Liquid-nitrogen natural-gas hydrate hole bottom freezing and rope coring drill bit

Abstract

The invention discloses an inner tube pulled type liquid-nitrogen natural-gas hydrate hole bottom freezing and rope coring drill bit. The drill bit consists of two parts, namely an inner tube assembly and an outer tube assembly, wherein an inner tube is pulled into a cold storage mechanism through an inner tube pulling mechanism during freezing, then, hydrate rock cores in a rock core tube are frozen through liquid nitrogen, and thus, the condition that the hydrate rock cores are not decomposed is guaranteed; the liquid nitrogen is used as a freezing agent and is rapidly gasified during freezing, so that rapid freezing can be realized, and the freezing effect is good; rope coring and hole bottom freezing are combined, so that no-drill-pulled rapid coring is realized; during drilling, the inner tube assembly does not rotate, so that the damage to the hydrate rock cores caused by a mechanical force resulting from the rotation of the drill bit is avoided to a relatively great extent, and the recovery percentage, integrity and representativeness of the rock cores are more effectively improved. A convective heat exchange process for a cold source and the hydrate rock core is realized by a method that the rock core tube filled with the rock cores is pulled into a freezing chamber; the drill bit is simple in structure, sampling and freezing processes are easily realized, the freezing efficiency is high, and the matched sampling method is simple in steps.

Description

Technical field [0001] The invention relates to a hole bottom freezing rope core drilling tool, which is especially suitable for freezing sampling at the bottom of a hole for natural gas hydrate drilling in marine and terrestrial tundra. Background technique [0002] With the rapid economic development, energy consumption is also increasing. Conventional energy sources such as oil, coal and natural gas are consumed in large quantities. Judging from its remaining reserves, conventional energy sources can no longer continue to support modern industry for a long time. At present, the total amount of carbon in methane in the global submarine gas hydrate is equivalent to twice the total amount of fossil fuels such as coal, oil and natural gas. Therefore, natural gas hydrate has become an important backup energy source that countries all over the world must consider in the balanced development of energy strategies. In the future, it is also recognized by mankind that it will become an...

AI Technical Summary

Problems solved by technology

Since dry ice is solid, alcohol needs to be used as a refrigerant, and it can be injected into the freezing chamber to realize freezing after it reacts with dry ice to become low-temperature alcohol, which makes the structure of the sampler more complicated; Alcohol is used as a refrigerant, a large part of the cooling capacity is taken away by alcohol, and the cooling capacity of the refrigerant cannot be fully utilized

Although the above problems can be avoided by using liquid nitrogen as a refrigerant, a large amount of liquid nitrogen will gasify during the injection process, resulting in the inability of liquid nitrogen to be injected into the freezing chamber. In this process, a large amount of liquid nitrogen is wasted, which leads to the use of liquid nitrogen. Larger volumes with increased sampler size and weight

A large amount of gasification during liquid nitrogen injection reduces the efficiency of liquid nitrogen use, and at the same time leads to uneven freezing of the core, resulting in partial decomposition of the hydrate core

Images