Characterization of Hydrocarbon Bearing Jardepahar Porcellanite Formation, Vindhyan Basin

Abstract

The commercial gas discovery has been established form Paleo-proterozoic Jardepahar Formation of Son valley sector, Vindhayan Basin. The geochemical, sedimentological and source rock analysis of the cutting samples collected during the drilling of Hatta#D were carried out, to comprehend the nature of source rock, their petrological characteristic. The geochemical and electro-log signatures help us to divide the porcellanite of Jardepahar Formation in to three cherty dominated units and a dolomitic limestone unit. Similar observations have been registered from petrographic studies, the bottom units is massive chert layer, middle unit is banded chert (limestone bands) and the upper unit is again massive with the interbed of shale. The middle unit has drawn lead attention, due to hydrocarbon discovery, it consists of amorphous silica interbedded with limestone with along with carbonaceous matter and micro-nano scale fractures. Textural characteristics of clasts indicates very limited transportation. The middle unit shows, higher biological productivity and better hydrocarbon source facies as compared to the lower and upper units, which is gas bearing in Hatta field of Oil and Natural Gas Corporation (ONGC). The sediments were derived from high K felsic to intermediate volcanic source (s) from active continental margin, deposited in anoxic environment. The trace elements postulate absence of biogenic fractions and negligible amounts of chemical alteration. The middle unit has the source potential and also act as reservoir with the dolomitic limestone as top seal.