Abstract: This paper analyzes the surge and swab pressures produced by the pipe running in the eccentric annulus, and derives the calculation formula of steady-state pressures of powerlaw fluid in eccentric annulus. The study provides the reliable theory and method for the design of hole structure and the control of the pressures in inclined and horizontal wells. The calculation charts of relevant parameters are also given for the convenient use in the fields.

Key words: Annular space, Annular flow, Fluctuation pressure, wave theory