Abstract

Paleocene to Early Eocene coal rich Panna sediments of D-33 of Deep Continental Shelf (DCS), Bassein South East (BSE) and Central Graben (CG) area of Mumbai Offshore Basin have been geochemically analyzed using high-resolution spectroscopic techniques. Biomarker study in this basin reveals that coal within oil window show some peculiar pattern of triterpanes distribution. Higher plant related diagnostic biomarkers such as bicadinanes, bisnorlupane and oleanoids are exceptionally high and sometimes their abundance exceeds the usually most abundant C30 triterpane. Homohopanes are generally low in these sediments. Similar biomarker signatures have been observed in Mukta oils of D-18 and Panna oils of D-33 Structure of DCS Block; Panna oils of A-10 and E-34-2 of Heera-Panna-Bassein (HPB) Block; Panna oils of C-1, E-105-4 and E-188-1 in northwest part of Mumbai High rendering these oils to be derived from coal source. Peak to late thermal maturity of these oils and positive oil-source correlation are suggestive of deep coal rich Panna sequences of their respective block as probable source of these oils. Good abundance of oleanoid triterpanes, high thermal maturity and occurrence of these oils near basinal lows suggest close proximity of these oils to their respective source. Early mature oils have also been observed in Oligocene reservoirs of wells F-13 and F-16 of South Bassein Field. Low API gravity (20.49