When a conventional aqueous squeeze treatment is not suitable for preventing scale formation, a non-aqueous treatment may be applied. Generally, this type of treatments includes a non-aqueous phase and can be divided into different types based on the delivery system. Despite the name, most non-aqueous treatments still contain some water, due to the scale inhibitor hydrophilic nature; it only truly dissolves in water.
The main purposes of this paper are, firstly to model a series of polymer non-aqueous scale inhibitor, SI, squeeze treatments deployed in the Heidrun field in the Norwegian sector of the North Sea. Secondly, investigate alternatives to optimize the squeeze design by studying the effect of the overflush. And finally, show the workflow to build the input data model from the available field data. All the field treatments designs under study included the injection of an amphiphilic solvent phase as the scale inhibitor carrier phase and a diesel overflush.
The simulation and optimization calculations were done using a specialized near wellbore model for scale treatments. The simulation study consisted in matching the well water cut for the time of the treatment, followed by the derivation of a pseudo adsorption isotherm, which was used to describe the SI retention in the formation. Heidrun core flooding data and SI return data were used to build the input model. Finally, based on the created input models, a sensitivity study on the effect of the overflush on the squeeze lifetime was carried out.