LOW PERMEABILITY RESERVOIR MODELLING AT SAWAHTAMBANG FORMATION, OMBILIN BASIN, WEST SUMATRA

• Main Author: RIMBA RAYA (NIM : 22013009), NICODEMUS
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/29621
• Institution: Institut Teknologi Bandung

<p align="justify">Ombilin Basin is an intramontana basin which have good hydrocarbon potential. Drilling at Sinamar-1, South Sinamar-1, and Sinamar-2 indicate the presence of hydrocarbons in the Sawahtambang Formation through wireline log analysis, cutting description, and Drill Steam Test (DST). The reservoir property in sand A of Sawahtambang Formations is very unique because of its low porosity (average 8.2%) and low permeability (average 1.45 mD) although it was deposited on the braided river environment. <br /> <br /> Low porosity and permeability in a tight gas sand reservoirs is generally caused by the diagenesis. The diagenesis in sand A Sawahtambang Formation was investigated by evaluating the thin section, X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) of the Sinamar-2 well. Petrophysical analysis was running with multimineral methods to obtain porosity, shale volume, and water saturation. Routine Core Analysis (RCAL) data then use to determine the rock type by using Flow Zone Indicator (FZI) method based on a cross plot of Rock Quality Index (RQI) versus normalized porosity. The research area is divided into three rocks types. Good reservoir quality demonstrated by rock type 1, moderate reservoir with rock type 2, and poor reservoir in rock type 3. <br /> <br /> Rock type in uncored zone and uncored well interval was predicted with the Multi-Resolution Graph-Based Clustering (MRGC) method. The petrophysical properties then distributed in reservoir modeling with geostatistical approach. Based on the modeling, the author advised to explore to northeast of Sinamar-1 which have good rock type and thick reservoir.<p align="justify">