Airborne Remote-Sensing Technologies Detect, Quantify Hydrocarbon Releases


Airborne imaging spectroscopy has evolved dramatically since the 1980s as a robust remote-sensing technique used to generate 2D maps of surface properties over large areas. Two recent applications are particularly relevant to the needs of the oil and gas sector and government: quantification of surficial hydrocarbon thickness in aquatic environments and mapping atmospheric greenhouse-gas components. These techniques provide valuable capabilities for monitoring petroleum seepage and for detection and quantification of fugitive emissions.

The Jet Propulsion Laboratory (JPL), a National Aeronautics and Space Administration (NASA) federally funded research-and-development center operated by the California Institute of Technology, has been a pioneer in optical remote sensing since the 1980s. JPL capabilities include expertise across all project phases, including sensor design and construction, airborne experiment execution, and data generation driven by science and customer needs. JPL has particular expertise in imaging spectroscopy, a passive method to interrogate objects or surfaces without physical contact. Such remote sensing has traditionally been applied to investigation of surface composition in terrestrial environments. These surface compositions are characterized by use of a spectral library that includes the surface-reflectance or emissivity fingerprints of constituent materials. Airborne imaging spectrometers provide a powerful method to survey wide spatial extents with high-performance surface characterization because of the wide contiguous spectral range at moderate spectral resolution. Novel quantitative methods have emerged recently for both atmospheric gases and surficial oil on water.

Imaging-Spectrometer Parameters

Fig. 1

Airborne pushbroom imaging spectrometers incorporate a 2D focal-plane array to collect data over a wide swath beneath the aircraft by use of a nadir-mounted sensor (Fig. 1). The areal coverage and spatial resolution depend on the sensor design characteristics and altitude. The crosstrack sensor characteristics include the sensor field of view (FOV), which determines the swath coverage as a function of altitude, while instantaneous FOV (IFOV) defines the across-track resolution, or pixel size as projected on the ground. On the basis of these sensor characteristics, a simple geometric relationship links sensor characteristics to crosstrack performance parameters.

Contemporary JPL pushbroom airborne imaging spectrometers include two major types: Offner and Dyson spectrometers. Offner spectrometers operate by collecting light through a narrow optical slit and, by use of a dispersive grating and multiple mirrors, focusing light onto the focal-plane array (FPA) with high spectral uniformity. Thus, during flight, pushbroom sensors simultaneously image pixels beneath the aircraft across the entire sensor swath width. The FPA images discrete spectral channels across the entire contiguous spectral range while crosstrack spatial information is captured across the second axis. Pushbroom approaches eliminate any moving optical subsystems by implementing a fixed optical train. In order to optimize sensor performance with respect to the signal/noise ratio, it helps to fly slowly with these systems (80–100 knots) to enhance oversampling. The second type of spectrometer in which JPL specializes is the Dyson spectrometer. The main difference in Dyson-spectrometer designs compared with Offner types is that the dispersion is accomplished by an arsenic-doped silicon block. These Dyson designs often result in a smaller form factor, particularly in the thermal infrared region of the spectrum, while still maintaining excellent spectral uniformity.

Application 1—Imaging-Spectrometer Applications for Investigation of Oil on Water
The Deepwater Horizon oil spill began on 20 April 2010. One of the NASA remote-sensing instruments was deployed less than a month later: the airborne visible/infrared imaging spectrometer (AVIRIS). The surveys were conducted from high altitudes (approximately 20 km) to maximize spatial coverage (i.e., 12.2-km swath width).

The results from these experiments revealed the suitability of optical remote sensing for oil-slick assessment in the visible (0.4–0.7 μm), near-infrared (1.2–1.7 μm), and shortwave infrared regions (2.3 μm). It was demonstrated through correlation with laboratory measurements that the depth of the 1.2-μm hydrocarbon absorption feature provided quantitative oil-thickness information.

The collection of these Deepwater Horizon data was the first time that optical imaging spectrometry demonstrated quantitative capability for oil-slick-thickness determination. Thus, the suitability of this technique for disaster response and estimates of net surface oil has been recognized.

