Evaluation of Infra-Cambrian Plays in Punjab Platform

Abstract

Punjab Platform is the eastern part of the Middle Indus Basin, Pakistan with no surface outcrops. It covers an area of more than 100,000 sq.Km. Exploration activities started in mid 1950s when Shell drilled first exploratory well, Karampur-1 in 1958, which shows an evidence for occurrence of heavy oil in Infracambrian rocks. In India, a petroleum system has been established after the discovery of Baghewala-1 in 1991 in Infra-Cambrian rocks of Bikaner-Nagaur Basin. In the Bikaner-Naguar Basin, the deepest occurrence of oil is recorded in Infra/Lower Cambrian Jodhpur Sandstone with porosity ranging between 16-25% and oil saturation of 65-80%. The similar type of crude oil has been discovered in the overlying Bilara Dolostone with porosity 07-15%. Thin siltstone layers in Hanseran Evaporite (equivalent to Salt Range Formation) also found to contain heavy oil (Sheikh et, al., 2003). Karampur-1, produced heavy oil from Salt Range Formation is geochemically similar to Baghewala oil. Geochemical studies, Seismic and well data of Punjab Platform suggest that Infra- Cambrian is the complete petroleum system in the Punjab Platform. It is to be noted that wells drilled in Paleo-highs are dry due to lack of maturity and insufficient depth of burial. Maturity tends to increase with depth and deeper source rocks expected to be present in Punjab Platform. So in future, the wells drilled on Paleo- lows should encounter Infracambrian Formations (Sheikh et, al., 2003).