Mechanical behaviour of a porous chalk and water/chalk interaction part 1: Experimental study

This paper is the first part of a general work on the mechanical behaviour of a porous chalk and the effect of saturating fluid. It presents an experimental investigation of the behaviour of a porous chalk by taking into account the effects of saturating fluid. Two representative fluids are concerned: a wetting fluid (water) and a non-wetting fluid (oil). The laboratory-testing program includes two topics. At first, conventional hydrostatic and triaxial compression tests are carried out on samples, which are respectively saturated with water and oil. The sensitivity of chalk behaviour to saturating fluid is clearly shown. Secondly, specific water injection tests are conducted in which water is injected in chalk, samples initially saturated by oil, under different hydrostatic and deviatoric stress conditions. A water induced plastic deformation is observed.