Application 2—Imaging-Spectrometer Applications for Remote Sensing of Atmospheric Methane
Contemporary demonstrations of advanced NASA airborne imaging spectrometers for detection of fugitive methane emissions yield impressive results. These imaging techniques use sensors with wide spectral ranges in the visible to shortwave infrared (VSWIR) or the long wave infrared (LWIR). The NASA sensors offer much greater signal/noise ratios and greater spectral resolution than the few imaging spectrometers available commercially. Thus, these JPL applications reap the benefits of the most advanced imaging spectrometers in the VSWIR and LWIR regions that have been built. JPL and colleagues have begun flights over conventional oil fields and unconventional production areas to help constrain natural and anthropogenic methane emissions, including quantification of fugitive-­emission sources by use of highly mature algorithms. These airborne spectrometers have demonstrated sensitivities at flux rates as low as <250 scf/hr when flown at low altitudes (approximately 1000 m) using VSWIR or LWIR sensors. These results were demonstrated with existing NASA spectrometers that were not designed specifically for methane detection.

Imaging spectrometers provide a unique solution for noninvasive investigation of large areas. The feasible spatial coverage for a daily survey at low altitude is on the order of hundreds of square kilometers (flight-plan dependent) while flying at relatively low altitudes (1–3 km).

One need that has resulted in wide adoption of imaging spectroscopy is that production of data products is typically labor intensive, resulting in significant delay in results because of the vast amount of data generated by these imaging spectrometers. One solution is to implement real-time algorithms as part of an onboard flight data system. A real-time detection system for methane point-source visualization currently exists as part of the AVIRIS onboard data system. This successful implementation results in real-time data analysis during collection and allows for an adaptive flight planning approach using the heads-up display.

Imaging Spectroscopy in the Shortwave Infrared (SWIR) Using AVIRIS
The JPL next-generation AVIRIS is a passive imaging spectrometer that operates by collecting the upwelling (reflected) solar radiation in discrete bands across the range of the visible (0.4 μm) through the shortwave infrared (2.5 μm). Using this technique, characteristics of surface features can be diagnosed by use of the detected spectral signatures or fingerprints. AVIRIS provides high spectral resolution for a visible/infrared imaging spectrometer (5-nm bandwidth), exceeding those of other flight systems by at least a factor of two. Increased spectral resolution allows for more-detailed discrimination between surface features.

In September 2014, six AVIRIS scenes were acquired over Garfield County, Colorado, a region with considerable gas and oil extraction. Flights were made approximately 1.4 km above ground level, which resulted in images approximately 0.8 km wide and 8 km long, with a ground resolution of 1.3 m per pixel. Quantitative methane retrievals were performed on all images, and a number of plumes were clearly visible emanating from multiple well pads.

Fig. 2

Fig. 2 clearly indicates a plume consistent with the local wind direction (white arrow) that extends 200 m downwind of the emission source. Google Earth imagery obtained from June 2014 indicates that the likely source is tanks located on the edge of the well pad. Five wells are located at the center of this well pad, and all use horizontal drilling to produce mostly gas.

Conclusions and Path Forward
The results demonstrate the utility of existing advanced NASA imaging spectrometers for detection of oil on water and quantitative mapping of methane plumes. While existing data sets for both applications are currently quite small, future opportunities to demonstrate these capabilities further are a high priority for the program.

The optimal solution for wide adoption of methane monitoring is to build an imaging spectrometer sensor fit for purpose. None of the technologies used was designed specifically for quantitative methane detection; however, ­sensitivities in the range of 250 scf/hr remain impressive. A new sensor would improve the achievable sensitivity (<10 scf/hr) and increase specificity for small point-source emissions sources. This is the optimal solution from a science perspective to help understand the spatio-temporal variability of natural and anthropogenic methane emissions. The major improvements of this spectrometer design include a narrower spectral range with enhanced spectral resolution. These factors will increase the sensitivity, specificity, and spatial resolution, while virtually eliminating any false positives. This sensor has been designed to be accommodated on a fixed-wing aircraft or helicopter for more-flexible flight implementation.

