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AAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain

Fractures Detection Using Multi-Azimuth Diffractions Focusing Measure: A Feasibility Study from the Arab D Reservoir

Abdulfattah A. Aldajani1; Sergey Fomel2

(1) Exploration Resource Assessment Department, Saudi Aramco, Dhahran, Saudi Arabia.

(2) Jackson School of Geosciences, The University of Texas, Austin, TX.

3D azimuthal P-wave post stack seismic data has been analyzed to investigate the feasibility of using multi azimuth scattering and diffractions focusing measure to detect azimuthal anisotropy anomalies at the Arab D carbonate reservoir; hence, assisting in the identification of potential fractures (i.e. sweet spots). Earlier studies and numerical examples demonstrated the azimuthal variations of scattering in vertically fractured media. Azimuthal variations of the focusing measure for the scattering energy and diffractions are estimated from stack data along a test 3D multi-azimuth sub-line, after segmenting the data into four azimuthal sectors (stacks), each 45 degrees wide, and separating the diffractions and scattering from the reflections, using the plane wave destruction technique. The analysis suggest the presence of azimuthal anisotropy anomalies in the focusing measure and they are generally oriented W-E (~N85E). This conclusion is consistent with the results obtained by using an independent seismic technique which is based on a different but more accurate 3D analysis using 3D azimuthal pre-stack reflection moveout, to study the amplitude variations with offset and azimuth (AVOA) and the normal moveout (NMO) velocity. The intensity of the azimuthal anisotropy anomalies in the focusing measure (hence, potential fractures), along the seismic profile, is also consistent with the results obtained from 3D prestack azimuthal anisotropy reflection moveout analysis. The structural geology of the area supports the outcome of this study. This is the first attempt to apply azimuthal scattering and diffraction focusing measure technology as a tool for fracture detection in Saudi Arabia. The technique is fast since it is applied on stack data, as opposed to 3D prestack reflection moveout. This technology could be applied to fracture detection by complementing existing seismic methods; especially in cases where the 3D seismic azimuthal data acquisition is rather challenged and the application of full 3D pre-stack AVOA and NMO velocity analysis for the target reservoir is less adequate.