SC-CO2 ore bed pre-dredging method and system and application

Abstract

The invention discloses an SC-CO2 ore bed pre-dredging method and system and application, according to the method, carbon dioxide is pressurized and heated to be in a supercritical state and injected into an ore bed, blockages in the ore bed can be removed through the high permeability and dissolving capacity of SC-CO2, the permeability of the ore bed is improved, and the permeability of the ore bed is improved; and in addition, the pre-dredging parameters are adjusted by utilizing detection data acquired by an underground sensor and analyzing the target ion concentration in the target ore bed, so that the pre-dredging effect is better. The method has the advantages of being efficient, environmentally friendly, low in cost and the like, and is suitable for pre-dredging of uranium ore, petroleum ore beds, natural gas ore beds and the like.

Description

Technical Field

[0001] This invention relates to the field of mineral seam mining technology, specifically to a method, system, and application for pre-dredging SC-CO2 mineral seams. Background Technology

[0002] With the continued growth of global energy demand and the urgent pursuit of clean energy, efficient and environmentally friendly mineral resource extraction technologies are becoming increasingly important. In many in-situ mineral resource extraction processes, the low permeability of ore layers severely restricts mining efficiency and resource recovery rates. This is especially true for some deep ore layers or ore layers under special geological conditions, where traditional pre-dredging methods are insufficient to meet practical needs. For example, in sandstone ore layers, due to their complex pore structure and low permeability, ore layer blockage easily occurs during mining, leading to insufficient injection fluid volume and severely impacting mining efficiency. According to relevant research, in sandstone uranium deposits suitable for in-situ leaching in my country, most ore layers have low permeability, which significantly reduces metal recovery efficiency during in-situ leaching mining.

[0003] Currently, common methods for pre-dredging mineral seams have many limitations. While some traditional chemical pre-dredging methods can improve the permeability of mineral seams to a certain extent, the chemical reagents used often cause significant environmental pollution and are costly. For example, certain strong acid and alkali chemicals may corrode equipment and the surrounding environment while clearing mineral seams, leading to subsequent environmental remediation challenges. Physical pre-dredging methods, such as simple hydraulic fracturing, are relatively environmentally friendly, but require sophisticated equipment and struggle to achieve precise control over the internal structure of the mineral seam, resulting in limited clearing effectiveness. Furthermore, most existing methods fail to fully consider the characteristics of the mineral seam, the properties of supercritical carbon dioxide (SC-CO2), and the coupling relationships between various process parameters, making efficient and precise pre-dredging of mineral seams impossible. Summary of the Invention

[0004] This application provides a method, system, and application for pre-dredging ore layers using SC-CO2. In this method, carbon dioxide is pressurized and heated to a supercritical state and injected into the ore layer. The high permeability and dissolving capacity of SC-CO2 can remove blockages in the ore layer and improve its permeability. Furthermore, by utilizing detection data acquired from downhole sensors and analyzing the target ion concentration in the target ore layer, pre-dredging parameters are adjusted to improve the pre-dredging effect. The method described in this application has advantages such as high efficiency, environmental friendliness, and low cost, and is suitable for pre-dredging of uranium mines, oil ore layers, and natural gas ore layers.

[0005] In a first aspect, this application provides a method for pre-dredging SC-CO2 ore seams, comprising:

[0006] The target mineral layer is subjected to feature analysis to obtain key information about the target mineral layer; wherein the key information includes permeability, mineral composition and mineral layer thickness;

[0007] Construct an SC-CO2 injection system; wherein, the SC-CO2 injection system includes a CO2 gas source, a pressurization device, a temperature control system, and an injection pipeline connected in sequence;

[0008] Based on the permeability, the initial injection pressure range and initial injection flow rate range of SC-CO2 are determined; the pressurizing device is controlled to pressurize the liquid CO2 provided by the CO2 gas source to obtain SC-CO2, and the injection pressure of the SC-CO2 is within the initial injection pressure range; the injection flow rate of the SC-CO2 is adjusted to be within the initial injection flow rate range.

[0009] Based on the mineral composition, an initial injection temperature range is determined; the temperature control system is then used to adjust the injection temperature of the SC-CO2 to within the initial injection temperature range.

[0010] The initial injection time range is determined based on the ore layer thickness and the preset reaction rate; the injection time of SC-CO2 is controlled to be within the initial injection time range.

