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Reservoir Delineation Using Spectral Decomposition, Spectral Inversion and Neural Network Analysis for an Oily Reservoir in Offshore Thailand

Cox, Dan¹; Castagna, John²; Gil, Gabriel²; Ripple, Robert¹; Rubio, Scott¹; Moon, Jerry¹; Roever, Robert¹; Laird, Andrew¹; Peace, Geoff¹; The, Ronald¹; Mitchell, James¹; Pringle, John¹; Htein, Nyan¹
¹Coastal Energy, Houston, TX.
²Lumina Geophysical, LLC, Houston, TX.

The Songkhla basin in offshore Thailand is an oily Tertiary rift basin, with lacustrine source rocks and reservoir sands. As no gas is present in this basin, traditional seismic attributes are not particularly helpful in identifying the black oil accumulations. Inversion to illuminate the presence of reservoir sands and optimally locate exploration and development drilling locations was very useful as part of a highly successful geophysical effort that resulted in significant reserve additions and new field discoveries. Early fast track and wedge model testing of the work flow resulted in the final stream of spectral decomposition, spectral inversion and neural network analysis, to derive the optimum combination of attributes to predict an accurate and useful target Vclay log 3D volume. The final inversion incorporated the total existing ~ 250 square miles of 3d seismic and was trained within three separate Tertiary reservoir intervals, using existing oil wells and the recent exploration discovery wells. As the inversion results had resolution superior to the input seismic data and are especially important in illuminating the stratigraphic variability and structural details within the three Tertiary intervals evaluated, this volume is now in use in final field development planning and exploration target mapping and evaluation.

 

AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012