Abstract

The Minas Field is located approximately 35 kilometers north of Pekanbaru in the Riau Province of Sumatra. The field is composed of some 466 production wells and 90 water injection wells in a peripheral pressure maintenance waterflood. Before 1980 production was treated through 150 small gathering stations. Calcium carbonate scaling occurred in many wells and production lines. Chemical treatment was a phosphonate scale inhibitor. In 1980 six large gathering stations were built to enable the use of produced water for injection and make the oil/water separation more efficient. Production line failures due to internal corrosion started to occur late in 1983, and a filming amine corrosion inhibitor was started in 1984.

Analysis of the system indicated that the corrosion was caused by the higher production line carbon dioxide pressure as the result of piping into the larger gathering stations. Most of the lines showed pressures above 150 psig, whereas the pressure rarely exceeded 75 psig when the smaller stations were used. Some of the smaller stations were still being used as individual well test stations at pressures lower than 75 psig and had to be protected from scale build up. Combination corrosion and scale inhibitors were tested to decrease the number of injection points in the field and to make the treatment more cost-effective. This paper presents a review of the background of the concept, chemical development, and field testing of several chemicals.