In-situ coal petrography heat-insulation pressure-maintaining coring device and application method

Abstract

The invention relates to the technical field of coal bed gas well-drilling coring, in particular to an in-situ coal petrography heat-insulation pressure-maintaining coring device and an application method. The device comprises an upper connector, an outer barrel and a coring drill bit, wherein the lower end of the upper connector is connected with the outer barrel; the lower end of the outer barrel is connected with the coring drill bit; a connecting sleeve is connected to the inner wall of the lower end of the upper connector; a pressure ball seat matched and sealed with a starting ball is designed at the lower end of the connecting sleeve; a communicating hole I is formed in the connecting sleeve at the upper end of the pressure ball seat; a differential sliding sleeve is connected ontothe pressure ball seat in a hanging way and shields the communicating hole I; and a communicating hole II is formed in the differential sliding sleeve. According to the in-situ coal petrography heat-insulation pressure-maintaining coring device and the application method provided by the invention, a taken-out coal petrography sample maximally maintains temperature and pressure of an original stratum, a tough pressure film is adopted to cover an original coal core entering the barrel so as to prevent the coal core from being polluted by extraneous fluids such as a drilling fluid, high-pressurehydraulic oil is isolated in the follow-up pressure-maintaining stage, original physical and chemical characteristics of the coal core are further maximally protected, and a high-quality truth-preserving coal core sample is ensured to be acquired.

Description

Technical field: [0001] The invention relates to the technical field of coalbed methane drilling and coring, in particular to an in-situ coal-rock thermal insulation and pressure coring device and an application method. Background technique: [0002] Coalbed methane is unconventional natural gas that is self-generated and stored in coal seams, and its main component is methane. With the advancement of exploration and development technology, the development of unconventional energy sources such as coalbed methane and shale gas has been increasingly valued by the world's energy powers. CBM development first needs to clarify key parameters such as the content of CBM in the reservoir, which is particularly important for CBM resource evaluation, production capacity prediction, and risk control. From the perspective of engineering technology, the most direct and effective way to accurately obtain the content of deep coalbed methane is to use coring technology to obtain original c...

AI Technical Summary

Problems solved by technology

It overcomes the disadvantage that existing coring tools cannot maintain the original formation temperature and pressure when obtaining deep coalbed methane in-situ cores

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