A Field And Laboratory Study Of Polysaccharides In Fracturing Treatments

With the increased use of polysaccharides in fracturing treatments, subsequent problems have been encountered with inadequate polymer hydration, weak or over crosslinked fluid, formation of fish eyes, low viscosity and uncontrolled breakout. Problems have also occurred due to inadvertent contamination from water supplies and fracturing tanks. In field studies of the Lost Hills and South Belridge areas in Kern County, Calif., field conditions and operational procedures were found to constitute critical factors in successful dispersion and in ideal cross-linking of polysaccharides. A comparison of field fluids with laboratory fluids was conducted with special emphasis on the quality of field water and on the effects of pH and temperature on the viscosity and sand fall rate. Laboratory tests indicate that fluid mixed in the field can exhibit a more effective cross-linking structure, a more stable viscosity strength and a lower sand fall rate if more control is exercised in the determination of pH range, in the selection of buffers and in the choice of treating water. Attention to these factors, as pointed out in this paper, can reduce lost time, save expense and increase well performance.