“Red” vs. “Green” Scale Inhibitors for Extending Squeeze Life– A Case Study from the North Sea, Norwegian Sector

Over the years environmental legislation has forced changes in the types of scale inhibitor molecule that can be deployed in certain regions of the world.  These regulations have results in change from phosphonate scale inhibitor to polymer based chemistry.  Over the past 10 years significant improvements in inhibitor properties of the so called “Green” scale inhibitors have been made.  For one particular operator the squeeze application of this “green” scale inhibitor resulted in poorer than expected treatment lifetimes and significant operating cost due to the frequency of retreatment.  To overcome the increasing operating cost an evaluation was made of the current treatment chemicals vs. the older more established phosphonate scale inhibitors.  The results for the laboratory evaluation suggested that the older chemistry would extend treatment life and reduce operating cost.  A case was made to the legislative authority and field applications started.  The squeeze lifetimes for the “red” phosphonate chemistry were shown to be better than the “green” inhibitors.  This paper will present the laboratory evaluation of the scale inhibitors, present the rational for the change back to phosphonate scale inhibitors and present field results form the 2 wells so far treated to demonstrate the extension in treatment life.