Experimental Study on Seepage Properties of Fractured Maokou Limestone

ZHANG Ying; XU Hong; LI Ping; ZHANG Li; ZHAO Yuan

doi:10.3969/j.issn.1008-4495.2016.01.004

Abstract：Experimental study was carried out on the seepage properties of Maokou limestone samples under the action of the same axial pressure and different confining pressure with MTS multi-function rock testing machine in order to study the seepage regularity of Maokou limestone under different loads, the seepage properties of Maokou limestone were tested by using of the transient osmosis process, and the seepage parameters of non-Darcy flow ( permeability,βfactor and acceleration coefficient of non-Darcy flow) were calculated according to the individual time series of porous pressure gradient. The test results showed that the fissure flow of Maokou limestone had the non-Darcy effect; its permeability gradually decreased and then trended to slow with the increase of the confining pressure under the action of the same axial pressure; the permeability coefficient and volumetric stress of rock samples were in an exponential attenuation relation, when the volumetric stress was small, the permeability coefficient of rock was more sensitive to its volumetric stress, but when the volumetric stress was large, its influence sensitivity to the permeability decreased;the permeability coefficient, volumetric stress and permeation pressure difference met an exponential relation;and in the process of the volumetric stress increasing from 14 MPa to 32 MPa, theβfactor of non-Darcy flow fluctuated near 0 and the acceleration coefficient fluctuated near 50×10-20 m-1.