Publications

PetroChina continues to carry out a very active exploration and development programs in the Jabung block to date, since this block was taken over in 2002. Production maintain plateau in average over 55,000 BOEPD at nearly 15 years from those all activities. The reservoir is Oligocene-Miocene syn-rift transgressive alluvial, fluvio-deltaic, local lacustrine and marginal marine facies sands of Talang Akar Formations that constitute the primary reservoir target. This hydrocarbon trapping system in Jabung Block is generally structural trap with stratigraphic component distributed mainly in the flank area. Over 70% of the production is contributed from this. Northeast Betara (NEB) is one of Jabung major contributing field that was discovered in July 1995 by Northeast Betara-1 as the first exploration well. NEB Field structure is a typical of half graben feature that became slightly inverted by subsequent younger tectonism event in Plio-Pleistocene time. Paleo-high is composed of granitic basement and in situ weathered granite, where the thin reservoir developed on the crest was cut trough by the northeast-southwest trending normal faults which then kept the hydrocarbon trapped in the west part of the structure. The reservoir types of the structure consist of terrestrial to transitional sands, typically moderate quality reservoir deposited during unstable basin movement from surrounding paleo-highs. Several core samples have been collected and analyzed in order to obtain better understanding of the history of terrestrial to transitional marine sediments through this area. Weathered basement and basement interval (NEB-6 well) is characterized by rapidly deposited sandstone granitized (4972’ – 49782.70’MD) with some aggregates of tightly interlocked grains and a few grains with gneissic composite fabric. And Granite Porphyry (4982.70’ – 4988.10’MD) with quartz and perthite commonly intergrown, with graphic or granophyric texture. Lower Talang Akar Formation (LTAF) interval is observable on core of NEB-7 and NEB-45 wells. In NEB-7 it is commonly dominated by lithic sandstone with comprises of medium grained, moderately well sorted, numerous quartz granules at base, leaf fragments and a single cross-lamina set Another integrated analysis on thin section, using Scanning Electron Microscope (SEM) and X-ray powder Diffraction (XRD), is done on Lower Talang Akar Formation (LTAF) interval which interpreted as transition environment (NEB-45 well). The analysis suggests that the sample is claystone, occasional siltstone & sandstone, variegated grey, blue, brown and red, variously disturbed by dewatering and roots. By the comprehensive information and understanding regarding reservoir properties, sedimentary facies and depositional environments expected to be able to unlock Jabung future development strategy in the varieties of NEB reservoir play.