Liquid nitrogen hole bottom frozen rope core drilling tool and core-drilling method

Abstract

The invention relates to a liquid nitrogen hole bottom frozen rope core drilling tool and a core-drilling method. The tool mainly comprises a fisher, an inner pipe assembly and an outer pipe assembly. Due to a liquid nitrogen cavity formed in the fisher, liquid nitrogen used for a frozen core is stored in the liquid nitrogen cavity, when roundtrip is ended, the fisher is thrown, the liquid nitrogen is injected into a freezing cavity through connection between the fisher and the inner pipe assembly, the heat is absorbed through liquid nitrogen gasification, and a hydrate core is frozen. The liquid nitrogen is arranged in the fisher, and compared with the method for storing the liquid nitrogen in the inner pipe assembly, the method has the advantages that the liquid nitrogen is prevented from being gasified due to vibration, heat dissipation and other reasons in the drilling process, and the liquid nitrogen freezing efficiency is improved, so that the core fidelity is improved. A clamp spring seat is detached during earth surface sampling, a semi-closing pipe and the core are withdrawn from a core pipe, and a core sample is preserved in a liquid nitrogen storage tank or a high-pressure container.

Description

technical field [0001] The invention relates to a wireline coring drilling tool and a coring method thereof, and is especially suitable for drilling and coring natural gas hydrates in permafrost layers on land. Background technique [0002] With the rapid development of the economy, the consumption of energy is also increasing day by day. Conventional energy sources such as oil, coal and natural gas are consumed in large quantities. Judging from their remaining reserves, conventional energy sources cannot continue to support modern industry for a long time, and the resources of natural gas hydrate are extremely large. Abundant and clean energy, so natural gas hydrate is regarded as the main energy source in the future. [0003] Natural gas hydrates form and exist in high-pressure and low-temperature environments. According to the pressure stabilization characteristic curve of natural gas hydrate, if the temperature or pressure condition changes beyond the equilibrium condit...

AI Technical Summary

Problems solved by technology

This idea is to store the liquid nitrogen in the inner pipe assembly. The disadvantage is that the liquid nitrogen may be vaporized due to the vibration and heat dissipation of the drilling tool during the drilling process, and the full use of the liquid nitrogen cannot be realized. lead to coring failure

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