Scale prediction in liquid flow through porous media: A geochemical model for the simulation of CaCO3 deposition at the near-well region

Currently available models of CaCO₃ scale formation during flow in porous media, provide simply a scaling tendency. We present a new tool that proceeds further to predict the distribution of scale precipitation in a one-dimensional porous medium and the consequent pore blocking. The innovative feature of this model is the combination of thermodynamics, kinetics and hydrodynamics for the prediction of scale deposition along and around the production wells. The development of the geochemical model was based on scale reaction calculations attempting to simulate/interpret dynamic tube-scale laboratory experiments. In this work, we present the equation scheme with the basic assumptions employed and some results with relevance to the experimental work. The paper also considers some of the issues associated with the generation and reliability of the laboratory data used in the construction of the geochemical model. The new laboratory scale data have been acquired from a series of sandpack blocking experiments using for the first time a radiotracer technique.