Treatment of shale gas wastewater in the Marcellus : a comparative analysis
This analysis focused primarily on three main treatment methods which were re-use, recycle, and disposal wells. The re-use treatment option is when wastewater is mixed with source water in order to meet fracturing water requirements. With this option, the hope is that the wastewater for re-use will require little or no treatment at all. The second treatment option is the recycle option. This option provides high quality water for re-use or discharge to the environment using a recycling technology. The credibility of this option is heavily dependent on its ability to recycle almost all of the wastewater with little or none left for disposal or treatment. The third option is well disposal. This entails disposing all of the wastewater into a deep formation. The software used for building the model is called @Risk. The model’s costs were estimates from recent research to capture the risks and uncertainties associated with wastewater disposal. The model revealed that re-use option remains the most cost effective treatment method to reduce overall water management cost in the Marcellus. The re-use option is most viable when a hydraulic fracturing schedule is continuous (no significant storage requirement) and infrastructure is available to transport wastewater from one fracturing operation to the other. The recycle option is the second most viable disposal option. This option is most effective when the hydraulic fracturing schedule is staggered in both time and distance because distilled water from recycling facilities can be easily discharged into the environment or stored. The most unfavorable option for wastewater management at the Marcellus is the well disposal option due to the high cost of trucking wastewater to disposal wells in neighboring states or counties. It also requires the highest usage of fresh water. A well disposal option can be favorable at the onset of a hydraulic fracturing schedule when there are low levels of infrastructure, hydraulic fracturing programs are not continuous or localized in proximity, and the volume of wastewater does not exceed the capacity for injection. In this case, disposal wells can be more favorable than recycle or re-use if they are in close proximity to drilling sites.