Roughnecks and Mud
Coleman takes us through the Deep Seas‘200-bunk living quarters, its offices, and the bridge, and then out onto a catwalk that hovers over the deck. Below is a rack holding “risers,” 75-foot-long sections of pipe that house the drill string on its way to the seafloor. The drill string isn’t actually a wobbly piece of cable but a series of 130-foot-long hollow pipes “strung” together, which push the bit down through the risers and into the earth. Enormous cranes lift each section of riser onto a conveyor belt. The belt then tips and guides each riser into position in the derrick.
The catwalk follows the riser belt onto the drill floor of the 226-foot-tall derrick. It’s the derrick, a giant scaffold narrowing toward a peak, that you think of when you think of an oil well. From it hangs the hook holding the drive that spins the drill string and the bit below. There used to be a guy way up there, on what’s called the monkey board, but automatic pipe-racking systems have recently replaced him. Dozens of sections of drill string are stacked inside the Deep Seas‘derrick, and they swing with the slow motion of the ship. Beneath the drill floor – which we’ll visit later – is the moon pool, the one spot of transcendent beauty on Deep Seas. There, the risers and the drill string within vanish into a pellucid square of water, fish shimmering around them.
Right now, two roughnecks – and yes, they still call themselves roughnecks – are helping guide sections of drill string down an opening in the drill floor, directing a machine that connects the segments. Overseeing the roughnecks are about eight guys watching computers in the glassed-in driller shack. They monitor information from sensors embedded in the drill, which measure things like how much weight the hook at the top of the derrick is holding, the pressure inside and outside the drill string, and the speed at which the bit is turning.
We leave the derrick and head down a few stories to see the mud module, which looks a little like a cross between a brewery and a sewage treatment plant. “Mud” is one of the most important tools in the driller’s kit, though it is rarely thought about or mentioned outside the industry. A synthetic or petroleum-based lubricant, mud is sometimes said to look like chocolate milk. Deepwater drilling requires the synthetic version, which was developed in the mid-1990s. It has two outstanding qualities: it maintains its lubricating properties under higher pressures than the traditional diesel-based mud, and it’s not classified as a pollutant by the U.S. Environmental Protection Agency. In the mud module, just past the derrick, are stored 15,000 barrels of the stuff, which – at $165 a barrel – is a king’s ransom in mud.
Mud does more than lubricate, though. It is pumped down the well – through the drill string and out the bit – and it comes back up inside the riser, bringing with it “cuttings,” chips and shards of sediment and rock. Mud can be made in different weights, and at great depth it exerts immense pressure on the casing and on the walls of the “hole” – the freshly drilled bottom of the well. That keeps equally huge geological pressures from collapsing the well or, worse, starting oil flow too early, which is the definition of a “blowout.” Spindletop, the 1901 Texas well that rained something like 800,000 barrels of crude on amazed prospectors, is the classic example of a blowout.
After leaving the mud module, we head back along the deck until we meet Hercules, a remote-controlled submarine, which is currently sitting under a crane and ready to swing out alongside the ship. At 4,000 feet below, everything is done by the unmanned Hercules; it is simply too deep for human divers. Hercules is a box of mechanical arms, propellers, cameras, and lights overseen by contract technicians. Of its two remote arms, one is controlled by joystick and the other by a glove of sensors attached to the hand and arm of the operator. The setup is accurate enough to turn a half-dollar-sized bolt with a wrench.