Early exploration well tests in the Colville River field (also known as the Alpine reservoir) drilled with water-based mud (WBM) systems exhibited unexplainably high near-wellbore residual skin damage documented by pressure-buildup 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. In-situ water saturation is significantly lower than 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 low-permeability sandstone.

Keywords:
facies, bennion, completion, upstream oil & gas, colville river field, drillstem/well testing, drillstem testing, spe production, formation damage, flow in porous media
Subjects:
Completion Installation and Operations, Core analysis, Drilling fluid management & disposal, Drilling fluid selection and formulation (chemistry, properties), Drilling Fluids and Materials, Drilling Operations, Drillstem/well testing, Flow in porous media, Formation Damage, Formation Evaluation & Management
Copyright 2005, Society of Petroleum Engineers
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