Abstract

Ramnad sub-basin, developed betweenPattukottai- Mannargudi ridge on the NW and Mandapam Delft horst on the SW, is situated in the southern part of Cauvery Basin, India (Fig: 1). The Nannilam reservoir sands of Coniacian-Campanian age in Ramnad onland area is the main producer. Two high gamma ray peaks mark the flooding surfaces within the Nannilam Formation and the lower gamma peak is identified as MFS (Maximum Flooding Surface) (Fig. 2). NannilamSand-A (Sand-A) and Nannilam-Sand-B (Sand-B) are developed below and above the MFS respectively. The present study is mainly based on well data and the objective is to evaluate these sands in respect to their depositional settings and to understand the areas of better reservoir distribution. This would help in further exploration / exploitation. For this purpose, maps of log signature & petrophysical properties of these sand units along with relevant geoscientific data of all the wells in this area have been analysed.environment, and the spatial variation of their petrophysical properties. For each of the sand units, log property maps viz. gross & net reservoir thickness & their ratio, porosity & porosity-thickness (?