عنوان مقاله [English]
This paper describes an experimental device which is used for determining radial permeability of rocks around well bore hole according to effective stress.
Permeability of rocks is a very important characteristic because it controls the flow of fluid.
Laboratory tests on thick-walled hollow cylinders of rock are relatively easy, economical and realistic means to understand better the mechanisms associated with wellbore failure.
The experimental device used to carry out tests on thick-walled hollow cylinders under two distinct conditions which are: 1) Tests without pore fluid 2) Tests with convergent radial flow of pore fluid. Two types of tests were carried out in conditions with pore fluid:
a) Tests under an increasing external pressure and a constant external pore pressure
b) Tests under a constant external pressure and an increasing external pore pressure
The tests were carried out on a very porous artificial material (CPIR09). The mode of rupture observed in the tests was a pair of radial rupture planes. The results obtained show that when the external pore pressure is constant the global permeability decreases with increasing external pressure. When the external pore pressure increases the convergent radial flow of pore fluid (due to the imposed pore pressure) slightly increased the global permeability samples. The convergent radial flow of pore fluid acts to remove fractured materials and to erode localization bands, therefore, the global permeability samples brutally increased.