MACROMOLECULAR SYSTEMS IN HEAT-RESISTANT DRILLING-FLUIDS - ADVANTAGESOF GELS ON LINEAR-POLYMERS

The degradation process of linear water-soluble vinyl polymers was fol lowed in aqueous medium at temperatures higher than 150-degrees-C. We found that, for any chemical structure, thermal oxidative degradation of the longest chains always occurs, leading to moieties of lower mole cular weight (20,000-60,000). The behavior of swollen tridimensionnal networks was tested under the same conditions, and it appeared that rh eological and fluid loss properties of the system could be maintained in that case for an optimum number of crosslinks. The corresponding ge ls were used in simple formulations containing some other drilling flu id components. The first results concerning the thermal stability of t he latter are very encouraging. (C) 1994 John Wiley & Sons, Inc.