Modeling a Series of Nonaqueous Field-Scale Inhibitor Squeeze Treatments in the Heidrun Field

Abstract

When a conventional aqueous squeeze treatment is not suitable for preventing scale formation, a nonaqueous treatment may be applied. Generally, these types of treatments include a nonaqueous phase and can be divided into different types on the basis of the delivery system. Despite the name, most nonaqueous treatments still contain some water because of the scale-inhibitor (SI) hydrophilic nature; it only truly dissolves in water.The main purposes of this paper are (1) to model a series of polymer nonaqueous SI squeeze treatments deployed in the Heidrun field in the Norwegian sector of the North Sea, (2) to investigate alternatives to optimize the squeeze design by studying the effect of the overflush, and (3) to show the workflow to build the input-data model from the available field data. All the field-treatment designs under study included the injection of an amphiphilic-solvent phase as the SI carrier phase and injection of a diesel overflush.The simulation and optimization calculations were conducted using a specialized near-wellbore model for scale treatments. The simulation study matched the well water cut for the time of the treatment, followed deriving a pseudoadsorption isotherm that was used to describe the SI retention in the formation. Heidrun coreflooding data and SI-returns data were used to build the input model. Finally, a sensitivity study on the effect of the overflush on the squeeze lifetime was carried out on the basis of the created input models.

Oil Field Mineral Scale Control

“…However, at certain low water-cut or water-sensitive wells, the water in the aqueous inhibitor pill may become the source of formation damage. It should be noted that, despite the name, most nonaqueous inhibitor compositions still contain water due to the hydrophilic nature of scale inhibitors [45]. Aqueous solutions may also alter the formation rock wettability and sometimes this could result in opening up of a water channel into a water pocket (water coning) and irreversibly damage the well.…”

“…The developed model considers the immiscible displacement of oil and water phases along with inhibitor transport in both phases and mass transfer between phases. In another effort [45], these authors modeled a series of polymeric nonaqueous scale inhibitor squeeze treatments deployed in North Sea to optimize the squeeze design by studying the effect of the overflush. These authors validated the model by comparison with analytical solutions, standard conventional single-phase squeeze calculations, and multiphase reservoir simulation calculations.…”