Shankar Mitra¹, William Leslie²
(1) University of Oklahoma, Norman, OK
(2) SONARCO, Plano, TX

Abstract: 3-D Structural Model of the Rhourde El Baguel Field, Ghadames Basin, Algeria

The Rhourde El Baguel Field, located in the Ghadames basin, is one of the largest oil fields in Algeria. It produces oil from fractured Cambrian sandstones at subsea depths of 2300 to 3070 meters. Redevelopment of the field is currently in progress through a joint agreement between ARCO and SONATRACH. The structure was originally mapped as a simple horst block, bounded by two normal faults. A recent 3-D seismic survey resulted in a revised interpretation, but many uncertainties regarding the structural geometry of the reservoir remained unresolved. Structural interpretation was conducted to determine the geometry and size of the structural trap and the pattern and timing of primary and secondary faults. Seismic and well data were integrated to develop a 3-D model of the structure.

The structure is reinterpreted as a compressive fold related to two reverse faults, which cut through a pre-existing normal fault. The structure formed during two main episodes of deformation: (1) Triassic to Liassic extension resulting in normal faults with significant throw, which provided the lateral seal for the structural trap; and (2) Austrian compression resulting in a basement-involved fault-propagation fold. The revised structural model explains the complex fault patterns and the anomalous thickness variations of units observed in a number of deep wells on the west flank of the structure. Based on the model, two of these wells have been successfully sidetracked to locations within the field. The model is being used to optimize the location of future wells in the field.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana