The oil accumulations of the Mehsana area are in rocks of Paleogene age. The Paleogene lithotopes of this region have been grouped into lower Cambay shales and the upper Kadi-Kalol coal-sand group. The main structural elements of the area are controlled by north-south basement faults. A major north-south midbasin synsedimentary fault system determines the lithofacies configuration and oil-pool patterns in this part of the basin.

The oil accumulations are in lenticular and bedded sandstone-siltstone reservoirs and the compositions of oils are related to the two types of reservoirs. The oils of the lenticular reservoirs, which show uniform character, are light and paraffinic whereas the oils of bedded reservoirs, which show variations in oil characteristics, are heavy and naphthenic to aromatic. Evidence suggests a common source and genetic origin of the oils of the two reservoirs. The variation in oil properties of bedded reservoirs is attributed to secondary factors. The characteristics of the oils of the Mehsana area do not show any relation to depth or geologic age.