The Schoonebeek heavy oil field was first developed by Nederlandse Aardolie Maatschappij BV (NAM) in the late 1940s. Due to economics, it was abandoned in 1996. In 2008, the Schoonebeek Redevelopment Project, using a gravity assisted steam flood (GASF) design concept, was initiated with 73 wells (44 producers, 25 injectors and 4 observation wells).
Steam injection and cool-down cycles subject a cement sheath to some of the most severe load conditions in the industry. Wellbore thermal modeling predicted surface and production sections would experience temperatures in excess of 285°C [545°F] and considerable stress across weak formations. A key design requirement was long-term integrity of the cement sheath over an expected 25-30 year field life span. Complicating this requirement was the need for lightweight cementing systems, as lost circulation issues were expected in both hole sections, particularly in the mechanically weak Bentheim sandstone.
The long-term integrity challenge was divided into chemical and mechanical elements. Prior research on high-temperature cement performance by the operator provided necessary guidance for this project. Laboratory mechanical and analytical tests were conducted to confirm the high-temperature stability of the chosen design.
In addition to using lightweight components, foaming the slurry allowed the density, mechanical and economic targets to be met. A standardized logistical plan was put in place to allow use of the same base blend for the entire well, adjusted as needed using liquid additives and applying the foaming process when necessary. This single-blend approach greatly simplified bulk-handling logistics, allowing use of dedicated bulk-handling equipment.
The first well was constructed in January 2009; all 73 wells have been successfully cemented to surface. The steaming process, initiated in May 2011, has progressed with no well integrity issues to date.