Abstract:The mechanism of seismic velocity attenuation caused by reservoir capillary strain is that seismic waves in porous two-phase medium make interpose capillaries in poorly-consolidated reservoir close transiently, the closure strain mainly controlling the volume of closed gas, wave energy dispersion and wave velocity attenuation. According to above fact, we find the mathematic relation between P-wave velocity and capillary pressure, pore structure, water saturation or elasticity modules of capillary-closed reservoir, so that Domenico effect can be interpreted desirably. Evaluating the quantitative influence of both pore structure and gas saturation upon seismic velocity is very significant to broadening the application of capillary pressere data in seismic data interpretation.