|Abstract Title:||Impacts of hydraulic fracturing on water quality: a review of literature, and an analysis of information gaps.|
|Session Choice:||Combining data from multiple sources to deliver new insight|
|Presenter Name:||Mr Jam Aleem Nawaz Khan|
|Company/Organisation:||Florida International University|
Abstract Information :
Introduction Hydraulic fracturing is an unconventional process for oil and gas extraction from shale formations that involves the use of a mixture of large volumes of water (approximately 4 million gallons per fractured well, an array of chemicals, and proppants (e.g., sand) to hold the fractures open, allowing natural gas to flow out. Over the past decade, hydraulic fracturing processes have been paired with horizontal drilling technology, allowing producers to achieve increased flow rates across a large surface area through a single well. In the United States, there are currently 15 shale plays used for shale gas extraction. However, seven key plays (Marcellus, Haynesville, Eagle Ford, Bakken, Denver Julesburg-Niobrara, Permian, and Utica) contribute over 95% of the domestic shale oil growth and all the natural gas production growth in the United States from 2011 to 2013 (EIA 2015). Factors contributing to groundwater contamination Well construction The process of developing a natural gas well (i.e., drilling, casing, cementing, and completing the well) raises concern for groundwater contamination. The most common issue with well integrity arises from a faulty seal around casings and or improper cementing (Rozell and Reaven 2012; Vengosh et al. 2014). In USA regulatory authorities in several states have revised their requirements and have placed greater emphasis on well construction requirements and monitoring. These requirements include the need for installing multiple layers of protective casing and cement to isolate the well from its surroundings and to protect aquifers (Thiemann and Vann 2013; Kharak et al. 2013). Stray gas contamination The potential for contamination of groundwater from methane in shallow aquifers near extraction sites is one of the major concerns associated with hydraulic fracturing. Stray methane gas contamination occurs when natural gas travels up from intermediate layers through the well annulus, poorly constructed or faulty well casings, and abandoned wells within the shale formation. Although the primary mechanisms contributing to stray methane gas migration are understood, it is difficult to predict the risk at individual sites due to varying geological conditions and drilling practices. Various studies suggest that stray methane gas contamination is a result of shale gas drilling, while other research suggests that methane in groundwater can be natural and unrelated to shale gas development. Identification and analysis of information gaps Some of the most common criticisms related to hydraulic fracturing are the potential impacts to water quality and the lack of available baseline water quality data. To safeguard surface and ground water quality in areas surrounding hydraulic fracturing operations, some jurisdictions have implemented baseline and post-operation water quality monitoring requirements. However, there are large variations in water quality monitoring requirements within the United States. The absence of “credible and comprehensive” data has been a major setback to properly assess and monitor hydraulic fracturing activities and their pertinent risk on the environment, particularly water quality.