Experimental research of Poisson´s ratio´s anisotropy with different porous medium for tight sandstone

To study the anisotropy of Poisson´s ratio with different porous medium for tight sandstone in the development process of reservoirs with the effective stress increasing, we experimented under hydrostatic pressure of 5-180MPa. Based on Autolab2000 petrophysical testing system, experiments measured 3 groups of typical sandstone samples from Changqing Oilfield which are in dry, water saturated and oil saturated, and then we computed and compared the Poisson´s ratios and the anisotropies of Poisson´s ratio using seismic velocities. Preliminary results showed that in dry state, Poisson´s ratio of Z direction is increasing rapidly with the increasing of confining pressure, and the anisotropy of Poisson´s ratio is notably decreasing with the increasing of confining pressure. The Poisson´s ratio´s anisotropy of sample B3 is decreasing from 80.99% to 3.11% when the confining pressure is increasing from 5MPa to 180MPa. Under the circumstances of water saturated or oil saturated, Poisson´s ratio is decreasing with the increasing of confining pressure. The value of Poisson´s ratio with water saturated or oil saturated is higher than the value in dry state.