Paper: HORIZONTAL AND HIGH-ANGLE RESERVOIR-DRILLING FLUID DESIGN IN HIGHLY-REACTIVE SHALE FORMATION

Fissile shale has strong potential to cause severe wellbore instabilities. It is highly laminated and can split easily into thin layers along its bedding planes. With the high concentrations of clay minerals, this type of rocks usually has high cation exchange capacity. Dispersion may not be strong, even in water, but the rock becomes highly broken mainly along bedding planes once it is in contact with fluids. Finding suitable drilling fluids to stabilize reactive fissile shale formations is an area of active research in M-I SWACO. A shale-stabilizing drilling fluid was designed for a highly-deviated lateral Morrow formation well in New Mexico. Morrow formation instability had caused serious drilling problems on a previous attempt to drill a lateral in this area and was the major obstacle to the exploration process. An oil-based fluid designed to stabilize the Morrow formation resulted in the successful drilling of an extended-reach lateral well.