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The Role of Sedimentological Studies for Deciphering the Reservoir from Pre-Tertiary Sections of Ganga Basin, India

Narender Pendkar, Prabha Tirkey, and Harinder Upadhyay
KDMIPE, ONGC Limited, Dehradun, India

The exploration of Ganga Basin in the northern part of India has been an ongoing effort for the last several decades. A number of wells have been drilled to explore and understand the hydrocarbon plays, with the presence of hydrocarbon shows reported from the Paleozoic siliciclastic sections. This has encouraged and added a renewed impetus for the current phase of exploration in the basin. To delineate and decipher the factors controlling the making of reservoir, a comprehensive study was undertaken to analyze available cores for their sedimentological attributes along with detailed laboratory studies for petrographic, textural, electrolog and reservoir characteristics. The reservoir sandstones were deposited in shoreface to tidal environments and are compositionally mature quartz arenites.

The study indicates that the hydrocarbons are associated with two possible types of reservoirs. The first kind is associated with open to partly open fracturing in brittle and highly silica cemented quartz arenites. The second association is facies controlled and is present in fine to medium grained sandstones deposited in foreshore/shore face environments encased in marine shale. Examination of texture for these facies controlled sandstones by SEM shows presence of low grade porosity. This study has resulted in understanding and constraining the factors that have led to the making reservoir section and can be used as predictive tool in the ongoing exploration efforts.

Presentation GEO India Expo XXI, Noida, New Delhi, India 2008©AAPG Search and Discovery