Method and system for heat insulation and efficiency enhancement in-situ conversion of oil shale

Abstract

The invention discloses a method and system for heat insulation and efficiency enhancement in-situ conversion of oil shale. The method comprises the following steps that 1, a heating gas injection well is constructed in an oil shale mining area, and a plurality of production wells are constructed on the periphery of the heating gas injection well; 2, an oil shale layer top plate heat insulation layer is built above an oil shale layer; 3, an oil shale bottom plate heat insulation layer is built under the oil shale layer; 4, hydraulic fracturing is carried out on an oil shale layer section; and5, pyrolyzing and mining are carried out on organic matter components of the oil shale layer by adopting high-temperature nitrogen. The system comprises the heating gas injection well, the multiple production wells, the oil shale layer top plate heat insulation layer above the oil shale layer and the oil shale layer bottom plate heat insulation layer built under the oil shale layer as well as a heating fluid flow channel and a high-temperature nitrogen transportation system for pyrolysis and mining. The method and system for for heat insulation and efficiency enhancement in-situ conversion ofoil shale have a simple construction process, a fast heating speed of oil shale formation, a high energy utilization rate, high practicability, a good use effect and convenient popularization and use.

Description

technical field [0001] The invention belongs to the technical field of oil shale exploitation, and in particular relates to an in-situ transformation method and system for oil shale heat insulation and efficiency enhancement. Background technique [0002] Oil shale is a sedimentary rock containing solid combustible organic matter (oil, gas) in the mineral body. my country's oil shale resources are very rich. According to statistics, the oil shale resources within 1000m are 719.9 billion tons. Calculated according to the oil content of 6%, pp The amount of shale oil resources is 43.2 billion tons. The efficient exploitation of oil shale oil and gas resources will greatly alleviate the current shortage of oil and gas resources in my country. [0003] The main methods of exploiting oil shale oil and gas resources at home and abroad are: open-pit mining high-temperature furnace dry distillation method and underground in-situ heating pyrolysis method. Among them, the open-pit min...

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Problems solved by technology

[0013] The above methods 4 and 5 are convective heating methods. The convective heating method heats the oil shale faster, but because it is easy to form a short circuit of the fluid, the heat flow is discharged from the formation without heat exchange with the oil shale.

Among them, method 4 heats oil shale deposits through convective transmission of high-temperature water vapor to exploit oil shale oil and gas. It is difficult to provide a large amount of water in deserts or water-deficient areas, and the supply of steam cannot be guaranteed, resulting in failure to mine; superheated steam is used as heat Carrier, if the equipment fails or other reasons may cause water vapor to liquefy due to the temperature drop during the underground heat exchange process, if it becomes liquid water and exists in oil shale reservoir fractures or wells, it will bring many problems to the heating process ;The heat capacity coefficient of superheated steam is low, which leads to slow heating of the mine layer, many cycle operations, increased loss and useless work, increased cost and reduced benefit

Although method 5 solves the defects of method 4 such as difficulty in obtaining water source, high cost, low benefit, and easy to turn into liquid water to bring problems to the heating process to a certain extent, there are still problems: in the process of convective heating In the process, the heat absorbed in the oil shale is lost to the upper and lower formations through heat transfer, the temperature rise of the oil shale layer is slow, and the energy utilization rate in the heating process is low

[0014] In the above method 6, a heating well must be drilled for every production well, and the efficiency of in-situ extraction of hydrocarbons in oil shale is low

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