Distribution and Origin of Groundwater Methane in the Wattenberg Oil and Gas Field of Northern Colorado

• Published in: Environmental science & technology Vol. 48; no. 3; pp. 1484 - 1491
• Main Authors: Li, Huishu, Carlson, Kenneth H
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 04.02.2014
• Subjects: Applied sciences; Aquifers; Colorado; Contamination; Drinking water; Drinking Water - standards; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental Monitoring - methods; Exact sciences and technology; Groundwater; Groundwater - chemistry; Groundwater pollution; Groundwaters; Methane; Methane - analysis; Natural Gas - analysis; Natural water pollution; Oil and Gas Fields; Oil fields; Oil pollution; Pollution; Pollution, environment geology; Water Pollutants, Chemical - analysis; Water Quality; Water treatment and pollution; Water Wells; United States; North America; Colorado; America; United States > US; USA, Colorado; Methane; Drinking water; Gas industry; Liquid waste; Aquifers; Oil industry; Industrial waste; Industrial waste water; Dissolved gas; Greenhouse gas; Water quality; Water pollution; Produced water; Concentration distribution; Ground water
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es404668b

Public concerns over potential environmental contamination associated with oil and gas well drilling and fracturing in the Wattenberg field in northeast Colorado are increasing. One of the issues of concern is the migration of oil, gas, or produced water to a groundwater aquifer resulting in contamination of drinking water. Since methane is the major component of natural gas and it can be dissolved and transported with groundwater, stray gas in aquifers has elicited attention. The initial step toward understanding the environmental impacts of oil and gas activities, such as well drilling and fracturing, is to determine the occurrence, where it is and where it came from. In this study, groundwater methane data that has been collected in response to a relatively new regulation in Colorado is analyzed. Dissolved methane was detected in 78% of groundwater wells with an average concentration of 4.0 mg/L and a range of 0–37.1 mg/L. Greater than 95% of the methane found in groundwater wells was classified as having a microbial origin, and there was minimal overlap between the C and H isotopic characterization of the produced gas and dissolved methane measured in the aquifer. Neither density of oil/gas wells nor distance to oil/gas wells had a significant impact on methane concentration suggesting other important factors were influencing methane generation and distribution. Thermogenic methane was detected in two aquifer wells indicating a potential contamination pathway from the producing formation, but microbial-origin gas was by far the predominant source of dissolved methane in the Wattenberg field.