Granitic Basement Fracture Analogue by Using Integrated Digital Outcrop Model and Fieldwork, at Muaro Silokek, West Sumatra

Abstract The study aims to determine fracture characteristics such as orientation, fracture attributes, fracture density distribution, and mineral composition of quartz and feldspar. The study used photogrammetry data to know the distribution and geometry of macro-scale fracture, linear scanline and windows scan data to understand the characteristics of mesoscale fracture attribute, and thin section rocks data from oriented samples to determine petrographic analysis and micro-scale fracture. After analyzing each of these data, analog basement fractured reservoir modeling could be built from integrating the data and modeling parameters based on available fieldwork data. The fault in the research area is represented as a Riedel shear with the orientation direction of NNW-SSE, NE-SW, and ENE-WSW. The fracture density is influenced by its position on the fault and increases in the fault damage zone. The granite type in the study area was divided into three types, namely alkali feldspar granite, syeno granite, and monzogranite. Each granite type has a different response to fractures and shows that the fracture density will increase with the greater quartz and k-feldspar in the fault damage zone. Fracture permeability values are strongly influenced by the geometry of fracture position, fracture aperture, and fracture length. This study produced a new perspective for fractured basement reservoirs, especially for granitic rocks, generally the primary target for basement fracture reservoirs along Sumatra.