Wells drilled through the challenging depleted Red Fork formation typically experience irreversible formation integrity issues, leading to severe mud losses and dramatically increased drilling costs. The efforts to keep mud weights lower than the fracture gradient while drilling through the Red Fork may be required to be completely altered before entering the sloughing shale in the lateral Woodford section.
Impact suggested pre-treating the drilling fluid system with a combination of STAR SHIELD® and STAR SHIELD® 500 at 5 lb/bbl prior to displacing to oil-based mud. The same concentration of the wellbore additives was maintained to total depth.
The operator significantly reduced the total well cost by eliminating the casing string and drilling 20,619 ft. open hole. The operator successfully drilled the two-string Woodford horizontal well to 22,164 ft. measured depth with zero mud losses or hole instability issues. The operator ran casing to bottom and cemented with full returns.