Shale in-situ heating product utilization process and applications

Abstract

The present application provides a shale in-situ heating product utilization process and application, the process comprises: determining the area of shale in-situ heating; according to the area of shale in-situ heating, the block of shale in-situ heating mining is divided, the mining well group deployment mode and heating mode of the block of shale in-situ heating mining are determined; the block of shale in-situ heating is heated and mined in batches, and the ground product of the block of shale in-situ heating mining is collected; the water and / or carbon dioxide gas in the ground product of the block of shale in-situ heating mining is injected back to the block of shale in-situ heating completed heating for re-mining. The process of the present application innovates the shale in-situ heating ground product comprehensive utilization process and the harmless treatment process of harmful gas, forms a complete set of technology, and provides technical support for safe, environmentally friendly and efficient mining of shale in-situ heating. The shale in-situ heating product utilization process of the present application can effectively utilize the shale in-situ heating product.

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration and development technology, and in particular to a process and application for utilizing shale in-situ heating products. Background Technology

[0002] Shale oil and gas has become an important area for global oil and gas exploration, development, and reserve and production enhancement. However, exploration and development practices have shown that when the vitrinite reflectance (Ro) of organic-rich shale is less than 0.9%, factors such as low or unconverted conversion rates of organic matter in the shale, viscous retained oil, underdeveloped organic pores, and difficult fluid flow prevent existing horizontal well volumetric fracturing technology from achieving large-scale efficient development. These resources include hydrocarbons already generated and retained in shale and unconverted solid organic matter, which can be extracted using in-situ heating technology. In-situ heating technology is a technique that uses in-situ heating methods to convert unconverted organic matter and generated hydrocarbons in shale into light oil and natural gas for extraction.

[0003] Preliminary research estimates that the global recoverable resources of shale suitable for in-situ heating extraction are approximately 1.4 trillion tons of oil and 1100 trillion cubic meters of natural gas. In China, the recoverable resources of shale suitable for in-situ heating extraction are greater than 70 billion tons of oil and greater than 60 trillion cubic meters of natural gas. The recoverable resources of shale suitable for in-situ heating extraction are more than three times that of conventional oil and natural gas, indicating enormous potential.

[0004] Shale in-situ heating technology for oil and gas extraction differs from existing technologies. After shale in-situ heating, the porosity increases, typically exceeding 20%, and the average temperature of the effective underground heating zone surpasses 300℃. Therefore, the product composition and temperature differ significantly from oil and gas extracted using existing technologies. Shale in-situ heating products include light oil, natural gas, and water, with a wellhead product temperature of approximately 200℃. Light oil, containing C5+, is liquid at normal temperature and pressure, but at the wellhead temperature of approximately 200℃, some C5+ components are gaseous. Natural gas components include methane, C2-C4, hydrogen sulfide, carbon dioxide, and hydrogen, requiring separation of these complex components for safe and environmentally friendly storage, transportation, and utilization. Water originates from the formation or dehydration of clay minerals and is gaseous at the wellhead. Once the recovery rate of shale in-situ heating reaches a certain level, it is difficult to further increase the recovery rate through self-flowing or pumping methods. A certain amount of oil and gas remains underground, which can be further improved by enhancing the recovery rate of this remaining underground oil and gas. Therefore, by separating the products from in-situ heated shale, harmful gases such as carbon dioxide can be rendered harmless, thereby increasing the recovery rate of residual oil and gas underground and achieving safe, environmentally friendly, green, and efficient mining.

[0005] Existing technologies are all developed for lower temperatures and single products during the extraction of different types of resources. Their applicable conditions and technical indicators are fundamentally different from the technologies required for the efficient utilization of shale in-situ heating products in this invention. Existing technologies all have deficiencies in terms of efficient utilization of shale in-situ heating products, improving oil and gas recovery rates, and harmless treatment of harmful products.

[0006] Existing technologies are mainly applicable to the processing, utilization, and enhanced oil and gas recovery of oil and gas with relatively simple components or at low temperatures. Numerous field tests of in-situ shale heating have been conducted abroad, but none have yet developed a complete set of technologies and processes for the efficient processing, utilization, and enhanced oil and gas recovery of shale products from in-situ heating.

[0007] Many existing oil and gas processing and enhanced oil and gas recovery technologies exist, but they are all suitable for oil and gas with relatively simple compositions and low temperatures. In contrast, oil and gas extracted through in-situ heating have more complex compositions and higher temperatures. Furthermore, the underground temperature remains high after extraction, and there is a significant amount of residual oil and gas. Current oil and gas extraction and processing technologies cannot effectively process and utilize the products of in-situ shale heating, nor can they improve the recovery rate of residual underground oil and gas. Summary of the Invention

[0008] To address the problems existing in the prior art, this invention provides a shale in-situ heating mining process and application. The process mainly involves the treatment and comprehensive utilization of shale in-situ heating products, so as to improve the recovery rate of underground residual oil and gas and the carbon dioxide burial, harmless treatment and utilization rate in the products, thereby improving the economic benefits of shale in-situ heating mining and realizing green, environmentally friendly and large-scale development of shale in-situ heating.

[0009] To achieve the above objectives, the present invention provides a process for utilizing shale in-situ heating products, the process comprising:

[0010] Identify the areas where shale is heated in situ;

[0011] Based on the area of ​​shale in-situ heating, divide the blocks for shale in-situ heating mining, and determine the deployment method of mining well groups and heating method for the blocks of shale in-situ heating mining;

[0012] The shale blocks that are heated in situ are heated and mined in batches, and the surface products of the heated shale blocks are collected.

[0013] Water and / or carbon dioxide gas from the surface products of the in-situ heated shale blocks can be reinjected into the in-situ heated shale blocks for further mining.

