Study of the Cleaning Capacity of Drilling Fluid in Horizontal Direction Drilling

摘要

One of the major concerns associated with horizontal directional drilling (HDD) operations is the hole cleaning capacity of drilling fluid. Compared to wells in the petroleum industry, wells in HDD have relatively larger diameters, shallower true vertical depths, and less borehole stability, which makes transport of the cuttings more challenging. The conventional methods of using funnel viscosity or Bingham plastic viscosity (PV) and yield point (YP) to predict drilling fluid behavior and evaluate hole cleaning capacity of drilling fluid are not accurate enough for the requirements of HDD operations. A more accurate method to correlate field measurements of drilling fluid’s rheological properties and its hole cleaning mechanism will be significant in helping engineers choose the optimum components of drilling fluids to lower cost and risk. In this study, water-based drilling fluids with different bentonite concentrations were tested using a six-speed rotational viscometer to obtain the rheological properties. Then, both the Bingham plastic (BP) and the Herschel-Bulkley (H-B) models were used to describe the rheological properties of the drilling fluids based on the test results. Instead of using rheological parameters directly to evaluate the cleaning capacity of drilling fluid, the hydraulic parameters, such as velocity profile and shear stress at the borehole wall, were adopted to reveal the mechanisms behind hole cleaning procedure and give improved reliability for drilling fluid selection. The authors suggest an experimental procedure, together with a calculation method, to obtain the rheological and hydraulic parameters of drilling fluids to evaluate the cleaning and carrying capacities of drilling fluids in HDD.