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper OTC 25984, “Crosscutting Airborne Remote-Sensing Technologies for Oil and Gas and Earth Science Applications,” by A.D. Aubrey, C. Frankenberg, R.O. Green, M.L. Eastwood, and D.R. Thompson, National Aeronautics and Space Administration Jet Propulsion Laboratory, California Institute of Technology, and A.K. Thorpe, University of California, Santa Barbara, prepared for the 2015 Offshore Technology Conference, Houston, 4–7 May. The paper has not been peer reviewed. Copyright 2015 Offshore Technology Conference. Reproduced by permission.

The Associated Press | 14 August 2015

Federal Appeals Court Hears Arguments on Polar Bear Habitat

A federal plan designating a huge swath of the US Arctic as critical polar bear habitat should be upheld over the objections of the state of Alaska, petroleum industry groups, and communities along Alaska’s north coast, a Justice Department lawyer told an appeals court on 11 August.

Robert Stockman acknowledged that the US Fish and Wildlife Service plan designating an area larger than California as critical habitat lacked specifics, such as the exact sites where polar bears establish dens. But the agency acted based on the best data available from polar bear experts as is required by endangered species law, he said.

“The service had to make a judgment call based on limited data,” Stockman said.

Polar bears, a marine mammal, were declared a threatened species in 2008 under former President George W. Bush because of diminishing sea ice brought on by global climate warming. Polar bears use sea ice to breed and hunt ice seals.

An endangered species listing requires the agency overseeing the species to develop a plan to help the population recover. The designation of a species’ critical habitat does not automatically block development, but it requires federal officials to consider whether a proposed action would interfere with the recovery of a threatened population.

The US Fish and Wildlife Service habitat plan designating 187,000 sq miles of polar bear critical habitat drew lawsuits from the state of Alaska, petroleum trade associations, local governments, and Alaska Native businesses with interests in the Alaska Arctic. The state and the trade associations said the designation would cost millions and lead to delays in projects, additional consultations with layers of government, and litigation for development projects.

San Antonio Business Journal | 14 August 2015

Several Eagle Ford Companies Testing Natural Gas Technology in San Antonio

Technology being tested atop a sun-soaked hill that overlooks downtown San Antonio could conserve natural gas and save money for several companies operating in the Eagle Ford shale.

The Environmental Defense Fund is sponsoring a Methane Detectors Challenge to create portable and unmanned methane detectors that will help reduce emissions from oil and natural gas operations.

All of the testing for the challenge is done out of San Antonio’s Southwest Research Institute where Statoil, Anadarko, Apache, BG Group, Hess, Noble Energy, Shell, and Southwestern Energy make up the eight corporate participants.

Prototypes designed by Dalian Actech/SenSevere, SenseAir AB, Quanta3, and University of Colorado/NDP Group are being tested at a natural gas facility at the institute for the eight companies to use in the field later this year.

Southwest Research Institute Fluid Dynamics Manager Shane Siebenaler is overseeing the challenge, which he said started in April and will finish outdoor testing in August.

Using controlled outdoor tests involving intentional releases of natural gas in various weather conditions, the methane detectors can detect even minute amounts of gas leaking from pipes or other sources up to 150 ft away, Siebenaler said.

With a target price of USD 1,000 or less per unit, three of the four portable prototypes use solar panels as a power source. One of the prototypes uses a laser beam system to detect methane gas while the other three use different types of sensors. A wireless air card in one of the prototypes sends data to the receiver using the nearest available cell phone tower.

“These are all designed to send messages to a person, and that person takes action,” Siebenaler said.

Rigzone | 14 August 2015

ONE Future Coalition Seeks To Achieve Emissions of 1% or Less

A group of energy companies is seeking to design a system that would ensure the reduction of methane emissions across the gas chain by an average of 1% or less of gross production. Officially incorporated in late 2014, the ONE Future Coalition was founded by Southwestern Energy and other companies across the entire natural gas supply chain, including Apache, BHP Billiton, AGL Resources, Kinder Morgan, Columbia Pipeline Group, Hess, and National Grid.

The coalition decided upon the 1% goal after 1% was identified as sort of a “magic number” in a study conducted by Environmental Defense Fund scientists—and published in the proceedings of the National Academy of Sciences—that concluded that a 1% or less loss rate would ensure natural gas would provide immediate climactic benefits over other fossil fuels in any application. This included the use of natural gas in its least efficient application, compressed natural gas in trucks.

