Reservoir Description And Geology Modeling Of LTAF Formation In R Field Of Indonesia

R oil field is located in South Sumatra Basin of Sumatra Island and its main production reservoir is LTAF. The reservoir strata here often consist of very thin sandstone. The reservoir is very complex, and the faces laterally change soon. The structures mainly consist of faulted anticlines and fault blocks, which are made by a series of faults, and thus this oil field belongs to a complex fault block oil field. Since the original development plan is imperfect, meanwhile, and there is no unified strata division and correlation, no systematic analysis of sedimentary micro-facies and sand distribution, no cognition of the law of the oil, gas and water distribution, it is necessary to carry out fine reservoir description.In this paper, fine reservoir description and3D geological model of LTAF are completed in R field, based on the subjects of the sedimentology, petroleum geology, sequence stratigraphy, geophysics, stochastic modeling and geostatistics and so on, combinedly taking advantage of geology, drilling, logging, testing of well, coring and dynamics analysis and multiple other kinds of data. As a result, LTAF is divided into Lumut and the Simpang, and Lumut, the main destination layer, is further divided into3sub-segment and15small layers. The study area is mainly delta depositional system, including two sub-phase, which are delta plain and delta front respectively. Based on the core petrology and logging phase study, ten micro-facies are divided, which are flood plain, distributary channel, levee, crevasse splay, marsh, underwater distributary channel, mouth bar, underwater levee, underwater crevasse splay and inter-distributary bay. The characters of lithology, physical property, electric property and hydrocarbon property and also the relationships between them are determined by coring analysis, test data and logging data study. Meanwhile, log interpretation thresholds are determined:clay content40%, effective porosity14%, water saturation60%and resistivity value7ohm-m. In terms of fluid identification, analysis by example here confirms that improved porosity curve superposition method can effectively distinguish gas layer from oil layer, and for DT only reflecting the characteristics of native splits, this method can also eliminate the influence of the induced splits and other adverse borehole conditions during the gas layer recognition. By the study of characters of faults in this field, three fault blocks and4oil, gas and water systems are determined here. Then, on the basis of the study above,3D geological model of this area is established with stochastic modeling techniques in Petrel software, and finally proved reserve is calculated. These study results provides a reliable geological basis for the improvement of the oil field development plan.