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Understanding Two-Phase Flow in Clay-Rich Formations: from the Molecular Scale to the Macroscopic Scale and beyond

Jougnot, Damien 1; Jardani, Abderrahim `.2; Revil, Andre 2; Ghorbani, Ahmad 3; Lu, Ning 4
1 ANDRA, Chatenay Malabry, France.
2 Geophysics, Colorado School of Mines, Golden, CO.
3 UMR Sisyphe, University Paris VI, Paris, France.
4 Civil Engineering, Colorado School of Mines, Golden, CO.

The hydro-mechanical behavior of clay-rich formations in multi-phase flow conditions is a very important challenge for gas production efficiency development in tight gas reservoirs and storage of wastes in the vadose zone. We have developed a model of transport of ions and fluids in clay-rich material. At the molecular scale, this model accounts for the electrochemical interactions at the solid / water interface (we have developed a new Triple Layer Model that is valid for any type of clay minerals). The local transport equations are upscaled by using a volume averaging of the local scale constitutive transport equations (stokes and Nernst-Planck). Two key parameters control the textural effect upon the transport properties. They are the formation factor (corrected for surface conductivity) and the permeability. Then, we have extended this model to multiphase flow. This approach is combined with a rheological model. This model is tested for a set of experiments where we look at the transport and electrical properties of various clay-rock samples in drying conditions. The clay-rock samples are confined in a hermetic chamber with a relative humidity control system. The drying is monitored by weight and electrical measurements (self-potential and spectral induced polarization) are performed at different relative humidities. The crucial parameters for multiphase flow transport, such as intrinsic and relative permeability, are then inverted from these experimental measurements by using a stochastic approach.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009