Content of PetroWiki is intended for personal use only and to supplement, not replace, engineering judgment. SPE disclaims any and all liability for your use of such content. One of several methods involving injecting a chemical into a formation to improve the production of hydrocarbon. May be from an injection well to a production well or injection into a producer with a soak period before recovery.
When conducting a polymer waterflood, a high-molecular-weight and viscosity-enhancing polymer is added to the water of the waterflood to decrease the mobility of the flood water and, as a consequence, improve the sweep efficiency of the waterflood. The primary purpose of adding polymer to most polymer waterfloods is to increase the viscosity of the flood water; however, polymer addition to the flood water in many instances also imparts a secondary permeability-reduction component. Polymer waterflooding is normally applied when the waterflood mobility ratio is high or the heterogeneity of the reservoir is high. Figure 1 shows the polymer waterflooding process. The method shown requires a preflush to condition the reservoir, the injection of a polymer solution for mobility control to minimize channeling, and a driving fluid (water) to move the polymer solution and resulting oil bank to production wells. Mobility ratio is improved and flow through more permeable channels is reduced, resulting in increased volumetric sweep. Waterflooding promotes improved sweep efficiency by improving the mobility ratio.
Content of PetroWiki is intended for personal use only and to supplement, not replace, engineering judgment. SPE disclaims any and all liability for your use of such content. The carbon dioxide gas is injected and alternated with water. CO2 lowers the viscosity of most oils, but may trigger severe asphaltene and scale precipitates.
Although conformance-improvement gel treatments have existed for a number of decades, their widespread use has only begun to emerge. Early oilfield gels tended to be stable and function well during testing and evaluation in the laboratory, but failed to be stable and to function downhole as intended because they lacked robust chemistries. Also, because of a lack of modern technology, many reservoir and flooding conformance problems were not understood, correctly depicted, or properly diagnosed. In addition, numerous individuals and organizations tended to make excessive claims about what early oilfield gel technologies could and would do. The success rate of these gel treatments was low and conducting such treatments was considered high risk. As a result, conformance-improvement gel technologies developed a somewhat bad reputation in the industry. Only recently has this reputation begun to improve. The information presented in this chapter can help petroleum engineers evaluate oilfield conformance gels and their field application on the basis of well-founded-scientific, sound-engineering, and field-performance merits.
Early application of polymers for use during oilfield conformance improvement operations was focused on improving volumetric sweep efficiency of waterfloods. More recently, polymers have been used extensively in disproportionate permeability reduction (DPR) and relative permeability modification (RPM) treatments for water shutoff and in conformance improvement polymer-gel treatments. This page discusses polymers used in oilfield operations and how they contribute to conformance improvement. Polymer molecules are the resultant chemical specie when a large number of relatively small and repeating molecular entities, called monomers, are joined together chemically. The chemical process of joining together the monomers and forming polymer molecules is referred to as the polymerization reaction process.
This page provides a brief review of illustrative field applications of polymer waterflooding as reported in the literature. In 1983, Manning et al. published a comprehensive and classic summary of the field results and performance of more than 250 polymer waterflooding projects and provided information relating to the early field applications of polymer waterflooding. Figure 1 shows the incremental oil production response for the North Burbank polymer flood. A polymer waterflooding project that involved a large full-field flooding project at the North Oregon Basin field in Wyoming's mature Big Horn Basin oil-producing area was reported in 1986 to be producing 2,550 BOPD of incremental oil production. It was reported that this polymer flooding project would recover ultimately more than 10 million bbl of incremental reserves from the mature North Oregon Basin field. The field project involved the flooding of both a fractured carbonate formation and a fractured sandstone formation with a polymer flood using partially hydrolyzed polyacrylamide(HPAM).
This page provides a reservoir management case study for a sandstone field in which polymer injection techniques have been implemented. Production is from three sandstone zones of a Cretaceous-age formation. Productive area of the polymer project was 3,560 acres. Gross thickness was 230 ft, and net-to-gross thickness averaged 0.3.