A five well trial with Environmentally Acceptable Invert Oil Emulsion Mud (EA-IOEM) has been carried out in the Balingian area offshore Sarawak during 1985 and 1986. The trial was initiated after an unsatisfactory outcome of a field test programme with KCl/polymer muds.
Two appraisal and three development wells with planned deviation angles ranging from 45 to 58° were selected. The trial was carried out in the 12¼" and 8½" hole sections.
The objectives of the trial were to eliminate drilling, evaluation and production problems caused by poor hole conditions which were experienced in high angle wells drilled with simple water based mud (WBM).
A suitable base-oil for the trial was selected to meet the following three criteria: a high flash point, a low kinematic viscosity and a low toxicity.
The experience gained in the field trial has been successfully applied to the Erb West infill drilling programme to solve the zonal isolation and drilling problems experienced in this area with WBM.
The paper addresses the operational, petrophysical and geological aspects of the trial and includes recommendations on cost and consumption estimating.