Abstract
This paper describes results from both experimental core flooding and modeling studies comparing the performance of aqueous and non-aqueous scale inhibitor (SI) treatments. Four detailed core floods have been conducted in outcrop Clashach sandstone cores. One pair of floods was performed using a simple ethylene glycol (EG) based non-aqueous SI system along with the same SI applied as a conventional aqueous treatment. The second pair of core floods used a phosphonate SI which was applied both as a commercial “oil soluble” package and as an aqueous system. Core floods are performed in a manner that allows direct comparison between them in that they have very similar flooding cycles, phase injection sequences, postflush volumes etc. In particular, we have compared scale inhibitor return profiles and possible formation damage in terms flowback oil permeability.
A two phase model for non-aqueous SI treatment including transport, inter-phase partitioning and adsorption has been applied to understand the main treatment and early posflush results for the simpler non aqueous (EG based) core flood. The good match obtained by the model in this region allows us to satisfactorily interpret the mechanisms operating in this flood. Work on modeling the more complex commercial oil soluble SI is still in progress and will be reported at a later time.