[0014] Furthermore, the area where the shale is in-situ heated includes,

[0015] The burial depth and effective shale thickness of the target shale layer were determined based on the core test analysis and well logging data interpretation of the target shale layer.

[0016] The well type of the production well group is determined based on the burial depth of the target layer and the effective shale thickness during in-situ shale heating. The well type of the production well group is one of the following: vertical well, inclined well, and multi-layered horizontal well.

[0017] Based on the well type of the mining well group and the return on investment, the area for in-situ shale heating is determined.

[0018] Furthermore, the step of dividing shale into in-situ heated mining blocks based on the area of ​​shale in-situ heating, and determining the deployment method of mining well groups and heating methods for the shale in-situ heated mining blocks, includes...

[0019] Based on the well type and production scale of the well groups in the shale in-situ heating area, the shale in-situ heating mining blocks are divided.

[0020] Determine the well network structure of the production wells and the well spacing of the heating wells within the blocks where shale in-situ heating is to be carried out. Based on the construction speed and investment recovery period of shale in-situ heating oil and gas production, determine the number of shale in-situ heating production blocks that can start heating at the same time.

[0021] Furthermore, the shale block undergoing in-situ heated mining has the following characteristics:

[0022] There was no fluid exchange in the adjacent shale blocks that were heated in situ during the heated mining process;

[0023] Each shale in-situ heated block includes multiple well groups, each with the same well layout and consisting of multiple heating wells and production wells.

[0024] The heating times of blocks in shale in-situ heated mining are sequential.

[0025] Furthermore, the shale blocks that are heated in situ are mined in batches, and the surface products from the heated shale blocks are collected.

[0026] The blocks of shale that are heated in situ are heated and mined in batches. The surface products of the heated shale blocks are used to generate thermoelectric power, and the electrical energy and gas-liquid mixtures generated by thermoelectric power are collected.

[0027] The gas-liquid mixture is separated to obtain liquid petroleum, water, and a mixed gas.

[0028] The mixed gas was separated to obtain sulfur, hydrogen, C2-C4 gas and residual gas;

[0029] The liquid petroleum, sulfur, hydrogen, and C2-C4 are transported separately to obtain liquid petroleum, sulfur, hydrogen, and C2-C4 products;

[0030] The remaining gas is purified to obtain carbon dioxide gas.

[0031] Furthermore, the step of reinjecting water and / or carbon dioxide gas from the surface products of the in-situ heated shale block into the in-situ heated shale block for further mining includes obtaining a planar distribution map of shale thickness and a planar distribution map of organic carbon content of the in-situ heated shale block.

[0032] Core samples were taken from the shale blocks that were in-situ heated for core analysis experiments, and a power function model for predicting the porosity of the shale blocks that had been in-situ heated was established.

[0033] Based on the power function model and the organic carbon content planar distribution map, predict the shale porosity planar distribution map of the shale in-situ heated block after the heating is completed;

[0034] Based on the shale porosity planar distribution map and the shale thickness planar distribution map, predict the volume of water and carbon dioxide gas available for reinjection in the in-situ heated shale block after heating is completed;

[0035] Water and / or carbon dioxide gas collected from the surface products of the in-situ heated shale blocks will be reinjected into the same or more in-situ heated shale blocks for further mining.

[0036] Furthermore, core samples were taken from the shale blocks that had undergone in-situ heating for core analysis experiments. A power function model for predicting the porosity of the shale in the in-situ heated blocks was established, including...

[0037] The formation pressure is obtained based on the shale burial depth of the shale block where shale is heated in situ.

[0038] Core analysis experiments were conducted on core samples taken from the shale blocks that were in situ heated to obtain the organic carbon content of the shale before heating.

[0039] The core was subjected to a porosity test under the formation pressure and heating to obtain the porosity of the heated shale.

[0040] A power function model for predicting the porosity of shale in in-situ heated blocks was established based on the organic carbon content of shale before heating and the porosity of shale after heating.

[0041] Furthermore, the power function model for predicting the porosity of the in-situ heated shale block after heating is as follows:

[0042] Φ=a×TOC b ;

[0043] Where Φ is the porosity of the shale after heating, TOC is the organic carbon content of the shale before heating, and a and b are parameters to be determined.

[0044] Furthermore, the reinjection of water and / or carbon dioxide gas from the surface products of the in-situ heated shale blocks into the same or more completed in-situ heated shale blocks for further mining includes...

[0045] When the well type of the in-situ heated shale block is a multi-layered horizontal well, the well is ready for production.

[0046] Water and carbon dioxide gas are reinjected into the same in-situ heated shale block. The carbon dioxide gas reinjection well is the uppermost production well on the edge of the multi-layer horizontal well, and the water reinjection well is the lowermost production well on the same side as the carbon dioxide gas reinjection well. Other production wells are closed, and the production wells on the lowermost edge of the multi-layer horizontal well on the symmetrical side of the carbon dioxide gas reinjection well and the water reinjection well in the block are opened in sequence for production. When a production well starts producing water, production in that production well is stopped, and the adjacent production well on the next higher layer is opened for production, until all production wells produce water.

[0047] Water or carbon dioxide gas is reinjected separately into multiple shale blocks that have undergone in-situ heating. When extracting shale by injecting carbon dioxide gas alone, the carbon dioxide gas injection well is the uppermost extraction well in the multi-layered horizontal well structure. Other extraction wells are closed, and the lowermost extraction well in the multi-layered horizontal well structure symmetrical to the carbon dioxide gas injection well in the block is opened for extraction. When extracting shale by injecting water alone, the water injection well is the lowermost extraction well in the multi-layered horizontal well structure. Other extraction wells are closed, and the uppermost extraction well in the multi-layered horizontal well structure symmetrical to the water injection well in the block is opened for extraction.

