HRS AFI guide:AVO Fluid Inversion (AFI) is a program which is used to analyze AVO responses, compare them with theoretically derived responses, and predict fluid properties. This process can be thought of as an extension of conventional AVO analysis in this way: Conventional AVO analysis is typically used to determine the fluid properties of a target reservoir. AFI attempts to determine, in addition, the probability or likelihood that this determination is reliable. It is a tool for analyzing and understanding the uncertainty in the AVO process.