Chemical stability limits of water-soluble polymers used in oil recovery processes
This work describes long-term thermal stability limits of water-soluble polymers under anaerobic conditions. Polymers investigated included polyacrylamide, xanthan, scleroglucan, cellulose sulfate, and a heteropolysaccharide of unknown structure. The primary mechanism of polyacrylamide degradation was found to be amide group hydrolysis. Interaction between hydrolyzed polyacrylamide and divalent metal ions present in solution caused significant losses in solution viscosity, and phase separation ultimately occurred in extreme conditions of high degrees of hydrolysis or high concentrations of divalent ions. The rate of hydrolysis was found to depend mostly on temperature. At 50/sup 0/C (122/sup 0/F), the rate was quite slow and polyacrylamide solutions were stable for many months, even in the presence of high concentrations of divalent ions. At 60 to 70/sup 0/C (140 to 158/sup 0/F), the rate of hydrolysis was moderate and the rate of viscosity loss depended on the precise temperature and divalent ion concentration. At 90/sup 0/C (194/sup 0/F), hydrolysis was rapid and polyacrylamide solutions were stable to precipitation only when the divalent ion concentration was less than about 200 ppm. When the divalent ion concentration was zero, solution viscosity increased because of a further expansion of the polyelectrolyte coil. The stability of xanthan was determined primarily by temperature and was independent of divalent ions. Although performance varies from xanthan to xanthan, the useful limit was generally found to be <70/sup 0/C (<158/sup 0/F). Viscosity retention was also found to be extremely shear-rate dependent. Other naturally occurring polymers exhibited variable performance. In alkaline brines, polyacrylamides were stable up to 90/sup 0/C (194/sup 0/F) for long periods of time, whereas xanthan was degraded at >50/sup 0/C (>122/sup 0/F).al
- Research Organization:
- American Cynamid Co. (US)
- OSTI ID:
- 5287759
- Journal Information:
- SPE (Society of Petroleum Engineers) Reserv. Eng.; (United States), Vol. 3:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DISPLACEMENT FLUIDS
CHEMICAL COMPOSITION
CHEMICAL PROPERTIES
STABILITY
OIL WELLS
WATERFLOODING
AMIDES
CELLULOSE
ENHANCED RECOVERY
GLUTIN
HYDROLYSIS
MEDIUM TEMPERATURE
PETROLEUM
PHASE STUDIES
POLYACRYLATES
POLYMERS
POLYSACCHARIDES
SULFATES
WELL STIMULATION
XANTHUM GUM
CARBOHYDRATES
CHEMICAL REACTIONS
DECOMPOSITION
ENERGY SOURCES
ESTERS
FLUID INJECTION
FLUIDS
FOSSIL FUELS
FUELS
LYSIS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC POLYMERS
OXYGEN COMPOUNDS
POLYVINYLS
PROTEINS
RECOVERY
SACCHARIDES
SCLEROPROTEINS
SOLVOLYSIS
STIMULATION
SULFUR COMPOUNDS
WELLS
020300* - Petroleum- Drilling & Production