Evaluation of alkaline-polymer formulations in Minnelusa reservoirs

Approximately 95% of the world s oil production is obtained by primary and secondary recovery methods, producing an average recovery factor of 35%. This recovery percentage indicates that a significant fraction of the original oil in place (OOIP) remains stranded in the reservoirs, which is the reason that methods and techniques have been developed to increase recovery. Enhanced Oil Recovery (EOR) operations have been increasingly applied as secondary and tertiary recovery methods. A number of chemical flooding alternatives are currently being evaluated and involve combinations of alkaline components, surfactants and polymers. Two of the more effective EOR techniques in clastics reservoirs applied today include the use of alkaline-polymer (AP) or alkaline-surfactant-polymer (ASP) flooding.;Research work presented in this thesis includes laboratory results from a general Alkaline-Polymer blend design tailored to Minnelusa formation conditions to increase oil recovery in this reservoir type.;A series of bottle laboratory tests were conducted, simulating Minnelusa reservoir conditions, with the purpose of evaluating fluid --- fluid and fluid --- rock compatibility to alkaline solutions, polymer solutions, and/or an AP blend. A linear coreflood test using Berea Sandstone core was also completed with the optimal AP blend formulation determined previously.;Three alkalis, Sodium Hydroxide (NaOH), Sodium Carbonate (Na2CO 3) and Sodium Metaborate (NaBO2 xH2O, typically 4H2O/mole NaBO2), an organic alkali, were evaluated in this study. Sodium Metaborate was included to determine organic alkali behaviors during a chemical flooding process. Four partially hydrolyzed polyacrylamides (HPAM), provided by SNF Floerger and containing varying molecular weights and 28% degree of hydrolysis, were evaluated.;During research, it was determined that Minnelusa synthetic brine was unsuitable for preparation of chemical blends with the proposed alkalis. Attempts to use this brine often led to the formation of mineral precipitates or poor dissolution of chemicals. Instead, alkalis and polymers were dissolved in low salinity NaCl brine that proved compatible with the chemicals at reservoir conditions.;The laboratory screening was based on interfacial tension (IFT) measurements, polymer rheological evaluation and consumption determinations of the alkaline and polymer solutions with Minnelusa and Berea Sandstone rock samples. Experimental results indicated that sodium hydroxide (NaOH) was the best interfacial tension reducer of the three alkalis. Additionally, polymers and alkalis exhibited smaller losses in concentration when the AP blend was evaluated with rock rather than without.