Publications

This study intends to introduce a new technique for solving the fracture detection problem in complex carbonate reservoirs by using AVO attributes analysis of pre-stack seismic data. The application of the method will be shown through the presentation of the case study in Rama oil reservoir of Sunda Basin offshore Java Sea, Indonesia. As of June 2009, Rama field has produced more than 137 MMBO, making the field one of the largest in CNOOC SE Sumatra contract area. Rama field is located at the southern part of Sunda Basin and covers an area of 70 km2. Three main reservoirs are oil productive in this field – Upper Baturaja, Lower Baturaja and Talang Akar Formations. The Upper Baturaja, the main reservoir in Rama field, is represented by a north - south trending carbonate platform with majority production from the platform margin which progrades westward. The reservoir properties are controlled by the lithofacies and depositional environments. Fracturing of Upper Baturaja carbonates is a major determinant of well productivity based on dynamic analyses and wells log analyses. With considerable seismic data covering Rama Field, including PSTM stack data and angle stack data, an investigation was undertaken to examine the capacity for detection and determination of distribution of the fracture system using these seismic data. According to AVO (Amplitude Versus Offset) * CNOOC SES Ltd According to AVO (Amplitude Versus Offset) theory, far offset seismic data records more information about porosity, permeability and fracture characteristics than near offset data, thus we investigate use the difference between far offset data and near offset to data detect fractured reservoir. Indeed, this study was successful and results show the method can be extended to other fields also influenced by fracturing.