Ice valve type pressure-maintaining and heat-preservation sampler

Abstract

The invention relates to an ice valve type pressure-maintaining and heat-preservation sampler, which comprises a drilling or sampling switch mechanism, a refrigerating fluid circulating system, a corebarrel lifting and positioning mechanism, an upper mechanical sealing mechanism, an ice valve forming mechanism, a corebarrel single-acting mechanism and a channel I-VIII which are connected. Pressure maintaining is realized by an ice valve formed below a corebarrel through mechanical sealing and refrigerating fluid circulation. Heat preservation is realized by coating porous foam, heat-preservation paint and a reflecting film on the outer wall of an inner circulation pipe. By adopting the invention, the problem that a mechanical valve is difficult to start, and is easily blocked by sundries in holes is solved, the reliability and the success ratio of pressure maintaining are improved, and a smaller radial dimension is beneficial to obtaining a larger-diameter core and improving the extraction rate of a hydrate core. Through tests, the ice valve realizes 25MPa sealing and is suitable for drilling a hydrate with a hole liquid column of 2500 m. When in pressure-maintaining sampling, a downhole reciprocating pump is started to drive the refrigerating fluid to circulate, and ice jamming is generated in an inner cavity at the lower end of the inner circulation pipe to form the ice valve so as to realize sealing pressure maintaining.

Description

Technical field: [0001] The invention relates to a drilling and sampling tool, in particular to a pressure-preserving and heat-retaining sampling drilling tool for natural gas hydrate drilling and sampling. Background technique [0002] Natural gas hydrate has the characteristics of wide distribution, huge reserves, and high energy density. It is a potential clean new energy for human beings in the future, and has an important impact on the global environment and the safety of marine drilling production. Experts preliminarily estimate that the total energy contained in natural gas hydrates in my country is more than twice the sum of the energy of known oil, natural gas and coal in the country. The exploration and development of natural gas hydrates is of great significance. [0003] The special form of natural gas hydrate determines that its stable existence requires high-pressure and low-temperature conditions, and the drilling tools for drilling and sampling are required t...

AI Technical Summary

Problems solved by technology

The existing pressure-holding drilling tools at home and abroad use mechanical structures such as ball valves or plate valves to close the lower port of the sampling drilling tool, so as to realize the pressure-holding function. The outstanding problem is that the ball valve or plate valve is often difficult to close normally, so that the pressure-holding cannot be performed normally. function, the number of times the function of maintaining pressure accounts for less than 60% of the total sampling times, and the reliability is poor; moreover, the ball valve or plate valve occupies a large radial dimension in design, so the diameter of the gas hydrate core is small and it is easy to be The core recovery rate is low, often less than 50%, which cannot meet the requirements of gas hydrate exploration and scientific research.

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