WASHINGTON — The saga of BP’s runaway Deepwater Horizon well, already entering its third month, has entered a crucial phase that will determine whether the Gulf of Mexico gusher ends in mid-August or persists, perhaps for months.
Unlike the previous public drama, this act will unfold miles below the seabed, as drill technicians begin delicately maneuvering a relief well that they hope will pierce and cap the gushing oil well.
This week, BP began using sensitive electronic equipment to detect differences in the rock’s electromagnetic field in an effort to pinpoint the metal pipes inside the wellbore. Based on what they find, they’ll make adjustments every few hundred feet in an effort to intercept those pipes and kill the gusher by pumping it full of tons of heavy drilling mud and then concrete.
The stakes riding on those adjustments are enormous, and the chance of failure, at least on the first try, is huge.
“The engineers will tell you that they have a 95 percent chance of success” in killing a runaway gusher with a relief well, said Bruce Bullock, the director of the Maguire Energy Institute at Southern Methodist University in Dallas. “But that depends on how you define success. It’s quite unlikely they’ll hit it on the first stab.
“They’re aiming at a salad plate thousands of feet down,” Bullock said: a 7-inch pipe buried in concrete, 12,000 feet below the seafloor.
Every time a relief well misses, its crew must back up the drill bit and try again. Last year, a relief well aimed at capping a blowout in the Timor Sea off Australia missed its target four times before connecting. Each new effort took an average of another week of drilling, for a total delay of 27 days after the drillers began closing on their target.
A similar delay at the Deepwater Horizon site would mean as much as 1.62 million barrels more crude dumped into the Gulf — more than 68 million gallons — if the latest government estimates of the flow are accurate.
Many obstacles lie in the way of the relief well, not least of which are the same vagaries of subsurface strata and gas pockets that put the Deepwater Horizon 43 days behind schedule before bad decisions and equipment failures sent it to the bottom of the Gulf.
“Things have gone well, down to this stage,” Kent Wells, BP’s senior vice president of exploration and production, said a week ago about the relief well drilling. “Of course, that doesn’t always mean things will continue to go well.”
His caution is echoed by Coast Guard Adm. Thad Allen, the Obama administration’s point man on the Deepwater Horizon catastrophe.
“They are slightly ahead of schedule,” Allen said of the relief wells during one of his daily briefings this week, “but I’m not coming off the second week in August date because we know, you know, things can happen.”
BP’s Wells said last week that the wellbore now lies tantalizingly close, just 200 feet laterally from the first relief well. That puts it within the limits of current electromagnetic ranging capabilities.
At 10,677 feet below the seafloor, however, the first relief well is still at least 1,000 vertical feet above where BP’s engineers would like to enter the Deepwater Horizon wellbore. While electromagnetic ranging helps, it can be off by as much as 10 percent, according to a study by John Wright, one of the world’s foremost experts on relief well drilling. Wright’s employer, the Houston blowout-killing company Boots &Coots, declined interview requests.
So for the next several weeks, drillers will take a path down parallel to the Deepwater Horizon’s wellbore while attempting to inch closer, guided by electromagnetic pulses in a process that in Wells’ descriptions sounds equal parts science and trial and error.
“We’ll drill a little bit, then we sort of use our tools to sort of test where we think it is,” he said. “We’ll pinpoint a place, then we’ll drill another couple hundred feet towards it, test again and see if we’ve, you know, made the right progress.”