[0048] When the well type for production in the block where the shale has been heated in situ is a vertical well or an inclined well.

[0049] Water and carbon dioxide gas are simultaneously reinjected into the same shale block that has undergone in-situ heating. The wells for water and carbon dioxide gas reinjection are located on the same side of the block. If the target shale layer has a dip angle, the carbon dioxide injection well is located on the side of the target shale layer in the updip direction, and the water injection well is located on the side of the target shale layer in the downdip direction. The remaining wells in the heated block are closed, and the outermost well on the side symmetrical to the water and carbon dioxide gas injection well is opened for extraction. If the target shale layer does not have a dip angle, the carbon dioxide and water injection wells are two wells on the same side of the well group in the heated block. The remaining wells in the heated block are closed, and the outermost well on the side symmetrical to the carbon dioxide and water injection well is opened for extraction.

[0050] Water or carbon dioxide gas is reinjected separately into multiple in-situ heated shale blocks. If the target shale layer has a dip angle, the well for water or carbon dioxide gas reinjection is located on the edge of the target shale layer in the updip direction. The remaining wells in the heated block are closed, and the wells on the other side of the target shale layer in the downdip direction are opened for extraction. If the target shale layer does not have a dip angle, the well for water or carbon dioxide gas reinjection is located on one side of the well group in the heated block. The remaining wells in the heated block are closed, and the outermost well on the symmetrical side of the well in the block is opened for extraction.

[0051] Furthermore, the purification of the remaining gas into carbon dioxide includes: combustion-liquefaction treatment or liquefaction treatment.

[0052] The combustion-liquefaction process involves directly burning the remaining gas to generate electricity, collecting the electricity generated from the combustion and the exhaust gas, pressurizing and liquefying the exhaust gas to obtain carbon dioxide, and depressurizing to obtain carbon dioxide gas.

[0053] The liquefaction process involves pressurizing and liquefying the remaining gas to obtain carbon dioxide, and then depressurizing to obtain carbon dioxide gas.

[0054] This invention also provides the application of the above-mentioned shale in-situ heating product utilization process.

[0055] Furthermore, the utilization of surface products from blocks used for in-situ heating of shale.

[0056] Compared with existing technologies, the efficient utilization process and application of shale in-situ heating products provided by this invention have the following beneficial effects:

[0057] This invention provides a process for the efficient utilization of shale in-situ heating products, the harmless treatment of harmful gases, and the improvement of underground residual oil and gas recovery rates. It establishes a complete technological process for the safe, environmentally friendly, and efficient utilization of shale in-situ heating products, improving mining efficiency, reducing mining risks, and filling a gap in this field. A method for determining the area of ​​shale in-situ heating mining blocks is proposed, providing a technical basis for improving mining efficiency and filling a gap in this field. The invention innovates the comprehensive utilization process of products and the harmless treatment process for harmful gases, forming a complete technological system that overcomes the lack of supporting technologies in this field and provides technical support for the safe, environmentally friendly, and efficient mining of shale in-situ heating. The invention also innovates the processes for carbon dioxide and water reinjection after product treatment, the selection of reinjection wells and production wells, and the determination of the reinjection cessation time, filling a technological gap in this area and improving mining efficiency. Applying the shale in-situ heating product utilization process of this invention can effectively utilize shale in-situ heating products. Attached Figure Description

[0058] Figure 1 A flowchart illustrating a process for utilizing in-situ heated shale products, as shown in an embodiment of the present invention, is presented.

[0059] Figure 2 The experimental analysis data and well logging data interpretation data of the 7th section core from the Ordos Basin in this embodiment of the invention are shown to determine the burial depth and effective shale thickness of the target layer for in-situ heating of shale.

[0060] Figure 3a This diagram shows the planar distribution of the burial depth of the target layer in the Chang 7 section of the Ordos Basin during in-situ heating, according to an embodiment of the present invention. Figure 3b The planar distribution of the effective shale thickness of the target layer for in-situ heating of the Chang 7 section shale in the Ordos Basin is shown in an embodiment of the present invention.

[0061] Figure 4 A cross-sectional view of the shale in-situ heating mining block and well layout in an embodiment of the present invention is shown;

[0062] Figure 5 This is a graph showing the relationship between the organic carbon content and porosity of shale in the mining block before heating and after heating, in an embodiment of the present invention. Detailed Implementation

[0063] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] One embodiment of the present invention provides a process for utilizing shale in-situ heating products, the flowchart of which is as follows: Figure 1 As shown, the process includes the following steps:

[0065] S1 determines the area of ​​in-situ heating of shale;

[0066] S2 divides the shale in-situ heating mining blocks according to the area of ​​shale in-situ heating, and determines the deployment method of mining well groups and heating method of the shale in-situ heating mining blocks;

[0067] S3 will heat and mine the shale blocks in situ in batches, and collect the surface products of the heated shale blocks in situ.

[0068] S4 will reinject water and / or carbon dioxide from the surface products of the in-situ heated shale block into the heated shale block for further mining.

[0069] The various steps involved in the above embodiments are described in conjunction with the appendix. Figures 2-5 The following is a detailed introduction:

[0070] Step S1: Determine the area for in-situ heating of shale.

[0071] Based on the core sample analysis and well logging data interpretation of the target shale layer, the burial depth and effective shale thickness of the target shale layer for in-situ heating are determined. Based on the burial depth and effective shale thickness of the target shale layer for in-situ heating, the well type of the production well group is determined, which can be one of a vertical well, an inclined well, or a multi-layered horizontal well. Based on the well type of the production well group and the return on investment, the area for in-situ shale heating is determined.

