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AAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain

Characterization of a Class IV AVO Sand in Central Saudi Arabia

Husam M. AlMustafa1; Luis Giroldi1

(1) Saudi Aramco, Dhahran, Saudi Arabia.

Rock physics modeling plus AVO inversion are combined to provide a heuristic approach to the characterization of the Unayzah A Sands in Central Saudi Arabia. These sands exhibit a Class IV AVO anomaly (large negative amplitude that dims slightly with increasing offset). Wells in the study area are used to construct a detailed petro-elastic model (PEM) to relate elastic properties in a physically consistent manner to the reservoir properties such as lithology, porosity and water saturation. This involves computing interval properties such as VpVs ratio, acoustic impedance, gradient impedance and interface properties such as intercept and gradient for different facies (oil saturated-, gas saturated-, brine saturated-sands and overlying shale). The established rock physics relationships are used to extract likely hydrocarbon charged-geobodies from seismic derived AVO attributes and simultaneous inversion results. Validity of the results is based on the detection of the anomalous zones on the different attributes.