Fracture intensity estimation in carbonate reservoirs using XMAC, STAR and VDL data analysis: A case study from Asmari reservoir in Aghajari oil field, SW Iran

The majority of Iranian hydrocarbon reservoirs are carbonate for which fracture evaluation and detection will play an essential role in maximizing production, reservoir development and cost optimization from fractured intervals. Nowadays, Cores and image logs are usual tools and direct methods as continuous data for studying of fracture; however, it is both technically and financially impossible to core or image the whole thickness of the reservoir. One application for Cross Multiple Array Acoustic Log (XMAC) is its capability to evaluate fractures by measuring Stoneley wave. Thus In this study, the XMAC was used to determine position fractures and evaluate its intensity in the fractured bearing Asmari formation. For this, the Stoneley wave data were analyzed using commercial software. After data processing and performance different type filtering methods for reflection enhancement, the direct and Up/Down as reflected Stoneley waves were subtracted from the original data and reflection coefficients were calculated afterwards. From the calculated reflection coefficients, positions and intensities of fracture were determined. The results were validated by STAR and VDL as two direct and indirect methods respectively. The results show the good correlation in the most of zones between fracture intensities derived from RC and star image log respectively provided Such features could be changes in lithology (beddings) and hole diameter (bad hole or break-out intervals) are determined and then eliminated. The reason of doing this project using Stoneley.