Of all the subjects one might pick to discuss on a West Texas board, the one subject that is universally recognized in some manner is oil drilling rigs and oilfield service companies. We run across something related to the oilfield virtually every day in our travels. Perhaps some of you are a bit embarrassed about your lack of knowledge of an industry that is so commonplace in your daily lives. Unfortunantly it is difficult to gain that knowledge unless you are treated to actual experience on locations and on the rigs. Why is it so difficult? The oil field has a language all its own that just does not match up with the jargon or accepted terms of any other activity. And the only way to learn the terms is by doing the work ... unless someone takes the time to describe the activity and explain the terms. And I am gonna do just that.
This is an oilfield drilling rig, a Jack-Knife Rig to be exact, typical of what you might see in West Texas. A Jack-Knife rig has the feature that a couple of pins can be pulled and it can be laid down using its own power for separating into two pieces for transport (instead of old ways of having to dismantle the derrick piece by piece.) The rig in the picture is just rigging up because I do not see the necessary guy wires or the safety line for the Derrickman (the Geronimo Line.)
First, terminologies: The derrick is more appropriately called the Mast. The red thing on top of the Mast is the Crown. The Crown houses the Crown Block which operates with the Traveling Block (red thing just above the drilling floor), each with 3 or 4 Sheaves (shivs) to form the oversize block and tackle that does the heavy lifting. The Traveling Block has a very large hook from which the heavy stuff hangs. The dead end of the Drill Line is anchored in the Crown, the other end of the Drill Line (the Fast Line) goes into the Drawworks on the Drilling Floor. The Drawworks has a Cable Drum that holds about 1,000 feet of Drill Line (necessary because the distance from Crown to Floor is more than 100 feet and the line makes about four loops around the pulley Sheaves.) How much will it lift? About a million pounds.
Next, how big is that rig? A medium size rig and its various components required to drill 10-15,000 feet weighs about 1,250,000 pounds plus about 250,000 pounds of drill pipe. It requires about 36 heavy oilfield truckloads to move it. The main components include the Mast; the Substructure (the big gray boxes that support the drilling floor, Rotary Table, the Mast and the Drawworks; Motors; Generators; Mud Pumps; Diesel Tank; Mud Tanks, etc. Assembling all this iron takes a couple of days.
Next, who are the players? The rig crew consists of the Driller, a Derrickman, and two or more floor hands. The Driller is the supervisor of the crew and is in charge of all drilling and hoisting operations. The Driller's office is in the blue Doghouse at the Drilling Floor in the picture. The Derrickman during the time drill pipe is being removed from the drill hole, or being returned to the hole, stands on the Monkeyboard (red catwalk 3/4 way up the derrick) and his job is to uncouple pipe from the hoisting Elevator and stand it neatly against the Mast in a rack called a Fingerboard. (When pulling the Drill String from the Bore Hole, when the Monkeyboard is about 90 feet above the Drilling Floor, the string is uncoupled at three joint intervals.)
Now where the Driller supervises the crew on one shift (a shift is called a Tower(i.e., Evening Tower) in the oil fields but it is spelled TOUR ... funny but true.) The person who is in charge of all rig drilling operations and crews is the Toolpusher (sometime called drilling superintendent.) The Toolpusher's job is to keep that Drilling Rig drilling, in three shifts, 24/7 until the Well is Completed. The reason for the heavy-duty "pushing" is that that Rig is charging the customer $1-2,000 per hour for their services.
Now we have a Rig and we have a drilling crew, what do we do next? Drill. The key to this is the Rotary Table ... a table with a square hole in it that rotates with great force. The square hole accommodates the Kelly, a heavy square pipe 43 feet long, that has a heavy duty Swivel on its top end that fits on the Hook of the Traveling Block. Feeding into the Swivel is a Mud Line that directs Drilling Mud through the Kelly and on into the Drill String. The Drill String consists of Drill Pipe that screws into the bottom end of the Kelly and down into other joints of Drill Pipe, Drill Collars, and the Drill Bit. The Rotary Table turns the Kelly which transfers Drilling Mud into the Drill String and twists the Drill Pipe which turns in the Bore Hole and turns the Drill Bit. Drill Pipe is 30 feet in length. Drill Collars are very heavy pipe (about 20,000 pounds each) are in the string just above the Drill Bit to help insure the drilling goes vertically and also adds strength to the Drill String just above the Bit. Drilling Mud is pumped through the String and Drill Bit to flush out cuttings by the Bit and to cool the Bit as it cuts. Drilling Mud has special properties that water alone cannot provide.
