrected using the measured drilling response information in the basic feature information to obtain a geothermal drilling simulation model adapted to the target well area.

2. The method for constructing a simulation model for geothermal drilling in magmatic reservoirs according to claim 1, characterized in that, The basic feature information formed includes: Acquire geological interpretation data, logging data, core and rock test data, geothermal data, and drilling engineering data for the target well area; The data are correlated according to unified spatial coordinates, well depth benchmarks and time benchmarks, abnormal data are identified and missing data is supplemented; The lithology, fracture characteristics, temperature characteristics, rock mechanics characteristics, and drilling response characteristics are matched according to the corresponding well depth to form the basic feature information with well depth correspondence.

3. The method for constructing a simulation model for geothermal drilling in magmatic reservoirs according to claim 1, characterized in that, The construction of the three-dimensional reservoir structure model includes: Based on the aforementioned basic characteristic information, different igneous rock lithological zones, stratigraphic interfaces, and tectonic interfaces are identified, and a fracture network is constructed based on the spatial location, occurrence, scale, and development degree of the fractures. The lithological zones, stratigraphic interfaces, tectonic interfaces, and fracture networks are mapped to a unified three-dimensional space to form the three-dimensional reservoir structure model with lithological region identifiers and fracture region identifiers, and the corresponding reservoir structure information is generated.

4. The method for constructing a simulation model for geothermal drilling in magmatic reservoirs according to claim 1, characterized in that, The generation of reservoir structure information also includes: The three-dimensional reservoir structure model is spatially discretized, and the density of discrete units is increased in the wellbore adjacent area, fracture development area, lithological change area, and area where the temperature change gradient is greater than a preset gradient threshold. Establish an attribute mapping relationship between discrete units and the basic feature information, so that each discrete unit has a corresponding lithological identifier, fracture identifier, spatial location and temperature attribute, and summarize the attribute mapping relationship into the reservoir structure information.

5. The method for constructing a simulation model for geothermal drilling in magmatic reservoirs according to claim 1, characterized in that, The formation model parameter information includes: Based on the basic characteristic information and the reservoir structure information, thermal parameters, seepage parameters and rock mechanical parameters are determined for different lithological regions and fracture regions respectively; Based on the correspondence between temperature and rock physical properties, the thermal parameters, seepage parameters, and rock mechanical parameters are corrected for temperature correlation, and the parameter mapping relationship between the model parameters and each discrete unit in the three-dimensional reservoir structure model is established, thereby forming the model parameter information.

6. The method for constructing a simulation model for geothermal drilling in magmatic reservoirs according to claim 1, characterized in that, The determination of the drilling boundary conditions includes: Based on the aforementioned basic feature information, well trajectory, drilling depth, drilling pressure, rotation speed, drilling fluid discharge, drilling fluid inlet temperature, wellbore pressure, and formation temperature information are obtained. The spatial correspondence between the wellbore and the three-dimensional reservoir structure model is determined based on the wellbore trajectory. The drilling fluid flow boundary, wellbore pressure boundary, wellbore temperature boundary, and drill bit action boundary are then loaded to their respective spatial positions to form drilling boundary information, which is part of the model parameter information.

7. The method for constructing a simulation model for geothermal drilling in magmatic reservoirs according to claim 1, characterized in that, The establishment of the wellbore-reservoir coupled simulation model includes: Based on the reservoir structure information and the model parameter information, the solution relationships for the temperature field, seepage field and stress field are established respectively, and the information interaction relationship between each field is established. The pressure information generated by the seepage field is transmitted to the stress field, and the temperature information generated by the temperature field is transmitted to both the seepage field and the stress field. The flow properties of the crack region are updated based on the deformation information generated by the stress field, so that the updated flow properties continue to participate in the calculation of the temperature field and the seepage field, forming a closed-loop interaction of thermal-fluid-solid information.

8. The method for constructing a simulation model for geothermal drilling in magmatic reservoirs according to claim 1, characterized in that, The wellbore-reservoir coupling simulation model also includes the interactive interface between the wellbore and the reservoir; Based on the interactive interface, the pressure and temperature information of the drilling fluid in the wellbore is transmitted to the corresponding reservoir boundary, and the state of the drilling fluid in the wellbore is updated according to the fluid exchange and heat exchange information generated by the reservoir boundary. Simultaneously, drill bit-rock interaction information is generated based on drilling pressure, rotation speed, and rock mechanics parameters at the corresponding position of the drill bit. This drill bit-rock interaction information, together with the wellbore state, is used to generate simulation response information for the drilling process.

9. The method for constructing a simulation model for geothermal drilling in magmatic reservoirs according to claim 1, characterized in that, The corrected wellbore-reservoir coupling simulation model includes: Measured drilling response information is extracted from the basic feature information, and the measured drilling response information is compared with the simulation response information generated by the wellbore-reservoir coupling simulation model to obtain response deviation information. Based on the response deviation information, determine the model parameters to be adjusted that meet the preset conditions for affecting the simulation response, and iteratively correct the model parameters to be adjusted until the response deviation information meets the preset correction conditions, thereby obtaining the corrected wellbore-reservoir coupling simulation model.

10. The method for constructing a simulation model for geothermal drilling in magmatic reservoirs according to claim 9, characterized in that, The method for obtaining a geothermal drilling simulation model adapted to the target well area includes: The measured drilling response information corresponding to the well section that did not participate in the model parameter correction was selected as the verification information. The verification information was compared with the simulation response information generated by the corrected wellbore-reservoir coupling simulation model to obtain the model verification information. When the model verification information meets the preset verification conditions, the corrected wellbore-reservoir coupling simulation model is determined as the geothermal drilling simulation model. When the preset verification conditions are not met, the model parameter information is readjusted based on the model verification information and model correction is performed.

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