Sedimentary Facies of T Structure in J Block of South Sumatra Basin, Indonesia

Abstract

With the continuous deepening of exploration and development, it is urgent to develop the T structure in order to increase reserves and productions. The block contains 4 sets of oil-gas bearing strata, including LTAF, UTAF, BRF, and GUF. The reservoir types are mainly sandstone and carbonate rocks. However, there are many problems having to face in this structure, among which is the distribution of sedimentary facies. Based on the study of high frequency sequence stratigraphy, the study of sedimentary facies was conducted from the point-line-plane by comprehensively using cores, wells and seismic data. According to the coring data of adjacent areas, single well facies study was carried out, and core facies-logging facies-seismic facies interpretation plates were established. The plane distribution of seismic facies was studied by using seismic techniques such as seismic attribute, strata slice and waveform classification, and the distribution of sedimentary facies was finely delineated by well-seismic combination. The study shows that the provenance of T block is located in/to the northeast or east of the study area. The LTAF formation is mainly composed of alluvial fan and braided river deposits, and braided river delta is locally developed. The UTAF formation mainly consists of braided river, delta front and sheet sand, and alluvial fans and underwater distributary channels locally developed. BRF formation mainly consists of the coastal and offshore, reef flat, inter-reef and delta front. Underwater distributary channels and sheet sand are locally developed. The GUF formation is mainly composed of delta plain, distributary channels, underwater distributary channels, levee, and locally developed mouth bar.KeywordsSeismic attributesStrata sliceWaveform classificationSeismic faciesSedimentary faciesSouth Sumatra basin