Paper: Sulphate Scale Problems in Producing Wells West Welch (San Andres) Unit a Case History

After five years of waterflooding, the West Welch (San Andres) Unit was experiencing acute production declines caused by calcium sulphate scale forming in the producing wells. A program was initiated at that time to investigate the cause of the scale growth and means of correcting it. The purpose of this paper is to summarize the field and laboratory work done to inhibit and remove CaSO4, scale from the producing wells in this waterflood. Evaluation of scale inhibitors and methods of applying them are covered as well as scale removal chemicals and procedures. In gathering and interpreting data a new use of an old tool, the caliper survey, was initiated with good success. Most of this work has been done in the last 1- 1/2 years and it is not yet considered finished as other questions must be answered for a long term and lasting conclusion.