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Limau Block, operated by Pertamina EP lies in South Sumatera basin, located 90 Km Western part of Prabumulih. Consisted of eight fields, the first well was drilled in April 1951. The production reached a peak of 49,000 BOPD. The reservoir was divided into 22 layers mainly due to faulting. The pilot water flood operation was initiated in April 1991 by injecting water. Currently, Limau block is a mature oil field. By April 2009 production had declined to 10,000 BOPD. It is estimated that more than 80% primary reserves have already been produced and recovery factor has reached 36 %. Most of the reservoirs have been intensively produced over the life of the field and only a few of them are still producing today at low rate due to depletion. EOR department tried to identify reservoir with remaining production potential that are candidates for Pilot Chemical Flooding Project, which will be the first Chemical Flood Project for Pertamina EP. The chemical selection is ongoing progress. It has become much more of a challenge for the team consisting of integrated Geophysics, Geology, Reservoir, Production, Process Facility, Project Management and Economic Evaluation. This paper presents the result of Production Part as integrated analysis for Chemical Flooding. The analysis, which was performed by integrated analysis of production and injection, tracer test, well history and surface data, has identified inter well communication between injection well and production well. It shows that the most prospective candidate for Chemical Flood pilot project was S layer in Q-51 field, the pilot project was planned for inverted five (5) spot patterns and predicted breakthrough time was 90 days, it was also predicted a tertiary peak of 3,100 BOPD. Currently, Q-51 field, which had reached a primary peak of 20,600 BOPD and secondary peak of 2,000 BOPD, is injecting 36,820 BWPD through seven (7) peripheral injection wells and producing 31,031 BFPD through 13 production wells. This analysis is useful result as a part of countercheck for Geology and Reservoir Modeling regarding to the plan of Chemical Flooding Pilot Project.

Limau Field is located in South Sumatra Basin, form as anticlinorium elongated from West – East. Limau Field are divided into 8 blocks and separated by normal fault and have been produce since April 1951. Description reservoir is needful in detail either lateral or vertical that can describe reservoir heterogenity in process designing and proposing a field development plan. Build a 3D model in Limau Field are challenge, which caused by complexity in stratigraphy and restrictiveness data. Integrated of multidiscipline science are needful to construct a static 3D model that can describe heterogeneity reservoir in Limau Field. Interpretation detail in geophysics and geology were doing by integration between petrophysics and core data. Seismic enchantments are conducted to increasing a quality of 2D seismic data in Limau Field and used to build an attribute seismic Pseudo-GR and Acoustic Impedance. Attribute seismic pseudo-Gamma Ray and Acoustic Impedance map were used to describe generally in lateral distribution reservoir. Log data and Biostratigraphy were integrated to decide depositional environment furthermore the correlation geology was built by sequence stratigraphy concepts. Identification of lithofacies was built by integration between log data and petrography, and those data are applied to wells that have no in core data; it will be used to estimate a distribution of reservoir properties in throughout field. Analysis of log is use to found a reservoir properties which validated by core data. Synthetic of logs (Neutron & Density) are approach by neural network concepts then obtainable the sufficient data for analysis of log in wells that have incomplete log data. Relation between porosity, permeability, and vclay are using as phenomenon to define flow unit with the result that estimation of permeability can be done throughout field. Fine geology model are build for 50 zones with total grid cell 97.886.742 with large scale of geology model; influences of variability regional toward reservoir quality can be seen. Application of geostatistic are use to build a model of lateral distribution and lithofacies vertical which guiding by attribute seismic map and facies pie from well as a trend and probability of distribution. Reservoirs properties are distributed by constrain sand zone and llithofacies. 25 of realization models are building by geostatistic application for each zone furthermore by blind test model is use as a validation of lithofacies distribution model and reservoir properties. Based on suitability of well production data then 5 final models have been chosen.