[0072] For example, Figure 2 The paper shows that the experimental analysis data and well logging data interpretation data of the 7th core section of the Ordos Basin determined that the burial depth of the target layer for in-situ shale heating is 1240-1260 meters and the effective shale thickness is 20 meters.

[0073] Preferably, when the burial depth of the target shale layer suitable for in-situ heating and mining is less than a certain value, 300 meters is preferred; and when the cumulative thickness of the shale segment is greater than a certain value, 20 meters is preferred. Vertical or inclined wells can be used for well layout; the spacing between heating wells is preferably 5–10 meters. When the burial depth of the target shale layer suitable for in-situ heating and mining is greater than a certain value, 300 meters is preferred; and when the cumulative thickness of the shale segment is greater than a certain value, 15 meters is preferred. Multi-layered horizontal wells can be used for well layout; the spacing between heating wells is preferably 5–20 meters.

[0074] Furthermore, Figure 3aThis diagram shows the planar distribution of the burial depth of the target layer in the Chang 7 section of the Ordos Basin, which was heated in situ. Figure 3a The unit is meters. Figure 3b This diagram shows the planar distribution of the effective shale thickness of the target layer in the Chang 7 section of the Ordos Basin, which is intended for in-situ heating. Figure 3b The unit is meters. Figure 3a and Figure 3b It can be seen that the target shale for in-situ heating of the Chang 7 section shale in the Ordos Basin is buried at a depth of 1000-1600 meters and the effective shale thickness is 14-25 meters. Therefore, it is determined that the in-situ heating of the Chang 7 section shale in the Ordos Basin adopts a multi-layer structure horizontal well layout.

[0075] The shale in-situ heating mining area refers to an area that meets the conditions for shale in-situ heating mining and has an investment return rate greater than a certain value, preferably 8%. Based on this, the area of ​​the shale in-situ heating zone in the Chang 7 section of the Ordos Basin is determined to be 600 square kilometers.

[0076] S2 divides shale in-situ heating mining blocks according to the regional shale in-situ heating, and determines the deployment of mining well groups and heating methods for the shale in-situ heating mining blocks.

[0077] In order to improve the efficient utilization of shale in-situ heating products and the recovery rate of residual oil and gas underground, a block mining method is adopted in the same shale in-situ heating mining area.

[0078] Specifically, based on the well type of the production well groups and the production scale of oil and gas production in the shale in-situ heating area, shale in-situ heating production blocks are divided; the well network structure of the production well groups and the well spacing of the heating wells within the shale in-situ heating production blocks are determined; and the number of shale in-situ heating production blocks that start heating at the same time is determined in combination with the construction speed and investment recovery period of shale in-situ heating oil and gas production.

[0079] Preferably, in step S1, the area of ​​the in-situ heating zone for the Chang 7 section of the Ordos Basin is 600 square kilometers. A multi-layered horizontal well layout is adopted, and based on the production scale of oil and gas, the area of ​​the shale in-situ heating mining block is divided into 5 square kilometers. Adjacent shale in-situ heating blocks do not exchange fluids during heating mining; the heating time for each shale in-situ heating block may be the same or different, and the heating time of the shale in-situ heating blocks is continuous; each shale in-situ heating block includes multiple production well groups, each production well group has the same well layout, and each production well group includes multiple heating wells and production wells.

[0080] Preferably, each shale in-situ heated block includes multiple well groups, preferably 20-50; each well group includes multiple heating wells and production wells, preferably 20-40 heating wells and 2-4 production wells; the well layout of each well group within the same mining block is the same. The distance between different well groups within the same mining block is consistent with the distance between production wells and heating wells within that well group; adjacent mining blocks are spaced at a certain distance, which is determined by the heating time and the lateral sealing properties of the target layer, preferably 20 meters, to ensure no fluid exchange between adjacent mining blocks during in-situ heated mining, i.e., the block has self-sealing properties. For example, Figure 4 The diagram shows the well layout of two well groups in two shale in-situ heated mining blocks. The two well groups have the same layout, using a 5-layer horizontal well layout. The two blocks are 20m apart. Each well group has 20 heating wells and 2 mining wells. The spacing between the heating wells is 10 meters in the longitudinal direction and 17.32 meters in the transverse direction. The length of the horizontal well section is 1200 meters.

[0081] In actual operation, the construction speed and investment recovery period of shale in-situ heated oil and gas production can be used to determine the number of production blocks to be heated within the same time frame, preferably 3 months. The number of blocks to be heated within the same time frame is preferably 3 to 5. The production blocks to be heated within the same time frame should preferably be deployed in the same way. All heated wells in the same well group should have the same preset heating start time. The preset heating start time of heated wells in different well groups within the same production block should be within a certain range, preferably 3 months. The heating time of heated wells in different production blocks may be the same or different, preferably 3 to 5 years. The start heating times of different production blocks within the entire production area should be sequential to stabilize oil and gas production and ensure that after the heating of one or more production blocks is completed, the products of the subsequent one or more production blocks can be used to improve the recovery rate of the remaining underground oil and gas in the previous one or more production blocks, while also achieving harmless carbon dioxide treatment.

[0082] S3 will heat and mine the shale blocks in situ in batches, collecting the surface products from the heated shale blocks.

[0083] When shale blocks that are in-situ heated are extracted, surface products, residual underground oil and gas, and residual underground heat are generated. In this embodiment, the shale blocks that are in-situ heated are extracted in batches. Therefore, by extracting the shale blocks in batches, the surface products from the blocks that are being extracted can be collected and utilized.

