- Politics and Social Issues»
- Environment & Green Issues
Analyst Receives Emails From Deep Horizon Oil Rig Workers About Cementing Dispute Before Gusher Blew
Problems with Drilling into the Ocean Floor
To resolve a problem, first, an analysis must be done to determine what caused the problem. A natural gas bubble is thought to have triggered the Deep Horizon rig explosion that has resulted in deaths, injuries, and millions of gallons of oil leaking into the Gulf of Mexico.
Michael Lynch, an energy and industrial expert, provides his analysis at Gerson Lehrman Group (GLG), a consulting firm that connects industries with experts in many fields. Since 1998, its technology-enabled platform for collaboration and consultation has helped the world's leading institutions find, engage, and manage experts across a broad range of industries and disciplines.
"According to one of the emails in circulation and I stress that these accounts cannot be verified and may be in error, a dispute arose between the BP Drilling Supervisor and one or more BP drilling engineers." The dispute concerned displacement of the heavy mud in the hole with sea water before beginning the cementation of the final plug. In the event, it was finally agreed to replace the heavy mud with sea water.
This appears to have been the fatal mistake. The displacement reduced the hydrostatic head by about 3,000 pounds per square inch. This greatly reduced the safety factor. Usually, the rig "stands cemented" for 24 hours to obtain ultimate cement strength. In this instance the rig stood cemented for 20 hours.
One possibility is that the casing failed, allowing crude oil and gas to enter the well. Another theory is that the natural gas began working its way up through the uncured cement and arrived at the "packoff".
The pressure of the gas column exceeded the containment strength of the "pack off", blew it away and began its ascent to the drilling rig. In an empty hole, natural gas travels at a rate of 1,000 feet per second. With salt water in the casing and riser, travel time would have been two or three minutes. Once the gas arrived at the surface and entered the engine room, the prime movers would have pulled the gas into the air intake manifold. The engines would have "run away", the generators would overload, a light bulb would explode (or something similar) and an explosion would have occurred. This was an exceptionally large gas flow and the secondary explosions must have damaged the ballast controls allowing the rig to list. At that point, the game was over. Again, I stress that this analysis is based on anecdotal evidence. But as a professional drilling and completion supervisor, I can read the tea leaves with some accuracy. (Little by little, facts emerge regarding Deepwater Horizon accident)
Perhaps BP might want to consult with the following experts who have been studying drilling into the ocean floor and retrieving methane gas for many years.
Timothy Collett, U.S. Geological Survey in Denver
Timothy Collett of the U.S. Geological Survey in Denver suggested one way to harness methane fuel. His solution was to liquefy the methane gas by partial combustion to form hydrogen and carbon monoxide atoms. The mixture would then be turned into a liquid hydrocarbon by use of a catalyst. Once in a liquefied form, the fuel would supposedly be easier to transport to its container. Thirty-five percent of the fuel would be lost during this procedure.
Roger Sassen of Texas A&M University
Roger Sassen of Texas A&M University proposed to have a production facility on the ocean floor. Here, emerging methane would be combined with water to form hydrate that would not be contaminated by mud or rock. The hydrate would then be towed by submarines to shallower waters where engineers could easily and safely decompose the hydrate into fuel.
Scientists at the U.S. Dept of Energy & Devinder Mahajan, Stonybrook University
In 2005, scientists at the U.S. Department of Energy's Brookhaven National Laboratory recreated the high-pressure, low-temperature conditions of the seafloor in a tabletop apparatus for the study of methane-hydrates, an abundant but currently out-of-reach source of natural gas trapped within sediments below the ocean floor.
A group built a vessel that mimics the seafloor temperature and pressure conditions, where they can study the kinetics of methane hydrate formation and decomposition. Unlike other high-pressure research vessels, the Brookhaven apparatus allows scientists to interchange vessels of different volumes, study even fine sediments, and visualize and record the entire hydrate-forming event through a 12-inch window along the vessel. In addition, mass-balance instrumentation allows the Brookhaven group to collect reproducible data in the bench-top unit.
One further advantage of doing this work at Brookhaven Lab is that the scientists can use the National Synchrotron Light Source -- a source of intense x-rays, ultraviolet, and infrared light -- to measure physical characteristics of the sediments under study. Using x-ray computed microtomography, the scientists gain information about the porosity and other physical characteristics that may affect the availability of nucleation sites where hydrates can form.
Such data about hydrate formation in natural host sediment samples are scarce. By studying different samples and learning what combinations of pressure and temperature keep the methane locked up, the scientists hope to identify ways to compensate for the changes the hydrates experience as they are brought to the ocean's surface so they can be extracted with a minimum loss. The comparisons of different sediment samples might also help pinpoint the most abundant sources of locked-up methane.
"It may be at least a decade before we can even think about mining these deposits, but answering these fundamental questions is certainly the place to start," says Devinder Mahajan, who holds a joint appointment as a Stony Brook University professor. "This is a very important issue tied to our future national energy security."
