Abstract
Harnessing energy from natural gas has become critical in today's energy mix. Natural gas is considered a clean source of energy and plays a key role in supporting local and domestic energy demands. Extraction of these resources, often from tight reservoirs, was made possible with fracking technologies that require utilization of high volumes of fresh water. In light of the regional effort to alleviate burden on lacking freshwater resources and achieve sustainability, this paper captures a successful implementation of waste water re-use for fracturing operations.
A new zirconium-crosslinked, polysaccharide-based fracturing fluid system was formulated using waste water from industrial sources, i.e. evaporation water ponds associated with natural gas processing plants. The fracturing fluid was formulated in the lab using waste water samples and had undergone field demonstration using a stabilizing package that controls shear stability of the fracturing fluid through the zirconium crosslinker reaction kinetics. The core flooding and rheological characterization, comprising of shear resilience and shear recovery capabilities of the new fracturing fluid, are demonstrated through various shear history profiling experiments.
At a constant temperature of 300°F and under various shear profiles, the fluid succeeded in maintaining a viscosity above 300 cp for 2 hours. A proppant suspension test succeeded in showing excellent proppant suspension capability at elevated temperatures. Additionally, the core flooding experiments using delayed breaker chemistries yielded excellent regain permeability results (86% regain permeability), showcasing high cleanup potential of the new fracturing fluid.
The fluid was then successfully deployed in the field, treating two stages in carbonate formation. The post treatment results from deploying this in-house fracking fluid recipe while re-using waste water showed an excellent flowback and stable commercial gas rates with no indication of reservoir damage. Around 3,000 barrels of ground water was safely replaced using this source of water, successfully stimulating a tight formation with acid fracturing.
This technology proves the viability of waste water re-use in petroleum upstream operations. It enables water-use sustainability, groundwater conservation and supports circular water economy. This work can potentially pave the way for larger deployment schemes across wider different upstream operations that can further maximize value of existing water assets, that previously were largely discharged.
