Geomechanic application for hydraulic fracturing in lower Pematang formation, Central Sumatra Basin

NN field is located onshore within the Malacca Strait Block. The field was discovered in 1990 by drilling N-01 exploration well which proven oil in the Manggala and Pematang Formations. In 1998, 3D Seismic was acquired and successfully identified three compartments in this field which separated by N-S faults. This study is focusing on Lower Pematang Formation which belongs to Pematang Group and deposited in braided-fluvial system. The Lower Pematang reservoir is tight sandstone with blocky log-type model. In this study Eaton method is used to calculate pore pressure prediction and to make transformation log Vp, Vs and density into Poisson’s Ratio and to calculate fracture pressure. In order to optimize the oil production, hydraulic fracturing stimulation was chosen and became proven technique in this reservoir. Further geomechanic study is required to support hydraulic fracturing jobs by providing a 3D model of pore pressure and fracture pressure. Several geo-mechanics rock properties such as pore pressure, Poisson’s ratio, Young’s Modulus and Fracture Pressure were calculated in wells and then propagate troughout NN fields. With 3D model, a robust recommendation on field deveopment via hydraulic fracturing can be achieved and oil recovery will optimum. Moreover, from 3D model, we could propose how much pressure can be applied in injection without damaging formation target.