Rheological Behavior of Hydrate Slurry with Xanthan Gum and Carboxmethylcellulose under High Shear Rate Conditions

As the development of oil and natural gas reaches deep-water regions, the flow assurance of gas hydrate in deep-water wellbores becomes a serious safety issue for drilling and production. In this work, a series of experiments are conducted to investigate the rheology of hydrate slurry with varied hydrate, xanthan gum (XG), and carboxmethylcellulose (CMC) concentrations. The hydrate slurries with XG and CMC are power law fluids and exhibit obvious shear-thickening behaviors in the relatively high shear rate region, which is from 200 to 750 s –1 . The increase of both XG and CMC concentrations induces the hydrate slurry to exhibit an increased shear-thinning behavior. But the influence of the hydrate concentration on the rheology of hydrate slurry highly depends on the additive type and its concentration. For hydrate slurry with XG, the hydrate concentration has a positive effect on making the hydrate slurry exhibit a shear-thickening behavior. For hydrate slurry with CMC, the hydrate concentration only enhances its shear-thickening behavior at CMC concentrations of 0.2 and 0.3%. The non-Newtonian index and the consistency factor are correlated from experimental data and are functions of the hydrate and additive concentrations. The rheology models of hydrate slurry with XG and CMC are developed based on the power law model, incorporating the correlations of the non-Newtonian index and the consistency factor.