The development and evaluation of polymers for enhanced oil recovery
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The main purpose of this research was to develop, test and evaluate polymers for enhanced oil recovery. Commercially available hydrolyzed polymacrylamide polymers were characterized in filtration tests and corefloods. Scleroglucan biopolymers were studied and developed as an alternative to synthetic polymers for enhanced oil recovery Strategies for preparing filterable solutions of scleroglucan were tested on Cargill CS-11 scleroglucan. As a result, an improved method was developed and the transport behavior of the filterable solution was characterized in corefloods without the presence of oil. Experiments showed that although the improved pH-treatment method produced solutions with excellent filtration ratios, the solution did not transport well through Bentheimer cores. A new prototype EOR-grade liquid scleroglucan sample, AD-10, was provided by Cargill. Filtration results were good and the AD-10 showed excellent viscosifying power in harsh conditions of high salinity, high hardness, and elevated temperature. Solutions of the AD-10 were tested in coreflood without oil through Bentheimer and Berea sandstones at room temperature and one coreflood at 100 °C. Polymer retention was lower at higher temperature for cores of similar permeability. Shear correction factors of 1.3-1.6 were determined for AD-10 scleroglucan solutions through sandstone at 25 °C. BASF Aspiro™ hydrolyzed polyacrylamide polymers, 4211x, 4261x, 4231, 4251, were tested for filterability. The higher the molecular weight of the HPAM polymer, the less consistently the polymer could be prepared to pass filtration tests. The Aspiro 4211x and 4261x polymers were tested in subsequent corefloods without the presence of oil through Bentheimer sandstones. Shear correction factors of 2.1 were determined for solutions of Aspiro 4211x and 4261x through Bentheimer sandstones at 25 °C. Polymer flood oil recovery experiments were performed with Hengju Hengfloc 63026 hydrolyzed polyacrylamide (HPAM) through reservoir sandpacks, as part of a blind study with other HPAM polymers.