Sampling method and sampler for gas hydrates by hole bottom freezing
US8074739B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 12, 2009 |
| Grant date | Dec 13, 2011 |
| Priority date | — |
| Expiry date | Apr 30, 2030 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B25/18
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The present invention relates to a sampler for gas hydrates by hole bottom freezing, the sampler comprises a fisher, a wire-line coring mechanism and an outer barrel, and it further comprises a refrigeration portion, a low temperature control portion and a frozen insulation sample portion, which constitute an inner barrel assembly located inside the outer barrel together, wherein a refrigerant in the refrigeration portion is injected into the frozen insulation sample portion under a control of the low temperature control portion, so that a cooling medium in the frozen insulation sample portion is always kept under a predetermined temperature, and a core sample of gas hydrates is frozen at the bottom of a drill hole. The invention also relates to a sampling method using the sampler as mentioned above. In the invention, the temperature of the sample can be decreased by using an external cooling source to suppress hydrate decomposition, the critical decomposition pressure of gas hydrates can be reduced by active decreasing the temperature of the sample, and the stability of gas hydrates is maintained by a passive pressure drop. The method of the present invention need not to keep the …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.