Rheology and molecular structure of HPG gels
Hydroxypropyl guar (HPG) polymer solutions crosslinked with titanates (Ti) are used in hydraulic fracturing operations. The rheology of these gels arise from the complex interaction of polymer chemistry, metal ion chemistry, and flow history. The authors have employed several techniques (steady shear viscosity, dynamic oscillatory shear, Laser Doppler Anemometry, and freeze fracture electron microscopy) to develop a consistent picture of the factors controlling gel rheology. An impingement mixing technique has been developed to prepare uniform HPG gels and reproducible rheological data has bee obtained. Dynamic oscillatory rheological measurements have been used as diagnostic probes of gel structure, and are shown to be useful in understanding chemical effects on gel structure. Laser Doppler Anemometry, a non-invasive technique for measuring velocity distributions, has been used to measure velocity profiles for gels under flow. Classical wall slip is not observed, rather distortions of the velocity profiles are observed for gels that have gelled under quiescent conditions. For gels made with impingement mixing linear velocity profiles are observed. Freeze fracture electron microscopy has been used to image gel structure and the results show the fracture of gel structure by shear. These observations demonstrate the mechaism of temperature stabilization of the viscosity of cross-linked gels. Temperature stability measurements of gel viscosity have been made using a novel reciprocating capillary viscometer.
- Research Organization:
- Princeton Univ.
- OSTI ID:
- 7075876
- Report Number(s):
- CONF-861080-
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020300* -- Petroleum-- Drilling & Production
ALKYL RADICALS
ANEMOMETERS
CHEMICAL COMPOSITION
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COLLOIDS
COMMINUTION
CROSS-LINKING
DISPERSIONS
DOPPLER EFFECT
ELECTROMAGNETIC RADIATION
ELECTRON MICROSCOPY
ENERGY SOURCES
ENHANCED RECOVERY
FLUIDS
FOSSIL FUELS
FRACTURING
FRACTURING FLUIDS
FUELS
GELS
HYDRAULIC FRACTURING
HYDROXY COMPOUNDS
LASER RADIATION
MEASURING INSTRUMENTS
MICROSCOPY
MIXING
MOLECULAR STRUCTURE
OIL WELLS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PETROLEUM
PHYSICAL PROPERTIES
POLYMERIZATION
POLYMERS
PROPYL RADICALS
RADIATIONS
RADICALS
RECOVERY
RHEOLOGY
SHEAR
STIMULATION
SYNTHESIS
THERMODYNAMIC PROPERTIES
TITANATES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
VISCOSITY
WELL STIMULATION
WELLS