Drilling Fluid Pressure Calculation In Horizontal Directional Drilling

摘要

Drilling fluid plays an important role in horizontal directional drilling (HDD).It cuts soil,suspends and transports cutting out of the borehole,it forms filter cake to prevent slurry lose and maintain the borehole stability.During HDD process,reasonable drilling pressure should be controlled.Maintaining the minimum mud pressure is required for regular drilling fluid flow.Maintaining the maximum allowed mud pressure is also required for borehole stability and prevention of frac-out.This paper briefly introduces the drilling fluid calculation method,then presents results of an application case in the Yangtze River crossing,which the length of HDD is 3300 meters.Base on the calculation,several recommendations are presented for this crossing.