Qualification and Field Injection of Scleroglucan

The application of EOR-grade scleroglucan for polymer flooding and enhanced oil recovery is an attractive opportunity for previously intractable high salinity and high temperature reservoir conditions. Scleroglucan has been demonstrated to be resistant to high shear, high temperature, and high salinity including divalent ions. It has also been shown to be insensitive to chemical additives and chemicals that naturally occur in oilfields such as biocides, hydrogen sulphide and iron species. From an application testing perspective, scleroglucan shows extremely interesting and advantageous shear thinning behaviour that is replicated in coreflood injectivity results. To further prepare the technology for field applications, laboratory qualification and establishing field injection readiness of scleroglucan for use in a targeted high temperature reservoir were undertaken. Tests of chemical and rheological properties of scleroglucan were used to determine the polymer’s compatibility with field relevant chemicals including topside biocides, formation water, and other additives that may be used in the field. Functionality of the polymer under specific targeted field conditions in the presence of those chemicals was assessed by measuring viscosity over time upon exposure of the polymer to those chemicals at high temperature. In parallel, our skid mounted standalone polymer make-down and injection system, which features a high-shear, on-the-fly hydration system, has been undergoing continuous development. The focus on further development of the skid mounted polymer make-down and injection system has been to expedite field-ready applications of injection quality hydrated dry polymer using scleroglucan manufactured at increased scale within our production facility and learnings will be discussed. Studies focused on assessment of both the microbiological risks to the polymer and the options for mitigation with biocide treatment at the target field were included in the preparations. Finally, the planning, execution, and results of a recent short-term field injectivity test in the Adena oilfield in Colorado is presented. The results showed the high quality of the prepared scleroglucan and successful injection into a well with no apparent wellbore plugging challenges. Further long-term mini-interwell pilot preparation is underway and will be implemented in the near future.