Abstract: Sequence Stratigraphic Approach to the Goru Petroleum System in the Middle Indus Basin, Pakistan

BRINK, GERHARD I., ANDREW M. LOGAN*

The sequence stratigraphy of the Cretaceous Late Barremian to Turonian succession encompasses the previous lithostratigraphic subdivisions of the Sembar and Goru Formations and introduces the informal nomenclature of Lower Goru and Upper Goru to subdivide the succession.

The Goru sequence framework is defined by unconformity and maximum flooding surfaces of chronostratigraphic significance. Unconformity bound lowstand, transgressive and highstand depositional systems tracts comprise each sequence within which potential reservoir, seal and source rock distribution are interpreted. All sequences are identified on electric logs with sequence stratigraphic framework constructed through stacking pattern analysis in conjunction with seismic at variable resolution. Third-order Lower Goru and Upper Goru sequences respectively encompasses a 23 m.y. siliciclastic regressive and transgressive second-order cycle during passive margin basin evolution.

Several Lower Goru third-order sequences contain stacked, high frequency, lowstand basin-floor fans basinward of shelf breaks, regionally sealed by transgressive systems tract marine shales and locally stratigraphically sealed by multidirectional sand pinch-out. Several Upper Goru third-order sequences contain transgressive shallow marine sandstones landward of relict shelf breaks, regionally sealed by transgressive and highstand systems tract marine shales and locally stratigraphically controlled by outer shelf marine and back barrier/lagoonal shale.

Significant source rocks are contained in marine condensed sections basinward of relict shelf breaks equivalent to the Sembar formation.

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