Analysis of Dissolved Hydrocarbon Gases in Water Pitfalls and Improvements

Oral Presentation

Prepared by E. Redman1, M. Bruce2
1 - TestAmerica, 880 Riverside Parkway, West Sacramento, CA, 95605, United States
2 - TestAmerica, 4101 Shuffel St NW, North Canton, OH, 44720,


Contact Information: eric.redman@testamericainc.com; 916-374-4342


ABSTRACT

Analysis of methane and other light hydrocarbons is frequently done as part of predrill background studies to support hydraulic fracturing activities in the various shale plays in the United States. Gaseous hydrocarbon analysis in water also is used to monitor degradation of environmental contaminants. There is no fully validated USEPA method for this type of analysis. Commercial environmental laboratories currently reference an SOP (RSK-175) from an EPA lab. There is significant variability in how this SOP is interpreted and implemented at various laboratories. There are no commercially available proficiency test samples. Hence, the method performance is not documented as well as other common environmental parameters. Some internal studies indicate there are opportunities to improve accuracy and reproducibility and provide data more suitable for the oil & gas industry.

Loss of these very volatile analytes during sample preparation by too much exposure to air prior to headspace-gas chromatographic analysis is a primary concern. In addition, analytical process differences between the handling of water samples and gas phase based standards can introduce bias. Several different options for producing water-based standards have been investigated. Development and use of water-based calibration standards and proficiency testing samples will facilitate other method improvements and documentation of method performance.