Xanthan gum has been used extensively as a viscosifier in theoil industry for different applications due to its uniquerheological properties. In this paper we introduce two biopolymersfor use in drilling, drill-in, completions, spacer fluidsand coiled tubing applications. The first bio-polymer yieldshigher viscosities and better temperature stability at lowerpolymer concentrations that welan and xanthan gum due to itshigher molecular weight; this polymer is particularly effectivein low salt fluids. The second bio-polymer has improvedsolubility in high density CaCl2 brines.Viscosity data over a wide shear rate range is presentedcomparing the new bio-polymers with xanthan and welan gumat temperatures between 75oF to 300oF. Viscoelasticmeasurement and settling test are presented to demonstrate theeffect of elasticity of the bio-polymers on solids transport andsuspension capabilities. Fluid-loss, formation damage testsand friction pressure tests in coiled tubing are also shown.
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