Degradation of Polymers Used in Geothermal Fracturing

Abstract

Long chain, water soluble polymers have been used for many years in hydraulic fracturing of oil wells. Recently their use has been attempted in geothermal wells. Very little is known about the high temperature degradation of these polymers other than an extreme viscosity drop as the temperature goes to 150°C. This paper describes the development of methods in the laboratory to characterize the degradation at temperatures of 150°C and above. Examined were hydroxyethyl cellulose (HEC) and hyrdoxypropyl guar guam (HP Guar) at 150°, 200° and 250°C. The chemical tests performed on the samples were carbohydrate content, total organize carbon, and molecular weight distribution by high presume liquid chromatography (HPLC). Hopefully, these tests can be used in the future to predict physical properties of fracturing polymers such as viscosity loss and formation plugging.