The Eunice Monument South Unit (EMSU) has historically experienced barium sulfate scale deposits in many producing oil wells prior to field unitization and initiation of the present waterflood. This problem was exacerbated with the waterflood due to incompatibility of the supply water and the water in the reservoir. Scale inhibitor treatments are used to control the barium sulfate scale deposition where water analyses indicate treatments are needed. Geological mapping techniques are used to show the wells with barium sulfate scaling tendencies. Maps are updated on an annual basis using current water analysis data from each well in the waterflood unit. KEYWORDS : scale, barite, scale inhibitor, geological mapping, waterflood, incompatibility, scale prediction index, barium sulfate, scale squeeze treating, San Andres, Permian Basin, Penrose, and Grayburg