SAGD Water Treatment
In 2011, OrganoCat was contracted by one of the world’s largest oil companies to work on a project to remove dissolved silica from SAGD process and blowdown water. After successfully completing Phase 1 work on dissolved silica removal, the client agreed to continue Phase 2 work with OrganoCat. The scope of work included further research into the best methods to (1) treat blowdown water with the goal of reducing silica and organics; (2) develop improvements and/or alternatives for warm lime softening based on findings in Phase 1; and (3) characterize the best methods for (1) and (2) in terms of specific process parameters like temperature, settling versus centrifuge, sediment characterization; and process characterization in terms of cost estimates, operability, reagent lead-times and shelf life, required spares and extraordinary factors. Other specific factors were also explored and tested. OrganoCat tested a matrix of electro-physical-mechanical devices and reagents in order to understand the underlying mechanisms of silica, organics and other dissolved minerals, to determine the best methods for their removal, and to characterize the byproducts and processes. In the course of the project, the mechanisms of dissolved silica removal, organic and mineral carbon removal, and calcium and magnesium removal were understood and documented. It was determined that blowdown water could be treated with one or a combination of two electro-physical-mechanical devices and one inexpensive reagent, resulting in an 88.7% reduction in dissolved silica, a 64% reduction in total carbon, a 64.5% reduction in organic carbon and a 53.5% reduction in inorganic carbon. With this blowdown water treatment process, the entire process water stream will be improved, reducing OTSG fouling, improving current WLS efficiency (and reducing the total chemical demand), improving boiler efficiency (even increasing the percentage of water available for boiling), reducing the unusable water that is currently deep-welled, and increasing the total usability of the water stream. The devices are believed to be relatively inexpensive (on the order of a pump of equivalent size), easy to maintain and service, and robust for the operating conditions found in Canada. The reagent is relatively inexpensive with standard lead-times and shelf-life compared to general chemicals. There are no known extraordinary factors at this stage of development.
Although the new technology has great potential for simplifying and improving the current total process and blowdown water treatment processes, OrganoCat recognizes that the current capital investment within typical 20-100K bbl/day SAGD operations is large, and the necessity to leverage the existing infrastructure is preferred. Therefore, it is recommended that the new technology be introduced first into the blowdown water stream as a new and secondary process, thus improving the overall water stream. The full technology could then be designed into future SAGD operations at the beginning stage.
The project is ready for the next phase of testing – pilot scale design and field test.