Dry ice sublimation hole bottom refrigerating and pressure keeping sampler and sampling method

Abstract

The invention relates to a dry ice sublimation hole bottom refrigerating and pressure keeping sampler and a sampling method. The device is mainly composed of a suspension differential action mechanism, a single action mechanism, a control mechanism, a refrigerating mechanism and a pressure keeping mechanism. The method comprises: using dry ice as refrigerant, alcohol as refrigeration assisting catalyst and secondary refrigerant, and applying low temperature alcohol to the hole bottom to refrigerate the rock core; closing a ball valve to keep pressure of the rock sample so as to inhibite the decomposition of the hydrate rock core; dismounting a blocking tube and a drill bit when sampling, dismounting a clamp spring and a clamp spring seat, pulling out a half combining tube and the rock core from the rock core tube, and using a liquid nitrogen holdup vessel or a high pressure container to keep the rock core sample. When drilling for sampling the rock core, the external tube and the drill bit gyre, but the internal tube assembly does not gyre, thus avoiding the damage of mechanical force to the rock core caused by the gyrus of the drilling tool to a larger degree, improving the rock core sampling rate, integrity and representativeness more effectively, and realizing pure refrigeration sampling as well as a combination of refrigeration sampling and rock core pressure keeping; compared with the prior art, the invention has simple process, convenient operation and greatly reduces the cost.

Description

Technical field: [0001] The invention relates to a drilling sampling device, in particular to a sampling device for freezing and maintaining pressure at the bottom of a natural gas hydrate dry ice sublimation hole for seabed or land permafrost preservation and a sampling method. Background technique: [0002] With the advent of the era of high oil prices, it has become a top priority to promote various alternative energy sources. The current total amount of methane carbon in the global seafloor gas hydrates is equivalent to twice the total amount of currently known fossil fuel resources such as coal, oil and natural gas. Therefore, natural gas hydrate has become an important backup energy that must be considered in the balanced development of energy strategies in countries all over the world. Drilling sampling is the most direct method to identify gas hydrates, and it is also a necessary means to verify the investigation results of other methods. Therefore, drilling sampli...

AI Technical Summary

Problems solved by technology

If the tightness of the ball valve is slightly reduced, the core cannot maintain the initial pressure, resulting in coring failure

And when the design pressure of the sampler reaches a certain level, if you want to increase the pressure, the material and sealing performance of the sampler will need to be greatly improved, and this is not easy to do

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