Abstract
Steam EOR pilot project has been deployed in heavy oil field of Petroleum Development Oman, South Operation, and interestingly after more than a year operation, recently failed due to convection tubes ruptured at "Once Through" steam generator facility. It was found that more than 10 tubes have been affected. When the facility inspection deployed, more than 10 Kg unknown grayish color loose solid has been found in the internals part of the tubes. The quick preliminary interpretation narrowed to inorganic scale due to high hardness in the soft water that feeding to the generator, but later, after conducted comprehensive Root Cause Analysis (RCA) study showed that a mix of H2S and Oxygen played as important roles in the damage, where in common systems, the presence of H2S and O2 are eliminating each others and very rare they are exist as one in a close loop systems. This paper pointing about Root Cause Analysis and understanding of Failure Mechanism through some detail damage study and integrated reservoir - process review analysis are able to achieve the objective to secure long term facility integrity and steam supply. After doing a comprehensive surveillance program and applying sophisticated XRF/XRD techniques, showed predominantly solids are Iron products, such as Iron Oxide and Sulfide. Both SRB and GAB Bacteria as the sources of H2S growth from the water supply wells, while the Oxygen are heavily ingress inside the RO Plant and soft water tank facilities. Finally, after injecting a proper biocide and oxygen scavenger and optimize the dosage, the problems have been mitigated successfully.
