A Continued Assessment of the Risk of Migration of Hydrocarbons or Fracturing Fluids into Fresh Water Aquifers in the Piceance, Raton, and San Juan Basins of Colorado

Abstract

Abstract The United States National Science Foundation has funded a Sustainability Research Network (SRN) focused on natural gas development in the Rocky Mountain region of the United States. The mission of this SRN is to provide a logical, science- based framework for evaluating the environmental, economic, and social trade-offs between development of natural gas resources and protection of water and air resources and to convey the results of these evaluations to the public in a way that improves the development of policies and regulations governing natural gas and oil development. In a previous paper (Fleckenstein et al 2015), the risk of shallow aquifer contamination was examined for the Denver-Julesburg Basin in Colorado, specifically for the largest field in the basin, the Wattenberg Field. Similar methods were used to assess the risk of wellbore failure leading to fresh water aquafer contamination for the Piceance, Raton, and San Juan Basins in Colorado. Wellbore construction methods, especially casing and cementing practices for the protection of fresh water aquifers, have been reviewed in these three basins. The wells in the three basins were classified based on coverage of water and hydrocarbon zones as well as age. The assessment confirms that natural gas migration occurs infrequently, but can happen from poorly constructed wellbores. There has been no occurrence of hydraulic fracturing fluid contamination, which was confirmed by our analysis. The significance of these results is to help quantify the risks associated with natural gas development, as related to the contamination of surface aquifers. These results are helping to shape the discussion of the risks of natural gas development and will assist in identifying areas of improved well construction and hydraulic fracturing practices to minimize risk.