Abstract: Petroleum systems of the Sulaiman Range-Central Pakistan

ELLOUZ*, N., E. LAFARGUE, J. LETOUZEY, A. MALIK and T. JASWAL

The Sulaiman Range constitutes an arcuate fold-and thrust belt, largely thrusted southwards. Its belongs to the major gas province of Pakistan, with oil/condensate fields to the East. The aim of this paper is to clarify the origin of the hydrocarbons in the whole area by performing oil/source rock correlation.

The distribution and the maturity of three potential source-rocks, Jurassic, Lower Cretaceous (Sembar) and Eocene (Ghazij, Habib Rahi) were extensively examined. The Sembar was considered to be the major rich source-rock of the Middle and Lower Indus basins, but its distribution, thickness and organic content seem to be much more heterogeneous than expected in the Sulaiman Range. The Cretaceous samples show a present-day high level of maturity in all the samples collected. The Middle Eocene source rocks, distributed only in the Eastern parts of the Range could be considered as a good source-rock, presently in the oil-window at depth. The correlation with the eastern oil samples nearby is likely.

In order to precise the timing of maturation of the potential source-rocks with respect to the structural evolution, a forward modeling along a North-South cross-section was realized, using the Thrustpack software with several thermal hypotheses. Since Middle Miocene, the Jurassic source-rocks are overmature, except in the very external part of the flexured platform (Jacobabad calibration). Only marginal portions of the basin have escaped the period of Mio-Pliocene burial and overmaturation of the Cretaceous source-rocks, thus preserving gas potential.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria