Publications

The Sundari field is one of the main oil producing fields in the central Sunda Basin. Discovered in 1980 by drilling seven exploration wells, this field comprises a productive oil area of 7.6 sq km, 200 ft of gross sand thickness, and 19 producing oil wells. This field has a strong water drive and a continuous reservoir, with excellent porosity and permeability. The reservoir is sandstone of the Upper Zelda Member, Talang Akar Formation. Zelda sandstone is a series of braided channel intercalated with shale. Core description and petrophysical properties analyses suggest that at least four petrophysical rock types can be applied to distinguish sand types. Based on log patterns and with the help of seismic attributes, the vertical and lateral reservoir distributions were predicted. Several projects can conducted to maintain the oil production in a mature field, such as water shutoff, add perforation, and infill well drilling in a suspected virgin area. To achieve good results, a geological model has been built and run as a simulation. This paper covers the activity of the geological modeling and history matching to support the reservoir management activities. Standard geological modeling steps were run from pillar gridding, making zones and layers, facies modeling, and petrophysical modeling. Facies were drawn using the Truncated Gaussian Simulation method, considered the best method for continuous sand. The property models created were porosity, permeability, net-to-gross, and water saturation. Several methods for determining the permeability and water saturation were performed to achieve good results. The lack of good seismic attributes to predict the porosity distribution was aided by creating the porosity distribution map manually. The finished geological model was then run in simulation using production and well test data. The result of the history matching was considered adequate to fulfill the needs of a detailed study to conduct further workover or infill drilling jobs.