A pressure-holding coring tool for subsea natural gas hydrate core

Abstract

The invention discloses a core pressure-maintaining coring drill tool for a submarine natural gas hydrate and belongs to the technical field of well drilling equipment. The core pressure-maintaining coring drill tool is matched with a rope fishing coring-drilling technique and comprises an inner pipe assembly and an outer pipe assembly. The outer pipe assembly is of the structure of a vertically-through cavity, the upper end of the outer pipe assembly is connected with a drill rod, and a drill bit is arranged at the lower end of the outer pipe assembly. The inner pipe assembly is placed in the cavity of the outer pipe assembly. A core pipe is arranged at the lower end of the inner pipe assembly, and a clamp spring and a clamp spring seat are arranged at the lower end of the core pipe. The core pressure-maintaining coring drill tool is characterized by further comprising a pressure compensation system; the pressure compensation system is provided with a pressure-maintaining cap assembly; the pressure-maintaining cap assembly is matched with the clamp spring seat in the inner pipe assembly; and when a core of the natural gas hydrate is transferred onto the submarine drilling machine from the bottom of a hole, the pressure-maintaining cap assembly is in inserted connection with the clamp spring seat so as to seal the lower end of the core pipe. The occurrence condition of submarine minerals can be restored to the largest extent through a core sample obtained by the core pressure-maintaining coring drill tool, and the basis is provided for improving the mining technology of the natural gas hydrate.

Description

technical field [0001] The invention relates to a pressure-holding coring drill, in particular to a pressure-holding coring drill for a seabed natural gas hydrate core, and belongs to the technical field of drilling equipment. Background technique [0002] Natural gas hydrate (that is, combustible ice) is known as the future clean energy and a substitute for petroleum. It has the advantages of large reserves, high calorific value, low emissions, and no pollution. Natural gas hydrate is divided into two types: land area and sea area, and the distribution range of the seabed is much larger than that of the land. There are a large number of natural gas hydrates distributed in the South my country Sea and the East China Sea. From 2002 to 2015, my country successively carried out investigations and researches on natural gas hydrate resources in the Xisha, Dongsha, Shenhu and Qiongdongnan waters on the northern slope of the South China Sea. With a series of exploration achievement...

AI Technical Summary

Problems solved by technology

However, natural gas hydrates are formed and stored in the low-temperature and high-pressure environment on the seabed. When coring is carried out by ordinary drilling and coring methods, the natural gas hydrates will decompose due to the pressure drop when they are taken out from the seabed and transferred to drilling platforms or drilling ships. , so that the undisturbed sample cannot be tested

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