Update on Improvements to Dissolved Hydrocarbon Gases in Water Analysis

Topics in Shale Gas Exploration and Production
Oral Presentation

Prepared by M. Bruce
TestAmerica Laboratories, Inc., 4101 Shuffel St NW, North Canton, Ohio, 44720, United States


Contact Information: mark.bruce@testamericainc.com; 330-966-7267


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. This type of testing also is used to monitor biological processes for in-situ remediation and natural attenuation. There is no fully validated USEPA method for this type of analysis. ASTM recently released D8028 to address many of the limitations of the previous analytical options. This presentation describes the advantages of this new method and implementation options at the laboratory. At this time there are no commercially available proficiency test samples. Hence the method performance is not documented as well as other common environmental parameters. Internal studies indicate there are opportunities to improve accuracy and reproducibility and provide data more suitable for the oil & gas industry.

Analytical process differences between handling of water samples and gas phase based standards can introduce a low bias. Switching to water phase calibration standards and QC samples can significantly improve the accuracy of the final results. One reference material provider is considering production of liquid phase reference materials. Several laboratory options for production of calibration standards have also been investigated. The stability of water based standards for methane, ethane, ethene and propane have been studied. Adding a representative surrogate compound to the sample early in the sample preparation process tracks the integrity of the process. Many fluorocarbon compounds were evaluated to determine which were the best surrogate options. A headspace autosampler was adapted to store and deliver the surrogate solution with zero headspace.