Basic Drilling Concepts

How are wells drilled?

The basic principles of offshore drilling between open-water exploration (mobilize a rig in the middle of the ocean without any platforms installed) and development drilling (drilling from a rig above a platform) are about the same. Land drilling applies the same concept - only diferrence is........ it's on land ha ha.

Formation/soil/dirt/ground is drilled using a drilled bit. There are two types of bits widely used in the industry - tri cones and pdc (polycrystalline diamond compact) bits. Sizes range from 3" up to 30". I've also heard of bigger bits but they're rarely used. The typical ones used in my company's operations are 17-1/2", 12-1/4" and 8-1/2". The oil field is famous for the use of fractions. I guess the old foggies thought it'd be cool or something. You sometimes wonder if a tubing has an OD (outer diameter) of 2-7/8", why don't they just make it as 3" and stardardize it? God knows.


The bits are driven into formation with the use of drill pipes. Drill pipes come in an assortment of sizes but 5-1/2" DPs is the typical size. Drill pipes come in lengths of roughly 30' per joint. Wells nowadays are drilled beyond the 10km mark - especially operational areas such as Sakhalin, Russia. So imagine how many DPs are needed to reach the objectives!

The major companies supplying bits are Baker Hughes Christensen (Baker Hughes was founded by Howard Hughes' dad. Howard was the main character in the movie 'The Aviator'), Reed Hycalog and Smith International.

This is a picture taken from the drill floor looking up the derrick. The derrick on a rig hangs what's called a 'top drive' and stores drill pipes in 'stands'. A stand is 3 joints of DPs made up and racked back in the derrick. A top drive is the heart and soul of drilling - this equipment provides the rotation needed and the hoisting capability of the pipes in the well.

Let's do some quick math - Say the DP weighs 21.9 pounds per foot and imagine we're drilling a 5,000 m well. The amount of steel in the well when we reach the objective will be 21.9 x 5000 x 3.281 ft/m = 360,000 lbs. that's a lot of weight! Top drives these days are rated more than 1,000,000 lbs. They act like cranes if you will.That's the monster top drive - rated to 1M lbs of weight, up to 180 rpm rotational speed, 40,000 ft-lbs of torque. I think it's a Varco TDS4.

Malaysia's first well

Grand Old Lady is the first oil well drilled in Malaysia. She was completed in 1910 and produced a total of 600,000 barrels at a 5 barrels per day rate. She was a mere vertical well (nowadays wells can be drilled directionally up to 100 deg!) and I have yet to receive confirmation about the depth of the well and method of completion. Would be interesting to find out!

Barnyard on the Rig??

There are many old terms and jargons that the people in the oilfield use worldwide. You can practically use these terms anywhere in the world and people in the oil patch will understand them. They are also normally based on parts of animals or are called after certain animals, for god knows what reason. Here are some we use on the drilling rig:

Rabbit: A tool use to drift pipes
Cathead: A device to tighten tubulars
Hawkjaw: A device to tighten tubulars
Sharkjaw: A device that secures anchors on vessels
Mousehole: A temporary space for tubulars to be placed before being picked up by a top drive Rathole: Access meterage drilled in the well for the purpose of reciprocating the string in the hole
Monkey board: Where the derrick man works to sort pipes in the derrick
Pig: A piece of heavy-duty vulcanized rubber used to clean pipelines
Possum Belly, Cow's Cunt



There are also terms that sound funny or silly but are used extensively:

Rough neck or Roustabout: The general labor on the rig
Shooting Nipple, X-Nipple, XN-Nipple, etc (notice that the term nipple is widely used)
Christmas Tree: A set of valves used to control the flow of the well and ensures integrity of the well
Mud: Drilling Fluid
Tool Pusher: The senior supervisor in charge of rig personnel and operations
Camp Boss: The man in charge of catering and house keeping. This is THE man to make friends with.
Dope: Lubricant used on pipe threads
Jar: The act of hammering using a device to add weight onto the string in the hole. This produces either an upward or downward force.
Dutchman: A tubing stump or a cut casing in the well
Mudline: Seabed


Widow Maker: A walkway to connect a platform to a tender-assisted platform rig (TAPR) or semisub in TAPR mode (the bridge in the upper right corner)

The terms used are also simple enough and straight forward to describe the work they do:

Driller: The main guy on the rig making things happen - he controls the brakes on the top drive, which is a massive crane-type device that carries all the tubulars in and out of a well
Motor man: The mechanic on the rig to fix motors
Pump man: The personnel in charge of pumps on the rig
Derrick man: The guy in the derrick sorting pipes
Company man: The Operator representative on the rig (the rig is normally owned by a 3rd party Contractor and the personnel are also from the same company. The Operator rep is responsible to supervise operations conducted by them)

The People in the Business

What's neat about the industry is that it is so uniformed that you won't feel a difference whether you're in the North Sea drilling or completing an extended reach drilling well in Sakhalin.

