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Posts Tagged ‘PNAS article’

Excellent NOIA/ICF GHG intensity report, including the important caveats

Posted in climate, Gulf of Mexico, Offshore Energy - General, tagged , , , , , , , on May 24, 2023| Leave a Comment »

The NOIA/ICF report is favorable from a Gulf of Mexico perspective, but 2 general caveats should be highlighted:

  • “The estimation of the production related GHG for various crude oils and condensates is a complex process that is hindered by lack of public, up-to-date, and high-quality data.“
  • “There is considerable controversy regarding certain critical data including quantity of gas flared, operational flare efficiencies, and the volumes of methane releases along oil and gas supply chains.”

Comments:

  • More work is needed to better determine cold venting volumes:
    • Table 7, p. 13, of the NOIA/ICF report indicates venting (methane) emissions of 71,200 metric tons/year for GoM operations. That number is aligned with the 2017 GOADS data (70,488 tons per Table 6-11, p. 112).
    • ONRR venting data are in the same ballpark as the ICF and GOADS data. Per ONRR data, 2.35 bcf (~61,000 metric tons) were vented in 2022.
    • The recent PNAS report found that much more gas is being vented: 410,000 – 810,000 tons annually. If the PNAS findings are accurate, venting is being significantly underestimated and/or under-reported.
    • Per ICF, lower flaring and venting volumes are the main reason for the GoM’s lower GHG emission intensity, so data accuracy is important. The difference between the government data and the PNAS findings (see table below) should be carefully assessed.
  • The NOIA/ICF report did not distinguish between GoM deepwater and shelf emissions.
    • The PNAS report indicates much higher methane emissions intensity on the shelf, as do most subjective assessments.
    • Future studies should provide separate GHG intensity data for shelf and deepwater facilities.
  • All production cannot be from the lowest emission intensity sources. The objective should be to minimize emissions from each source, not to eliminate production. GoM shelf operations have other advantages, most notably the production of nonassociated natural gas.
sourceGoM gas vented (annual in metric tons)
ICF report71,200
GOADS 201770,488
ONRR 2022 data61,000
PNAS report410,000 – 810,000

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PNAS article: “Excess methane emissions from shallow water platforms elevate the carbon intensity of US Gulf of Mexico oil and gas production”

Posted in climate, Gulf of Mexico, Offshore Energy - General, tagged , , , , , , , , , on April 11, 2023| Leave a Comment »

An interesting study published in the Proceedings of the National Academy of Sciences (PNAS) was brought to my attention by leading offshore energy historian Tyler Priest. The study used airborne observations and emissions reports to measure the carbon intensity (CI) of Gulf of Mexico oil and gas production. Their CI measure is grams of CO2 equivalent of greenhouse gas emissions per megajoule of energy produced.

The authors conclude that inventory emissions of CO2 (as reported to BOEM) “are generally consistent with observations from our aircraft survey, suggesting that combustion is well represented in the federal inventory.“

However, that is not the case for methane (CH4) emissions which are underestimated by the Federal inventories. As summarized in the chart below, deepwater facility methane emissions are consistent with the reported inventories, but shelf emissions in State and Federal waters differ significantly.

Comments:

  • As previously discussed, the lower CI for deepwater production is entirely consistent with expectations. When the most modern 5% (57) of GoM platforms are producing 93% of the oil and 76% of the gas, their CI should be impressive (which indeed it is).
  • As summarized using ONRR data, more gas-well gas was vented from 2015-2021 than was flared, which is not what you want from a GHG standpoint. Gas wells are predominantly at shallow water facilities, many of which are not equipped with flare booms.
  • Oil-well gas, most of which is produced at deepwater platforms, is flared rather than vented by a ratio of approximately 4 to 1.
  • About 15 years ago, the Federal government (MMS) considered requiring that older production platforms be retrofitted with flare booms, but safety, space limitations, and cost considerations precluded such a regulation. Instead, additional flaring/venting limits, and measurement and reporting requirements were imposed.
  • One bad actor may have been a major contributor to the shelf methane emissions observed during the study’s observational flights. That company entered into bankruptcy proceedings. Presumably those issues have been resolved and more rigorous monitoring and enforcement practices have been implemented. I’ll be looking at the 2022 ONRR flaring and venting data for evidence of such improvement. The remainder of the 2022 data should be available in May.
  • The subject study’s only observational measurements were in August 2020. Followup airborne measurements would be helpful.
  • The study only considered production emissions. Shelf facilities are primarily natural gas producers and would thus have a lower relative CI when consumed.
  • When will updated BOEM GOADS flaring and venting data be available? The latest data are for 2017 (cover below)? Are GOADS data being compared with ONRR and World Bank data?

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