Depositional environment and geomechanical properties of Cambay Shale: potential reservoir for shale oil and gas in Indi
- PDF / 3,498,281 Bytes
- 12 Pages / 595.276 x 790.866 pts Page_size
- 63 Downloads / 182 Views
ORIGINAL PAPER
Depositional environment and geomechanical properties of Cambay Shale: potential reservoir for shale oil and gas in India Sanjukta De 1
&
Aastha 1 & Debashish Sengupta 1
Received: 31 January 2020 / Accepted: 18 May 2020 # Saudi Society for Geosciences 2020
Abstract This study aims to investigate mineralogy, depositional environment and rock mechanical properties of Cambay Shale Formation in Jambusar-Broach block of South Cambay Basin, India, by an integrated approach of combining wireline logs and laboratory studies. The study involves the analysis of spectral gamma ray (SGR) logs and laboratory studies of core samples using X-ray diffraction (XRD), thin-section analysis and scanning electron microscope-energy-dispersive X-ray spectroscopy (SEM-EDS). The results show that in the Cambay Shale, mineral components are dominated by clay minerals, quartz and siderite with minor amounts of feldspar, mica and pyrite. Both thorium (Th)–potassium (K) cross-plots derived from SGR logs and XRD analysis have revealed that kaolinite and chlorite are the dominant clay minerals. The dominant clay mineralogy and the analysis of thorium to uranium ratio plots indicate the deposition of the shale in marginal marine to marine environment. Pyrite framboid size distribution, used as a redox proxy, indicates deposition under anoxic conditions. The geomechanical property of Cambay Shale has been analysed based on the overall mineral composition of the core samples. Mineralogy-based brittleness index (BI) has been evaluated and found to vary between 0.21 and 0.66, suggesting low to moderately high brittleness. Kaolinite and chlorite, the dominant clay minerals, are the less swelling clays and exhibit a lower plasticity. It may be concluded that these factors might facilitate the intrinsic fracking properties of Cambay Shale. Keywords Cambay Shale . Clay mineralogy . Depositional environment . Brittleness index . Clay swelling . SGR log
Introduction In recent years, shale oil and gas resources are receiving extensive attention due to the increasing demand for secure and stable energy resources throughout the world. The momentous advancement with increasing efficiency of horizontal drilling and multi-stage hydraulic fracturing technologies has made exploitation of unconventional shale and tight hydrocarbon resources economically viable. Soon after the commercial success in the early 2000s, shale plays have significantly revolutionized the energy business in the USA. As per the EIA report, shale gas accounts for
Responsible Editor: Santanu Banerjee * Sanjukta De [email protected] 1
Department of Geology and Geophysics, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
70% of the total dry gas production and tight oil accounts for 60% of the total oil production in the USA by the end of 2018 (Perrin and Geary 2019). China is the third country in the world and the first outside North America to realize industrial shale gas production and has the largest reservoirs of technically recoverable s
Data Loading...
