# Dr. Anthony Pearson

J R A Pearson's current research interests are all connected with oilfield problems involving flow in porous media.

### Research

- The specification of rheological equations of state for worm-like surfactant fluids, and their detailed parametrisation by comparison with observed flow behaviour. This involves the use of stress measurements on "controlled" flows in rheometers as well as velocimetry measurements for "uncontrolled" flows in more complex geometries. The application sought is to simulation of flow of these fluids in network models for real porous media (reservoir rocks), from which Darcy-scale continuum models models can be derived.
- Phase separation, such as shear banding, in systems with a shear stress "maximum" in uniform steady simple shear flow. This in turn has led to a consideration of mass transfer in non-uniform flow fields, whereby the surfactant, and hence micelle concentration, becomes a function of the deformation rate in a complex flow field. Surprisingly, experimental observations have demonstrated large concentration variations in flow patterns typical of real reservoir flows.
- Comparison of models for dispersion in porous-media flows of multi-phase and complex fluids. The simplest model, and the one currently favoured in reservoir simulation, is a simple diffusive one where the diffusion coefficient is a second rank tensor multiplied by the Darcy viscosity, i.e. linearly proportional to the local Peclet number. However experiments at all scales in real rock flows suggest that diffusion is always "anomalous", and depends on Peclet number in a more elaborate analytical fashion.