Structural Uncertainties in Mature Field ; Example from Sungai Gelam-C Field

Abstract

Normally in mature fields, structural configuration had been established and therefore not considered as major uncertainties. However in the case of the Sungai Gelam-C field in Indonesia’sJambi Sub-basin, structural interpretation and the position of the fluid contacts are major uncertainies that need to be considered in further development. The problem came from not acquiring enough fit for purpose data during early drilling program. Lack of reliable well-to-seismic-ties especially in the eastern part of the field prevented accurate velocity model to be constructed. The result of two recent stepout/infill drilling showed the effect of this problem where the main Air Benakat Reservoir (‘N’ Sand) fell into water zone due to their significantly deeper than prognosed structural positions . New VSP data was acquired in one of these wells and new structural interpretation conducted before the drilling campaign resumes. On a brighter note, the presence of oil rim in the younger interval (‘M’ sand) had been proved by production tests in these wells. Previously ‘M’ Sand had been thought to be fully gas bearing and had not been developed. The position of Oil-Water-Contact (OWC) in this interval will have a big impact on the reserves and economic of the field.

AAPG Datapages/Search and Discovery Article #90354 © 2019 AAPG Asia Pacific Technical Symposium, The Art of Hydrocarbon Prediction: Managing Uncertainties, Bogor, (Greater Jakarta), Indonesia, August 7-8, 2019