[0011] During the SC-CO2 injection time, downhole sensors are used to acquire detection data and analyze the target ion concentration in the target mineral layer; wherein the detection data includes the internal pressure, internal temperature and internal flow rate of the target mineral layer;

[0012] Based on the internal pressure, internal temperature, internal flow rate, and / or target ion concentration, the pre-dredging parameters are adjusted; wherein, the adjustment of the pre-dredging parameters includes adjusting the injection pressure of SC-CO2 using the pressurizing device, adjusting the injection temperature of SC-CO2 using the temperature control system, adjusting the injection flow rate of SC-CO2, adjusting the injection time of SC-CO2, and adding one or more additives.

[0013] In some embodiments, the pore structure includes a pore size distribution; the step of performing feature analysis on the target ore layer to obtain key information about the target ore layer includes:

[0014] The target ore layer was analyzed by X-ray diffraction to determine the mineral composition of key information in the target ore layer;

[0015] The pore size distribution and permeability of the target mineral layer were determined using mercury intrusion porosimetry.

[0016] In some embodiments, the step of determining the initial injection pressure range and the initial injection flow rate range of SC-CO2 based on the permeability includes:

[0017] Determine whether the penetration rate is less than a preset penetration rate;

[0018] If the permeability is less than the preset permeability, the initial injection pressure of SC-CO2 is determined to be in the range of 8 to 15 MPa, and the initial injection flow rate is determined to be in the range of 0.5 to 2 L / min.

[0019] In some embodiments, the step of determining the initial injection temperature range based on the mineral composition includes:

[0020] Determine whether the mineral composition contains carbonate minerals;

[0021] If carbonate minerals are present, the initial injection temperature range is determined to be 35–45°C.

[0022] In some embodiments, the step of determining the initial injection time range based on the ore layer thickness and a preset reaction rate includes:

[0023] Determine whether the thickness of the mineral layer is greater than a preset thickness;

[0024] If the thickness is greater than the preset thickness, the initial injection time range is determined to be 1 to 3 days.

[0025] In some embodiments, the adjustment of pre-unblocking parameters based on the internal pressure, internal temperature, internal flow rate, and / or target ion concentration; wherein, the adjustment of pre-unblocking parameters includes adjusting the injection pressure of SC-CO2 using the pressurizing device, adjusting the injection temperature of SC-CO2 using the temperature control system, adjusting the injection flow rate of SC-CO2, adjusting the injection time of SC-CO2, and adding one or more additives, the steps of which include:

[0026] When the rate of increase of the internal pressure is higher than the preset rate, the injection pressure of SC-CO2 is reduced by the pressurization device, and the injection flow rate of SC-CO2 is increased.

[0027] In some embodiments, the target mineral layer has a pore size of less than 10 μm, a porosity of less than 10%, and a permeability of 0.1 × 10⁻³ μm. 2The mineral composition includes 20% carbonate minerals by mass; the injection pressure of the SC-CO2 is 10 MPa within the initial injection pressure range; the injection flow rate of the SC-CO2 is 1 L / min within the initial injection flow rate range; the injection temperature of the SC-CO2 is 38°C within the initial injection temperature range; and the injection time of the SC-CO2 is 2 days within the initial reaction time range.

[0028] In some embodiments, the target mineral layer has a pore size of 10–30 μm, a porosity of 10%–25%, and a permeability of 0.05 × 10⁻³ μm. 2 The mineral composition includes quartz, feldspar, carbonates, and clay minerals; the injection pressure of the SC-CO2 is 12 MPa, which is within the initial injection pressure range; the injection flow rate of the SC-CO2 is 0.8 L / min, which is within the initial injection flow rate range; the injection temperature of the SC-CO2 is 40°C, which is within the initial injection temperature range; and the injection time of the SC-CO2 is 3 days, which is within the initial reaction time.

[0029] Secondly, this application provides an SC-CO2 ore seam pre-dredging system for:

[0030] The target mineral layer is subjected to feature analysis to obtain key information about the target mineral layer; wherein the key information includes permeability, mineral composition and mineral layer thickness;

[0031] Construct an SC-CO2 injection system; wherein, the SC-CO2 injection system includes a CO2 gas source, a pressurization device, a temperature control system, and an injection pipeline connected in sequence;

[0032] Based on the permeability, the initial injection pressure range and initial injection flow rate range of SC-CO2 are determined; the pressurizing device is controlled to pressurize the liquid CO2 provided by the CO2 gas source to obtain SC-CO2, and the injection pressure of the SC-CO2 is within the initial injection pressure range; the injection flow rate of the SC-CO2 is adjusted to be within the initial injection flow rate range.