Instead of a prescriptive approach, which mandates the adoption of specific technologies, practices, or procedures for all facilities or certain operations, the coalition is designing a system that will offer each company the flexibility to determine the most cost-effective way to achieve the 1% or less goal. This could include adopting a new technology, work practice, or even retiring an asset.

To achieve the collective 1% target, the coalition plans to identify performance targets for each of the four major industry sectors—exploration and production, gathering and processing, transmission and storage, and distribution and retail—which would cumulatively add up to the industry’s overall 1% goal, ONE Future said on its website. The coalition will work to set these performance targets in rough proportion to each industry sectors’ respective share of current emissions, taking into account reduction potentials given the current regulatory barriers.

The Energy Collective | 29 July 2015

Can US Canadian Oil Sands Imports Be Nearly Carbon Neutral?

The US Department of Energy’s Argonne National Laboratory recently published a study that determined the production and consumption or “well-to-wheel” (WTW) greenhouse gas (GHG) emissions of Canadian oil sand crude imports are 20% greater than conventional US domestic crudes. This study appears to support the Obama administration’s climate change policy and decision to not approve the Keystone XL pipeline. However, based on the study’s major assumption that oil sands crude imports will primarily displace US lighter, lower-sulfur conventional domestic crudes, does this 20% WTW GHG increase finding reasonable cover the actual full life cycle impacts on world emissions? If not, is it feasible that the full lifecycle GHG emissions of oil sands crude imports are nearly carbon neutral based on actual overall oil market impacts? The answers to these questions were analyzed and developed based on recent actual oil market performance data.

Energy in Depth | 29 July 2015

New Methane Study Finds Low Emissions From Transmission and Storage Facilities

Researchers at Colorado State University, partnering with the Environmental Defense Fund (EDF), released a new study focusing on methane emissions from natural gas transmission and storage facilities. The study finds very low methane emissions that are very much in line with the Environmental Protection Agency’s (EPA) estimates in its Greenhouse Gas Inventory.

Here are a few quick highlights from the report:

  • Data show lower emissions than the EPA Greenhouse Gas Inventory.
  • Researchers included “super-emitters” in their data, yet still found low methane emissions.
  • Methane emissions well below the threshold for natural gas to maintain climate benefits.
  • New report corroborates top methane studies finding low emissions.

Find the report here.


San Antonio Express-News | 29 July 2015

Interstate Gas Pipeline Rerouted To Avoid Fragile NY Forest

A section of the planned Constitution Pipeline, designed to bring natural gas to New York City and New England, has been redrawn to avoid a 1,000-acre private forest with fragile wetlands.

Christopher Stockton, spokesman for the 124-mile pipeline to bring cheap gas north from Pennsylvania’s shale fields, confirmed the route change on 28 July. Stockton said the change adds almost 3 miles to the route and affects 11 landowners, who recently signed right-of-way agreements.

The new route avoids the private Charlotte Forest in Harpersfield, about 50 miles southwest of Albany.

Reuters | 29 July 2015

Report: Green Group Sues ConocoPhillips, CNOOC Over China Oil Spill

A maritime court in the coastal city of Qingdao has said it will hear a landmark case brought by a nonprofit organization against US oil giant ConocoPhillips and China’s CNOOC, the official China Daily reported.

The China Biodiversity Conservation and Green Development Foundation will not claim compensation but is calling for the two firms to accept responsibility for damage caused by the 2011 oil spill in northeast China, the paper reported.

The case will be the first public-interest litigation brought by a nonprofit organization over marine environmental pollution, it said.

ConocoPhillips and CNOOC have been embroiled in a series of legal claims following oil spills in 2011 in Bohai Bay that polluted over 6,200 square km of water.

Eco World News | 20 July 2015

DOE Selects Projects To Assess Offshore Carbon Storage

The Department of Energy’s (DOE) National Energy Technology Laboratory (NETL) has selected four offshore projects to receive funding through NETL’s Carbon Storage program.

According to DOE, “The funded research projects will assess the prospective geologic storage potential of offshore subsurface depleted oil and natural gas reservoirs and saline formations on the east coast and the Gulf of Mexico. These projects will use existing geologic and geophysical data to conduct a prospective storage resource assessment that will approximate the amount of carbon dioxide that can be safely stored.”

