Improved Water-Soluble Polymers for Enhanced Recovery of Oil

Abstract

Abstract Two principal types of polymers have been used extensively for enhanced recovery of crude oil: partially hydrolyzed polyacrylamide (HPAM) and xanthan gum (XG). Because of its lower cost, HPAM is being used in a majority of the field projects when water-soluble polymers are applied. However, HPAM does lose viscosity in brines, particularly when divalent ions are present, and is susceptible to mechanical degradation under high shear conditions. Although many different polymer structures were evaluated in our laboratory tests, the main focus consisted of modifying the structure of HPAM and observing the effects on brine and shear stability. Testing of these analogs provided a systematic correlation of polymer structure with polymer performance so that improved compounds could be developed. Two modified acrylamide polymers were synthesized that show improved performance when compared to HPAM. The main improvement with these modified materials is the higher viscosities generated in salty waters. This paper presents highlights of the laboratory program and conclusions from the polymer synthesis work. Results obtained with the improved polymers are summarized and compared to commercially available products.