Velocity-porosity transforms and effective stress in gas bearing reservoirs, a case study

Acoustic velocity logs commonly contribute to porosity estimation in hydrocarbon wells, and various equations have been proposed to transform sonic travel time (At) into porosity. The observed compressional acoustic velocity (Vp) for a sedimentary rock in a perfect borehole, however, is a function of many other factors apart from porosity, such as matrix mineralogy (framework), effective stress, pore geometry, cement type, clay pore-fill, fluid saturation, and nature of the pore fluid.