DOE is aiming for widespread commercial deployment of such technologies in the 2025–35 time frame. Project funding ranged from USD 1.3 million to just under USD 5 million with an average non-DOE cost share of 21%.

The four projects are

  • Mid-Atlantic US Offshore Carbon Storage Resource Assessment Project, led by Battelle Memorial Institute
  • Assessment of Carbon Dioxide Storage Resources in Depleted Oil and Gas Fields in the Ship Shoal Area, Gulf of Mexico, led by GeoMechanics Technologies
  • Southeast Offshore Storage Resource Assessment, led by Southern States Energy Board
  • Offshore Carbon Dioxide Storage Resource Assessment of the Northern Gulf of Mexico (Upper Texas-Western Louisiana Costal Areas), led by The University of Texas at Austin

Bloomberg | 14 July 2015

California Farms Are Using Drilling Wastewater To Grow Crops

California’s epic drought is pushing the oil industry to solve a problem it has struggled with for decades: what to do with the billions of gallons of wastewater that gush out of wells every year.

California drillers have pumped much of that liquid back underground into disposal wells. Now, amid a 4-year dry spell, more companies are looking to recycle their water or sell it to parched farms as the industry tries to get ahead of environmental lawsuits and new regulations.

The trend could have implications for oil patches across the country. With hydraulic fracturing boosting the industry’s thirst for water, companies have run into conflicts from Texas to Colorado to Pennsylvania. California could be an incubator for conservation efforts that have so far failed to gain traction elsewhere in the US.

Drillers may have little choice. The state’s 50,000 disposal wells have come under increased scrutiny this year, after regulators said they’d mistakenly allowed companies to inject wastewater near underground drinking supplies. Environmental groups sued the state to stop the practice at 2,500 sites considered most sensitive.

A win for environmentalists could drive up disposal prices and delay drilling by months for Chevron, Linn Energy, and other companies, according to a 12 June report by Bloomberg.

Eco Magazine | 9 July 2015

Governments Advance Binding Law of the Sea Agreement

The UN General Assembly last week adopted a formal resolution to develop a legally binding treaty for the conservation of marine biodiversity on the high seas. The new ocean regulations are proposed to include area-based management tools, such as marine planning and marine protected areas; environmental impact assessment requirements; the transfer of marine technology; and a regime for managing marine genetic resources, including benefit-sharing. These developments have potentially significant implications for ocean economic activities, such as shipping, oil and gas, cruise tourism, fishing, marine mining, biotechnology, submarine cable, as well as for related sectors, such as maritime law, insurance, and investment.

The resolution identifies “the need for the comprehensive global regime to better address the conservation and sustainable use of marine biological diversity in areas beyond national jurisdiction.” The resolution calls for a 2-year preparatory process in 2016–17 to develop the treaty elements.

Eco Magazine | 9 July 2015

Clean Water Wins in Court

A federal Third Circuit Court of Appeals opinion, released 6 July 2015, upholds a lower court decision that affirmed the legality of the multistate Chesapeake Bay cleanup effort. The historic ruling found in favor of the US Environmental Protection Agency (EPA), the Chesapeake Bay Foundation (CBF), and other intervenors. It will ensure that efforts to clean up local rivers, streams, and the Chesapeake Bay will continue.

After decades of failed voluntary efforts, and as part of the settlement of a 2008 Clean Water Act lawsuit by CBF in December 2010, the EPA established science-based limits on the pollution fouling the Chesapeake Bay and its rivers and streams (formally known as a total maximum daily load, or TMDL). In addition, the states developed individual plans on how to achieve those limits and committed to 2-year milestones that outline the actions they will take to achieve those limits, and the EPA promised consequences for failure. Together, the limits, plans, and milestones make up the Chesapeake Clean Water Blueprint.

“The Chesapeake Bay TMDL will require sacrifice by many, but that is a consequence of the tremendous effort it will take to restore health to the bay,” said CBF President William C. Baker. “Farm Bureau’s arguments to the contrary are unpersuasive, and thus we affirm the careful and thorough opinion of the district court.”