Abstract
In the North Sea, due to the extensive use of water injection for oil displacement and pressure maintenance, many reservoirs experience the problem of scale deposition when injection water starts to breakthrough. In most cases the scaled-up wells are caused by the formation of sulphate scales of Barium and Strontium. Due to their relative hardness and low solubility, there are limited processes available for their removal and the preventive measure such as the ‘squeeze’ inhibitor treatment has to be taken. It is therefore important to have a proper understanding of the kinetics of scale formation and its detrimental effect on formation damage under both inhibited and uninhibited environment.
In this paper, we will present results of BaSO4 formation kinetics in both beaker tests and in highly reproducible sandpacks which simulates the flow in porous medium. The effect of scale deposition on the dynamics of formation damage will also be discussed. In the studies of BaSO4 crystal growth kinetics and formation damage, we have included both normal formation/injection brine mixture and the addition of scale inhibitor chemical. There are significant differences in the results of static (beaker tests) and dynamics (core flood) conditions, and between the normal and inhibited brine mix.