[0033] Based on the mineral composition, an initial injection temperature range is determined; the temperature control system is then used to adjust the injection temperature of the SC-CO2 to within the initial injection temperature range.

[0034] The initial injection time range is determined based on the ore layer thickness and the preset reaction rate; the injection time of SC-CO2 is controlled to be within the initial injection time range.

[0035] During the SC-CO2 injection time, downhole sensors are used to acquire detection data and analyze the target ion concentration in the target mineral layer; wherein the detection data includes the internal pressure, internal temperature and internal flow rate of the target mineral layer;

[0036] Based on the internal pressure, internal temperature, internal flow rate, and / or target ion concentration, the pre-dredging parameters are adjusted; wherein, the adjustment of the pre-dredging parameters includes adjusting the injection pressure of SC-CO2 using the pressurizing device, adjusting the injection temperature of SC-CO2 using the temperature control system, adjusting the injection flow rate of SC-CO2, adjusting the injection time of SC-CO2, and adding one or more additives.

[0037] Thirdly, this application provides an application of the SC-CO2 mineral seam pre-dredging method, which is applied to the pre-dredging of uranium mines, oil and gas mines, and geothermal mines.

[0038] This invention provides an SC-CO2 mineral layer pre-dredging method, system, and application. In this method, carbon dioxide is pressurized and heated to a supercritical state and injected into the mineral layer. The high permeability and dissolving power of SC-CO2 can remove blockages in the mineral layer, improving its permeability. Furthermore, by utilizing detection data acquired from downhole sensors and analyzing the target ion concentration in the target mineral layer, pre-dredging parameters are adjusted to improve the pre-dredging effect. The method in this application has advantages such as high efficiency, environmental friendliness, and low cost, and is suitable for pre-dredging of uranium mines, oil reservoirs, and natural gas reservoirs. Attached Figure Description

[0039] Figure 1 A flowchart of a pre-dredging method for SC-CO2 ore seams is illustrated, according to some embodiments. Detailed Implementation

[0040] To make the objectives and implementation methods of this application clearer, the exemplary implementation methods of this application will be clearly and completely described below with reference to the accompanying drawings of the exemplary embodiments of this application. Obviously, the exemplary embodiments described are only some embodiments of this application, and not all embodiments.

[0041] It should be noted that the brief descriptions of terms in this application are only for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise stated, these terms should be understood in their ordinary and common meaning.

[0042] The terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar or related objects or entities, and do not necessarily imply a specific order or sequence, unless otherwise specified. It should be understood that such terms are interchangeable where appropriate.

[0043] The terms “comprising” and “having”, and any variations thereof, are intended to cover but not exclude inclusion, for example, a product or device that includes a range of components is not necessarily limited to all of the components that are clearly listed, but may include other components that are not clearly listed or that are inherent to such product or device.

[0044] To address the aforementioned problems, this application provides an SC-CO2 mineral layer pre-dredging method, system, and application. In this method, carbon dioxide is pressurized and heated to a supercritical state and injected into the mineral layer. The high permeability and dissolving power of SC-CO2 can remove blockages in the mineral layer, improving its permeability. Furthermore, by utilizing detection data acquired from downhole sensors and analyzing the target ion concentration in the target mineral layer, pre-dredging parameters are adjusted to improve the pre-dredging effect. The method in this application has advantages such as high efficiency, environmental friendliness, and low cost, and is suitable for pre-dredging of uranium mines, oil reservoirs, and natural gas reservoirs.

[0045] Figure 1 A flowchart of a pre-dredging method for SC-CO2 ore seams, provided according to some embodiments, is illustrated. The method includes steps S100-S700.

[0046] S100. Perform feature analysis on the target mineral layer to obtain key information about the target mineral layer; wherein the key information includes permeability, mineral composition and mineral layer thickness.

[0047] In this embodiment of the application, a comprehensive feature analysis of the target ore layer is conducted before pre-dredging to obtain key information about the target ore layer. Specifically, geological exploration data, core sample analysis, and other methods can be used to conduct a comprehensive feature analysis of the target ore layer to obtain key information such as the pore structure, permeability, mineral composition, ore layer thickness, and rock type of the target ore layer.

[0048] In some embodiments, the pore structure includes a pore size distribution; the step of performing feature analysis on the target mineral layer to obtain key information of the target mineral layer includes: determining the mineral composition of the key information in the target mineral layer by X-ray diffraction analysis; and determining the pore size distribution and permeability of the target mineral layer by mercury intrusion porosimetry.