Let's talk about the engineers first. The main groups are Drilling, Completion, Reservoir, Facilities. Obviously, the drilling people drill, the completion people complete wells (completion is a process where a tubular is ran in the well with 'jewelry' to aid the production of the mineral. Jewelry simply means completion equipment such as a sliding sleeve door, a nipple / profile where plugs are set, downhole pressure gauge which reads the pressure and temperature of the reservoir or close.

Some Operators would have the same engineers work as Drilling and Completion engineers. Some Operators separate the two. Some Completion Engineers also do what's called a "Workover", a process of repairing completed wells. Over time, tubulars or "Casings" or "Tubings" corrode with CO2 content in the produced gas or jewelry stop functioning and production is disrupted.

The Drilling Engineers obviously drill holes in the ground. They design how wells are drilled, the trajectory that the well takes, the equipment to be used (Equipment are supplied by "Contractors" or "3rd Party Services"), establish a cost estimate for the project, duration of the project. The deeper the "Target" is, typically it gets tougher. Deeper could translate to higher temperature, higher pressure, more abrassive formation, faults, etc. These are elements of mother nature that a Drilling Engineer has to factor in his design of a well.

The Reservoir Engineers estimate the volume of the reservoir from the data gathered. Reservoir Engineers normally work closely with the Geologists to determine the location of the minerals. Reservoir Engineers estimate the rate of extraction and depletion using sophisticated softwares and models. During the production of a well, a "Surveillance" Engineer monitors the production and performance of that well. The surveillance engineer is normally the reservoir engineer in charge of the field. In the Oil Majors, the top Executives normally have reservoir background.

The Facilities Engineers are normally chemical and mechanical engineers who design the processes on a platform. A "satellite" platform or a small platform could hold between 3-6 wells and a "Mother" platform could house as many as 48 wells. On the platform, numerous equipment are installed such as "Test Separators" or "Multi-Phase Flow Meters" to accurately measure production, Compressors to generate power, chemical injectors to transport curative additives in the well and so forth. Facilities Engineers design and ensure the functionability of these equipment.

There are also support groups in the business, from Marine, Procurement, Accounting, HR, etc like other business setups.

Making holes in the ground

With the advent of the internet and border-less world, I'm attempting to keep people abreast with the development of the oil industry by creating this blog. There are a lot of interesting issues to talk about as this industry has been strong for the last decade. Let's just start with the basics of oil & gas development, which many seemed to be unaware of.

Everything starts with "Exploration" phase where "Operators" (Companies given rights by the Government to extract the mineral) attempt to find reservoir in the ground, be it oil or gas, and estimate a volume. The means of exploration is using seismic, an acoustic method of determining the content in the ground. This applies whether it is on land, offshore, in the artic or so forth.

Once data is obtained, Operators will drill "Wild Cats" or "Appraisal" wells or "Exploration" Wells to determine the real value of the data. A Drilling Rig will be deployed in this phase. A rig can be of many types, whether a semi-sub, jack-up, drill ship, tender-assisted platform rig (TAPR), platform rig. The well is then drilled and tested to determine the real production value of the reservoir.

Once the true economic value of the reservoir is realized through actual "well testing" (the act of producing an exploration well and estimating the production flow rate by using flow meters), drilling, reservoir and facilities engineers get together to come up with a development plan, normally called a Field Development Plan or FDP. The FDP is then submitted to the regulatory body for approval. The FDP also includes an estimate of the cost involved in developing a field of interest.

When the approval comes in, money pours in. "Platforms" (Stationary structures in the ocean to act as conduit for wells and house production equipment) are built, pipelines are laid. Rigs are then leased from third party contractors and mobilized to platforms. Wells are then drilled and completed.

All of these processes are classified as the "Upstream" business. When crude or gas are transported via pipelines or tankers and refined in plants, it is now considered the "downstream business". Crude is then refined to many grades, from the lightest kerosene, jet fuel to the heaviest tar. Derivatives are also used for the production of plastics, chemicals, polymers.