JONES, PETER, J. and THOMAS STUMP
The Early Silurian Qalibah Formation consists of two members, the upper member is termed the Sharawra and the lower is termed the Qusaiba. The latter member is the main hydrocarbon source rock facies for the known Paleozoic hydrocarbon accumulations in Central Saudi Arabia. The Qusaiba Member organic rich facies occurs at the base of the unit and has up to 8% total organic carbon content.
Burial history/thermal modeling in the Arabian Basin of Saudi Arabia has yielded a new method for estimating thermal maturity throughout mapped areas. The method involves deriving mathematical relationships between thermal maturity models and the combined effects of burial depth and heat flow. This mathematical relationship was applied by using a series of grid to grid operations on maps of the input parameters. The result is an improved regional Qusaiba maturity map that accounts for the changing depth of burial and geothermal gradient. The simplicity of the relationship implies that, for any given time period, the area evaluated has had a very similar tectonic history, sedimentation rate, and heat flow history. Moreover, the present-day heat flows are representative of those during the time when maturation was occurring.
The same type of relationship has also been used for generating maturity maps for different times in the geologic past, allowing the assessment of the timing of hydrocarbon generation and how it varies throughout the basin. This, in combination with paleostructure maps has been used to determine available migration paths and their relationship to exploration prospects.
AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria