Method for large well spacing in-situ conversion mining of shale oil and gas of medium and low maturity shale oil

Abstract

The invention provides a method for large well spacing in-situ conversion mining of shale oil and gas of medium and low maturity shale oil. The method comprises the steps that a horizontal well groupwith at least three wells and with the well number being an odd number is deployed in a reservoir according to the well spacing of 15-50 meters; fracturing of the reservoir is performed, cracks are divided into three sections at equal intervals from a central injection well to production wells, and different types of propping agents are separately injected into the three sections in three stages;hot gas is injected into the central injection well and electrically heated, and is mined from the production wells; when temperatures between the central injection well and first-line round injectionwells reach a complete pyrolysis temperature, electric heating of the central injection well is stopped and normal temperature gas is injected into the central injection well; electric heating of thefirst-line round injection wells is started; when the temperatures between the first-line round injection wells and second-line round injection wells reach the complete pyrolysis temperature, injection of the normal temperature gas to the central injection well is stopped; electric heating of the first-line round injection wells is stopped, and normal temperature gas is injected into the first-line round injection wells; electric heating of the second-line round injection wells is started; and the cycle is repeated until reservoir temperatures between the production wells and adjacent last-line round injection wells reach the complete pyrolysis temperature.

Description

technical field [0001] The invention relates to a method for in-situ transformation and exploitation of shale oil and gas with large well spacing of middle and low maturity shale oil, and belongs to the technical field of shale oil exploitation. Background technique [0002] Oil shale is a sedimentary rock containing solid combustible organic matter, which is generally called kerogen or kerogen, and is often gray-brown or black. In the natural state, natural oil shale is a kind of argillaceous shale with extremely low permeability and porosity, and kerogen exists in the oil shale in solid form and is integrated. The micro-bedding inside the oil shale is completely closed in situ underground. Among all fossil fuels, if the reserves are converted into calorific value, oil shale ranks second only to coal; the shale parent oil reserves in the world are quite large, and if converted into shale parent oil, oil shale ranks second. More than 400 billion tons, equivalent to more th...

AI Technical Summary

Problems solved by technology

Since the invention requires that the injection well and the production well be rotated at intervals during the production process, a large amount of injection heat is converted to the output of the original heat injection well of the production well during the rotation process, resulting in an ineffective circulation of heat; in addition, due to the expansion of high-temperature shale oil, In addition, during the water steam injection process, the shale oil mainly containing clay minerals expands with water, causing the fractures to reclose, making the fracturing fractures unable to serve as channels for transmitting hot steam. It will float on the top of the shale oil layer near the injection well, and repeatedly heat the cap rock, making the cap rock very prone to high-temperature cracks and the risk of cap rock being broken through, resulting in safety accidents

[0007] None of the above shale oil production methods can solve the two major problems in the process of high-temperature in-situ conversion of shale oil: the problem of heat transfer with large well spacing and the problem of continuous and effective thermal cracking of fracturing fractures

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