Software tools for designing downhole scale inhibitor (SI) squeeze treatments are widely available and have been successfully applied in thousands of wells worldwide. Many SPE papers have been published describing such squeeze design case studies from the conceptual modelled design, to implementation and post treatment analysis. These models are based on the fundamental transport equations for the SI in the near well formation. These equations must also include a model describing the SI/rock interaction, regardless of whether it occurs by an adsorption/desorption or by a precipitation (phase separation) mechanism. A number of papers have appeared in the literature on these fundamental equations and on the analytical and numerical models based on them.
In this paper, we present a re-evaluation of the equations that have been proposed to model SI transport and adsorption in porous media. We have analysed the various approaches in terms of two basic aspects: (a) the mathematical structure of the various equations used to describe transport; and (b) the surface chemistry assumptions and models used to describe the SI/rock retention mechanism, particularly by adsorption. We specifically focus on comparing and reconciling our own (Heriot-Watt U. and Halliburton) respective approaches, which have been developed over the last few years.