GEOLOGY AND 3-D STATIC RESERVOIR MODELLING IN AIR BENAKAT FORMATION, ALFA FIELD, SUB-BASIN OF SOUTH PALEMBANG, SOUTH SUMATRA BASIN

• Main Author: Safira, Arike
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/43860
• Institution: Institut Teknologi Bandung

Alfa Field has an upside resource potential on Air Benakat Formation as indicated by the presence of gas based on the result of tested data on exploration wells. This field covering an area of approximately 161 km2. Administrively, Alfa Field located in Ogan Komering Ulu Regency, South Sumatra Province. This field is physiographically part of South Palembang Subbasin which lies in Tertiary-aged of South Sumatra back-arc basin. Geological studies and reservoir modelling are focused on Air Benakat Formation with four reservoir interval comprise of sandstones respectively. This study aim to comprehend the geological condition, determinating static reservoir model and estimating hydrocarbon reserve from four reservoir in Alfa Field. Data used in this study consist of wireline log, cuttings description, biostratigraphy report and three dimensional seismic data. Several methods used in this study comprise of well correlation using sequence stratigraphy concepts, petrophysical analysis, analysis of facies and depositional environment, isopach determination; creating depth structure map using seismic data; three dimensional structural model, facies and petrophysical properties models; determination of fluids contact and hydrocarbon reserve estimation. The outcome from all those methods showing an overview about the geological condition of study area. The main geological structure in Alfa Field consists of northwest-southeast orientation of anticline associated with the same orientation of reserve faults as a result of compressive deformation with northeast-southwest compression axes. Normal faults with the orientation of northeast-southwest are thought to form on the final phase of compression. This compression generate a northwest-southeast trending extension which manifested by normal fault. Air Benakat Formation was deposited during regressive phase on depositional environment that evolve from lower estuarine channel to barrier sand ridges. Petrophysical analysis showing the result of shaly sand categories for all reservoir interval with porosity range from 10-40% and water saturation range from 60-80%. The estimation of hydrocarbon reserve (IGIP) in the study area divided into three segments with total hydrocarbon reserve from all reservoir interval within all segments give the value of 531,41 bscf.