Amanda Barlow


Blog Post created by Amanda Barlow on Jan 1, 2017

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The drilling of offshore oil and gas wells is almost as far “upstream” as you can possibly go in the oil and gas industry. “Upstream” refers to the source of the supply chain for hydrocarbon products while “downstream” refers to the refining and transporting to the final end user. Naturally there’s a whole range of stages between these two end points but the stage that most people have least exposure to is the initial drilling of the wells, as only the specialists who are involved in the operations are allowed access to this environment. Barring the few VIP dignitaries that visit the rigs, it is practically impossible to visit a rig as a “tourist” unless you are directly involved in the operations. Due to the extremeness of the locations and the hazards involved in not only getting the people to the rig but also guaranteeing their safety while on the facility, only appropriately trained essential personnel are allowed to fly to offshore drilling rigs.


With the majority of Pink Petro community members being involved mainly in the downstream operations within the Oil and Gas industry I thought it would be of interest to people to read about what is involved in the drilling process. I doubt if too many of the existing Pink Petro members would be interested in working in this environment but it may give you some useful information to pass on to young adult family members or friends who are wanting to start out a career in the O & G industry, so they can see what skills are needed to be able to work in the offshore drilling environment. The technical expertise in this industry is phenomenal and for anyone interested in geoscience or engineering disciplines you couldn’t ask for a more dynamic and exciting career. As well as exploring all the different professionals and trades people involved in the operations, I’ll also explain the hierarchal structure of the work force - from the O & G company men to the drilling contractor, third-party contractors and all the other specialists involved in the drilling of a well. It is a huge collaboration by all people involved and everyone has their part to play in the successful drilling of a well.


flowchart of companies


But before we discuss the people who work on a rig, lets first get a brief introduction to the drilling rigs themselves and the most common types of rigs in use today.



Offshore Drilling Rigs


Offshore drilling rigs fall into two main categories: bottom founded units that have legs that sit on the seabed, and rigs that float on top of the water. They are all commonly referred to as mobile offshore drilling units (MODU’s). Deciding what type of rig to use is most commonly dependent on the depth of the water and the weather conditions expected at the well location.


The main types of offshore drilling rigs are:


Jack-Up Rigs


jackup rigA jack-up rig consists of a platform that is supported by usually three legs (but sometimes four) whose footings are seated on the sea floor and the rig is then “jacked up” to a specific height above the surface of the sea where it won’t be adversely affected by wave and tidal movements. The jack-up rig is towed to location with its legs elevated and once on location, the legs are lowered to the seafloor and the platform is "jacked up" above the wave actions by means of hydraulic jacks. Due to the fact that there is a limit on how high a rig can safely be jacked-up, this type of rig can only be used in water depths up to approximately 550 ft (167 m).


Semisubmersible Rigs


semi sumersible rigbA “Semi-sub” is a floating unit that obtains most of its buoyancy from ballasted, watertight pontoons located below the water surface and wave action. With its hull structure submerged at a deep draft, the semi-sub is less affected by wave loadings than a normal ship. Semi-subs are commonly subdivided into generations, depending upon the year they were built and the water depth capability. Generation 1, 2 and 3 rigs commonly use mooring systems and operate in waters less than 1,500 ft (500 m) while generation 4, 5 and 6 rigs can drill to a water depth of up to approximately 10,000 ft (3,000 m).

 generations of rigs

Semisubmersible rigs are kept on location over the well by a computer-controlled system known as “dynamic positioning” (DP). Position reference sensors, combined with wind sensors, motion sensors and gyrocompasses, provide information to the computer pertaining to the vessel’s position and the magnitude and direction of environmental forces affecting its position. This knowledge allows the computer to calculate the required steering angle and thruster output for each thruster. This allows rigs to operate where mooring or anchoring is not feasible due to deep water or seabed problems. Dynamically positioned vessels are categorized into three classes: Class 1 has no redundancy so loss of position may occur in the event of a single fault. Class 2 equipment has redundancy built in to the system so that no single fault in an active system will cause the system to fail. Class 3 systems also have to withstand fire or flood in any one compartment without the system failing. These vessels have at least two independent computer systems with a separate backup system.





drillshipDrillships have the functional ability of semisubmersible drilling rigs but being a ship means they have greater mobility and can move more quickly under their own propulsion from drill site to drill site. They generally have a higher POB (persons on board) capability, as they require a full marine crew to operate the vessel as well as a drilling crew for drilling operations. Like semisubs, drillships are subdivided into generations, depending upon the year they were built and the water depth capability, and also classes of dynamic positioning capabilities.




