Basin Evolution and Geochemical Modeling
The Nubian sandstone and associated igneous activity:
A basin evolution study of the Hameimat Trough, Sirt Basin, Libya
Postgraduate research by Mustafa Karer, Dr Jonathan Redfern and Dr Dorthe Møller Hansen
Introduction:
Sponsored by Wintershall, this project aims to provide insight in to seismic imaging of intrusive and extrusive igneous events within the Sirt basin, Libya. The presence of volcanics can prove a hazard to drilling, and of emplacement volcanics can have serious detrimental effects on reservoir quality.
Aims and Objectives:
A number of major oil fields in eastern Sirt basin (fig. 1) produce from the Early Cretaceous Nubian sandstone. This significant reservoir is highly structured and has a poorly understood facies distribution. As drilling targets deeper reservoirs or more complex structural areas, developing a better understanding of the
Nubian is crucial to successful future exploration. In some localities the Nubian also contains interbedded volcanics, which have affected and often degraded reservoir quality. The volcanics also affect the seismic response and this makes the exploration program very challenging.
To improve reservoir predictability, it requires a better understanding of the complex depositional environment and facies, the structural control on sedimentation and subsequent trapping, and the establishment of a robust stratigraphy for this interval. The assessment of the volcanic distribution may be crucial to understanding the controls on the reservoir quality.
The research utilizes high-resolution 3D seismic data, combined with gravity, aeromagnetic , well data and cuttings samples within the volcanic intervals from Hameimat Trough in eastern Sirt basin to develop a detailed geological model for deposition of the Early Cretaceous Nubian Sandstone and to understand the structural evolution and control on the sedimentary deposition of the succession and the effects of the interbedded volcanic deposits on reservoir characteristics. Consequently, Interpretation will involve use of Charisma (or IESX), Petrel and Oasis Montage software to:
- (1) define the stratigraphy and facies distribution for the Nubian interval in the region
- (2) assess distribution and origin of interbedded igneous units (intrusive and extrusive)
- (3) build an integrated geologic model for Nubian
- (4) evaluate the reservoir characteristics
- (5) produce a tectono-stratigraphic evolution of the basin.