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Discover the potential of next-generation methane sensors for characterizing emissions at small-scale sources in the oil and gas industry. This pilot study examines sensor performance, data quality objectives, and applications for emission reduction and process improvement.
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Piloting Next-Generation Sensor Technology at Upstream Oil and Gas Facilities By Kenneth Craig, Ryan Moffet, Josette Marrero, and Paul Roberts For Petroleum Technology Alliance of Canada (PTAC) February 28, 2019 917057-7081
Study Overview • Demonstrate the application and utility of next-generation methane (CH4) sensors to characterize emissions from small-scale sources at upstream oil and gas (O&G) facilities • Collect high-quality data in the lab and in the field to • Characterize sensor performance for various measurement objectives • Provide examples of data quality objectives for new and emerging sensor technologies Aeris Technologies CH4 sensor. Package (top) weighs 3 kg with battery.
The Potential of Emerging Sensor Technology • Low-to-moderate cost • Potential for ubiquity, practical for low-intensity sources • Costs expected to fall over time • Minimal human intervention • Practical for transient and unpredictable sources • Minimal infrastructure • Lightweight, deployable anywhere • Quantitative, time-resolved, specific for CH4, sensitive at global background concentrations (currently 1.85 ppm)
Purpose of Pilot Study • Examine strengths and limitations of the technology • Clarify scientific merits, proper application(s) • Understand how to defend against misuse or misinterpretation • Understand how to leverage the technology for emission reductions and process improvements
Pilot Study Elements • Sensor selection • Bench testing • Calibration and range checks, accuracy, precision, drift • Site selection • Instrument siting • Three-week deployment • Controlled release experiments • Optical gas imaging (OGI) and equipment survey • Analysis and synthesis Sensor deployment in the field.
Sensor Selection Aeris Technologies MIRA Pico Series Sensor • Mid-IR laser-based gas analyzer (absorption spectrometry) • 1-second measurements • 1% accuracy (CH4) • Also measures ethane (C2H6) • Lightweight and portable • 15 W power consumption • About $30,000 (at release, expect price to decrease over time) Aeris sensor inside custom instrument enclosure.
Sensor Package • Two Aeris methane sensors • Meteorological data • 2-D sonic anemometer (1-second winds) • Fast-response temperature, humidity, and pressure probes • Communications • Wired (internal) • Cellular (external) • Power • Line power at pump jack
Bench Testing Sensor agreement (1%) is one measure of measurement precision or uncertainty Sensor accuracy was generally within 2% (published accuracy was 1%) No instrument drift over study period
Site Selection Edmonton Drayton Valley • “Site 8-8” near Drayton Valley, Alberta • Site attributes • Reasonable access • Line power • Good cell signal • Flat, limited obstructions • Confirmed CH4 emissions (FLIR) • Operational • Cooperation from site operator CH4Sensors CH4 Controlled Releases This Subheading Bar Is Optional 9 Image Source: Google Earth
Site 8-8 field deployment site. Sensors are to the left of the pump jacks. 10
Site 8-8 Operations • 3 pump jacks with adjoining well shacks and equipment • 6 oil production tanks • Periodic tank unloading activity
Instrument Siting • Use wind climatology to assist with instrument siting • Winds predominately from the northwest and southeast Climatological wind roses during June and July at Edmonton International Airport. This Subheading Bar Is Optional 12
Instrument Siting 3-Week Deployment.Two CH4 sensors 60 m downwind of production tanks (tank emissions were confirmed by Alberta Energy Regulator prior to site selection) Controlled Releases.CH4 sensors placed upwind of equipment and downwind of releases (25, 54, 59 m distances) when winds were from the south and southeast CH4 Sensors CH4 Controlled Releases Image Source: Google Earth
Deployment 6/21/2018 – 7/11/2018 • Continuous real-time data collection and transmission • Ingested into STI’s Insight data management system for real-time monitoring and QA/QC • Daily site logs • Successful deployment • No equipment issues • Very high data capture (>99%)
Methane Data Summary • Analysis conducted with 1-minute averaged data • Good instrument agreement (1% for baseline and median concentrations) • Background CH4 measured at the site was 1.85 ppm
Methane Data Summary Wind Rose CH4 Time Series
Week 1 Data Summary Wind Rose CH4 Time Series Pollution Roses
Week 2 Data Summary Wind Rose CH4 Time Series Pollution Roses
Week 3 Data Summary Wind Rose CH4 Time Series Pollution Roses
Data Examples 6/30/2018 0500-0600 LTWinds from the southwestCH4 emissions from pump jacks or well shacks 7/2/2018 1915-2015 LTWinds from the northwestCH4 emissions from production tanks 6/24/2018 1800-1900 LTWinds from the southeastBaseline CH4 concentrations(no Site 8-8 equipment upwind of sensor)
Ethane Measurements Sensor downwind of production tanks when winds are from the northwest. Sensor downwind of pump jacks and well shacks when winds are from the southwest. Low-ethane signal (10 ± 20 ppb) when sensor is generally upwind of Site 8-8 equipment. Ethane measurements can be used to distinguish CH4 emissions from different sources, or distinguish from natural emissions.
Site Logs • Completed daily by site operators and personnel during the deployment. • STI reviewed logs after completing initial data analysis. • No correlations between specific site activities and the methane peaks.
