Triassic Gas Detection by Frequency Spectral Decomposition in the Offshore Arabian Gulf, Saudi Arabia

T.M. Sodagar¹

Abstract

Two offshore fields in the Arabian Gulf were examined to evaluate the applicability of using the mono frequency spectral decomposition (FSD) technique to detect the presence of hydrocarbons in Triassic reservoirs. The FSD application was combined with other seismic attributes to identify possible new hydrocarbon leads or prospects (sweet spots). Wells in the first field have hydrocarbon indications by testing and logs in the Triassic reservoirs of interest, while wells in the second field do not. Relative amplitude processed (RAP) 3D seismic data was used to create acoustic impedance inversion and FSD data volumes. Gas bearing reservoirs attenuate high frequencies more than wet reservoirs. Therefore, mono FSD volumes of 5, 10, 20, 30, 40 and 50 Hz were generated to identify gas saturated reservoir locations. Horizon maps were then produced, which included RMS of surface seismic amplitude, acoustic impedance inversion and FSD attributes.

AAPG Search and Discovery Article #90188 ©GEO-2014, 11th Middle East Geosciences Conference and Exhibition, 10-12 March 2014, Manama, Bahrain