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Barnett Shale Emissions: Data Collection and Analysis

The TCEQ is increasing the understanding of air quality data through ground based monitoring and flyover surveys using infrared camera technology. Oil and gas calculation methods are also being studied to improve data on upstream oil and gas operations.

Barnett Shale Area Special Inventory

The TCEQ is conducting a special inventory to determine the location, number, and type of emissions sources located at upstream and midstream oil and gas operations associated with the Barnett Shale formation. Data Collection Helicopter

Flyover Camera Surveys

The 2005 and 2007 Remote Sensing Projects on volatile organic compounds (VOCs) identified many oilfield storage tanks with hydrocarbon plumes. A helicopter-mounted HAWK passive infrared camera was used to aerially survey and image hydrocarbon plumes. TCEQ used these images to identify sources of VOC emissions that may have gone unreported or underreported.

Ten sites imaged during the 2007 aerial surveys in the Dallas–Fort Worth area were selected for follow-up investigations based on the apparent magnitude of the hydrocarbon plumes imaged. The TCEQ is actively working with the sites to address these emissions and is using the information to better understand emissions from natural gas processes. Ten sites were also selected in the Gulf Coast area.

Additional information pdf file concerning this study.

Ground-based Monitoring

The TCEQ is studying the emissions from gas production and their impacts in the Barnett Shale area. To gather information, the Mobile Monitoring Team has conducted multiple trips to monitor emissions in this area. Phase I of the study was conducted August 24–28, and Phase II occurred October 9–16, 2009. These trips included surveying the area using infrared imagery, total vapor analyzers (TVA), hydrogen sulfide monitors, monitoring for nitrogen oxides (NOx) and collecting VOC samples.

Over 80 locations pdf file were monitored in five counties: Tarrant, Parker, Wise, Denton, and Johnson. Air samples and other relative data collected from the two trips are currently being processed through the TCEQ Air Laboratory for quality assurance and reviewed by the TCEQ Toxicology Division.

A third monitoring trip was conducted in November 2009. The main goal of the trip was to monitor for sulfide-related compounds, such as carbon disulfide, which were indicated to be present in reports commissioned by the City of Dish and a private citizen. A fourth phase will occur in conjunction with a proposed study funded by the Chief Engineer’s Office and will include determining emission rates and characteristics of emissions at sources along with off site impacts of the emissions.

The TCEQ is pursuing deployment of an additional stationary monitoring site for VOCs and NOx in the area. Currently, a preliminary location of the monitors is around the TCEQ Eagle Mountain CAM station and possibly in the Dish area.

The TCEQ contracted with the University of Texas at Austin to conduct an ambient monitoring project pdf file in the Barnett Shale area. The UT monitoring van was outfitted with instruments to sample ambient air quality around oil and gas facilities in Northeast Texas, including the Barnett Shale area. The purpose of the project is to sample ambient emissions, primarily downwind of gas compressor engines and develop typical compressor engine ambient signature of emissions. These signatures have allowed the agency to help determine if there is an impact from gas compressors and oil and gas extraction on ozone levels in the DFW area under varying conditions.

Improved Emission Factors and Emission Calculation Methods

The Texas Commission on Environmental Quality EI reflects years of continuous emissions data improvement, including extensive point and area source inventory reconciliation with ambient emissions monitoring data. Since the Texas Air Quality Study 2000 (TexAQS 2000), when ambient VOC concentrations were measured to be greater than EI estimates, EI improvements have targeted more accurate speciation, source identification, and reporting of industrial VOC emissions. The following projects have improved, or will significantly improve, the point source or area source inventory.

In conjunction with the Houston Advanced Research Center, the TCEQ identified thousands of tons of VOC flash emissions from upstream oil and gas operations and developed emissions factors to quantify these emissions. It is important to note that the TCEQ emissions factors developed from this project are intended to be used on a larger scale, such as developing the area source county-level emissions inventory. Area sources are stationary emission sources that are not included in the point source EI. Since area source categories represent individual emission sources that are small and numerous and that have not been inventoried as specific point or mobile sources, the EI for an area source category is developed for a specified geographic area, typically a county, by estimating the emissions collectively. Report Exit the TCEQ

The TCEQ continues to research calculation methodologies for upstream oil and gas storage tank emissions along with other upstream sources. One example is the Flash Emissions Model Evaluation project, which is nearing completion. The results of the report are anticipated to improve agency guidance and policy on calculating upstream oil and gas-tank emissions. The draft report was posted on the contractor’s Web page for comments and the final report will be published on TCEQ’s Web page.

The TCEQ continues to review and update oil and gas calculation methods and is developing updated permits requirements for the upstream oil and gas industry. The latest TCEQ published guidance for calculating and reporting emissions from oil and gas operations is available at the following locations:

List of Upstream Oil and Gas Research Projects pdf file Lists past, current, and planned research projects to improve emissions factors and emissions calculation methods of upstream oil and gas activities.