Seismic attributes for characterizing gas hydrates: a study from the Mahanadi offshore, India
- PDF / 6,447,671 Bytes
- 14 Pages / 595.276 x 790.866 pts Page_size
- 66 Downloads / 149 Views
ORIGINAL RESEARCH PAPER
Seismic attributes for characterizing gas hydrates: a study from the Mahanadi offshore, India Jitender Kumar1 · Kalachand Sain1 · K. P. Arun1 Received: 17 July 2017 / Accepted: 23 May 2018 © Springer Science+Business Media B.V., part of Springer Nature 2018
Abstract Seismic attributes have become successful in illuminating subsurface features and are widely used for identifying hydrocarbon reservoirs. The present work delivers case study carried out in the Mahanadi offshore basin lying in the eastern margin of India to delineate gas hydrates bearing zones using high resolution 2D seismic data. The presence of gas hydrates is identified by a bottom simulating reflector (BSR) on seismic section based on its characteristic features. Seismic attributes are computed to ascertain whether the BSR is related to gas hydrates. The data is conditioned using several post-stack processing steps such as detailed and background steering. The conditioning begins by steering of seismic data, which stores dip and azimuth information at every sample location. The Original seismic data is then filtered using a statistical filter to generate the dip-steered median filter data for extracting the instantaneous amplitude, instantaneous phase, instantaneous frequency, RMS amplitude and sweetness attributes. These are then used in demarcating the zones of gas hydrates or free gas occurrences. The low amplitude, high frequency and low sweetness attributes characterize the presence of gas hydrates. Whereas, free gas zones are characterized by bright amplitudes associated with low frequency and high sweetness below the BSR. Keywords Seismic attributes · Gas hydrates · BSR · Mahanadi offshore
Introduction Gas hydrates are ice-like crystalline substances in which gas molecules (mainly methane) reside into a cage-like structure formed by water molecules. Globally, these are found in shallow sediments of the outer continental margins or under the ice sheets where the temperature is low, and the pressure is moderately high, and methane concentration exceeds the solubility limit (Sloan 2003; Paull and Dillon 2001; Milkov 2004; Sain and Gupta 2012). Gas hydrates are considered as one of the most viable major unconventional energy resources for the next generation because of their huge potential (1–120 × 1015 m3 of methane) and natural occurrences (Boswell and Collett 2011). Only 15% production from global reserve can meet the world’s energy requirement for about 200 years (Makogon et al. 2007). Successful production tests in Alaska (USA) and McKenzie delta (Canada) on land, and in continental margins of Japan * Kalachand Sain [email protected] 1
CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad, India
and China provide great hopes that the commercial use of gas hydrates is not too far. This has increased tremendous interests to both the scientific and technological community of many countries like India, South Korea, China, Taiwan, New Zealand, Australia, Canada, Germany, etc. (Sain et al. 2015
Data Loading...
