The ultra-high temperature & high pressure (UHTHP) rheometer is an important apparatus that test and optimize the resistance to high temperature and high pressure of drilling fluid system, the pressure control technology is one of key technologies of UHTHP rheometer. In this paper, the characteristics of high temperature and high pressure environment are analyzed. The relationship between temperature and its saturated vapor pressure is particularly computed. On the basis, two pressure control schemes are presented, and their application characteristics are analyzed. This paper provides some theoretical basis for trial- manufacture of UHTHP rheometer.
