Research progress and development trend of high-temperature drilling fluid in hor dry rock

Abstract:

With decline in traditional energy reserves， the development of new geothermal resources such as hot dry rock is particularly important. The requirements of hot dry rock drilling are very demanding for traditional drilling fluid systems due to ultra-high temperature downhole environment. Filtration loss of traditional drilling fluids increases greatly at high temperature， and common additives often cannot perform well. Although common drilling fluids based on “three sulfonate materials” have satisfactory temperature resistance， they contain a large amount of toxic substance， leading to serious pollution； therefore， it is necessary to develop a new environment-friendly drilling fluid system with high temperature resistance. Research on hot dry rock in foreign countries is more than 30 years earlier than that in China， and very important experience and technology has been obtained on high temperature resistant drilling fluids. Though domestic research on hot dry rock just started， a very important research project “Qinghai Gonghe Basin Qiapuqia Hot Dry Rock Project” has already been initiated. This article introduces the current situation of hot dry rock drilling and the performance requirements for drilling fluids， explains their components and design approaches in light of the research progress of domestic and foreign scholars on high temperature resistant drilling fluids and environmentally friendly drilling fluids， and discuss the development trend of hot dry rock high temperature resistant drilling fluids in reference to the characteristics of hot dry rocks so as to provide support for the research of hot dry rock drilling fluid technology.

Key words:hot dry rock;high temperature drilling fluid;environment-friendly drilling fluid