Development of solids-free low temperature drilling fluid system:To be used for natural gas hydrate drilling in Tibet Plateau permafrost

It is very essential o develop a proper drilling fluid system for natural gas hydrate drilling which is to be put into operation in Tibet Plateau permafrost. This paper analyzed on the characteristics of environmental conditions and the features of core drilling technology of natural gas hydrate in plateau permafrost. By reference to the specific low-temperature fluids theory and based on the advanced experiences of foreign countries,a low temperature drilling fluid system is suggested based on the inhibited decomposition method. Taking the 15%NaCl solution as a basic liquid,we developed a kind of solids-free low temperature drilling fluid system,meeting the requirement for natural gas hydrate drilling in plateau permafrost,and this fills in the domestic research blanks.