Publications

Jatibarang Field is one of the biggest oil producers in Northwest Java basin. The main storage of hydrocarbon come from fractured volcanic reservoir. Fractures within volcanic rock has played a significant role in the storage and movement of fluid and also significantly enhanced the secondary porosity. The biggest challenge is to understand the nature of the fractures within the reservoir including lateral connectivity between fractures in this complex fracture system. We present a robust implementation of integrated fracture detection analysis which consist of well data, pre-stack azimuthal inversion including Amplitude versus Offset and Azimuth (AVAZ), Velocity Variation with incident Angle and Azimuth (VVAZ) and post-stack geometrical attributes including coherence and curvature. For Pre-stack azimuthal inversion, we used 5D azimuth gathers generated through special angle domain imaging system for a wide range of reflection angles and a full range of phase velocity azimuth. Inversion results are then combined with others geometrical attributes including curvature and coherence and further validated with Fullbore Micro Imaging (FMI). Fracture orientation identified from Full Azimuth inversion is predominantly a NE-SW direction. Good fracture density is located in the Eastern and Western areas and correlates well with producing wells. Coherence and Dip azimuth volumes indicate that the fractures are dominantly oriented in NE-SW direction and a lesser amount in the N-S direction. From FMI log analysis, most of the fractures in study area are open, conductive types with several fractures being filled by secondary minerals. Most of conductive fractures dip SE with dip magnitude ranging from 50o-80o. From this result, Full Azimuth inversion gives better confidence in fracture analysis and shows a good correlation with fracture analysis from well data. Keywords: Volcanic Reservoir, Fracture Analysis, 5D Angle Gathers, AVAZ Inversion, VVAZ Inversion