Kansas Is Flatter than a Pancake

Someone recently did a geometrical comparison between the topography of Kansas and the roughness of an ordinary pancake, and found the pancake to be rougher.  So Kansas really is flatter than a pancake.  Texas isn’t flatter than a pancake, though it feels like it is.  (Before my sophomore year in college, I helped lead one of the so-called Freshman Trips, a sort of initiation rite for incoming Dartmouth freshmen run by the Outing Club.  It’s a three-day excursion, usually hiking, in backwoods New Hampshire or Vermont, concluded by an evening celebration at the college’s ravine lodge on Mount Moosilauke.  One of the incoming freshmen in my group was from Texas, and I thought he was a grandstanding liar, especially when he talked about the great piney forests of east Texas…until years later, when I learned about the great piney forests of east Texas.)

But Brownsville is sloped enough to go from dry land down to sea level, though tides in the Gulf of Mexico aren’t much to speak of.  In fact, if you aren’t looking for them, and paying close attention, you won’t notice any tide at all.  That tends to be the way with semi-enclosed seas, like the Gulf, or the Mediterranean (in fact the Gulf is sometimes called the American Mediterranean).

I’m on an oil drilling rig, lying in the port of Brownsville waiting to be towed out of the harbor and down along the coast to offshore Mexico, where we will potentially then be towed further offshore to the drilling location.  I say potentially, because that is of course the plan, but the offshore relocation could be immediate or a matter of a few more weeks.  If the latter, I won’t be staying on board to wait.

There are many types of drilling rigs, depending on just how particular you want to get, but I’ll break them down into three categories: (1) fixed, (2) jackup, and (3) semisubmersible.  The oldest kind, hearkening back to the development of offshore oil drilling in California and Louisiana, is fixed.  In California, the rigs were really just derricks mounted on very long piers which extended out from  the beach.  The southern half of Louisiana is basically a gigantic swamp, so piers weren’t as practical as self-standing platforms, fixed in the soil but unattached to any dry land.  The very first platform was built in 1937-8, about a mile offshore of Cameron, Louisiana, in about 14 feet of water (14 foot water depth at a mile out! Now that’s delta country).  The pilings were driven deep into the mud and sand, and a deck was built 15 feet above the water, designed to detach and float away in the event of a hurricane, so as not to pull up all the pilings with it.  In 1940 this design was vindicated, as a hurricane destroyed the deck but left most of the pilings, so the platform could be rebuilt.  The offshore oil industry was off and running.

 

Such fixed platforms were the standard throughout the subsequent decades, but eventually, the water depths (over 1000 feet) became prohibitive in building the enormous leg structures.  By the 50's, a second kind of rig had already become common: the jackup, basically a mobile version of the fixed platform.  Jackups have three or four legs which can be cranked up or down, and the platform thus jacked up over a specific location in the water for drilling.  Cranking the legs down and planting them on the sea floor is known as “pinning”.  The rig might have its own motor, and be able to power itself to its next location, or it might require towing.  This kind of mobile platform is economical for exploration in the event that no oil is found (known as a dry well, though there is always water).  Movable rigs save the expense of building permanent fixtures where finding oil is uncertain—that is, for all exploration--and the same rig can be used to drill many different wells at different spots.  Functionally, jackups operate in maximum depths of 300 feet.  Longer legs become structurally impractical.

In 1988 Shell commissioned the tallest fixed oil rig in history, Bullwinkle, in the Gulf of Mexico.  The platform stands over 1700 feet (nearly 500 m) above the sea floor.  But transporting, positioning and successfully sinking (on its feet and not it side) such huge leg assemblies was risky and difficult.  And the search for oil was already moving deeper.

For this deeper water the semisubmersible was developed, the giants of today, huge platforms of over 300’ on a side, sitting on gargantuan

pontoons.  The rig is towed out to its drilling location and the pontoons partially filled with water, so that the hull sinks to a depth below ordinary wave depth (i.e. out of range of all wave motion except for hurricanes), while the platform deck is more than 50 feet above the water.  This provides enough stability, considering the size of the platform, for drilling operations, and is tall enough to keep the deck equipment from being ruined by the waves of a hurricane.  This type of platform is known, straightforwardly enough, as a semisubmersible.  They are quite complex now, self-propelled and using GPS and computer models to position themselves dynamically to within a few centimeters’ accuracy.  The Deepwater Horizon was such a rig, going to show (again, as ever) that the fanciest tools count for nothing against human recklessness and incompetence.

The Noble Tom Jobe, where I am, is no such giant.  It’s a modest enough three-legged jackup, with legs over 200 feet tall, due to be towed by three tugs down to Mexico.  The quarters are identical to every survey and research vessel (except for the Persistence, but that was just a fire boat unfit for survey work) I’ve ever boarded.  That is to say, steel and composite flooring, plastic paneled walls, fluorescent lighting, the annoying stench of Simple Green, and piercingly cold air conditioning in the bunks.  The food’s about as bad as any other ship, too.  There’s one somewhat subtle difference: the crew’s quarters are a three-story structure toward the bow of the rig, so you go up and down the stairs much more than you would in a ship, which tends to be longer and not so vertical. 

But the biggest difference between a ship and a rig is the deck.  On a ship, you generally have open space at the bow and stern, where you can walk out and enjoy a bit of a view, perhaps feel some of the spray (provided it’s not an ice-cold shower bath).  On a rig, there is no such place except for the helideck, which is frighteningly exposed (for someone fearful of heights like I am), and of course off-limits (for exactly that reason) except for those getting on or off the helicopter, and the landing crew.  Otherwise, the deck is cramped with the huge machinery needed to drill for oil: cranes, tanks full of drilling mud (pumped into the borehole for two reasons: to lubricate the drill bit and, by means of its weight, to keep oil, gas and other pore fluids in the rock from rushing to the surface—which is what happened to the Deepwater Horizon), the drilling derrick.  It’s a crowded, dangerous, dirty, ugly space, befitting the complexity and difficulty of the oil drilling industry.  Rigs like this are part of the bowels of modern society as we know it.  With these machines we gain the leisurely, energy-rich life we know.  For how much longer is a very good question.

I have lots of down time, particularly when the rig is being moved (as we are now—the tugs are rotating the rig in preparation for tomorrow morning’s departure).  I’ve run a few very basic tests on the sonar units, but haven’t even put them in the water.  I might not get that chance.  My job here is to operate a small scanning sonar—like a sidescan, only it’s not a torpedo-like fish that we tow, but instead a little cylinder that I drop into the water and rotate—to take an image of the seafloor where we might put the legs down, in order to verify that there are no hazards (like equipment or big holes).  I’m basically part of the insurance policy against a storm, if the rig needs to put its legs down and ride out rough weather while the tugs cast off and leave.  If all goes well on this transit, I will have no work to do but remain on standby.

There are worse ways to support the family, I guess.