Abstract

Nagapattinum sub-basin of Cauvery Basin hosts many important hydrocarbon bearing structures viz. Kamalapuram, Vijayapuram, Kovilkaloppal, Narimannam etc. Evaluation of low resistivity reservoirs developed within Kamalapuram formation in Kamalapuram field is difficult with conventional interpretation techniques because of their complex nature. The pay sands within Kamalapuram formation are characterized with low formation resistivity, erratic GR response and higher Neutron porosity. The SP response is also not quite consistent with production profiles of respective wells. The analysis of various logs and lithological cross-plots suggest sand-silt-shale composition of these reservoirs. The same is corroborated by geological descriptions also. The conventional deterministic techniques do not yield realistic results as computed shale volumes are higher and computed porosities are pessimistic. The present paper discusses the development of suitable interpretation technique for realistic evaluation of such reservoirs with complex log responses and applies the same for evaluation of entire field. The computed results are consistent with production data.