Drilling Fluid to Accelerate Drilling in Top Formations in Mid-Sichuan

A new drilling fluid was formulated incorporating potassium-polymer-sulfonate drilling fluid technology, silicone-base inhibitive drilling fluid technology and anti-balling technology, which was aimed at reducing mud weight and increasing drilling rate in the mid-Sichuan area. Laboratory study showed that this drilling fluid formulation is tolerant of salt contamination and reduces the potential of bit balling. Percent recovery of shale samples tested with this drilling fluid formulation was 95.0%, while shale core swelling test gave a percent reduction of swelling of 96.8%, both of which were better than polymer mud and polymer-sulfonate mud, but inferior to oil base mud. In field application in mid-Sichuan basin, average ROP was increased by 48.66%, time spend in reaming was reduced by 74.9%, and average percent hole enlargement was reduced by 18.14% in wells drilled with the said drilling fluid formulation.