The drilling contractor not only operates, and is in charge of, the drilling operations in offshore drilling operations but they are also the owners and operators of the vessel that is being used to drill the wells. Particularly in the case of drillships, they need to employ a full compliment of marine crew who run the vessel while the drilling is taking place. Like all sea-going vessels there are a number of ranks, which are recognized positions on most offshore oil and gas drilling rigs. Due to the nature of jack-up rigs being non-floating rigs, they will have minimal marine crew as they get towed from one location to the next. The more autonomous a drilling unit becomes (i.e. the less dependent it is on external forces for propulsion and stability), the greater the need for a full compliment of marine crew.
The marine crew can generally be divided into four main categories: the bridge, the deck, the engineering department and the steward's department. Depending on the type of rig, you may find all or only some of the following personnel working on a rig. Given that their duties are solely to do with the running of the vessel and not the drilling of the well, they nearly always will come from a marine industry background rather than a drilling industry background.
The “captain” or “master” is the vessels highest responsible officer, acting on behalf of the rig’s owner. The captain is legally responsible for the day-to-day affairs of the rig as they are in command. It is their responsibility to ensure that all the departments under them perform legally to the requirements of the ship's owner.
The captain/master will have his own cabin on the rig that contains his bedroom and office. He’ll generally work out of here with his job involving mainly administrative duties, which keeps him tied to a computer for much of the day. Like all senior roles on a rig, he gets heavily bogged down with daily reports, on-site meetings, phone calls, conference calls and emails.
They are responsible for keeping the ship and the machinery running. Today’s mobile offshore drilling units are complex vessels that combine a lot of technology within a small space. This includes not only the engine and the propulsion system, but also, for example, the electrical power supply, devices for loading and discharging, garbage incineration and fresh water generators. The chief engineer is responsible for all operations and maintenance that have to do with all machinery and equipment throughout the vessel.
Dynamic Positioning Operator (DPO)
The bridge on any rig is filled with sophisticated navigational equipment, with 7th generation drillships having the most advanced systems in the offshore industry. To maintain their position, drillships and semi-submersible rigs may utilize their anchors or use the ship’s computer-controlled system on board to run off their dynamic positioning. DPO’s are the people who are in charge of controlling the Dynamic Positioning System. The purpose of this system is to automatically maintain a vessel’s position and heading by using its own propellers and thrusters. This is a very complex task because DP systems need to combine position reference sensors, wind sensors and motion sensors to calculate the impact of environmental forces that affect the vessels position.
DP systems are vital for safely carrying out operations in water too deep for stabilization using anchors or jack-up legs. The system was created in the 1960’s to meet the demands of the oil & gas industry and allowed offshore drilling units to operate in deeper waters than was previously done. This paved the way for the discovery of new fields and gave birth to the deepwater and ultra-deepwater drilling industry. Dynamic positioning has many advantages, such as excellent maneuverability, no additional vessels required to work with anchors, able to operate at any water depth, quick set-up and not limited by an obstructed seabed.
There can be very serious consequences resulting from the loss of position of the floating rig, the main ones being:
- The rig could disconnect from the subsea wellhead, BOP or marine riser, which could cause uncontrolled oil spills and possibly create serious environmental problems.
- If there are crane operations taking place with a supply boat alongside the rig then the possibility of a collision with the two vessels is very high and could result in serious damage to either vessel as well as the risk of injuries or even deaths of personnel working on them.
- If there are divers working beneath the rig they are completely dependent on the vessel while working underwater so if the rig was to lose position it could have fatal consequences for the personnel working under it.
The computer program contains a mathematical model of the vessel that includes information pertaining to the wind and current drag of the vessel and location of the thrusters. This knowledge, combined with the sensor information, allows the computer to calculate the required steering angle and thruster output for each thruster. Dynamic positioning may either be absolute in that the position is locked to a fixed point over the bottom, or relative to a moving object like another ship or an underwater vehicle. One may also position the ship at a favorable angle towards wind, waves and current, called “weathervaning”.
Dynamic Positioned vessels are described as being Class 1, Class 2 or Class 3.
Equipment Class 1 (DPS-1) has no redundancy - Loss of position may occur in the event of a single fault.
