Brittleness modelling of shale gas reservoir: Case study of Pematang formation, Central Sumatera basin

The Pematang formation, which is located at Central Sumatera basin become the prospective shale gas reservoir in the Kisaran area. It is shown by a large potential amount of gas and oil in place. However, there is still a lack of information about the shale properties in this field so it becomes a big challenge for developing the shale gas exploration. Based on the core and petrophysical analysis, it is shown that the formation is dominated by shale and some part is laminated by sand layers. There is a significantly large deposit of shale underneath sand layer. This paper aims to perform the brittleness modeling, which is based on the integration of geophysical and geomechanical data. In the application, the brittleness distribution map is used to delineate the brittle zone of the shale reservoir that has potential to be fractured by using an artificial hydraulic fracturing. The brittleness modeling is performed by using Statistic Linear Gaussian Simulation (SLGS) approach based on the 3D seismic data and the well log data. The brittleness map shows that the potential shale reservoir to be fractured, which is indicated by brittleness index greater than 0.5, is distributed in the eastern part and the north-eastern part of the study area at the depth range of 6308 feet to 7432 feet.