Development of an Oil-Soluble Scale Inhibitor for a Subsea Satellite Field

Abstract

Abstract The formation of oilfield scales is often caused by the mixing of incompatible waters and/or by changing pressure and temperature causing a reduction in the solubility of the dissolved solids in the produced water. To inhibit scale formation chemical inhibitor typically operates by either nucleation inhibition or crystal growth modification, is added to the water. Almost all scale inhibitor chemicals are water soluble and are typically deployed continuously or by squeeze from an aqueous phase. In most circumstances water is the preferred carrier medium since it allows instantaneous mixing and rapid interaction with the scaling ions. However, for treating a water sensitive formation or a well with poor lifting energy, the application of a conventional water based scale inhibitor squeeze may have many drawbacks. These include extended clean up period, increased water saturation in the near wellbore area, cessation of production due to water ingress. Either of these can result in significant loss or deferment in the oil production. In this paper a new range of scale inhibitors which are solubilised in the hydrocarbon phase will be described. These new oil soluble scale inhibitors offer some advantages over the conventional water based products. Furthermore, unlike the oil ‘miscible’ products of the past, these new scale inhibitors do not contain any mutual solvent which sometimes can cause process upset during the backflow after the squeeze treatment. The paper will focus on the development of a product which is specifically designed for a sub-sea satellite field. Due to its unique properties some of the standard test methods and selection processes have to be modified. Special considerations on the treatment design are also needed due to the deployment constraints in the field.