Equipment Class 2 (DPS-2) has redundancy so that no single fault in an active system will cause the system to fail. Loss of position should not occur from a single fault of an active component or system such as generators, thruster, switchboards, remote controlled valves etc., but may occur after failure of a static component such as cables, pipes, manual valves etc.
Equipment Class 3 (DPS-3) also has to withstand fire or flood in any one compartment without the system failing. Loss of position should not occur from any single failure including a completely burnt fire sub division or flooded watertight compartment.
Unlike the rest of the workplaces on the rig, the bridge is a spacious, quiet, clean office with the best views in the “building”. It looks more like the flight deck on the Starship Enterprise than a bridge on a drilling rig. Everyone appears to talk in hushed tones and keeps to themself – well that’s what it seems like after working out on the deck where everyone is screaming at each other to be heard over the noise of the rig.
Because the loss of position may cause financial, environment, health and safety risks it is essential that only highly qualified personnel can control DP systems. There will generally be two DPO’s on-tour at any one time (one of which will be a senior DPO), so there is always someone “on watch” while the other has meal/bathroom breaks. The DPO has to be competent to use the DP systems in manual and automatic modes without supervision. There is a special training scheme for achieving safety standards for DPO’s in the offshore oil & gas industry. This scheme defines the basic stages of professional training for future DPO’s with three main blocks of instruction – practice on board a DP vessel, theoretical sessions and simulator training at special training centres. The DP “UNLIMITED” certificate will be issued after the successful completion of all phases of the training scheme. This certificate confirms the competence of an operator and allows him to work on DP systems without supervision. The DPO will generally also assist in the co-ordination of all deck, crane, gangway, and helicopter and supply boat operations, as well as safety operations that are carried out from the bridge, such as emergency shut-in procedures and safety drills.
The radio operator generally works out of the bridge, alongside the DPOs, and they will generally be the first point of call in any emergency situation. Their main role is to provide reliable communications between the vessel and the shore, other vessels and helicopter traffic.
The radio operator works under the supervision of the Captain/Master, and reports directly to them. They establish and maintain the ‘flight watch’ during all helicopter operations, and record all details of landings and departures of aircraft. They also keep detailed records of all the persons on board (POB) and what cabin everyone is sleeping in. On fly-out day all departing crew have to report their bag and body weights to the radio operator so they can provide an accurate manifest for the outgoing chopper during crew change operations.
The maintenance of all radio equipment and emergency power sources, stock keeping of radio spares, etc. are all an integral part of the Radio Operators role. In addition, the Radio Operator assists the Master with general clerical work such as vessel documentation, daily reports, timesheets and meeting minutes, so they must be computer literate. The Radio Operator also takes on a support role in emergency situations, in both a communication role and as part of the vessels emergency command and control team. This involves assisting with POB reconciliation, log keeping, emergency radio communications, etc.
Because of the prerequisite marine certifications that are required for radio operators, it is quite common for ex-navy personnel to be working in these positions. There is always a nightshift and dayshift radio operator on the rig and when they need to have a food or comfort break throughout their shift they will get the medic or someone else to cover for them so the phone is always manned for emergency calls.
With the radio operators job being so critical for communications to and from the rig it is no wonder satellite communications equipment is an integral part of offshore operations these days. Not only is this equipment necessary for the receipt of weather warnings, transmission of position reports, priority traffic, distress messages and just keeping in touch with family and friends, but also the dissemination of well data to and from the rig. Enormous amounts of drilling data is sent in real time to the head office onshore so the specialists and project managers working in the head offices of the energy companies can view the data via a live feed from the rig. All major decisions made on the rig are nearly always in consultation with project managers onshore, so a reliable communication network is essential for timely decisions to be made. Remember…time is money…BIG money!
With the improvements in offshore communication technologies comes an improved work-life balance for offshore workers. Now, offshore personnel are able to use wifi, talk to family and friends on the phone and watch television during their off-tour time. If the Internet goes down you’ll soon hear about it! And it quite often does go down; severe weather plays havoc with the satellite hardware and also the satellite TV reception…just like your Foxtel does during a severe storm when you’re at home.
