Evaluating the geomechanical properties of Cambay Shale, Cambay Basin, India using advanced wireline logs for shale hydrocarbon exploration

Abstract

Brittleness index (BI) is an important parameter in evaluation of rock frackability. Two different methods are used to estimate continuous BI of Cambay Shale of Jambusar-Broach block, Cambay Basin, India, using advanced logs like ECS, Sonic Scanner (SS) and mineralogical analysis of core samples by XRD. First method is based on mineral composition using ECS log and second method is based on elastic moduli using SS log. ECS-based BI is in good agreement with BI from XRD-based mineralogy. BI estimated by two log-based methods will provide a cost effective and continuous information to identify potential regions for effective hydro-fracture.

Keywords:

• brittleness index
• Cambay Shale
• elemental capture spectroscopy log
• Litho-scanner log
• Poisson’s ratio
• Sonic Scanner log
• Young’s modulus

Acknowledgement

The authors express their deep sense of gratitude to Director (Exploration), Basin Manager of Western Onshore Basin and COD-Shale Exploration Group of Oil and Natural Gas Corporation Limited, India for providing the required log data and core samples to carry out the present study. The Department of Geology and Geophysics, IIT Kharagpur, India has also been gratefully acknowledged for providing the laboratory facilities to carry out this study. We also extend our appreciation to Dr. Partha Mitra, Geophysical Domain Specialist, for his valuable advice and suggestions. Authors are thankful to Dr. Dandina N. Rao, Editor-in-Chief of Petroleum Science and Technology, and the anonymous reviewer for the review and valuable suggestions to improve our manuscript.