Publications

A field study made over the Eastern Block of the Sangatta Field, East Kalimantan, gave an opportunity to develop and refine evaluation techniques in sands containing significant amounts of lignitic material.The paleoenvironment of East Kalimantan is known to have been for long periods of time similar to what it is nowadays, v/ith, among other features, luxuriant vegetation. Cyclic destruction of this vegetation yielded the easily identifiable lignite beds which are used as main markers in most, if not all, fields in the area.However in many reservoirs, particularly in Sangatta field, one can also identify spots of lignitic debris which, if not accounted for in reservoir evaluation, can yield over-optimistic values of the main petrographic parameters, porosity and oil saturation.A method was designed to identify qualitatively and then correct quantitatively for the effect of these lignitic debris, often referred to as detrital coal, on the reservoir evaluation.In parallel to the formation evaluation, a sand body analysis, using extensive dipmeter data through GEODIP+ processing and interpretation, yielded a better understanding of the paleoenvironment. A detailed study of the paleocurrurents revealed the probable configuration of the delta at various geological times and provided an explanation for the observed changes in sand-shale ratio over the field.This analysis, integrated to the petrophysical parameters evaluation allows the analyst to make reliable recommendations for the best remaining prospects.