Early exploration well tests in the Colville River Field (also known as Alpine) drilled with water-based mud systems exhibited unexplainably high near-wellbore residual skin damage documented by pressure build-up testing. Typical formation damage mechanisms including clay reactions, mechanical damage, and gas trapping could not explain the damage.

Between March 1998 and July 2001, laboratory testing determined imbibition-induced water trapping to be the primary formation damage mechanism. Insitu water saturation is significantly lower than the residual or connate water saturation, a condition rarely encountered in the field. Lab tests quantified impacts and identified methods to minimize or eliminate formation damage. This paper documents how successful identification of a unique damage mechanism improved drilling results in a low permeability sandstone.

Keywords:
bennion, drilling fluid formulation, completion, saturation, permeability, relative permeability curve, invasion, drillstem/well testing, drilling fluids and materials, fluid dynamics
Subjects:
Drilling Operations, Pressure Management, Formation Damage, Drilling Fluids and Materials, Well & Reservoir Surveillance and Monitoring, Reservoir Characterization, Reservoir Fluid Dynamics, Improved and Enhanced Recovery, Reservoir Simulation, Formation Evaluation & Management
Copyright 2003, Society of Petroleum Engineers
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