[0084] Specifically, the shale blocks that are heated in situ are extracted in batches. The surface products from these heated shale blocks are used for thermoelectric power generation, collecting the electrical energy and a gas-liquid mixture. The gas-liquid mixture is then separated to obtain liquid petroleum, water, and a mixed gas. The mixed gas is further separated to obtain sulfur, hydrogen, C2-C4, and residual gas. The liquid petroleum, sulfur, hydrogen, and C2-C4 are then transported separately to obtain liquid petroleum, sulfur, hydrogen, and C2-C4 products. The residual gas is then purified to obtain carbon dioxide gas.

[0085] It should be noted that, in the embodiments of the present invention, C2-C4 refers to alkanes with 2 to 4 carbon molecules.

[0086] More preferably, a thermoelectric generator and an oil-gas-water separator of appropriate scale can be selected based on the temperature of the shale in-situ heating product and the oil, gas and water production data.

[0087] Table 1. Temperature and yield of products from a single well group

[0088] Temperature (°C) Oil production (10,000 tons) Gas production (100 million cubic meters) Water production (10,000 tons) 300～350 15～25 1.7～3 2～5

[0089] For example, Table 1 shows the temperature and production of a production well group. Shale in-situ heated production is produced from the wellhead and enters a thermoelectric generator. The generated electricity is fed into the power grid or converted into electricity for in-situ heating. The gas-liquid mixture, after being cooled by the thermoelectric generator, enters a gas-liquid separator to separate liquid oil, water and gas. The liquid oil enters the external pipeline or is loaded onto trucks and transported away, while the water is recovered and will be reinjected into the underground target layer of the heated production block.

[0090] Table 2. Experimental analysis results of gaseous components of ground products.

[0091]

[0092] Table 2 shows the experimental analysis results of the gaseous components of the ground products. Based on these results, a suitable gas component separation device was selected for component separation. Separation was performed based on the differences in boiling points and critical temperatures and pressures of each gas component, or the different adsorption and permeability of different substances to each gas component. The boiling points and critical temperatures and pressures of the separated gases are shown in Table 3.

[0093] Table 3. Boiling points and critical temperatures and pressures of the separated gases

[0094]

[0095]

[0096] The process involves separating liquid petroleum, water, and a mixed gas to obtain a mixed gas. The specific process flow for separating the components of the mixed gas is as follows:

[0097] The mixed gas enters the hydrogen sulfide separation unit and adopts a wet desulfurization process, such as wet oxidation, where hydrogen sulfide is oxidized into sulfur and transported away; or wet absorption, where hydrogen sulfide is further utilized through physical or chemical absorption.

[0098] The remaining gas after the removal of hydrogen sulfide enters a hydrogen separation unit, where hydrogen is separated using technologies such as membrane separation, pressure swing adsorption, and cryogenic separation, and then transported away for further utilization.

[0099] The remaining gas after the removal of hydrogen sulfide and hydrogen enters the C2-C4 separation unit, where separation is performed using the boiling points and critical temperature and pressure characteristics of C2-C4. Based on the boiling points and critical temperature and pressure of the gases shown in Table 3, the temperature is lowered to a certain range, preferably 0℃~20℃, and the pressure is increased to a certain value, preferably 4~5MPa, to liquefy and separate the C2-C4. The separated gas is then transported away using a compression device for further utilization.

[0100] The final residual gas is mainly methane, with small amounts of carbon dioxide, carbon monoxide, and nitrogen. This residual gas is directly burned in a power generation unit to generate electricity, which is then fed into the power grid or used for in-situ heating of shale. The exhaust gas produced after power generation is mainly nitrogen and carbon dioxide. This exhaust gas is fed into a carbon dioxide liquefaction unit, where carbon dioxide is separated using its boiling point and critical temperature and pressure characteristics. The temperature is lowered to a certain range, preferably 20°C, and the pressure is increased to a certain value, preferably 7 MPa, to liquefy and separate the carbon dioxide. The liquefied carbon dioxide is then depressurized and converted into gas, which is injected through pipelines into the target underground layer of the heated mining block to improve the recovery rate of residual underground oil and gas and achieve carbon dioxide storage.

[0101] Alternatively, the remaining gas can be fed into a carbon dioxide liquefaction unit, where the temperature is reduced to a certain range, preferably 20°C, and the pressure is increased to a certain value, preferably 7 MPa, to liquefy and separate the carbon dioxide. The liquefied carbon dioxide is then depressurized and converted into gas, which is then reinjected through pipelines into the underground target layer of the heated mining block. Finally, the remaining gas is mainly methane, and also includes small amounts of carbon monoxide, nitrogen, etc., which is fed into a natural gas pipeline for external transport from the well site and further utilization.

[0102] The above process for separating components of mixed gas must be kept away from air to prevent the introduction of oxygen and potential explosion.

[0103] Shale in-situ heating: The underground target layer products of both the mining blocks that are being heated and those that have completed heating undergo the above process to achieve safe, environmentally friendly mining and efficient utilization of shale through in-situ heating.

[0104] Step S4 involves reinjecting water and / or carbon dioxide gas from the surface products of the in-situ heated shale block into the completed in-situ heated shale block for further extraction.

[0105] After processing in step S3, liquid petroleum, sulfur, hydrogen, and C2-C4 products, as well as water and carbon dioxide, were collected. In this embodiment of the invention, in-situ heating is performed in blocks within the same region. Water and / or carbon dioxide gas collected from the surface products of the in-situ heated shale blocks can be reinjected into one or more completed in-situ heated shale blocks, allowing for further mining of the completed in-situ heated shale blocks.

