By Jennifer A. Dlouhy and Emily Pickrell
The 2010 Gulf of Mexico oil spill focused attention on the hazards of drilling for oil a mile below the surface of the sea, but recent incidents have brought new attention to dangers that still lurk on the shallow continental shelf, where companies rely on decades-old pipes and platforms to tap aging fields.
The explosion of a natural gas well 55 miles from Louisiana’s coast in July, along with a fatal production platform fire last November and a leaking gas reservoir in February, dispel the argument that the biggest offshore drilling risks exist only amid bone-crushing pressures in deep waters hundreds of miles from the shore.
“There are differences in drilling exploratory wells in deep water versus ongoing production in shallow water,” said former deputy Interior Secretary David Hayes. “But the point is that you’re dealing with an inherent risk proposition in both. We’re moving what can be explosive or volatile hydrocarbons in an environment where you’ve got water issues and isolation.”
Bud Danenberger, a consultant and the former federal chief of offshore regulatory programs, notes that the vast majority of the 150 well control incidents recorded in U.S. waters since the 1950s have occurred in shallow stretches.
And the management failures that investigators say contributed to the 2010 blowout of BP’s Macondo well can happen on land or close to shore too.
“You have to consider the whole array of risks,” Danenberger said. “There are some risks associated more with deep water and some more associated with the shelf and then there are other risks, like whether you are in a hurricane prone area.”
Workers are still responding to the blowout of a Walter Oil & Gas well in the Gulf of Mexico July 23 that forced the evacuation of 44 workers and ignited a fire on the drilling rig operated by Hercules Offshore.
Although no oil was spilled and sand eventually clogged the well, halting the flow of natural gas at the site, it could take weeks to plug the hole permanently.
More workers on shelf
While the future of energy development in the Gulf may lie in its deepest frontiers, the shelf is where more people are working every day – boring new wells and maintaining aging production platforms and facilities.
Since the start of this year, federal regulators have issued 151 permits authorizing drilling in shallow water, generally defined as less than 500 feet, and 68 permits for deep water.
Overall, the shallow Gulf contains 10,093 oil and gas wells, compared with just 1,578 in deep water, according to the Bureau of Safety and Environmental Enforcement.
And while 2,790 production platforms draw oil and gas from shallow stretches of the Gulf, only 73 work in deep water.
Michael Bromwich, who spearheaded the reorganization of federal drilling oversight after the 2010 spill, said good well design and careful drilling practices are the key to safety, in both deep and shallow water.
“Whenever you have a lot of people engaged in an inherently risky activity where judgments have to be made – and those judgments can sometimes be wrong – you’re going to have the risk of a blowout,” Bromwich said.
Still, deep water and the shelf each present unique challenges.
For instance, in the ultra-deep waters of the Gulf of Mexico, oil companies don’t have the benefit of years of geological assessments to guide them.
“If you are on the shelf, most of the time you know when and where the problems are going to pop up,” said Don Van Nieuwenhuise, director of the professional geoscience programs at the University of Houston’s Department of Earth and Atmospheric Sciences. “For frontier areas, like the deep water, you are drilling in the dark.”
The technological challenges of the deep water are formidable, and access is tricky, as the weight of water prevents divers from reaching the subsea wells and emergency equipment on the sea floor.
“You are pushing the thresholds of water depth, temperature and pressure, which challenges your limits of safety,” Nieuwenhuise said.
But in the shallow waters, drillers can run up against unexpected pressure variations within a reservoir, which can compromise the integrity of the well and cause a blowout. They also must guard against washouts – collapses in sections of well that don’t contain the reinforcing pipe called casing.
“On the shelf, you have different issues. Instead of having high pressure, you have a challenge of having low pressures. You don’t want to lose your well control fluids in the well,” said Charlie Williams, a former Shell engineer who now heads the industry’s Center for Offshore Safety.
Danenberger said hurricanes can pose greater risks to pipes, platforms and jack-up rigs standing in just a few hundred feet of water, while floating drilling units typically used in deep water may be better able to ride out a storm.
The shelf also contains a lattice of pipes and platforms developed since drilling began there in the 1940s. That aging equipment may be more prone to malfunction, and maintaining it can require frequent welding, cutting and heavy lifting that pose dangers to workers.
There’s a human factor too. The cost of entry for deep-water drilling is so high that it is dominated by a handful of major oil companies, whereas thousands of smaller companies are working on the shallow shelf.
Danenberger said companies tend to steer their most skilled people and top technological innovations toward the deep water, where the potential payoffs are bigger.
After the 2010 disaster, federal regulators made some broad changes for all offshore drilling, although some new rules applied solely to deep-water activity.
At the time, shallow-water supporters, led by Hercules Offshore Executive Vice President Jim Noe and Mississippi’s former natural resources director, Scott Angelle, complained that drilling permits were flowing too slowly and that new requirements were being applied too broadly.
“The shallow water industry already has a demonstrated track record of operating without major incident since the 1940s,” Noe said in 2011. “We just want to get back to work.”
Regulation vs. risk
Bromwich, the former regulator and now a consultant in Washington, said shallow-water boosters weren’t explicitly seeking exemption from the new rules, but sometimes came close. They contended, Bromwich said, that his agency was overstating the case for shallow-water regulation.
Federal regulators insisted on robust new modeling of the “worst case discharge” of oil and gas from all proposed offshore wells.
The shallow-water advocates argued unsuccessfully that regulators should accept smaller worst-case flow estimates because blown-out shallow-water wells often bridge over – essentially plugging themselves with sand and debris – as happened at the Walter Oil & Gas well last month.
History: Major accidents in Texas
Noe defends that approach today, and insists that worst-case spill modeling, drilling permit reviews and federal oversight should be targeted, with more scrutiny devoted to the riskiest operations.
“Our industry should have a robust regulatory regime. It’s important,” Noe said in an interview last week. “But the regulations must be based on facts, based on science and based on calibration of risks, because not all operations are the same.”
Regulators say they will consider what they learn from investigations into the most recent shallow-water incidents, but it appears unlikely they’ll make major changes.
For the time being, they are encouraging companies more actively to share information with each to boost safety and learn from accidents.
Tommy Beaudreau, head of the Bureau of Ocean Energy Management that oversees offshore leasing, made the point last week when he and other regulators visited Houston for a meeting with oil executives prompted by the recent accidents.
“There is a lot of room for industry to step up on these issues,” he said.
Shallow water accidents
Recent Gulf of Mexico offshore energy incidents that have drawn new regulatory attention to shallow water work:
July 23: Forty-four workers safely evacuated a rig after a natural gas well blew out 55 miles off Louisiana. No oil spilled, but leaking natural gas ignited on the rig.
Feb. 4: Workers aboard a rig activated its blowout preventer after detecting an uncontrolled flow called a kick. No hydrocarbons escaped, but subsequent tests showed natural gas had migrated from the bottom of the well to a shallower formation
Nov. 16: Three Grand Isle Shipyard workers died and several others were injured in an explosion and fire while they refurbishing a production platform.