Optical Gas Imaging and Equipment Survey • Tank release rates estimated from visual OGI inspection • Well shack release rates estimated with HiFlow Sampler • Unclear if well shack emissions were fugitive or venting
Findings from Field Deployment • Majority of CH4 measurements were between 2.00 and 3.00 ppm; 10% were greater than 2.50 ppm (local background was 1.91 ppm) • Largest CH4 spikes during overnight hours when winds were light and from the southwest (from pump jacks and/or adjoining equipment) • Moderate and steady increases in CH4 during periods when winds were from the northwest (from production tanks) • Background CH4 concentrations observed when winds were from the north and southeast (sensors upwind of Site 8-8 equipment) • Ethane data were reliable and methane/ethane ratio can be used to differentiate between different types of releases • Findings confirmed by OGI and equipment survey (reviewed after the data analysis)
Controlled Release Experiments 6/20/2018 • Provide additional data to • Evaluate and demonstrate the sensors’ capabilities and limitations • Demonstrate and test the emissions quantification approach and establish uncertainty • 14 controlled releases of pure (99.9%) CH4 • Generally ideal atmospheric conditions • Consistent winds of 3-6 m/s from the south and southeast
Instrument Siting for Controlled Releases Releases placed upwind of CH4 sensors at 25, 54, 59 m distances Winds were from the southeast Synchronized meteorological data collected CH4 Sensors CH4 Controlled Releases WindDirection Image Source: Google Earth
Controlled Release Experiments 14 tests at 25-59 m distance with flow rates spanning from small (<0.5 g/min) to “super-emitter” (>40 g/min)
Emissions Quantification • Calculate baseline CH4 concentration • Controlled releases: Upwind CH4 between experiments • Deployment data: Lowest 10% of data • Calculate difference between measured and baseline (∆CH4) • Controlled releases: Averaged over the release • Deployment data: Select 15-minute intervals with upwind source and stable winds and concentrations • Use WindTrax Lagrangian particle model to estimate release rate based on sensor geometry, surface and meteorological conditions, and ∆CH4measurements • Use controlled release data to estimate uncertainty
Emissions Quantification Instrument uncertainty was 1% based on bench and field testing.
Emissions Quantification 6/30/2018 0500-0600 LTWinds from the southwestCH4 emissions from pump jacks or well shacks 7/2/2018 1915-2015 LTWinds from the northwestCH4 emissions from production tanks
Emissions Quantification: Selected Deployment Data Instrument uncertainty was ±1% based on bench and field testing Emissions rate uncertainty was ±50% based on controlled release results “As found” emissions reported from 6/20/2018 OGI and equipment survey Simplified approach shows ability to use sensor data to quantify real-world emissions within at least a factor of two
Overall Findings and Recommendations (1) • Aeris sensor data were successfully used to identify continuous CH4 emissions from equipment at Site 8-8. • Higher CH4 concentrations were consistently observed when sensors were downwind of equipment at Site 8-8. • Coincident ethane measurements showed two clear ethane-methane ratio signatures that could be traced to emissions from specific equipment at Site 8-8, and one signature that could not. • OGI and equipment survey (reviewed post-analysis) confirmed emissions from all three well shacks and 3 of 6 production tanks. • Sensor data can be used to quantify real-world emissions.
Overall Findings and Recommendations (2) • Establishing background concentration is critical to establish context for CH4 measurements and quantifying emissions. • Synchronized meteorological measurements are critical and should be co-located with CH4 measurements. • Coincident ethane measurements are helpful to differentiate between multiple potential CH4 emission sources. • Measurement uncertainty within ±4% is needed to reliably detect and quantify methane emissions (∆CH4> 0.100 ppm) and support emissions characterization. The Aeris sensors met this minimum requirement. • 1% measurement uncertainty was established in this study, and is sufficient to support a broad range of applications at O&G facilities.
Sensors and Measurement Objectives • Measurement objectives matter • Identify emissions • Locate emissions • Quantify emissions • Short-term vs. long-term measurement • Good accuracy (1-2%), precision (1-4%), and time resolution (1-minute to 1-second) are needed to locate and quantify transient methane emissions • The Aeris sensor proved capable of meeting these measurement objectives.
Heat shield Practical Considerations • Temperature Control.Overheating was the biggest concern. Untested for cold weather. • Power.Line power reduced pilot project risk. Solar setup is feasible, but requirements could be substantial if climate control is needed. • Calibration.None needed during short deployment, but quarterly calibration is recommended. • Instrument Issues.Sensors were relatively new to market. Aeris made some changes in response to our pre-deployment testing. • Cost.Must also consider deployment design and execution, operations and maintenance, data management, data analysis, and data delivery.
Project Partners • PTAC • Funding, coordination, technical oversight • Alberta Energy Regulator • Site selection, FLIR surveys, coordination, technical oversight • GreenPath • Installation and logistics • OGR and equipment survey • Site Operator • Site access, logistics, daily log • Todd Tamura, Tamura Environmental, Inc. • Technical review
Sensors and Measurement Objectives • Measurement objectives matter • Identify emissions • Locate emissions • Quantify emissions • Short-term vs. long-term measurement • Good accuracy (1-2%), precision (1-4%), and time resolution(1-minute to 1-second) are needed to locate and quantify transient methane emissions • The Aeris sensor proved capable of meeting these measurement objectives.
Kenneth Craig Manager, Atmospheric Modeling Group kcraig@sonomatech.com Ryan Moffet Manager, Meteorological & Air Quality Measurements Group rmoffet@sonomatech.com Levi Stanton Sensor Program Lead lstanton@sonomatech.com SonomaTech.com 707-665-9900
About STI For over 35 years, STI has provided innovative science and technology answers to air quality questions for clients around the world. We are a green-certified small business with headquarters in northern California and offices in New York, Washington, D.C., and southern California. Business Areas and Services Air Quality Meteorology Monitoring Modeling Emissions Software Development Fire and Fuels Expert Testimony Our integrated teams of atmospheric and physical scientists, policy and data analysts, engineers, software and database developers, and technical editors are ready to solve your air quality issues. 40