Particle sizing of drilling fluid (Correction of the model for suspension flow in porous media)
Zakaria, Nurul, A
Engineering Honours 2008
University of Adelaide
Injection of particulate suspensions in porous media has long been recognized to cause formation damage. This phenomenon is called deep bed filtration. Transport of particle suspensions and colloids in porous media is accompanied by particle capture that causes the formation damage and consequent permeability impairment.
The particles from the drilling or the injected fluids are captured by the rock due to electric forces, straining and diffusion. The current work is dealing with the particle capture by straining mechanism only, where the pores are plugged due to size exclusion of the particle. This work is based on the mathematical model developed by Santos and Bedrikovetsky (2006) and Bedrikovetsky (2008) where the pore accessibility and flux reduction due to inaccessible pore volume have been taken into account in the basic equations.
In order to optimise the particle size in drilling fluid based on particle retention profile in porous media and associated formation damage, we analysed suspension flow in porous media with particle capture by straining. It was found out that the concentration wave must have a travelling wave type. Formulae for travelling wave profiles for equations of suspension flow in porous media with particle capture by straining were derived, and it has been found out that the travelling waves profile do not exist for the traditional mathematical model.
The analysis of the phenomenon shows that two main physics cases need to be considered: attraction and repulsion of particles by rock. Each case requires correction of the traditional model. We derived a micro scale and macro scale systems for the repulsion case and developed a travelling wave model for the case of particle-rock repulsion.