Abstract

Study of the attributes of a reservoir through multilog sensors has been termed as electrofacies. This can be used in visual or mathematical mode. Visual mode corresponds to composite mode after sensitivity matching to effect a visual impact. Present paper deals with the use of visual electrofacies in studying an enigmatic low resistive pay zone in Gandhar area of South Cambay Basin First oil strike in this low resistive payzone was encountered in Gandhar well no. A. This payzone belongs to GS11 sand group and occupies the bottommost position and is characterized by shaly sand separation on density-neutron combination. The study has brought out that (1) Sands appear to be constituted by a channel - bar couplet (2 ) This low resistive payzone shows pinch out and rising tendency westward. Concentration of oil producers e.g. Gandhar - A, B, C, D etc. towards westward pinch out limit corroborates the findings. (3) A prospective area for this payzone has been deciphered east of pinchout line towards its northern extremity. This area is highlighted through cross-hatching & surrounded by Gandhar wells A, D, E, F & G. (4) Subsequent drilling and testing of Gandhar wells I & H in the identified prospective area has testified the finding.