HARD SCIENCE: Research to better understand cement and how to control it could be put to good use, helping companies like BP and Halliburton design more reliable cements for sealing oil wells deep beneath the ocean and, hopefully, avoid catastrophes such as that which occurred in the Gulf this year.
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After months of hearings and finger-pointing, a Deepwater Horizon investigative commission formed by President Obama has begun to shed light on what led to the April 20 explosion that killed 11 and initiated a deep underwater gusher that spewed more than 750 million liters of crude into the Gulf of Mexico. Yet one of the biggest mysteries remains—why did the drillers use cement designed to shore up the well despite warnings that the mixture would not hold?
The National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling earlier this week concluded in their report (pdf) that there were clear indicators of problems with the cement mixture prior to the explosion. In particular, negative-pressure tests designed to determine whether the well casing could provide a barrier to the gas and oil failed, meaning there was a danger of hydrocarbons escaping up to the rig and catching fire, according to the seven-member, bipartisan commission, which President Obama appointed in May.
Judged through the lens of science, the commission's report is less a condemnation of well owner BP or cement contractor Halliburton than an indicator that, even though the binding agent has been in wide use since Roman times, the chemical properties of the material itself is still largely a mystery.
"It's pretty amazing that, given the importance of it, not a lot of scientific study has been done of cement," says Brad Chmelka, a chemical engineering professor at the University of California, Santa Barbara. "We're asking it to do things in extreme conditions that it wasn't designed to do and isn't optimized for."
Cement begins as a powdery mix of grains made by grinding and then heating limestone with small amounts of other materials such as clay. The addition of water to the powder initiates a chemical reaction that causes the grains to adhere to each other and form strong, stable bonds. For this reason, cement is used as the main binding agent in concrete, a building material that also includes sand, gravel and other granular substances. Certain formulations of cement, those used for deep sea drilling, for example, have the ability to harden and set even underwater.
The way cement is currently used in different industries is the result of a tremendous amount of accumulated wisdom, says Chmelka, who is part of a team that for several years has been studying the molecular properties of cements. That team includes researchers from the University of California, Santa Barbara, Princeton University, Imperial College London, Roberts Consulting Group in Acton, Mass., RTI International in Research Triangle Park, N.C., and Halliburton, which has provided much of the project's funding. Halliburton's ongoing role in the research has been to inform the researchers on the conditions that matter when formulating and working with cement, such as realistic temperatures and cement compositions, Chmelka adds.
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7 Comments
Add CommentThe problems Halliburton had with their cement in Iraq should have given you a clue in how they do business and you should had stayed away from them.
Reply | Report Abuse | Link to thisDon't you have to burn the limestone instead of just heating it up a little bit? How is cement going to hold under water if you put all those chemicals in it to keep it fluid? Isn't it obvious now that the chemicals and minerals in the seawater reacted against those chemicals and developed a problem?
Didn't Chevron conduct their tests according to the specifications of Halliburton. It is going to be a bit difficult for Halliburton to lie their way out of this one and place the blame on Chevron's store bought cement.
I was told that the secret of the roman's cement was lost, as well as the way they produced the red pottery "terracota". Is this still true ?
Reply | Report Abuse | Link to thisFor all the obvious potential of this research, it's worth noting one thing. All the science in world won't help if well operators can ignore findings they don't like, and get away with it. We'll have more blowouts until the culture changes.
Reply | Report Abuse | Link to thisI doubt that the well operators(those on the rig)will knowingly endanger themselves by using unsafe materials or practices .
Reply | Report Abuse | Link to thisThe men on the rigs are skilled intelligent and to suggest that stupid like alflanagan is being dim.
Sounds like we have a smoking gun to me... Haliburton may have been paid to sabotage the well and create a disaster, or a diversion.
Reply | Report Abuse | Link to thisTo clarify a misquote attributed to me in the 4th paragraph of the article:
Reply | Report Abuse | Link to thisThere has of course been a great deal of scientific study conducted on cement chemistry and properties; this is evident in a number of scientific journals that focus on the science, research/development, and/or technologies of cement, including for example the Journal of Cement and Concrete Research.
The quote in the first sentence of the 4th paragraph should have properly stated:
"It's pretty amazing that, given the importance of it, much still remains unknown at a molecular level, which current research seeks to address."
A great deal remains still to be learned, especially at a molecular level and under the harsher and more specialized conditions associated with increasingly diverse applications, including for deepwater oilwells.
Roman cement was a mix of volcanic ash and hydrated lime. Very slow set time but very strong. When heating limestone, the CO2 is “burned off” and you have lime (quicklime). It must be hydrated to work as cement. Lime cement is not hydraulic (it will not set under water). The volcanic ash mixed with the hydrated lime made a pozzolin, i.e., a material, with calcium hydroxide that will set under water. Its name comes from Pozzuoli, Italy where it was first used by the Romans.
Reply | Report Abuse | Link to thisPortland cement is made from limestone and clay and needs a much hotter oven to make.