[0106] Furthermore, the volume of water and carbon dioxide gas available for injection into the in-situ heated shale block can be predicted:

[0107] Obtain planar distribution maps of shale thickness and organic carbon content in the in-situ heated shale blocks; conduct core analysis experiments on core samples from the in-situ heated shale blocks to establish a power function model for predicting shale porosity in the heated shale blocks; predict the planar distribution map of shale porosity in the heated shale blocks based on the power function model and the organic carbon content planar distribution map; predict the volume of water and carbon dioxide available for reinjection in the heated shale blocks based on the shale porosity planar distribution map and the shale thickness planar distribution map; and reinject the water and / or carbon dioxide gas collected from the surface products of the heated shale blocks into one or more heated shale blocks for further mining.

[0108] Specifically, core samples were taken from the shale blocks that had undergone in-situ heating for core analysis experiments. A power function model for predicting the porosity of the shale in the in-situ heated blocks was established, including:

[0109] Based on the shale burial depth of the shale block undergoing in-situ heating, the formation pressure of the target shale layer is obtained. Core samples are taken from the in-situ heated shale block for core analysis to determine the organic carbon content of the shale before heating. Porosity experiments are then conducted on the core samples under the formation pressure and heating conditions to determine the porosity of the shale after heating. It should be noted that the heating temperature used here is the final heating temperature for the in-situ heated shale block before mining. Based on the organic carbon content of the shale before heating and the porosity of the shale after heating, a power function model for predicting the porosity of the shale in the completed in-situ heated shale block is established.

[0110] The power function model is specifically as follows:

[0111] Φ=a×TOC b ;

[0112] Where Φ is the porosity of the shale after heating, TOC is the organic carbon content of the shale before heating, and a and b are parameters to be determined.

[0113] Preferably, in this embodiment, 18 shale core samples were collected from the shale block where in-situ heating was performed. Based on the burial depth of the target shale layer, the overlying formation pressure was calculated according to the People's Republic of China Petroleum and Natural Gas Industry Standard SY / T 5815-2016, "Method for Determining the Volumetric Compression Coefficient of Rock Pores." In this embodiment, the average shale burial depth was 1350 meters, and the calculated overlying formation pressure was 30 MPa. Based on the overlying formation pressure of the target shale layer and the final heating temperature during extraction, porosity tests were conducted on each shale sample under high temperature and high pressure conditions. Table 4 shows the analysis results of the shale porosity test of the 18 shale core samples at a temperature of 425℃ and a pressure of 30 MPa. Before heating, the total organic carbon (TOC) content was 7.23%–17.68%, and after heating, the shale porosity was 18.35%–31.30%. Based on the data of the TOC content before heating and the porosity after heating, as... Figure 5 As shown, the power function model for predicting the porosity of heated shale is Φ = 7.2293 × TOC. 0.4855 .

[0114] Table 4. Experimental Test Results of Shale Porosity

[0115]

[0116]

[0117] Using a power-function model for predicting shale porosity after heating and a planar distribution map of organic carbon content in shale blocks undergoing in-situ heating, the planar distribution map of shale porosity in the completed heating mining blocks is predicted. Based on the planar distribution map of shale thickness and the planar distribution map of shale porosity after heating, the volume of shale in the completed heating mining blocks that can be reinjected with carbon dioxide and water is predicted. For example, in this embodiment, one mining block has an area of ​​5 square kilometers, a shale organic carbon content of 16%–18%, and a thickness of 20–25 meters. The predicted volume of carbon dioxide and water that can be reinjected from the completed heating mining block is 0.2–0.38 billion cubic meters. Based on the carbon dioxide and water production data of the heated mining block, the formation temperature and pressure conditions of the reinjection target layer, the volume of recovered carbon dioxide and water under the formation temperature and pressure conditions is calculated. Combined with the predicted reinjectable volume of shale in the completed heating mining block, the completed heating mining block for carbon dioxide and water reinjection is determined. For example, in this embodiment, one mining block recovers 9 to 1.5 billion cubic meters of carbon dioxide gas and 800,000 to 2 million cubic meters of water. The formation temperature of the target layer is 75°C and the formation fluid pressure is 5 MPa. The calculated volume of recovered carbon dioxide and water reinjected into the underground target layer is 46 to 77 million cubic meters, which can be used to reinject into 2 to 3 fully heated mining blocks.

[0118] Specifically, when the well type for the in-situ heated shale block is a multi-layered horizontal well,

[0119] Water and carbon dioxide gas are reinjected into the same in-situ heated shale block. The carbon dioxide gas reinjection well is the uppermost production well on the edge of the multi-layer horizontal well, and the water reinjection well is the lowermost production well on the same side as the carbon dioxide gas reinjection well. Other production wells are closed, and the production wells on the lowermost edge of the multi-layer horizontal well on the symmetrical side of the carbon dioxide gas reinjection well and the water reinjection well in the block are opened in sequence for production. When a production well starts producing water, production in that production well is stopped, and the adjacent production well on the next higher layer is opened for production, until all production wells produce water.

[0120] Water or carbon dioxide gas is reinjected separately into multiple shale blocks that have undergone in-situ heating. When extracting shale by injecting carbon dioxide gas alone, the carbon dioxide gas injection well is the uppermost extraction well in the multi-layered horizontal well structure. Other extraction wells are closed, and the lowermost extraction well in the multi-layered horizontal well structure symmetrical to the carbon dioxide gas injection well in the block is opened for extraction. When extracting shale by injecting water alone, the water injection well is the lowermost extraction well in the multi-layered horizontal well structure. Other extraction wells are closed, and the uppermost extraction well in the multi-layered horizontal well structure symmetrical to the water injection well in the block is opened for extraction.

