Acoustics Deep Shear Wave Imaging DSWI Analysis in Fractured Carbonate Reservoirs

Abstract

The evaluation of carbonate reservoirs is challenging for different reasons related to stratigraphic and structural features' heterogeneities. One of the major challenges is the evaluation of a fracture's nature, intensity, aperture and extension. Near and far field evaluation techniques have been utilized to achieve advanced fracture evaluation and modeling, the latter being a key factor in successful carbonate reservoir development. Resistivity images and cores help in the quantitative analysis of the near wellbore fracture's intensity and aperture, while high resolution seismic data can help to evaluate major structural features at a larger scale. It is essential to bridge the gap between the borehole and field scales to further enhance evaluation of these fractures. By using an acquired sonic log and special processing, deep shear wave imaging (DSWI) can take cross-dipole shear wave components and use them to "image" reflectors up to 70 ft away from the borehole, whether they are intersecting the borehole or not. This radial distance coverage-which was the radius of this investigation-can be even greater depending on many parameters. The combination of resistivity imaging and acoustic DSWI techniques offers a great value added to fractured carbonate reservoir evaluation. This article discusses a case study and the lessons learned in a challenging evaluation well where both techniques were deployed to validate this process with the goal of enhancing petrophysical and reservoir characterization models. Future work will involve the integration of results achieved using the DSWI technique with both borehole seismic and surface seismic data to enhance the fracture model and ultimately optimize well placement as well as reservoir performance.