7th Middle East Geosciences Conference and Exhibition
March 27-29, 2006
1 SAUDI ARAMCO, Dhahran, Saudi Arabia, phone: 9663 873-5170, [email protected]
2 WesternGeco, Dhahran, 31311, Saudi Arabia
3 Saudi Aramco, Dhahran, 31311, Saudi Arabia
Fractures in carbonate reservoirs affects both the porosity and permeability. The characterization of fractures is therefore essential for successful exploration and production of the reservoir. Multi-component VSP data can identify fracture density and orientation by measuring the P and S wave anisotropy caused by the fractures.
Recently, a deviated well was drilled in a direction perpendicular to possible reservoir fracture orientation in the Qatif Field in Saudi Arabia. A multi-azimuth VSP was acquired for the purpose of characterizing the vertical fractures within the Arab and Lower Fahdili reservoirs. The VSP data consist of a total of seven offsets including two nearly orthogonal pairs. This carefully designed survey data provides an opportunity to employ different methodologies for the fracture characterization including: 4C-pseudo Alford rotation method, C-wave hodogram, and P wave traveltime analysis.
Analysis of the P-wave traveltime from symmetrical shot points and shear-wave hodogram provide a clear indication of fractures within the reservoir units. The prominent fracture orientation is confirmed by the rotation analysis of the orthogonal shot point data.