Now let's go back to the surface and answer more questions. The first would be "What is a Rathole Driller?" During site preparation before the Drilling Rig moves in, a shallow well driller is called in. The first thing he does is drill a hole for the Conductor Pipe ... this is a large diameter (24 inches +/-) hole fairly shallow and casinged as the initial drilling of the bore hole. (Some call this Spudding In.) The Conductor Pipe keeps the loose sidewalls at the surface from caving in when drilling starts. The pipe will be cemented in and the initial stack for Blow Out Preventors will be installed. When drilling commences it will be through the Conductor Pipe. Next the driller will drill a Rathole. The Rathole is a casinged hole under the Drilling Floor where the Kelly will be stowed when the Rig is hoisting pipe instead of drilling. When drilling, the Kelly drives one length of Drill Pipe (30 feet), then the Swivel and Kelly are taken from the Hook and stowed and another device called an Elevator is placed on the Hook in order to lift and add another joint of Drill Pipe. When that joint is added to the string, the Elevator is exchanged for the Kelly and drilling resumes. The Rathole Driller drills another hole during site preparation called the Mousehole. The Mousehole is also casinged and holds the next joint of Drill Pipe that will be added to the Drill String.
Life on the Drilling Rig gets complicated when drilling commences and that is where outside services must be called in for specialized work.
As the rig drills it may pass through water aquifers. To keep from contaminating the ground water an intermediate string of casing will be installed in the Bore Hole to the bottom of the lowest water. This calls for a Casing Crew. Then companies like Halliburton or BJ Services will be called in to pump cement into the casing. Heavy Drilling Mud will then be pumped into the casing to force the cement down out of the casing and up into the airspace between the outside of the casing and the bore wall until it reaches the surface. This cement will prevent contamination between stratas. Then drilling resumes.
Eventually the drilling with luck will hit the planned oil production zone. This is the end game and all sorts of specialists are called in here ... but assuming the verdict is a good pay ... this is time to run another string of casing, the Production Casing. Since the casing wall is solid, it must be perforated at the desired place to allow oil to flow into the casing. This is done by a Gun Perforator ... The device is lowered into the hole and small shaped charges are fired to blow holes in the casing.
Next the well must be "stimulated" to get the oil flowing into the casing... this requires more specialists. Acid is sometime used to dissolve fissures into limestone as pathways for oil to travel. Or the situation may call for Fraccing. In Fraccing, compressors drive great quantities of water and sand under extreme pressure into the well to fracture the formation to initiate flow. When oil begins to flow into the casing and the amount is deemed adequate to continue completion efforts, the Drilling Rig crew will have completed its job. Now is the time for them to move on to their next location.
When the Drilling Rig moves off the hole a Workover Rig will be moved in to run the Tubing, Sucker Rod, and Pump into the hole.
Throughout the entire drilling operation the Drilling Rig crew must be aware of the threat of drilling into a high pressure gas pocket and cause a well blowout. To safeguard, a stack of Blow Out Preventors (called the B.O.P.s) attaches to the Casinghead throughout. Rams, powered by hydraulic fluid under great pressure from Accumulators filled with nitrogen are at the ready to automatically seal the hole. The Shear Rams is capable of slicing through Drill Pipe as it slams closed. A nice thing to have on your side!
In addition to casing crews, cementing crews, workover crews, there are a myriad of other specialties that can be called in. Wireline operators, well logging, mud experts,etc. All are a part of an extended team. You see their trucks on the road every day and maybe now you will appreciate the work they do.
You have to give a big thumbs up to the folks who work to get that crude oil out of the ground. Their workday every day is in the face of the elements ... hot sun or freezing rain. And everything they do is hard, heavy, and hazardous. They are good at their work ... and they take great satisfaction in that. And they are a fun bunch to be around.
There are dozens of other unique terms in the oilfields but the ones above are enough to get you started ... they might even help you get a job on a Rig is you are also stout looking, alert, smart and just love the outdoors.
[This message has been edited by fossil_ag (edited 5/26/2006 7:58a).]
[This message has been edited by fossil_ag (edited 8/7/2008 3:17p).]