ROOT CAUSE FAILURE ANALYSIS, REMOVAL AND MITIGATION OF IRON SULFIDE SCALE DEPOSITION IN THE BP BRUCE PRODUCED WATER REINJECTION PLANT

摘要

Significant solids were found in the BP operated Bruce produced water reinjection (PWRI) pipework during routine intrusive work. The 6" discharge pipework was 50% choked and the suction pipework 30% choked. Analysis later confirmed this scale to be mostly mackinawite (FeS0.93-0.96) with minor amounts of siderite (FeCO_3) and strontium bearing barite (Ba(Sr)SO_4). Approximately 1.8 mT was removed from one 40 meter run of pipework.The root cause of scale deposition was the alkaline H_2S scavenger. A combined treatment of jetting and online dissolver was used to solve this problem. Treatment implementation was complicated by the complex nature of the plant and tie backs, and thus had to be closely managed and monitored. A novel iron chelating agent injected at a few hundred mg/1 was used to dissolve remaining scale. Discovery of the scale, and the rapid treatment and removal program saved the PWRI plant from total blockage and shut down.