[0121] Specifically, when the well type for the in-situ heated shale block is a vertical well or an inclined well,

[0122] Water and carbon dioxide gas are simultaneously reinjected into the same shale block that has undergone in-situ heating. The wells for water and carbon dioxide gas reinjection are located on the same side of the block. If the target shale layer has a dip angle, the carbon dioxide injection well is located on the side of the target shale layer in the updip direction, and the water injection well is located on the side of the target shale layer in the downdip direction. The remaining wells in the heated block are closed, and the outermost well on the side symmetrical to the water and carbon dioxide gas injection well is opened for extraction. If the target shale layer does not have a dip angle, the carbon dioxide and water injection wells are two wells on the same side of the well group in the heated block. The remaining wells in the heated block are closed, and the outermost well on the side symmetrical to the carbon dioxide and water injection well is opened for extraction.

[0123] Water or carbon dioxide gas is reinjected separately into multiple in-situ heated shale blocks. If the target shale layer has a dip angle, the well for water or carbon dioxide gas reinjection is located on the edge of the target shale layer in the updip direction. The remaining wells in the heated block are closed, and the wells on the other side of the target shale layer in the downdip direction are opened for extraction. If the target shale layer does not have a dip angle, the well for water or carbon dioxide gas reinjection is located on one side of the well group in the heated block. The remaining wells in the heated block are closed, and the outermost well on the symmetrical side of the well in the block is opened for extraction.

[0124] Carbon dioxide and water reinjection can be performed simultaneously in the same heated production block or separately in different heated production blocks. It should be noted that if the amount of reinjected water and / or carbon dioxide gas is large, three or more production wells can be used for reinjection; if the extracted oil and gas volume is relatively large, one or more production wells should be activated to extract the remaining underground products. The number of reinjection wells and production wells can be determined based on the actual production operations.

[0125] When reinjecting carbon dioxide into a heated mining block, the method for determining the termination time of carbon dioxide injection is as follows: When the sum of the carbon dioxide injection operation cost and the product operation cost and processing cost from the well in the mining block is greater than the utilization value of the product in the mining block, the processing of the product in the mining block can be stopped, and the product can be directly used for thermoelectric power generation. When the utilization value of the wellhead product is equal to the cost of carbon dioxide injection and product utilization, carbon dioxide injection should be stopped, and further injection will no longer be profitable.

[0126] When reinjecting water into a heated mining block, the method for determining the water injection termination time is as follows: when the uppermost well of a vertical well, inclined well, or multi-layered horizontal well begins to produce water, the output of the mining block is not processed and is only used for thermoelectric power generation. When the temperature of the water produced at the wellhead is less than or equal to 74°C, the produced water can be used for heating and other treatments. When the temperature value of the water produced at the wellhead is equal to the cost of water injection and utilization, water injection can be stopped, and further injection will no longer be profitable.

[0127] In another embodiment of the present invention, an application of the shale in-situ heating product utilization process of the above embodiment is provided, wherein the shale in-situ heating product utilization process is applied to the utilization of surface products of shale in-situ heated blocks.

[0128] The specific application methods and steps in the application embodiments have been described in detail in the embodiments of the relevant processes, and will not be repeated here.

[0129] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for utilizing shale in-situ heating products, characterized in that, The process includes: Identify the areas where shale is heated in situ; Based on the area of ​​shale in-situ heating, divide the blocks for shale in-situ heating mining, and determine the deployment method of mining well groups and heating method for the blocks of shale in-situ heating mining; The shale blocks that are heated in situ are heated and mined in batches, and the surface products of the heated shale blocks are collected. Water and / or carbon dioxide gas from the surface products of the in-situ heated shale blocks are reinjected into the in-situ heated shale blocks for further mining. The blocks where shale is extracted through in-situ heating have the following characteristics. There was no fluid exchange in the adjacent shale blocks that were heated in situ during the heated mining process; Each shale in-situ heated block includes multiple well groups, each with the same well layout and consisting of multiple heating wells and production wells. The heating times of the shale blocks in in-situ heated mining are consecutive; The process involves heating and mining shale blocks in situ in batches, and collecting the surface products from the heated shale blocks. The blocks of shale that are heated in situ are heated and mined in batches. The surface products of the heated shale blocks are used to generate thermoelectric power, and the thermoelectric power and gas-liquid mixture are collected. The gas-liquid mixture is separated to obtain liquid petroleum, water, and a mixed gas. The mixed gas was separated to obtain sulfur, hydrogen, C2-C4 gas and residual gas; The liquid petroleum, sulfur, hydrogen, and C2-C4 are transported separately to obtain liquid petroleum, sulfur, hydrogen, and C2-C4 products; The remaining gas is purified to obtain carbon dioxide gas.

2. The process according to claim 1, characterized in that, The areas where the shale was in-situ heated include... The burial depth and effective shale thickness of the target shale layer were determined based on the core test analysis and well logging data interpretation of the target shale layer. The well type of the production well group is determined based on the burial depth of the target layer and the effective shale thickness during in-situ shale heating. The well type of the production well group is one of the following: vertical well, inclined well, and multi-layered horizontal well. Based on the well type of the mining well group and the return on investment, the area for in-situ shale heating is determined.

3. The process according to claim 2, characterized in that, The process of dividing shale into in-situ heated mining blocks based on the area of ​​shale in-situ heating, and determining the deployment of well groups and heating methods for these blocks, includes... Based on the well type and production scale of the well groups in the shale in-situ heating area, the shale in-situ heating mining blocks are divided. Determine the well network structure of the production wells and the well spacing of the heating wells within the blocks where shale in-situ heating is to be carried out. Based on the construction speed and investment recovery period of shale in-situ heating oil and gas production, determine the number of shale in-situ heating production blocks that can start heating at the same time.

