Publications

Given twelve years of production and several years of implementing a waterflood system in Kaji Semoga Baturaja formation, one characterized by multiple flow units, there is a very high possibility of finding bypassed oil between the flow units. One successful key factor in developing such a reservoir is by utilizing a cased-hole log to locate bypassed intervals.There are two kinds of cased-hole logs: cased-hole resistivity and cased-hole saturation. Both of these have been widely used to analyze the existing perforation interval and to identify any bypassed oil in the reservoir. However, to conduct a deep analysis in this waterflood reservoir (one which has various and low salinity in its area) a logging tool independent of water salinity, one which will work accurately in a low salinity formation is more preferable. Considering the economic aspects of conducting cased-hole logs, slim saturation tool technology, which allows thru tubing operation, has become a promising method. This technology eliminates any requirement for a rig in extracting tubing, which signifies less operating time, less shut-in time and a lower cost. Based on technical and economic considerations, slim saturation tools, i.e. pulsed neutron neutron (PNN) and carbon/oxygen (C/O) logging, were chosen to be implemented in nine wells in Kaji Semoga in 2009. The nine wells in question were selected based on analysis of remaining oil reserves, oil potency from open hole logs, and well configuration. As a strategy of securing maximum oil recovery, a work over job, combined with production optimization through ESP installation, was successful in recovering bypassed oil identified in Well-A, and resulted in an additional gain of 631 BOPD. This paper discusses tool and well candidate selections, general aspects of selected tools, implementation of the logging job, workover result based on the logging interpretation, and certain improvements implemented in this project.