Analysis of Travel-Time and Attenuation Anisotropy in Walkaround and Walkaway VSPs from Tiguentourine Field, Algeria

摘要

Theoretical models predict that both travel-time and attenuation anisotropy can be used to derive information about the fracture network. In this paper we analyse a range of azimuthally varying attributes from walkaround and multi-azimuth walkaway VSP data from a fractured gas reservoir in Algeria. Anisotropy is detected in both dynamic and kinematical attributes, and reasonably consistent estimates of the fracture strike direction are derived. The magnitudes of the effects are different however, and it is noticeable that the attenuation anisotropy is strongly localised in the fractured reservoir. This suggests that the attenuation anisotropy is particularly sensitive to the fracture and fluid properties. The results of the study are validated through modelling exercise.