Liu T.,Geotechnical Drilling and Excavation and Protection of Ministry of Education Engineering Research Center |
Liu T.,Wuhan University |
Jiang G.,Geotechnical Drilling and Excavation and Protection of Ministry of Education Engineering Research Center |
Jiang G.,Wuhan University |
And 9 more authors.
Zhongguo Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of China University of Petroleum (Edition of Natural Science) | Year: 2015
Nature gas hydrate is stable only under conditions of high pressure and low temperature. During the process of drilling low temperature, drilling fluid should be used to maintain the hydrate stability. At low temperature whether drilling fluid can play a role in softening the surface of downhole rock is very important for improving drilling speed. This paper analyzes the softening mechanism of drilling fluid for the surface of downhole rock and established the corresponding relationship functions and evaluation method, which is able to provide theoretical and technical support for improving drilling fluid performance and drilling efficiency during drilling in low temperature formations, such as gas hydrate bearing sediments. On the basis, the softening effect of drilling fluid for thin sandstone samples through comparative experiments of six simulation drilling fluids (with the amount of 0.1% wt of common surfactants and organic salts) for drilling in gas hydrate bearing sediments with pure water at low temperature was studied. Experimental results show that the experimental drilling fluids with surfactants at low temperature have good softening effect for used rock samples and are conducive to reduce the strength of downhole rock surface, increase rock breaking efficiency and drilling speed. The drilling fluid with sodium dodecyl sulfate (SDS) has the best softening effect among the four drilling fluids with surfactants. ©, 2015, Zhongguo Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of China University of Petroleum (Edition of Natural Science). All right reserved.