Environment

Long-Term, Periodic Aerial Surveys Cost-Effectively Mitigate Methane Emissions

This paper presents 2 years of results from an ongoing multiyear initiative consisting of periodic, large-scale aerial methane surveys paired with ground crew inspection, validation, and prioritized repair.

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<b>Fig. 1—</b>A methane plume, colored by methane concentration from blue (low) to white (high) and generated by an imaging spectrometer, emanates from a well pad imaged using a high-resolution optical camera.
Source: SPE paper 201312

Detecting and reducing fugitive methane emissions can be time-intensive and costly for the oil and gas industry. Currently, leak detection and repair (LDAR) surveys are required periodically to inspect equipment and infrastructure for potential problems. Traditional LDAR, while effective for identifying the source of an emission, generally requires personnel traveling to each site to inspect equipment in situ, which can be costly in terms of labor and travel time. Moreover, prioritizing inspections by a set schedule and available manpower, rather than the known presence of ongoing methane emission, creates a situation where fugitive emissions can occur undetected for a long time between site visits. This can be especially problematic for a large emission because the distribution of emissions tends to be skewed, with only a small number of sites responsible for most of the volume of methane emitted.

An alternative approach is Smart LDAR, whereby large, fugitive emissions are found through some form of cost-effective yet frequent monitoring. This reduces overall costs and increases the efficiency and speed with which fugitive emissions can be repaired. A similar implementation is Guided LDAR, in which a large area is quickly surveyed for emissions and ground crews are dispatched to detection sites. While some approaches use ground vehicles to assess a large area, an airborne or spaceborne approach allows for a more comprehensive survey of a large footprint.

Nadir-view emissions monitoring historically has been challenging because of the ephemeral nature of some fugitive emissions and the need to identify a precise source point of the emission while discriminating between those caused by malfunction (which can be repaired) and those occurring during proper function (such as while relieving pipeline or tank pressure).

Additionally, such surveys require technology that can remotely detect methane emissions across a variety of meteorological and illumination conditions and thus represent the cutting edge of current remote sensing methods. This paper presents 2 years of results from an ongoing multiyear initiative consisting of periodic, large-scale aerial methane surveys paired with ground crew inspection, validation, and prioritized repair.

Results of multiple years of periodic aerial methane surveys over Pioneer Natural Resources’ operations footprint, consisting of approximately 680,000 acres in the Permian basin, are presented, including effects on operational efficiency, cost, and methane-emission mitigation. Aerial methane detection was performed using a light-aircraft-mounted, integrated methane-imaging spectrometer. Geo-referenced methane emissions data combined with real-time geo-referenced optical imagery provided accurate methane localization and source attribution. Ground inspection teams used optical gas-imaging technology to validate the aerial results and dispatch repair teams. Externally validated leak quantification provided by the spectrometer further allowed accurate measurement of methane mitigation (Fig. 1).

Aerial methane inspections of nearly 10,000 operations sites per survey, including wells, tank batteries, and all associated equipment, are reported for multiple years of periodic surveys. The data show a complete picture of the most significant methane emissions from the Pioneer operations footprint over consecutive years and has proven invaluable for enhancing operational efficiency. Based on the data, Pioneer has been able to identify the areas of highest effect and focus operational resources on those improvements. Surveys identified types of emission sources that can be addressed immediately within Pioneer operations and areas where Pioneer would need to work with others to improve overall gas takeaway challenges in the Permian basin.

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Find paper SPE 201312 on OnePetro here.