Injecting water, whether for disposal or for water flooding requires removal of solids and produced oil to some specified level. In general, the cleaner the water, the less pump power required, the greater the oil sweep and the higher the ultimate recovery. Often however, the quality requirements (oil and solids concentration and size distribution) and the benefit in terms of incremental hydrocarbon cannot be predicted with accuracy. Further, oil drops and solids particles can become combined in ways that produce suspensions of high viscosity sticky conglomerate material. The properties of such conglomerate vary significantly with the properties and composition of the oil and solids. The reservoir plugging tendency varies widely as well. Therefore facilities design requires built-in flexibility. Flexibility requires technical understanding and careful analysis in order to reduce costs. Oman is a mature water flooding region where many of the issues described have been encountered and dealt with in one fashion or another. The session will discuss both the problems solved and the remaining challenges in water treating for waterflooding.
Steam flooding, including SAGD, like other enhanced recovery processes requires large volumes of water. In most locations of the world, water for such activity is scarce and produced water must be used to generate steam. Generating steam from produced water has several challenges. First, oil must be reduced to low levels in order to prevent fouling of the desalination equipment. Second, desalination in one form or another must be applied. There are several options for desalination ranging from warm lime softening to industrial evaporation systems. Selecting the appropriate technology is critical as the cost of the water treating equipment can be as high as 30% of the overall project cost. In Oman, several steam projects are underway with a variety of approaches. The various approaches will be discussed from a project concept standpoint. Operational experience will be discussed for the various technologies.
Polymer flooding and ASP have the very strong incentive of high ultimate recovery of oil. From a water treating standpoint, the chemicals used and the properties of the back flow water could not be much worse. In the case of polymer, oil drop size, and oil concentration of the produced water are typically higher than conventional. The high viscosity of the produced water reduces the effectiveness of all gravity and enhanced gravity (hydrocyclone) operations. Also, the shear thinning property of the typical polymer containing produced water causes gas bubbles to form jets which diminish the effectiveness of conventional flotation technology. In the case of ASP back flow fluids the situation is even worse due to low surface tension. In Oman, the Marmul polymer flood has been in operation for a few years and back produced fluids are now being treated. In this session, design considerations, and operational experience of polymer and ASP will be explored.
In all of the IOR/EOR projects discussed above there is a strong need for fundamental understanding and new technologies to address the challenges. A range of new technologies are needed including new separation technologies, and new chemistries for treating produced water. In this session, new technologies will be discussed which have potential to provide solutions to the many challenges involved in IOR/EOR water treating.