ENVIRONMENTAL DEPOSITION ANALYSIS AND FORMATION EVALUATION INTERVAL FS 1A- SB A, AREA B, DIAR FIELD, CENTRAL SUMATRA BASIN, RIAU, INDONESIA

• Main Author: Olytia, Lika
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi ekonomi
• Online Access: https://digilib.itb.ac.id/gdl/view/34313
• Institution: Institut Teknologi Bandung

Diar field is the largest oil field in Riau, Central Sumatra Basin. This field consists of twelve areas, which observation is in Area B for interval FS 1A-SB A in Duri Formation. Objectives of this observation are to determine distribution of architectural facies, environmental deposition of Duri Formation, and subsurface mapping for reservoir petrophysical properties. The data that have been used for this observation are core, petrography report, biostratigraphy report, and electric log from 233 wells. Based on biostratigraphy report and core analysis, reservoir in FS 1A-SB A was deposited about 20 million years ago in Early Miocene. Core analysis shows that intervals are consists of six sandstone lithofacies are Sbcvf, Sbfvf, Smvf, Smf, Sbvf, Sbf and three claystone-siltstone lithofacies are Fblc, Fbc, and Fm. Distribution analysis of architectural facies is made with stratigraphic correlation that shows this area have Highstand System Tract (HST) and Transgressive System Tract (TST). Based on core analysis, electrofacies distribution, and ichnofossil analysis, the depositional environment is estuarine. The architectural facies are estuarine channel, tidal mud flat, and marine shale with sedimentation trend is NE-SW. Core, XRD, and petrography data analysis on FS 1A-SB A shows that major mineral existed and consisted on rock are from grain and clay group. Clay mineral type which dominates the observation interval is mixed layer illite/smectite. The result of petrophysical analysis from estuarine channel facies for A1 a and A1 b shows that average value for effective porosity is 0,35, average value for effective water saturation is 0,53, average value for permeability is 573 mD, and average value for Vclay is 0,142. For petrophysics result from estuarine channel facies for A2 shows that average value for effective porosity is 0,32, average value for effective water saturation is 0,57, average value for permeability is 409 mD, and average value for Vclay is 0,19.