Evaluation of highly viscous polymeric fluids and recrosslinked degraded gel

”This work presents the evaluations of two products. One can be used for hydraulic fracturing to achieve viscosity stable under high shear rate, and the other is potential to be applied to enhance oil recovery from mature oilfield. The first experiment is to synthesize and evaluate a new polymeric fracturing fluid that can resist high shear rate of 511-1 with favorable viscosity. Zirconium crosslinked fracturing fluids are lack of self-healing ability after shearing, and the difficulties still exist in maintaining viscous with lower polymer content exposed to high shearing conditions, therefore, the research is trying to develop a new product to fix the problem. As a result, optimal formulation of polymer and crosslinker is obtained, and the impacting factors to viscosity improvement are discovered specifically. Experiment shows that sample with a polymer concentration at 5 gpt can stay viscous greater than 10 mPa S after 3 mins shearing. The result is encouraging and the product is potential to be used in oilfield application by further optimization. The second evaluation is to characterize the interactions and impacting factors of degraded gel in recrosslinking process. Reusing the degraded gel from producing water is in sake of reducing the cost. The research is expected to get strong gels with a cost-effective manner. Experiments were conducted towards clay optimization, degraded gel selection, thermos-stability and other parameters that influence gel performance. Polymer concentration at a range of 0.5 wt% to 0.7 wt% can bring the recrosslinked gel with both better elastic and rigid properties, with proper additives of clay and crosslinker”--Abstract, page iv