This paper analyzes the pore pressure transmission test within the framework of the Biot theory of poroelasticity, extended to include physicochemical interactions. The main outcome of this laboratory experiment, which is aimed at quantifying the osmotic properties of a chemically sensitive shale in contact with a water-based fluid, is the membrane efficiency. On the basis of a mathematical model of the test, we show that under certain conditions there is equivalence between the membrane efficiency and the reflection coefficient R, a transport parameter that quantifies the departure of the shale from an ideal osmotic membrane. Under these conditions, which hinge on the existence of an intermediate time asymptotic solution linked to a separation of time scales, the membrane efficiency is virtually independent of the specific experimental setup. We also report the results of several pore pressure transmission tests on Pierre II shale, as well as the identification of some chemoporoelastic parameters from these experiments.
|Original language||English (US)|
|Number of pages||14|
|Journal||International Journal of Rock Mechanics and Mining Sciences|
|State||Published - Jul 2011|
Bibliographical noteFunding Information:
Partial support for this research has been provided by TOTAL , France and by CSIRO , Australia. This support is gratefully acknowledged. The authors would like to thank Dr. Philippe Charlez for providing the initial impetus for this research and Dr. Chee Tan for his valuable contribution to the experiments reported in this paper.
- Membrane efficiency
- Osmotic pressure
- Reactive shale
- Reflection coefficient