Integrated Gravity and Seismic Data Interpretation for Basement Depth Estimation in Sadiya Area of Assam-Arakan Basin

Sadiya area is located close to the syntaxial bend of eastern Himalaya in the Assam–Arakan basin which was developed as a composite shelf-slope-basinal system during early Cretaceous and closed in Oligocene. The study area falls at part of the Brahmaputa plain bounded by Himalayan ranges in the north, Naga-Patkai ranges to the south and Mismi hill ranges in the east. In this present study, an attempt has been made to estimate the basement depth using spectral analysis and 3D Euler deconvolution of gravity data constraints with seismic data. 2D Spectral analysis for six selected profile data and 3D radial average power spectrum analysis have been carried out for basement depth estimation and the results are correlated with the corresponding seismic data. Spectral analysis and Euler deconvolution show basement depth at 6.3km and 6km respectively. Basement depth is deeper in the south-eastern part compared to the north-western part. The nearest well Mechaki-1 was drilled 10km away in the south-southwestern part where basement depth was 5750m. The study area is gently dipping towards the south-eastern part and hence the basement depth increases from 5750 m to 6950m which is an average depth 6350m and is justified from gravity and seismic data.