4. The process according to claim 1, characterized in that, The method of reinjecting water and / or carbon dioxide gas from the surface products of the in-situ heated shale block into the heated shale block for further mining includes... Obtain planar distribution maps of shale thickness and organic carbon content in the shale blocks where shale is heated in situ; Core samples were taken from the shale blocks that were in-situ heated for core analysis experiments, and a power function model for predicting the porosity of the shale blocks that had been in-situ heated was established. Based on the power function model and the organic carbon content planar distribution map, predict the shale porosity planar distribution map of the shale in-situ heated block after the heating is completed; Based on the shale porosity planar distribution map and the shale thickness planar distribution map, predict the volume of water and carbon dioxide gas available for reinjection in the in-situ heated shale block after heating is completed; Water and / or carbon dioxide gas collected from the surface products of the in-situ heated shale blocks will be reinjected into the same or more in-situ heated shale blocks for further mining.

5. The process according to claim 4, characterized in that, Core samples were taken from shale blocks that had undergone in-situ heating for core analysis. A power function model for predicting the porosity of shale in these heated blocks was established. The formation pressure is obtained based on the shale burial depth of the shale block where shale is heated in situ. Core analysis experiments were conducted on core samples taken from the shale blocks that were in situ heated to obtain the organic carbon content of the shale before heating. The core was subjected to a porosity test under the formation pressure and heating to obtain the porosity of the heated shale. A power function model for predicting the porosity of shale in in-situ heated blocks was established based on the organic carbon content of shale before heating and the porosity of shale after heating.

6. The process according to claim 5, characterized in that, The power function model for predicting the porosity of the shale block after in-situ heating is as follows: Φ=a×TOC b ; Where Φ is the porosity of the shale after heating, TOC is the organic carbon content of the shale before heating, and a and b are parameters to be determined.

7. The process according to claim 4, characterized in that, Reinjecting water and / or carbon dioxide gas from surface products of in-situ heated shale blocks into one or more completed in-situ heated shale blocks for further mining includes... When the well type of the in-situ heated shale block is a multi-layered horizontal well, the well is ready for production. Water and carbon dioxide gas are reinjected into the same in-situ heated shale block. The carbon dioxide gas reinjection well is the uppermost production well on the edge of the multi-layer horizontal well, and the water reinjection well is the lowermost production well on the same side as the carbon dioxide gas reinjection well. Other production wells are closed, and the production wells on the lowermost edge of the multi-layer horizontal well on the symmetrical side of the carbon dioxide gas reinjection well and the water reinjection well in the block are opened in sequence for production. When a production well starts producing water, production in that production well is stopped, and the adjacent production well on the next higher layer is opened for production, until all production wells produce water. Water or carbon dioxide gas is reinjected separately into multiple shale blocks that have undergone in-situ heating. When extracting shale by injecting carbon dioxide gas alone, the carbon dioxide gas injection well is the uppermost extraction well in the multi-layered horizontal well structure. Other extraction wells are closed, and the lowermost extraction well in the multi-layered horizontal well structure symmetrical to the carbon dioxide gas injection well in the block is opened for extraction. When extracting shale by injecting water alone, the water injection well is the lowermost extraction well in the multi-layered horizontal well structure. Other extraction wells are closed, and the uppermost extraction well in the multi-layered horizontal well structure symmetrical to the water injection well in the block is opened for extraction.

8. The process according to claim 4, characterized in that, Reinjecting water and / or carbon dioxide gas from surface products of in-situ heated shale blocks into one or more completed in-situ heated shale blocks for further mining includes... When the well type for production in the block where the shale has been heated in situ is a vertical well or an inclined well. Water and carbon dioxide gas are simultaneously reinjected into the same shale block that has undergone in-situ heating. The wells for water and carbon dioxide gas reinjection are located on the same side of the block. If the target shale layer has a dip angle, the carbon dioxide injection well is located on the side of the target shale layer in the updip direction, and the water injection well is located on the side of the target shale layer in the downdip direction. The remaining wells in the heated block are closed, and the outermost well on the side symmetrical to the water and carbon dioxide gas injection well is opened for extraction. If the target shale layer does not have a dip angle, the carbon dioxide and water injection wells are two wells on the same side of the well group in the heated block. The remaining wells in the heated block are closed, and the outermost well on the side symmetrical to the carbon dioxide and water injection well is opened for extraction. Water or carbon dioxide gas is reinjected separately into multiple in-situ heated shale blocks. If the target shale layer has a dip angle, the well for water or carbon dioxide gas reinjection is located on the edge of the target shale layer in the updip direction. The remaining wells in the heated block are closed, and the wells on the other side of the target shale layer in the downdip direction are opened for extraction. If the target shale layer does not have a dip angle, the well for water or carbon dioxide gas reinjection is located on one side of the well group in the heated block. The remaining wells in the heated block are closed, and the outermost well on the symmetrical side of the well in the block is opened for extraction.

9. The process according to claim 1, characterized in that, The purification of the remaining gas into carbon dioxide includes: combustion-liquefaction treatment or liquefaction treatment. The combustion-liquefaction process involves directly burning the remaining gas to generate electricity, collecting the electricity generated from the combustion and the exhaust gas, pressurizing and liquefying the exhaust gas to obtain carbon dioxide, and depressurizing to obtain carbon dioxide gas. The liquefaction process involves pressurizing and liquefying the remaining gas to obtain carbon dioxide, and then depressurizing to obtain carbon dioxide gas.

10. An application of the process according to any one of claims 1 to 9, characterized in that, Utilization of surface products from shale blocks used for in-situ heating.

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