Identification and Characterization of Low Resistivity Pay Zone, Case Study “L” Field

Abstract

In general, sandstone reservoir containing hydrocarbons has high resistivity values based on the response of well log measurement. This is because hydrocarbons are unable or difficult to conduct electric current (resistive). However, in some cases, rocks with low resistivity value have the potential to become hydrocarbon reservoirs.

On the other side, the decrease of production makes the company need new approach to increase oil production. One of the alternative methods is to reevaluate the well log data in suspended well, especially in low resistivity pay zone. Low resistivity pay zone is a unique reservoir that usually identified as water bearing zone, but in fact has hydrocarbonpotential. Test production on several wells in L Field shows the presence of hydrocarbon with resistivity value less than 10 ohmm (2 – 5 ohmm).  By focusing on the low resistivity pay zone, the company can also reduce the production costs by opening new layers on existing wells instead of drilling new wells.

This paper focuses on identifying the main causes of low resistivity pay zone in L’ Field, South Sumatera Basin. By using openhole log, core data, petrography analysis, and cutting data, it can be concluded that the main cause of low resistivity pay zone in this area are the presence of illite & kaolinite as clay minerals, sand shale lamination, silty-fine sand grain size and conductive minerals.