Abstract

Shale gas plays are very active and there is little time available for the practicing engineer to spend on well studies that would describe the effectiveness of particular treatment chemical additives. Each shale play has variations within its own lithotypes and mineralogy suite, not to mention that shales differ from each other individually in key mineralogical and geomechanical measures. These differences in lithologies, mineralogies and geomechanics within the formation itself should be evaluated to develop a minimum standard application for fields. Particular attention should be paid to the clays as they are the most ion-influenced components of the rock. Clay minerals in shales seem to be misunderstood in some cases. Lithologies and clay mineral suites that should require minimal temporary and/or permanent clay protection are being disproportionately treated with expensive clay protection chemicals.

By evaluating the geologic age, formation temperature, mineralogy, Brinell hardness, and Capillary Suction Time test results one can draw some conclusions about clay responses to fluid exposure. Using the results of these analyses in conjunction with previous experience and other independent well data can give reasonable information to make proper fluid selections in shale reservoir completions.

The results presented in this study show very different responses for several different clay protection chemistries when tested on shales of known clay content. Although most of the shales studied here contain very little, if any, swelling clay, certain additives yielded a questionable response. The study presents both test results and laboratory evaluation techniques for selection of clay protection chemical additives and economical considerations in shale reservoir completions.

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