Drilling For Oil in Oklahoma...A brief look at operations on a modern oil rig

The Oil and Gas resources in Oklahoma have been tapped for a very long time. Two well known companies still have major facilities in the state, Phillips Petroleum in Bartlesville OK, and Conoco in Ponca City. Tulsa has been a major center for US petroleum for many years and is where the premier trade magazine of the industry, the Oil and Gas Journal, is published. More important for our story are the wildcatters, independent small drilling rig operators who drill for oil at the behest of small exploration companies. Comanche Exploration is one such company and they recently hired the H40 Drilling company to drill a new hole in an old oil field in west central Oklahoma. Petroleum geologists who have studied this oil field know there a substantial oil reserves in a layer of strata called the Hunton....and they have reason to believe that an older, deeper, layer of rock known as the mississippi layer may contain reasonable amounts of natural gas.

And so it begins....

• Here is a picture of a modern drilling tower and the ancilliary equipment. This picture is NOT of the rig featured in this story...I couldn1t drive the 60 miles back out to the rig during the day so I took a picture of another rig owned by the same company that was closer to town! Here is the rig featured...along with the driller and derrickhand (my brother) in this article.
• A giant diesel engine provides the primary power for operating the rig.
• Large chains and a complex transmission system transfer the power from this diesal to the rotory table.
• The rotary table is where all the action is. A drive chain from the main diesal comes in from the upper left (it is coverd by white (?) guard). This turns the rotary table which turns the yellow bushing, that turns the Kelley. The Kelley is the square pipe on the right. Also visible in this picture are pressure gauges for the rig and devices that are used to switch to a new piece of pipe (their use will be explained below).
• Down in the hole is the drill bit, a complex rolling bit with three main grinding wheels as shown here. The bit is attached to the end of the string, a chain of thirty feet long sections of pipe. The entire string of kelley, pipe, and bit is held by the blocks, a giant block and tackle capable of holding 340,000 lb of pipe and mud.
• Mud is not the stuff you get on your boots in the wintertime but a much more complicated mixture of material which serves a number of purposes on the rig. First and formost is to provide a fluid material to wash the bit clean of newly formed chunks of rock. Secondly, the mud provides weight to push down on the string, and the bit, to increase the force on the bit. Third, the mud lubricates the outside of the string as it is pumped down through the hollow pipes and then travels back up the outside of the pipe string. Mud is composed of a complex mixture of Soda Ash, Bentonite, Lignite and Sodium Hydroxide which is mixed on site and stored in large tanks. The mud is pumped down into the well using another large diesal engine and a set of reciprocating pumps with impressive pump heads. The mud is tested often to examine the type of rock being drilled through and to ensure that its physical properties are optimal for keeping the spinning string operating efficiently. If a pocket of loose rock is encountered a large amount of mud can be lost into the hole. It is common to add material called LCM or Loss of Circulation Material to help plug up the cracks. LCM is basically any cellulosic product that is handy and cheap at the site of a particular rig. Old newspaper, chopped up boxes...anything.
• The rig, while normal drilling is going on, is controlled from < a href=doghouse.jpg>inside the dog-house. A set of guages display the weight of the drilling string, the mud pressure, and the rate of rotation of the rotary table. Off to the side is a rotating drum recorder that keeps track of the drill string depth.
• When operating normally the rig emits a steady, low growl....good drillers, as the person who actually controls the rig is called, can tell how well the bit is doing and whether there are any problems by simply listening to the groans and squeeks coming from all the various engines, pumps, gears and the string of pipe.
• Everyone fears a strong, high pressure pocket of gas...which may posses enough force to pick up the entire string, mud and all, and push it back out of the hole. In reality, the classic hollywood movie scene of oil gushing out of the ground with smilling people is just wrong. If a well does blow out it is a very serious physical hazard and an even greater fire hazard.
• Under the main working area are a set of pressure monitoring apparati and plumbing directly tied to the the blowout preventers. The blowout preventer has two basic stages. The first is a pipe ram which will kick in and simply try to pinch down on the pipe string to keep it from coming out of the hole. The second is a blind ram which, using very high pressure hydraulics, will slice the string off and cap the well in the event of a full blow-out. Almost all of the time this will stop a blowout from escalating. When it does not you leave the rig quickly and RUN! (let Adair and Co come in and clean up the mess!)
• Once the drill bit has penetrated down close to 30 feet it is time to connect to a new piece of pipe (making a connection at the tool joint). This is when the deck area gets very busy and dangerous.
• First you must pull the bushing and the attached string up and put a collar around the pipe.
• Then you disconnect the kelley from the pipe using the tongs. The tongs are giant plier like devices that allow you to grab onto and torque the pipe. The tongs are suspended on seperate cables so that you only have to push hard enough to swing them into position, you do not have to lift them. Next, the Kelley is swung over to connect to a new pipe .
• Pull up the new pipe and make the new connection using the tongs. The new connection is tightened initially by throwing a loose chain around it and pulling on the chain using the cathead drum to pull the chain.
• Next, you drop the kelley down and reengage the bushing in the rotary table.
• Finally, a new piece of pipe is brought up from the side of the rig and placed in the mouse hole in prepartion for the next tool joint connection.
• the whole sequence of events take place over a few minutes time and requires three people, the driller, the chainhand, and the breakout hand. The driller controls all the hydraulics, including the block, from the deck control position just behind the rotary table. The chain behind the driller is being pulled taught by the cathead to tighten a new connection being made.
• Thirty feet at a time this sequence is repeated over and over again....to 5000, 7000, 10,000 feet. (that is a lot of mud and pipe!) At some point the bit wears out and the whole shebang has to be brought up out of the hole.
• Tripping out involves the rapid removal of three pipe segments at a time (for a rig like this one (called a triple for this reason), which tops out at over 90 feet tall...smaller rigs would only be able to take out two at a time (so they are called doubles).
• the pipe is stacked upright in the rig by the derrick hand, who works far up at the top of the rig on a little platform called the comb. The pipe is stacked in the slats as it gets disconnecected. It is ninety feet straight down from the comb to the deck. (note the thick safety rope and harness that Mark is attached to)(yes that is Mark Steffen, my brother)
• once the string has been fully removed and a new bit installed the string is rapidly reattached (yes, it takes many many hours) and sent back down the hole.
• The rig needs lots of electric power...which is generated on sight with another big diesal engine and enough switches and connections to thrill the heart of any electrician.
• When a rig is done another crew from a workover rig will come in and finish the hole...which means they will do final testing to find out really what is down there, monitor the pressure of the oil and, if there is enough pressure, cap the rig with a bunch of pipes called a christmas tree. Many holes need a little help after a while and they will be fitted with the familiar grasshopper pump to bring the oil up. The oil is stored in tanks close to wells which are periodically emptied into tank trucks and the oil taken to a refinery.