Green Completions

Overview

Before a well can start producing oil and gas, residual material from the drilling process (i.e., drill cuttings, fluids, or sand particles) trapped in the wellbore and surrounding reservoirs must be cleared. If not cleared, these materials will inhibit the producing flow and/or damage the reservoirs. The traditional method of clearing these residues is to pump air down the well to lift the solids and fluids out. The solids and liquids collected are then dumped in a pit/tank, and the gas is either vented or flared. Flaring is more common because venting natural gas or methane (CH₄) directly into the open air is usually not permitted (due to regulations) because methane is a greenhouse gas. While flaring still creates carbon dioxide (CO₂), it is a better method because CO₂ is a less potent greenhouse gas than CH₄. The concept of green completions is essentially to process natural gas without flaring it. Methane can be used commercially as an energy source. By separating methane from other residue, it can be processed and sold to a processing plant. In green completion, the gas is separated from other liquids and solids in heavy-duty separators/a flowback unit at the surface. The flowback unit directs separated water to a tank for reuse, solids into a reserve pit, and natural gas to a pipeline for sale.

Advantages

A major advantage of green completions is the significant reduction in emissions. According to the EPA, this could reduce emissions at hydraulically fractured wells by 95% per well. Although green completions are costly, according to Goldman Sachs and NRDC, an investment of $8,700 to $33,000 per well leads to a methane capture rate of 7,000 to 23,000 Mcf/well and a profit of $28,000 to $90,000 per well, meaning the equipment could pay for itself in as little as a few months and as long as a year. The EPA estimates as little as 60 days. This completion type also improves the industry’s public image, as only tanks are visible.

Disadvantages

One disadvantage of green completions is the equipment cost, $8,700 to $33,000 according to Goldman Sachs and NRDC. Another problem is the need for a pipeline to move the gas; even with a pipeline, back pressure can cause problems and significantly reduce equipment effectiveness.

Conclusion

Rapid development of natural gas plays in the US through fracking has resulted in venting or flaring natural gas during well completion. This has increased emissions and caused revenue loss. Green completions offer a solution to both issues. Green completion designs eliminate the need for venting or flaring. Additionally, natural gas that would have been lost is captured and sold. Revenue generated offsets the cost of the additional equipment. The process requires existing production infrastructure, such as pipelines, to sell the produced gas. Arguably the most important benefit is the positive environmental impact. Eliminating flaring and venting practically eliminates emissions during the completion process in natural gas wells. This improves the industry's image and provides sustainable operations for future development.

References

[1] "Flareless Completions," in Earth Works. [Online]. Available: https://www.earthworksaction.org/issues/detail/flareless_completions#.WDoY_LIrKUk. Accessed: Nov. 25, 2016.
[2] "Flaring vs. Green Completions," in Natural Gas Now. [Online]. Available: http://naturalgasnow.org/hydraulic-fracturing-2/flaring-versus-green-completions/. Accessed: Nov. 25, 2016.
[3] R. Bunzey, “Natural Gas and Green Completion in a Nut Shell,” Energy In Depth, 26-Nov-2012. [Online]. Available: https://energyindepth.org/marcellus/natural-gas-and-green-completion-in-a-nut-shell/. [Accessed: 20-Nov-2016]
[4] "EARTHWORKS | Flareless Completions", Earthworksaction.org, 2016. [Online]. Available: https://www.earthworksaction.org/issues/detail/flareless_completions#.WDXFReYrI2w. [Accessed: 20- Nov- 2016].

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