[0049] The aforementioned feature analysis methods can be used to obtain key information such as mineral composition, pore size distribution, and permeability. Furthermore, the thickness of the ore layer and the rock type can be determined using conventional methods in this field, such as geological methods, geophysical methods, geochemical methods, and drilling methods.

[0050] S200. Construct an SC-CO2 (supercritical CO2) injection system; wherein, the SC-CO2 injection system includes a CO2 gas source, a pressurization device, a temperature control system, and an injection pipeline connected in sequence;

[0051] In this embodiment, a CO2 gas source is used to provide liquid CO2; a pressurizing device is used to pressurize the liquid CO2 provided by the CO2 gas source to a supercritical state; a temperature control system is used to adjust the temperature of the supercritical CO2 during the injection process, ensuring that the temperature of SC-CO2 remains stable during the injection process and avoiding the impact of temperature fluctuations on its physicochemical properties. An injection pipeline is used to inject supercritical CO2 with regulated temperature and flow rate into the ore layer.

[0052] In this embodiment, the CO2 gas source is high-purity liquid carbon dioxide. The pressurization equipment has a pressurization capacity that can control a pressure greater than 7.38 MPa, and the temperature control system has a temperature control capacity that can control a temperature greater than 31.1°C. This ensures that the liquid CO2 can be pressurized and heated to a supercritical state.

[0053] S300. Based on the permeability, determine the initial injection pressure range and initial injection flow rate range of SC-CO2; control the pressurizing device to pressurize the liquid CO2 provided by the CO2 gas source to obtain SC-CO2, and the injection pressure of the SC-CO2 is within the initial injection pressure range; adjust the injection flow rate of the SC-CO2 to be within the initial injection flow rate range.

[0054] In some embodiments, the step of determining the initial injection pressure range and the initial injection flow rate range of SC-CO2 based on the permeability includes:

[0055] Determine whether the penetration rate is less than a preset penetration rate;

[0056] If the permeability is less than the preset permeability, the initial injection pressure of SC-CO2 is determined to be in the range of 8 to 15 MPa, and the initial injection flow rate is determined to be in the range of 0.5 to 2 L / min.

[0057] In this embodiment of the application, for mineral layers with low permeability, a higher initial injection pressure range (generally 8 to 15 MPa) and a relatively lower initial injection flow rate range (0.5 to 2 L / min) are used to allow SC-CO2 to gradually penetrate into the pores of the mineral layer and expand them.

[0058] For example, the preset penetration rate can be 1×10 -4 μm 2 .

[0059] In some embodiments, the initial injection flow rate and initial injection pressure are also related to the pore structure. In-situ mining requires a "just right" pore system: it needs to have sufficiently high porosity to hold the minerals, and a predominantly mesopore, interconnected pore size distribution to ensure fluid flow and provide channels for mining.

[0060] S400. Based on the mineral composition, determine the initial injection temperature range; control the temperature control system to adjust the injection temperature of the SC-CO2 to the initial injection temperature range;

[0061] In some embodiments, the step of determining the initial injection temperature range based on the mineral composition includes:

[0062] Determine whether the mineral composition contains carbonate minerals;

[0063] If carbonate minerals are present, the initial injection temperature range is determined to be 35–45°C.

[0064] In the embodiments of this application, different mineral layer compositions react differently to temperature. For mineral layers containing carbonate minerals, the injection temperature of SC-CO2 is generally between 35 and 45°C. This can accelerate the chemical reaction between carbonates and SC-CO2, generating bicarbonates with higher solubility, thereby expanding the porosity of the mineral layer.

[0065] S500. Determine the initial injection time range based on the ore layer thickness and the preset reaction rate; control the injection time of SC-CO2 to be within the initial injection time range;

[0066] In some embodiments, the step of determining the initial injection time range based on the ore layer thickness and a preset reaction rate includes:

[0067] Determine whether the thickness of the mineral layer is greater than a preset thickness;

[0068] If the thickness is greater than the preset thickness, the initial injection time range is determined to be 1 to 3 days.

[0069] In this embodiment, the injection time of SC-CO2 in the target ore layer is reasonably controlled according to the ore layer thickness and reaction rate. For thicker ore layers, the initial injection time is generally 1 to 3 days to ensure that the reaction proceeds fully.

[0070] For example, the preset thickness is 10m.

