Seismic Sequence Stratigraphy and Facies Analysis to Delineate the Reservoir Potential in Cretaceous –Tertiary Unconformity of Middle Indus Basin, Punjab Platform

ABSTRACT Punjab Platform is one of the least explored areas in Pakistan. The reasons are: lack of favorable mature source rock in the area, shortening of structural traps, and its distance from collision zone. The rocks in Punjab Platform represent the diverse system of clastics to carbonates with several sea-level fluctuations within the basin. These sea level variations represent prograding clinoforms, truncation with tertiary unconformity and pinch out in Goru Formation. The petrophysical analysis of different wells in Punjab platform shows that it was first transgressive cycle and then regressive cycle. Seismic data acquired in different areas of Punjab Platform indicate the possibility of stratigraphic traps in the sedimentary package from Jurassic to Eocene especially in the Cretaceous sandstone units. Such traps if found in Punjab Platform offer preferred location for exploratory drilling. The presence of sand dunes weaker the resolution of seismic data and makes it difficult for stratigraphic interpretation. However, numerous gas discoveries have been made in Lumshiwal Formation of Cretaceous and Samanasuk Formation of Jurassic, demonstrating to an extent, optimistic hydrocarbon prospect in the area. After the interpretation of seismic sequence stratigraphic and the analysis of seismic attributes, a framework of complete petroleum system in Goru Formation is developed, which shows that shale in lower Goru acting as a source rock and sand beds in lower part of Goru consider being a reservoir rock. Past exploration has been mainly focused on drilling structural traps, whereas we emphasize stratigraphic traps especially those modified by erosion during unconformities should be preferred exploration objectives. Probable structural faults and progrades at Cretaceous level which are showing truncation at Tertiary Unconformity were identified on several lines that have been marked on the stack sections.