Types of Oil and Gas Wells


Wells are classified according to their purpose and fall into three major categories. Exploration wells are tentative ventures that drill in new areas with the hope of discovering untouched resources. Appraisal wells are drilled to evaluate the characteristics of existing hydrocarbon accumulation discoveries and production/development wells are drilled specifically for commercial production of oil and gas from proven hydrocarbon reservoirs. The different types of wells are basically all drilled in the same way but they differ in the way they are completed. In exploration wells there is a very strong focus on end-of-well testing to determine petrophysical properties of any potential reservoir zones, while production wells are completed to allow for future infrastructure to be set up over the well to enable the extraction of the hydrocarbons. Every stage of all types of wells is performed by a collaboration of many teams of people who have very specific expertise in the tasks being undertaken. Experts are flown in from all around the world, which results in a rig full of the most culturally diverse workforce unlike any other workplace in the world. It’s this cultural and professional diversity that makes working offshore more exciting and rewarding than any land-based job could ever be.



Working Offshore


The following series of articles in “Offshore Oil and Gas PEOPLE” will explore the different professions and trades that offshore workers require to be able to perform the highly specialized jobs that are involved in the successful drilling of offshore oil and gas wells. While it’s possible for anyone to find a niche occupation within the many varied roles that are represented offshore, being able to work in this type of environment is another story. Working 12+ hours every day for up to 28 days straight is not for everyone, especially when it might be on the other side of the world from your family and friends.

Before even being allowed on the chopper to fly to the rig, every worker must have completed a sea survival course, which includes helicopter underwater escape training (HUET). This 2-3 day course has to be renewed every four years and is a mandatory prerequisite to be allowed to fly to an offshore facility. The HUET component involves being strapped into a helicopter simulator module, which is submerged in water and then rotated until the occupants are sitting upside down while submerged completely under water. They then have to perform an emergency escape out of the windows of the module and swim to the surface of the pool. Not everyone’s idea of fun! This step alone has been known to end some peoples offshore career before it even begins.


While there are many transient workers offshore who come out from time-to-time, the articles to follow will cover only the main personnel who provide the core of the offshore team. There are many others who act as support crew onshore but their positions are beyond the scope of these articles. The offshore workers will be grouped according to the categories below (but not limited to…I’m sure to think of others as the series progresses!):


Oil and Gas Company

  •        Permanent company employees – Wellsite Managers, drilling engineers
  •      Contractor company representatives – Logistics coordinators, wellsite geologists, HS&E personnel, drilling fluids engineers (mud engineers)


Drilling Contractor

  •       Offshore Installation Manager (OIM)
  •       Drilling crew – toolpushers, drillers, assistant drillers, derrickmen, roughnecks
  •       Deck crew – deck pusher, crane operators, roustabouts
  •       Subsea crew – subsea engineers
  •       Marine crew – drillship captain, dynamic positioning operators (DPO), ballast control operators (BCO), storemen
  •       Radio operators
  •       Medics
  •       RSTC – rig safety and training coordinator
  •       Mechanical tradespeople
  •       Electrical tradespeople


Third Party Contractors

  •       Mudloggers/Data engineers
  •       Fluids control engineers
  •       Casing personnel
  •       Cementing personnel,
  •       MWD/LWD engineers (Measurement while drilling/Logging while drilling)
  •       Directional drillers
  •       Wireline engineers
  •       Well testing engineers
  •       ROV operators (remotely operated vehicle)
  •       Catering contractors – camp boss, cooks and kitchen staff, utilities (cleaners)
  •       Many various specialists 


I will explain what all these roles entail, what qualifications and experience is needed to work in these positions, and also the day-to-day routine that all offshore workers have to follow. There are uncompromising HS&E standards that must be adhered to and countless meetings and reports are an unwelcomed, but very necessary, part of everyone’s responsibilities offshore. Due to the 24-hour operations, men and machinery can be pushed to their limits – and quite often are! The unpredictability of drilling operations means that everyone has to be on their toes and alert for any signs of danger. As the Deepwater Horizon incident has shown, ignoring warning signs can lead to catastrophic events. If something goes wrong offshore, it can go disastrously wrong!


With this article giving a broad overview of operations on an offshore drilling rig, the second article will explain the day-to-day routine of all offshore workers before breaking down the different roles people work and the expertise needed to perform these roles in subsequent articles. Please feel free to ask questions or give feedback, as I want to write about things you want to know. If one person has a question then you can bet lots of others are probably wondering the same thing.



I hope you enjoy reading the articles and gain a better understanding of the people and jobs associated with the offshore oil and gas industry.




Amanda Barlow is a wellsite geologist in the offshore oil and gas industry with a field-based geology career spanning over three decades. As well as being a recreational marathoner who has run over 40 marathons in 16 different countries she is also a published author of two books: “Call of the Jungle – How a Camping-Hating City-Slicker Mum Survived an Ultra Endurance Marathon through the Amazon Jungle” and also “An Inconvenient Life – My Unconventional Career as a Wellsite Geologist”. You can connect with her through the Pink Petro community, Linkedin or through her Facebook page