Ballast Control Operators (BCO)
Semi-submersible rigs (and to a lesser degree Jack-ups) also need operators to control the buoyancy of the rig from the ballasted, watertight pontoons located below the ocean surface. With its hull structure submerged at a deep draft, the semi-submersible is less affected by wave loadings than a normal ship but with a small water-plane area, the semisub is sensitive to load changes, and therefore must be carefully trimmed to maintain stability. Semisubs are able to transform from a deep to a shallow draft by deballasting (removing ballast water from the hull), thereby becoming surface vessels. Usually they are moved from location to location in this configuration. Jack-up rigs also need a certain degree of ballast control as they have large ballast tanks built into the structure. When the rig is jacked down, its hull floats on the surface of the water like a ship. The ballast tanks can be flooded with water or pumped free of water to control its buoyancy.
The BCO is the designated person in charge to maintain stability of the rig and evaluate the possible effect of load combinations while on station and when undertow. He has to maintain the rig at the required operating draft and keep it upright and on an even keel unless otherwise requested by the OIM / Barge Engineer/Master. Other responsibilities of the BCO include:
- Evaluate the possible effects of load combinations on the rig during unloading and back loading of supply vessels when the rig is under tow or on station
- Assist the Barge Engineer during anchor handling, shifting and moving operations.
- Supervises all major changes in deck load distribution, as well as shifting, loading and off-loading of fluids to and from the rigs tanks.
- Assist the Barge Engineer in maintaining rig drawings and other documents related to the structure and equipment of the rig.
- Trim the rig whenever required by ballasting or deballasting.
- Complete standard control room logbook, daily ballast report and official logbook.
Keeping the rig trimmed so the deck is perfectly horizontal is critical to drilling operations as the laser sensors on the mud pits will read incorrect volumes if the pits are not level. This effect could mask potential dangers of the well either “kicking” or “taking a drink”, in which the well either has too much mud coming back out of the hole or it loses mud into the formation – both of which can have severe consequences. It is critical that the BCO makes a general announcement over the rigs PA system to alert everyone on the rig if he is “trimming the rig”, so people know to account for the corrections should it affect the mud pit volumes or any drilling parameters.
An even more critical reason to maintain control of the ballast of the rig is to prevent any catastrophic “listing” events. Semisubs have been known to suffer from such severe listing from errors in ballast control they have literally sunk into the sea. No one ever wants to see this happening while they’re on the rig!
Mechanics and Electricians
All rigs have a chief mechanic and chief electrician who lead the electrical and mechanical teams onboard. With offshore rigs being heavily mechanized and automated, both teams are kept very busy. It’s not uncommon to find rig mechanics branching into other fields after they get experience on a rig and find career progressions with specialist third party contracting companies (which will be the topic of the next article).
There will nearly always be a dayshift and nightshift medic onboard and generally at least one of them will be a fully qualified medical doctor. It’s quite common for rig medics to have a military background as they are well trained in emergency medical care and used to working in harsh environments and away from home for long periods of time. While the drilling contracting company is responsible for employing them they will nearly always be sourced from a third-party agency and not directly employed through the drilling company.
The medics work out of the rig “hospital” which is equipped to handle comprehensive first aid care and emergency medical procedures when needed.
Storeman is an entry-level position that requires no prior offshore experience, although working in a similar role at onshore operations would be an advantage. They are responsible for the storage and distribution of consumable items on the rig, ranging from mechanical and electrical equipment to personal protective equipment. They will also oversee the offloading and storage of chemicals that are needed for drilling operations, which get stored in either the store area or the sack room.
As you can imagine, there would be many other roles involved in offshore drilling operations that I wouldn’t have covered in this article but I have provided an overview of the main ones that all rigs generally have. In the next article we’ll start to look at the many third-party contractor roles that are performed on the rig.
Don’t forget to supply any feedback or questions you may have about anything in this article or the previous ones. I’m attempting to give you a general overview in these articles of the typical offshore rig environment. I hope it helps give you a better understanding of what it’s like to work offshore.
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: https://au.linkedin.com/in/amanda-barlow-21a08b22 or through her Facebook page: https://www.facebook.com/AnInconvenientLife