Abstract:

With the advantages of sensitive and quick monitoring hydrocarbon gases in different stratigraphies, gas logging has become a mature technology for exploring the conventional or unconventional oil and gas. Considering that while the drilling tool is grinding strata bearing gas hydrate, the gas hydrate could decompose and release numbers of hydrocarbon gases which can be sensitively monitored by gas logging, this paper tries to discuss and establish a real-time prognosis method to recognize gas hydrates in permafrost regions in Muli of Qinghai. Taking drillhole DK8-19 in Sanlutian coal field in Muli of Qinghai as an example, the application, problems and suggestions of this realtime prognosis through gas logging was discussed. The practical application shows that the goodness of fit between the result of singly using gas logging and that of combining geological analysis and testing is up to 85.71%, and the result of combining gas logging, geological analysis and testing will be better.

Key words: gas logging, permafrost region, natural gas hydrate, prognosis, Sanlutian