[0071] S600, During the injection time of the SC-CO2, downhole sensors are used to acquire detection data and analyze the target ion concentration in the target mineral layer; wherein the detection data includes the internal pressure, internal temperature and internal flow rate of the target mineral layer;

[0072] For example, the injection time for SC-CO2 is two days. Therefore, within the two days of the SC-CO2 injection time, it is necessary to use downhole sensors to acquire detection data and analyze the target ion concentration in the target ore layer. This allows for the adjustment of pre-dredging parameters based on the detection data and target ion concentration acquired by downhole sensors in advance, preventing poor SC-CO2 injection results once the injection time arrives.

[0073] S700. Based on the internal pressure, internal temperature, internal flow rate and / or target ion concentration, adjust the pre-dredging parameters; wherein, adjusting the pre-dredging parameters includes adjusting the injection pressure of SC-CO2 using the pressurizing device, adjusting the injection temperature of SC-CO2 using the temperature control system, adjusting the injection flow rate of SC-CO2, adjusting the injection time of SC-CO2, and adding one or more additives.

[0074] In one example, the target ion could be a bicarbonate ion.

[0075] In this embodiment, the dredging effect is evaluated in real time through various monitoring methods during the pre-dredging process. Downhole sensors are used to monitor changes in pressure, temperature, and flow rate within the ore layer.

[0076] Simultaneously, water samples from the ore layer are collected regularly to analyze indicators such as target ion concentration and pH level, in order to determine the dissolution of minerals in the ore layer. Based on the monitoring data, pre-dredging parameters are adjusted in a timely manner. If the dredging effect in certain areas of the ore layer is found to be unsatisfactory, the injection pressure, flow rate, temperature, time, and / or additives in those areas are adjusted accordingly to achieve precise control of the pre-dredging process.

[0077] The method described in this application can solve the problems of low efficiency, high cost, environmental pollution, and inability to precisely control existing ore seam pre-dredging methods. By comprehensively considering the characteristics of the ore seam, the properties of SC-CO2, and the synergistic effect of various process parameters, it achieves efficient, environmentally friendly, and precise pre-dredging of the ore seam, thereby improving ore seam mining efficiency and resource recovery rate.

[0078] In some embodiments, the adjustment of pre-unblocking parameters based on the internal pressure, internal temperature, internal flow rate, and / or target ion concentration; wherein, the adjustment of pre-unblocking parameters includes adjusting the injection pressure of SC-CO2 using the pressurizing device, adjusting the injection temperature of SC-CO2 using the temperature control system, adjusting the injection flow rate of SC-CO2, adjusting the injection time of SC-CO2, and adding one or more additives, the steps of which include:

[0079] When the rate of increase of the internal pressure is higher than the preset rate, the injection pressure of SC-CO2 is reduced by the pressurization device, and the injection flow rate of SC-CO2 is increased.

[0080] In this embodiment, as pre-dredging progresses, the injection pressure and flow rate are adjusted in real time based on feedback from the internal pressure and flow rate of the target ore layer. When it is detected that the internal pressure of the target ore layer is rising too rapidly, the injection pressure is appropriately reduced while the flow rate is increased to maintain effective SC-CO2 penetration.

[0081] In some embodiments, the target mineral layer has a pore size of less than 10 μm, a porosity of less than 10%, and a permeability of 0.1 × 10⁻⁶. -3 μm 2 The mineral composition includes 20% carbonate minerals by mass; the injection pressure of the SC-CO2 is 10 MPa within the initial injection pressure range; the injection flow rate of the SC-CO2 is 1 L / min within the initial injection flow rate range; the injection temperature of the SC-CO2 is 38°C within the initial injection temperature range; and the injection time of the SC-CO2 is 2 days within the initial reaction time range.

[0082] In some embodiments, the target mineral layer has a pore size of 10–30 μm, a porosity of 10%–25%, and a permeability of 0.05 × 10⁻⁶. -3 μm 2 The mineral composition includes quartz, feldspar, carbonates, and clay minerals; the injection pressure of the SC-CO2 is 12 MPa, which is within the initial injection pressure range; the injection flow rate of the SC-CO2 is 0.8 L / min, which is within the initial injection flow rate range; the injection temperature of the SC-CO2 is 40°C, which is within the initial injection temperature range; and the injection time of the SC-CO2 is 3 days, which is within the initial reaction time.

[0083] The method in this application embodiment has the following advantages: High efficiency in clearing blockages: The high permeability and dissolving power of SC-CO2 can effectively remove blockages in the ore layer and significantly improve the permeability of the ore layer; Environmentally friendly and pollution-free: SC-CO2 is non-toxic and pollution-free, avoiding the environmental problems of traditional methods; Low cost: SC-CO2 can be recycled and reused, reducing operating costs; Wide applicability: Applicable to various types of ore layers (such as in-situ leaching of sandstone uranium ore, oil, natural gas, etc.).

