Dec 15 2020
Leaking natural gas wells are considered a potential source of methane emissions, and a new nanomaterial cement mixture could provide an effective, affordable solution for sealing these wells, according to a team of Penn State scientists.
“我们发明了一种非常灵活的水泥，对破裂具有更具耐药性。”said Arash Dahi Taleghani, associate professor of petroleum engineering at Penn State.“这很重要，因为世界各地都有数百万个孤儿和废弃的井，壳体中的裂缝可以使甲烷逃到环境中。”
When natural gas wells are drilled, cement is used to secure the pipe, or casing, to the surrounding rock, creating a seal that prevents methane from migrating into the shallow subsurface, where it could enter waterways, or the atmosphere, where it is a potent greenhouse gas, the scientists said.
Wells can extend miles underground and over time changing temperatures and pressures can degrade the cement, causing cracks to form. The scientists said repairs involve injecting cement in very narrow areas between the casing and rock, requiring special cement.
“在施工中，您可以将水泥混合并倒入水泥，但是要密封这些井，您正在固定一个区域，其厚度小于毫米或胶带的区域，”Dahi Taleghani said.“能够通过甲烷分子可以逃脱的这些非常狭窄的空间更好地水泥是这项工作的美。”
Adding almost 2D graphite created a cement mixture that better filled these narrow spaces and that was also stronger and more resilient, the scientists found. They recently reported their findings in the国际温室气体控制杂志.
玛丽亚姆·塔巴塔巴（Maryam Tabatabaei）是约翰和威利·利昂（Willie Leone）能源和矿产工程系的博士后学者，也为这项研究做出了贡献。
The scientists developed a multi-step process to uniformly distribute sheets of the nanomaterial into a cement slurry. By treating the graphite first with chemicals, the scientists were able to change its surface properties so the material would dissolve in water instead of repelling it.
"如果我们只是将这些材料倒在水中并混合，这些小颗粒会趋于粘在一起并形成一个砾岩，yabo214" Dahi Taleghani said.“如果它们不均匀分散，那么石墨在水泥内部的不那么强。”
The cement mixture can be used in active unconventional wells like those found in the Marcellus Shale gas play, or to seal orphaned and abandoned gas wells, the scientists said. It also shows promise for use in carbon dioxide capture and storage technology.
Graphite is more affordable than other nanomaterials previously used to bolster cement performance. In addition, very little of the material is needed to strengthen the cement, the scientists said.
"Considering the low cost of the amount of graphite nanoplatelets required for this test, this technology may provide an economic solution for industry to address possible cementing problems in the field,"Dahi Taleghani said.
来源：https://www.psu.edu/