Summary

Although petroleum industry has obtained a good practice in unlocking the shale reservoirs, more comprehensive geomechanical experimental and modeling research is required to optimize the drilling, completion and hydraulic fracturing processes due to the significant heterogeneity and anisotropy of shale formations. Acoustic and mechanical properties strongly depend on several factors including the mineralogy, density and distribution of natural fractures, bedding plane orientation, total organic carbon (TOC), maturity and in-situ stress state and pore pressure which are significantly different in various shale reservoirs and even within a shale basin. The strong anisotropy of acoustic and mechanical properties has a major impact on the reservoir characterization and field development plan. In this paper, we present the results of an experimental study on several U.S. shale basins with different maturity including Eagle Ford, Green River and Mancos shales to provide more insight on the shale acoustic and mechanical properties. We discuss the effect of shale bedding plane orientation and emphasize on the impact of shale mineralogy and petrophysical characteristics on the acoustic and mechanical properties. The mineralogy and petrophysical properties of each shale sample have been examined. Using both ultrasonic and mechanical methods, dynamic and static Young Modulus and Poisson's Ratio have been obtained at different bedding plane angles. A relationship between dynamic and static moduli has been consequently developed to determine in situ static moduli directly from seismic or well log data obtained in the same field.

Introduction

As the global energy demand increases with limited undiscovered conventional reserves left, the developments of unconventional reservoirs have been increasing worldwide. Shale formations have various minerals and vary in their petrophysical and geochemical properties from the conventional reservoirs. Therefore, they introduce new challenges to the oil and gas industry on many development stages. These challenges need further laboratory and field research, and require a more integrated, multi-disciplinary approach to study their characteristics.

URTeC 1619144

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