Zhu Fu Jian Hong Yang Yun, Chen Ping and Professor Zhao Jinhai.

State Key Laboratory of Reservoir Geology and Development, Southwest Petroleum University, Chengdu, Sichuan 6 10500.

Abstract: Because the lower end of slim hole is deep sea and deep well, resistivity, rotary drill string and drilling fluid performance have significant influence on annular pressure drop. This leads to the traditional calculation model can not be applied to deep wells designed by hydraulics. Using spiral flow theory and H-B rheological model, the eccentricity of non-Newtonian fluid, rotating drill string and annular pressure drop ring are analyzed in dimensions. Drilling hydraulic pressure provides a good. The results show that the annular flow region. In deep well drilling, there is a great difference between static mud density and equivalent circulating density.

Key words: slim hole drilling, annular velocity, annular pressure drop, hydraulic system.