Abstract: New Seismic Reflection Techniques Applied to Gas Recognition in the Rharb Basin, Morocco

Haddou Jabour, Mohamed Dakki

The Rharb basin in Morocco is a Tertiary foreland filled by clastic series during the Miocene and Pliocene. This terrigenous influx, derived from the prerif to the northeast and the Meseta to the south, is characterized by a sandy episode during much of the Messinian and the Tortonian. The sand deposits were probably related to the uplift and major erosion of a part of the prerif during the sliding of an olistostrome (prerif nappe).

Although most of the wells drilled in the basin have encountered biogenic gas accumulations, the problem still facing exploration in the area is seismic resolution and thin-bed tuning analysis.

Recent studies using high seismic resolution techniques have permitted us to gain a deep insight into the stratigraphy and depositional environment of the thin sand reservoirs and their fluid content.

AVO stratigraphy, inversion of seismic traces into acoustic impedance traces and seismic attributes calculation, and computing provide a remarkable example of the possibilities of depicting the lateral and vertical evolution of reservoir facies and localizing biogenic gas accumulations.

Out of five recent exploratory wells drilled based on this new technique, three encountered gas-bearing sands with economic potential.

Fifty-three amplitude anomalies have been identified and await processing.

AAPG Search and Discovery Article #90982©1994 AAPG International Conference and Exhibition, Kuala Lumpur, Malaysia, August 21-24, 1994