Method and device for intermittent in-situ recovery of oil shale by alternating high and low temperature fluid fracturing

Abstract

The invention provides a method and device for intermittent in-situ exploitation of oil shale by high-temperature and low-temperature fluid alternate fracturing, wherein the method comprises the following steps of: fracturing an oil shale reservoir by using high-temperature fluid so that the oil shale reservoir generates an artificial main crack with a preset length; stopping fracturing the oil shale reservoir by using the high-temperature fluid, heating the oil shale reservoir by using the high-temperature fluid, and reversely discharging the high-temperature fluid after reaching a first preset time; the oil shale reservoir is fractured by adopting liquid nitrogen, so that secondary fractures are generated on two sides of the artificial main fracture, and meanwhile, nitrogen is generatedby vaporization of the liquid nitrogen, so that multi-stage fractures are generated on two sides of the secondary fractures. And the wellhead is closed, the wellhead is opened after reaching a secondpreset time, and the nitrogen is reversely discharged so as to enable the oil shale reservoir to form a series of mutually communicated seam nets. According to the method, the kerogen in the oil shalecan be converted into the oil gas resource, the permeability of the oil shale reservoir can be effectively improved, and large-scale in-situ exploitation of the oil shale can be achieved.

Description

technical field [0001] The application belongs to the technical field of hydraulic fracturing of oil shale reservoirs, and in particular relates to a method and device for intermittent in-situ exploitation of oil shale by alternately fracturing high and low temperature fluids. Background technique [0002] At present, my country's oil shale mining technology is relatively backward, and oil shale development basically adopts above-ground dry distillation technology, the oil yield is low, it is difficult to meet large-scale development and application, and the pollution problem is serious. Therefore, relevant scholars have carried out research on oil shale underground carbonization technology to promote the large-scale development and utilization of oil shale. Because oil shale is relatively compact and has extremely low permeability, it is difficult for the recoverable oil and gas resources produced by the pyrolysis of kerogen in the oil shale reservoir to enter the wellbore ...

AI Technical Summary

Problems solved by technology

Oil shale reservoirs are generally buried relatively deep. Under the action of high temperature and high pressure in the formation, oil shale will show thermoplasticity. Therefore, the hydraulic fractures produced in oil shale reservoirs by conventional hydraulic fracturing are relatively simple, and the reservoir stimulation effect not good

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