This research was initially funded by Brookhaven's Laboratory Directed Research and Development program and is now funded by the Department of Energy's Office of Fossil Energy. The symposium on Gas Hydrates and Clathrates is being co-sponsored by the Petroleum and Fuel Divisions of the American Chemical Society. (Scientists Create, Study Methane Hydrates in "Ocean Floor")
Devinder Mahajan lives in South Setauket, New York; Michael Eaton lives in New Haven, Connecticut.
The Risky Business of Mining Methane Hydrate
The potential rewards of releasing methane from gas hydrate fields must be balanced with the risks. And the risks are significant. Let's start first with challenges facing mining companies and their workers. Most methane hydrate deposits are located in seafloor sediments. That means drilling rigs must be able to reach down through more than 1,600 feet (500 meters) of water and then, because hydrates are generally located far underground, another several thousand feet before they can begin extraction. Hydrates also tend to form along the lower margins of continental slopes, where the seabed falls away from the relatively shallow shelf toward the abyss. The roughly sloping seafloor makes it difficult to run pipeline.
Even if you can situate a rig safely, methane hydrate is unstable once it's removed from the high pressures and low temperatures of the deep sea. Methane begins to escape even as it's being transported to the surface. Unless there's a way to prevent this leakage of natural gas, extraction won't be efficient. It will be a bit like hauling up well water using a pail riddled with holes.
Believe it or not, this leakage may be the least of the worries. Many geologists suspect that gas hydrates play an important role in stabilizing the seafloor. Drilling in these oceanic deposits could destabilize the seabed, causing vast swaths of sediment to slide for miles down the continental slope. Evidence suggests that such underwater landslides have occurred in the past with devastating consequences. The movement of so much sediment would certainly trigger massive tsunamis similar to those seen in the Indian Ocean tsunami of December 2005.
But perhaps the biggest concern is how methane hydrate mining could affect global warming. Scientists already know that hydrate deposits naturally release small amounts of methane. The gas works itself skyward -- either bubbling up through permafrost or ocean water -- until it's released into the atmosphere. Once methane is in the atmosphere, it becomes a greenhouse gas even more efficient than carbon dioxide at trapping solar radiation. Some experts fear that drilling in hydrate deposits could cause catastrophic releases of methane that would greatly accelerate global warming.
The Future of Frozen Fuel
In 1997, the U.S. Department of Energy (DOE) initiated a research program that would ultimately allow commercial production of methane from gas hydrate deposits by 2015. Three years later, Congress authorized funding through the Methane Hydrate Research and Development Act of 2000. The Interagency Coordination Committee (ICC), a coalition of six government agencies, has been advancing research on several fronts. Much of what we know about the basic science of methane hydrate -- how it forms, where it forms and what role it plays, both in seafloor stabilization and global warming -- has come from the ICC's research.
Interesting ideas about how to extract the methane from hydrates efficiently are also emerging. Some experts propose a technique in which miners pump hot water down a drill hole to melt the hydrate and release the trapped methane. As the methane escapes, it is pumped to the seafloor through a companion drill hole. From there, submarine pipelines carry the natural gas ashore. Unfortunately, such pipelines would need to travel over difficult underwater terrain. One solution is to build a production facility on the seafloor so it is situated near the hydrate deposits. As methane escapes from the heated sediments, workers in the plant would refreeze the gas to form "clean" methane hydrate. Submarines would then tow the frozen fuel in huge storage tanks to shallower waters, where the methane could be extracted and transported safely and efficiently.
According to the Energy Information Administration (EIA), total U.S. natural gas consumption is expected to increase from about 22 trillion cubic feet (0.622 trillion cubic meters) today to about 27 trillion cubic feet (0.76 trillion cubic meters) in 2030. Global natural gas consumption is expected to increase to 182 trillion cubic feet (5.15 trillion cubic meters) over the same period . Tapping into the methane locked away in hydrates will obviously play a key role in meeting that demand. (How Frozen Fuel Works)
Boosting Energy Production From 'Ice That Burns'
How Frozen Fuel Works, William Harris, science.howstuffworks.com/earth/green-technology/energy-production/frozen-fuel.htm/printable
Little by little, facts emerge regarding Deepwater Horizon accident--glgroup.com/News/Little-by-little-facts-emerge-regarding-Deepwater-Horizon-accident-48251.html
Scientists Create, Study Methane Hydrates in "Ocean Floor"
Lab Data may help develop strategies for mining natural gas locked up in seafloor sediments, March 13, 2005, bnl.gov/bnlweb/pubaf/pr/PR_display.asp?prID=05-17
Significant Gas Resource Discovered in Gulf of Mexicosciencedaily.com/releases/2009/05/090531100819.htm
Stabilization of methane hydrate by pressurization with He or N2 gas
ncbi.nlm.nih.gov/pubmed/18062683, Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, Canada. firstname.lastname@example.org