[0084] The methods in the embodiments of this application are described in detail below through specific examples.

[0085] Example 1: Pre-dredging of a sandstone uranium ore layer

[0086] Analysis of ore layer characteristics: Geological exploration and core analysis of this sandstone uranium deposit revealed that the rock type is mainly fine sandstone, with a pore structure dominated by small-diameter pores (less than 10 μm), porosity less than 10%, and an average permeability of 0.1 × 10⁻⁶. -3 μm 2 The mineral composition contains approximately 20% carbonate minerals.

[0087] SC-CO2 Injection System Construction: An SC-CO2 injection system was constructed. The CO2 source was liquid carbon dioxide with a purity of 99.9%. The pressurization equipment pressurized it to 10MPa, and the temperature control system maintained the SC-CO2 temperature at 38℃.

[0088] Multi-parameter coupled control:

[0089] Pressure and flow rate coordinated control: The initial injection pressure was set at 10 MPa and the flow rate at 1 L / min. During the injection process, the downhole pressure sensor detected a rapid increase in pressure inside the ore layer. One hour after injection, the injection pressure was reduced to 8 MPa, while the flow rate was increased to 1.5 L / min.

[0090] Temperature and reaction time control: The SC-CO2 injection temperature was maintained at 38℃, and the reaction time was determined to be 2 days based on the ore layer thickness and mineral reaction rate.

[0091] During the pre-dredging process, water samples from the ore layer were collected periodically for analysis. One day after injection, low bicarbonate ion concentrations were found in certain areas of the ore layer, indicating unsatisfactory dredging results in those areas. By adjusting the injection pressure to 12 MPa, the flow rate to 1.2 L / min, and increasing the additive concentration to 0.8%, the dredging effect in those areas was significantly improved in subsequent monitoring. After two days of pre-dredging, the permeability of the ore layer increased to 0.3 × 10⁻⁶. -3 μm 2 This increased by 200%, significantly improving the efficiency of subsequent uranium leaching.

[0092] Example 2: Pre-dredging of a deep natural gas reservoir

[0093] Analysis of ore layer characteristics: This deep natural gas ore layer is buried at a depth of 4000m. The rock type is alternating sandstone and shale, with a complex pore structure, pore size of 10-30μm, porosity of 10%-25%, and permeability of 0.05×10⁻⁶. -3 μm 2 The mineral composition is mainly quartz, feldspar, and small amounts of carbonate and clay minerals.

[0094] SC-CO2 injection system construction: A large CO2 gas source is used, and the pressurization equipment pressurizes the liquid carbon dioxide to 12MPa. The temperature control system stabilizes the SC-CO2 temperature at 40℃.

[0095] Multi-parameter coupled control:

[0096] Coordinated control of pressure and flow rate: Initially, the injection pressure was 12 MPa and the flow rate was 0.8 L / min. As pre-dredging progressed, the pressure and flow rate were gradually adjusted according to changes in pressure and flow rate within the ore layer. After 3 hours of injection, the pressure was adjusted to 10 MPa and the flow rate was increased to 1.2 L / min.

[0097] Temperature and reaction time control: Maintain the injection temperature at 40℃, and set the reaction time to 3 days due to the thick ore layer.

[0098] Downhole sensors were used to monitor changes in internal parameters of the formation in real time. Two days after pre-dredging, slow growth in natural gas production was observed in some areas. Analysis of the monitoring data indicated insufficient permeability improvement in these areas. The injection pressure was increased to 13 MPa, the reaction time was extended to 4 days, and the additive concentration was appropriately increased. Ultimately, the permeability of the formation increased to 0.2 × 10⁻⁶. -3 μm 2 Natural gas production has increased significantly, improving extraction efficiency.

[0099] This application also provides an SC-CO2 ore seam pre-dredging system for:

[0100] The target mineral layer is subjected to feature analysis to obtain key information about the target mineral layer; wherein the key information includes permeability, mineral composition and mineral layer thickness;

[0101] Construct an SC-CO2 injection system; wherein, the SC-CO2 injection system includes a CO2 gas source, a pressurization device, a temperature control system, and an injection pipeline connected in sequence;

[0102] Based on the permeability, the initial injection pressure range and initial injection flow rate range of SC-CO2 are determined; the pressurizing device is controlled to pressurize the liquid CO2 provided by the CO2 gas source to obtain SC-CO2, and the injection pressure of the SC-CO2 is within the initial injection pressure range; the injection flow rate of the SC-CO2 is adjusted to be within the initial injection flow rate range.

