ABSTRACT:

Common laboratory protocols for measuring rock strength, Young's modulus and Poisson's ratio commonly do not account for moisture content in the rocks, yet these parameters are critical in fracture designs and are affected greatly by the moisture content. We study the effects of spontaneous fluid imbibition (brine and dodecane) on Young's modulus and hardness in shale using nanoindentation. The shales studied include the Marcellus, Woodford, Eagle Ford and Wolfcamp. Irrespective of the shale wettability, brine always led to a greater reduction in Young's modulus (45% reduction in Marcellus, 25% in Woodford, 12% in Eagle Ford, and 21% in Wolfcamp) than dodecane (25% reduction in Marcellus, 17% in Woodford, 4% in Eagle Ford, and 3% in Wolfcamp). Clay stabilizing solutions like KCl brine had limited success in reducing the water weakening effect. Based on the measurements it seems that wettability plays a key role in water weakening.

Keywords:
strength, Upstream Oil & Gas, Wolfcamp, Reservoir Characterization, Brine, dodecane, mineralogy, shale sample, brine imbibed sample, porosity
Subjects:
Reservoir Characterization, Formation Evaluation & Management, Seismic processing and interpretation
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2018. American Rock Mechanics Association
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