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Abstract High pressure packer test(HPPT) is an important field technique for estimating the permeability of rocks subjected to high seepage pressure. Up to now，no effective method has been proposed to estimate the permeability of rocks subjected to high seepage pressure and the estimation is still commonly performed based on the Darcy?s law as assumed in the constant head packer tests(CPTs). A formula for estimating the permeability of rocks through single borehole HPPTs was established based on Izbash?s empirical nonlinear equation between the apparent velocity and the hydraulic gradient. The P-Q curve obtained from HPPTs was divided into a linear，a nonlinear and a hydraulic fracturing stage correspondingly，where P is seepage pressure，and Q is seepage quantity. The proposed formula was validated against the in-situ measured data obtained in HPPTs performed to the surrounding rocks of the underground bifurcated pipe at Qiongzhong pumped storage power station. It was discovered that the permeability of rocks was not influenced by the flow pattern，and the estimated permeabilities in the linear and nonlinear stages basically had the same values. As the hydraulic fracturing occurred，however，the permeability increased drastically. The proposed formula provides an effective method for permeability estimation in rocks subjected to high seepage pressure.
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Received: 28 April 2014
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2014, Vol. 33 