[0103] Based on the mineral composition, an initial injection temperature range is determined; the temperature control system is then used to adjust the injection temperature of the SC-CO2 to within the initial injection temperature range.

[0104] The initial injection time range is determined based on the ore layer thickness and the preset reaction rate; the injection time of SC-CO2 is controlled to be within the initial injection time range.

[0105] During the SC-CO2 injection time, downhole sensors are used to acquire detection data and analyze the target ion concentration in the target mineral layer; wherein the detection data includes the internal pressure, internal temperature and internal flow rate of the target mineral layer;

[0106] Based on the internal pressure, internal temperature, internal flow rate, and / or target ion concentration, the pre-dredging parameters are adjusted; wherein, the adjustment of the pre-dredging parameters includes adjusting the injection pressure of SC-CO2 using the pressurizing device, adjusting the injection temperature of SC-CO2 using the temperature control system, adjusting the injection flow rate of SC-CO2, adjusting the injection time of SC-CO2, and adding one or more additives.

[0107] It should be noted that other corresponding descriptions of the functional units involved in the SC-CO2 ore seam pre-dredging system provided in the embodiments of this application can be found in the corresponding descriptions in the SC-CO2 ore seam pre-dredging method provided in the above embodiments, and will not be repeated here.

[0108] This application also provides an application of the SC-CO2 mineral layer pre-dredging method, which is applied to the pre-dredging of uranium mines, oil and gas mines, and geothermal mines.

[0109] This application provides an SC-CO2 mineral layer pre-dredging method, system, and application. In this method, carbon dioxide is pressurized and heated to a supercritical state and injected into the mineral layer. The high permeability and dissolving power of SC-CO2 can remove blockages in the mineral layer and improve its permeability. Furthermore, downhole sensors are used to acquire and analyze data to determine the target ion concentration in the target mineral layer, allowing for adjustments to pre-dredging parameters and improving the pre-dredging effect. The method described in this application has advantages such as high efficiency, environmental friendliness, and low cost, and is suitable for pre-dredging of uranium mines, oil reservoirs, and natural gas reservoirs.

[0110] It will be readily understood by those skilled in the art that the above-described advantageous methods can be freely combined and superimposed without conflict. The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A method for pre-dredging SC-CO2 ore seams, characterized in that, include: The target mineral layer is subjected to feature analysis to obtain key information about the target mineral layer; wherein the key information includes permeability, mineral composition and mineral layer thickness; Construct an SC-CO2 injection system; wherein, the SC-CO2 injection system includes a CO2 gas source, a pressurization device, a temperature control system, and an injection pipeline connected in sequence; Based on the permeability, the initial injection pressure range and initial injection flow rate range of SC-CO2 are determined; the pressurizing device is controlled to pressurize the liquid CO2 provided by the CO2 gas source to obtain SC-CO2, and the injection pressure of the SC-CO2 is within the initial injection pressure range; the injection flow rate of the SC-CO2 is adjusted to be within the initial injection flow rate range. Based on the mineral composition, an initial injection temperature range is determined; the temperature control system is then used to adjust the injection temperature of the SC-CO2 to within the initial injection temperature range. Based on the thickness of the ore layer, determine the initial injection time range; control the injection time of SC-CO2 to be within the initial injection time range; During the SC-CO2 injection time, downhole sensors are used to acquire detection data and analyze the target ion concentration in the target mineral layer; wherein the detection data includes the internal pressure, internal temperature and internal flow rate of the target mineral layer; Based on the internal pressure, internal temperature, internal flow rate, and / or target ion concentration, the pre-dredging parameters are adjusted; wherein, the adjustment of the pre-dredging parameters includes adjusting the injection pressure of SC-CO2 using the pressurizing device, adjusting the injection temperature of SC-CO2 using the temperature control system, adjusting the injection flow rate of SC-CO2, adjusting the injection time of SC-CO2, and adding one or more additives.

2. The method according to claim 1, characterized in that, The pore structure includes the pore size distribution; the step of performing feature analysis on the target ore layer to obtain key information about the target ore layer includes: The target ore layer was analyzed by X-ray diffraction to determine the mineral composition of key information in the target ore layer; The pore size distribution and permeability of the target mineral layer were determined using mercury intrusion porosimetry.

