An operator drilling through the lower Bunter sands experienced extreme overbalance (greater than 6800 psi) severe cavings and excessive washout (11-15” hole diameter). In previous wells, the operator used conventional bridging materials (over 76 ppb) creating a challenge of controlling drilling fluid rheology.
Impact worked with the operator to define the two KPI’s – sealing the depleted sands and improving drilling fluid properties. Impact suggested the use of 6 ppb FLC 2000 to prevent hole washout, increase the mud density and drill through the problematic interval (5 7/8” section from 15,583 to 16,236 feet).
The 5 7/8” section was drilled with a gauge hole and the drilling fluids properties were improved by the use of 6 ppb of FLC 2000, compared to the 76 ppb conventional bridging material. Impact met the operator’s KPI’s by sealing the depleted sands and improving the drilling fluids solids loading. Five successful wells have been drilled to date.