--> Abstract: Integration of Borehole Images and Shear Sonic Anisotropy for Quantitative Fracture Evaluation, by Romain C. Prioul, Jeroen Jocker, Austin Boyd, William H. Borland, and Claude Signer; #90077 (2008)
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Integration of Borehole Images and Shear Sonic Previous HitAnisotropyNext Hit for Quantitative Fracture Evaluation

Romain C. Prioul1*, Jeroen Jocker1, Austin Boyd1, William H. Borland2, and Claude Signer1
1Schlumberger, USA
2Schlumberger, UAE
*[email protected]

The characterization of natural fractures can greatly improve recovery in many hydrocarbon reservoirs. Surface seismic, borehole seismic and borehole sonic techniques are commonly used to estimate effective anisotropic elastic properties, but interpretation is often ambiguous. Effective medium theories used to infer fracture properties from seismic or sonic data usually assume the cause of the Previous HitanisotropyNext Hit without necessarily taking into account the in-situ geological complexity. However, in boreholes, the measurements of borehole images provide a very high-resolution picture of the borehole wall under geological conditions. The quantitative link between geological fractures observed in-situ and the effective elastic properties of the near-wellbore region is often missing. We developed a methodology to model and interpret borehole dipole sonic Previous HitanisotropyNext Hit related to the effect of geological fractures using a forward modeling approach. We used an excess-compliance fracture model that relies on the orientation of the individual fractures, the compliances of the fractures, and the compliances of the host rock. We extracted the orientation of individual fractures from borehole image log analysis. We validated the model using borehole resistivity images and sonic logs in a reservoirs in the Middle East region, where we observed significant amounts of sonic Previous HitanisotropyNext Hit and numerous fractures. We will show that using a few adjustable fracture compliances, we can explain the fracture-induced Previous HitanisotropyNext Hit response. Predicted fast-shear azimuth and slowness Previous HitanisotropyTop are compared to the measured ones and help to discriminate natural fractures and stress effects. This information can be used as input to seismically constrained fracture characterization workflows.

 

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain