Insitu Processes Chemical EOR landscape

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Thursday 24th of January 2013 6:33 PM

In chemical EOR or chemical flooding, the primary goal is to recover more oil by either one or a combination of the following processes: (1) Mobility control by adding polymers to reduce the mobility of the injected water, and (2) Interfacial tension (IFT) reduction by using surfactants, and/or alkalis. The number of active chemical EOR projects peaked in 1986 with polymer flooding as the most important method. However, since 1990’s, oil production from chemical EOR methods has been negligible around the world except for China. Polymer flooding is an established and mature technology. There are ongoing pilots or large-scale polymer floods in Argentina (El Tordillo Field), Canada (Pelican Lake), China with approximately 20 projects (e.g., Daqing, Gudao, Gudong and Karamay fields, among others), India (Jhalora Field) and the U.S. (North Burbank, Oklahoma). Other reported polymer flooding projects include Brazilian Carmópolis, Buracica and Canto do Amaro fields. India also reports a polymer flood in Sanand Field. Oman also documented a polymer flood pilot developed in Marmul Field and almost twenty years later a large-scale application is under way. Additionally, Argentina (El Tordillo Field), Brazil (Voador offshore Field), Canada (Horsefly Lake Field) and Germany (Bochstedt Field) announced plans to implement polymer flood projects. Listed ongoing and planned polymer floods provide a representative sample of field experiences that validates EOR potential of this recovery process. While polymer flooding has been the most applied EOR chemical method in sandstone reservoirs, the injection of alkali, surfactant, alkali-polymer (AP), surfactant-polymer (SP) and Alkali-Surfactant-Polymer (ASP) have been tested in a limited number of fields. Micellar polymer flooding had been the second most used EOR chemical method in light and medium crude oil reservoirs until the early 1990’s. Although this recovery method was considered a promising EOR process since the 1970’s, the high concentrations and cost of surfactants and co-surfactants, combined with the low oil prices during mid 1980’s limited its use. The development of the ASP technology since mid 1980’s and the development of the surfactant chemistry have brought up a renewed attention for chemical floods in recent years, especially to boost oil production in mature and waterflooded fields. At the present time Daqing Field represents one of the largest, if not the largest, ASP flood implemented as of today. ASP flooding has been studied and tested in Daqing for more than 15 years through several pilots of different scales. Gudong, Karamay, Liahoe and Shengli fields are other examples of Chinese ASP projects documented in the literature. Reportedly, there are ongoing and planned ASP pilots in other countries. Chemical EOR faces significant challenges, especially in light oil reservoirs. One of the reasons is the availability, or lack of, compatible chemicals for high temperature and high salinity environments. R&D will play a critical role in the future of chemical EOR.