Azimuthal AVO (AZAVO) refers to the directional<br>variation of P-wave reflection amplitude at a fixed offset.<br>There are several possible causes for this azimuthal<br>amplitude variation: reservoir property, structural change of<br>the reflector, near surface effects, overburden property<br>variation, acquisition footprint, processing artifacts,<br>source/receiver radiation/reception patterns, etc. While<br>paying close attention to all these causes is necessary for<br>meaningful azimuthal AVO analysis, geophysicists are<br>most interested in the azimuthal amplitude variation caused<br>by a particular reservoir property: fracturing of the<br>reservoir. Through a decade of theoretical study and some<br>well-documented case histories it’s now generally accepted<br>that aligned open fractures will introduce azimuthal<br>anisotropy to the host rock and can therefore be detected<br>from analyzing P-wave reflection amplitude variation as a<br>function of azimuth.