External-cold-source natural-gas-hydrate hole-bottom freezing rope sampler

Abstract

The invention discloses an external-cold-source natural-gas-hydrate hole-bottom freezing rope sampler and a sampling method. The external-cold-source natural-gas-hydrate hole-bottom freezing rope sampler is composed of a salvaging device, an internal-pipe assembly and an external-pipe assembly. The salvaging device comprises a salvaging mechanism, a cold-source storing mechanism, a connecting positioning and locking mechanism and a connection valve mechanism; the internal-pipe assembly comprises a connection valve mechanism, an elastic-clamp lifting mechanism, an elastic-clamp positioning mechanism, a hanging mechanism, a single action mechanism, an adjusting mechanism and a core mechanism. According to the external-cold-source natural-gas-hydrate hole-bottom freezing rope sampler and the sampling method, the salvaging device carrying cold sources can be connected with the internal-pipe assembly underground in a sealed mode, low-temperature cold sources are controlled by the connecting positioning and locking mechanism and the connection valve mechanism to be injected into a core freezing cavity from a cold-source storing cavity, and the core freezing process is completed through heat conduction between low-temperature cold sources and a core. Sealing connection between the salvaging device and the internal-pipe assembly is controlled, and connection is accurate and stable. According to the external-cold-source natural-gas-hydrate hole-bottom freezing rope sampler and the sampling method, sealing connection between a cold storing cavity and an underground drilling tool does not rely on impact of the salvaging device.

Description

technical field [0001] The invention relates to an external cold source type hole bottom freezing rope core drilling tool and a coring method, which is especially suitable for natural gas hydrate drilling and coring in deep sea and land permafrost. Background technique [0002] Natural gas hydrate is a crystalline compound with a cage structure formed by hydrocarbon molecules and water molecules at a certain temperature and pressure (below 0°C and above 10MPa). It is also called "combustible ice" because it can burn when exposed to fire. It has the advantages of high energy density, cleanness, wide distribution, and large reserves. It is considered to be the most promising new energy to replace traditional energy. Both at home and abroad are actively studying how to develop and utilize natural gas hydrate. In order to solve the problem that gas hydrate cores are easily decomposed during the sampling process, since the 1970s, researchers at home and abroad have designed a var...

AI Technical Summary

Problems solved by technology

Built-in cold source type uses the cold source stored in the bottom hole drilling tool to freeze the core before coring. If the bottoming time is too long, too much cold energy will be lost in the environment, and the remaining freezing energy will not be able to meet the requirements of freezing cores; the external cold source will store the cold source in the cold storage of the salvage device, and put it in from the surface during coring In the hole, the problem of too long downhole cold storage time is avoided, but the existing cold source external sampler relies on the inertial force during impact to realize the sealed connection between the cold storage chamber and the downhole drilling tool, and there is uncertainty in the connection process

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