PINK,ANDREW T.; STEPHEN R. CARNEY, , RICHARD E. DRUMHELLER Anadarko Algeria Corporation, London, U.K.; LYNDA OKBI, Sonatrach,Algiers,Algeria

Abstract: The Structural Evolution and Reservoir Architecture of the HBNS Field from  3D Seismic, Berkine Basin, Algeria

The HBNS Field is located in Block 404 within the Berkine Basin, Eastern Algeria, part of the regionally extensive intra-cratonic Berkine-Ghadames Basin.The field is in a structurally complex setting on the northwestern flank of the basin.The Triassic TAGI sandstone reservoir directly overlies the Hercynian Unconformity separating Palaeozoic and Jurassic depocentres.

The present day structural configuration of the field is a broad, low relief northwest-southeast trending asymmetric anticline, with a steeply dipping northeast flank and gently dipping southwest flank, complicated by a series of northeast-southwest trending horsts and grabens and by minor east-west faulting. The structure formed as a result of polyphased tectonism with five main phases interpreted with the aid of 3D seismic data.

Reservoir architecture is closely controlled by available accommodation space as the Hercynian peneplaned surface began to subside preferentially overlying Palaeozoic thicks resulting in deteriorating reservoir quality and thickness from southeast to northwest across the field. Reservoir units onlap from the basin centre with older units pinching out progressively across the field. Seismic amplitudes relate to reservoir thickness over much of the field allowing refinement of the gross reservoir architecture established from well data.

The acquisition and processing of 3D seismic over the field, combined with a seismic stratigraphic approach, has unravelled the complex structural evolution of the HBNS area. This was previously unattainable from 2D data and wells alone. In addition, imaging of the TAGI for the first time has aided significantly the understanding of reservoir architecture.

AAPG Search and Discovery Article #90923@1999 International Conference and Exhibition, Birmingham, England