Empirical mode decomposition approach for delineating gas-hydrates and free gas in Mahanadi offshore, eastern Indian margin

Abstract

Empirical mode decomposition (EMD) is an effective tool for signal analysis that splits the data into individual modes, called the intrinsic mode functions, which are associated with symmetric and narrow-band waveform ensuring that the instantaneous frequencies are smooth and positive. However, some negative features encumber its direct application namely the mode mixing and splitting, aliasing and endpoint artefacts. Two variants, ensemble EMD (EEMD) and complete ensemble EMD (CEEMD) have been recently introduced to overcome these problems. We intend to show the application of the EMD for demarcating the zones of gas-hydrates and free-gas bearing sediments. Gas-hydrates are ice-like crystalline substances that occur in shallow sediments along the outer continental margins and in the permafrost regions, and are considered as viable major future energy resources of the world. Gas-hydrates in marine environment are generally identified by an anomalous reflector, known as the bottom simulating reflector, on seismic section. The present study demonstrates that the EMD can be effectively utilised in demarcating the zones of gas-hydrates and free-gas bearing sediments with a field example in the Mahanadi basin of the eastern Indian margin.

KEYWORDS:

• EMD
• EEMD
• CEEMD
• gas hydrates
• demarcation

Acknowledgements

The Director, CSIR-NGRI is acknowledged for permission to publish this work. The dGB Earth SciencesTM is thanked for providing an academic license of the OpendTectTM v.6.2.6 for pursuing this research. Director, Wadia Institute of Himalayan Geology, Dehradun is acknowledged for his consent of publication. Thanks are due to Dr. Mahak Singh Chauhan for fruitful discussions and the anonymous reviewers for useful suggestion. KS acknowledges DST-SERB for according him with JC Bose National Fellowship.. This is Wadia contribution No. WIHG/2021/04/10.

Disclosure statement

No potential conflict of interest was reported by the author(s).