3. The method according to claim 1, characterized in that, The step of determining the initial injection pressure range and initial injection flow rate range of SC-CO2 based on the permeability includes: Determine whether the penetration rate is less than a preset penetration rate; If the permeability is less than the preset permeability, the initial injection pressure of SC-CO2 is determined to be in the range of 8 to 15 MPa, and the initial injection flow rate is determined to be in the range of 0.5 to 2 L / min.

4. The method according to claim 1, characterized in that, The step of determining the initial injection temperature range based on the mineral composition includes: Determine whether the mineral composition contains carbonate minerals; If carbonate minerals are present, the initial injection temperature range is determined to be 35–45°C.

5. The method according to claim 1, characterized in that, The step of determining the initial injection time range based on the ore layer thickness includes: Determine whether the thickness of the mineral layer is greater than a preset thickness; If the thickness is greater than the preset thickness, the initial injection time range is determined to be 1 to 3 days.

6. The method according to claim 1, characterized in that, The step of adjusting the pre-unblocking parameters based on the internal pressure, internal temperature, internal flow rate, and / or target ion concentration includes: adjusting the injection pressure of SC-CO2 using the pressurizing device, adjusting the injection temperature of SC-CO2 using the temperature control system, adjusting the injection flow rate of SC-CO2, adjusting the injection time of SC-CO2, and adding one or more additives. When the rate of increase of the internal pressure is higher than the preset rate, the injection pressure of SC-CO2 is reduced by the pressurization device, and the injection flow rate of SC-CO2 is increased.

7. The method according to claim 1, characterized in that, The target mineral layer has a pore size of less than 10 μm, a porosity of less than 10%, and a permeability of 0.1 × 10⁻³ μm. 2 The mineral composition includes 20% carbonate minerals by mass; the injection pressure of the SC-CO2 is 10 MPa within the initial injection pressure range; the injection flow rate of the SC-CO2 is 1 L / min within the initial injection flow rate range; the injection temperature of the SC-CO2 is 38°C within the initial injection temperature range; and the injection time of the SC-CO2 is 2 days within the initial reaction time range.

8. The method according to claim 1, characterized in that, The target ore layer has a pore size of 10–30 μm, a porosity of 10%–25%, and a permeability of 0.05 × 10⁻³ μm. 2 The mineral composition includes quartz, feldspar, carbonates, and clay minerals; the injection pressure of the SC-CO2 is 12 MPa, which is within the initial injection pressure range; the injection flow rate of the SC-CO2 is 0.8 L / min, which is within the initial injection flow rate range; the injection temperature of the SC-CO2 is 40°C, which is within the initial injection temperature range; and the injection time of the SC-CO2 is 3 days, which is within the initial reaction time.

9. An SC-CO2 ore seam pre-dredging system, characterized in that, Used for: The target mineral layer is subjected to feature analysis to obtain key information about the target mineral layer; wherein the key information includes permeability, mineral composition and mineral layer thickness; Construct an SC-CO2 injection system; wherein, the SC-CO2 injection system includes a CO2 gas source, a pressurization device, a temperature control system, a flow regulating device, and an injection pipeline connected in sequence; Based on the permeability, the initial injection pressure range and initial injection flow rate range of SC-CO2 are determined; the pressurizing device is controlled to pressurize the liquid CO2 provided by the CO2 gas source to obtain SC-CO2, and the injection pressure of the SC-CO2 is within the initial injection pressure range; the injection flow rate of the SC-CO2 is adjusted to be within the initial injection flow rate range. Based on the mineral composition, an initial injection temperature range is determined; the temperature control system is then used to adjust the injection temperature of the SC-CO2 to within the initial injection temperature range. The initial injection time range is determined based on the ore layer thickness and the preset reaction rate; the injection time of SC-CO2 is controlled to be within the initial injection time range. During the SC-CO2 injection time, downhole sensors are used to acquire detection data and analyze the target ion concentration in the target mineral layer; wherein the detection data includes the internal pressure, internal temperature and internal flow rate of the target mineral layer; Based on the internal pressure, internal temperature, internal flow rate, and / or target ion concentration, the pre-dredging parameters are adjusted; wherein, the adjustment of the pre-dredging parameters includes adjusting the injection pressure of SC-CO2 using the pressurizing device, adjusting the injection temperature of SC-CO2 using the temperature control system, adjusting the injection flow rate of SC-CO2, adjusting the injection time of SC-CO2, and adding one or more additives.

10. The application of the SC-CO2 ore seam pre-dredging method according to any one of claims 1-8, characterized in that, It is used for pre-dredging of uranium mines, oil and gas ore layers, and geothermal ore layers.

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