Amanda Barlow


Blog Post created by Amanda Barlow on Feb 4, 2017

launching ROV


Offshore oil and gas drilling rigs are a melting pot of races, cultures, professions and 21st century technology. While the general perception is that of grease-covered workers throwing tongs around the drillfloor, the reality is much different. With every minute of the day having to be accounted for in daily reports and converted into monetary costs, it’s no wonder only highly trained specialists are employed to undertake the myriad of roles performed in offshore drilling operations. Everyone on board the vessel works as a team to support the drilling operations and to make sure the well is drilled safely, and on time. Rig operations can cost up to (or even more than) $1 million dollars a day, which breaks down to up to $1,000 per minute for every minute of the 24-hour operations. This means that every minute of the day has to be accounted for and non-productive time (NPT) is not an option – well, it can be an option but you’ll have a lot of explaining and arse-covering to do!


Routine testing and preventative maintenance are a huge component of the tasks performed by all offshore drilling contractors because when the time comes for their equipment to be used in the drilling operation they can’t be causing delays by not having fully operational equipment. Before any equipment goes “down the hole” it has to be fully tested, strapped (external dimensions measured) and drifted (internal measurements measured) to ensure compliance with very strict operational tolerances. Errors in calculations or faulty equipment can cost millions of dollars in lost productive time. Getting something wrong can see you with a one-way ticket on the next chopper!


I want to highlight a major difference between the salaried rig crew (although in the downturn this is now also true of the rig crew) and the third-party service providers (contractors). The contractors are regarded as dispensable – if you stuff up, you’re generally out on your first strike. There’s no soft-touch HR department on the rig that holds your hand and says: “Ohhh, we’ll give you another chance”…if you want that treatment then you’re in the wrong place! Go back to a cruisy 9 to 5 job in the city where managers aren’t allowed to hurt your feelings…you’re not going to get that out here. And if you can’t work 12-hour shifts for 28 days straight then you’re also in big trouble. Twelve hours are a MINIMUM shift; during critical times of the drilling operations it’s common to be “on-tour” for up to 15 hours or longer (with written approval) and if things are busy/bad enough that you have to do overtime then you can bet you won’t have time for meal breaks during that shift either.


And if the work schedule isn’t enough to put you off, then be aware that the contractors are also given the shittiest rooms on the rig, which may even mean sharing a 4-man room with people who all work different shifts so your sleep gets disturbed every time someone enters the room. It pays to learn to sleep with ear plugs in your ears because the shittiest rooms are always on the lowest level in the accommodation block and generally positioned over the pump room, the engine room or the anchor chain winches…or a combination of all three because on a small rig there’s no escaping all of these! I’m not going to sugarcoat the jobs out there – the work and lifestyle can be tough and new-starters need to know this before they embark on a career offshore.


I’ll go through the most common contractor jobs that are performed on the rig but there are many others that I won’t have time to mention in this series of articles. These are the main ones that are pretty well always a part of the standard operations.


 Remotely Operated Vehicle (ROV) Operators


ROVs are tethered, unoccupied, highly maneuverable remotely operated underwater vehicles, which are operated by a crew aboard the rig. They are linked to the rig by a load-carrying umbilical cable, which is used along with a tether management system (TMS). The TMS is either a garage-like device, which contains the ROV during lowering through the splash zone or, on larger work-class ROVs, a separate assembly that sits on top of the ROV. The purpose of the TMS is to lengthen and shorten the tether so the effect of cable drag where there are underwater currents is minimized. The umbilical cable is an armored cable that contains a group of electrical conductors and fiber optics that carry electric power, video, and data signals between the operator and the TMS. The TMS then relays the signals and power for the ROV down the tether cable. Once at the ROV, the electric power is distributed between the components of the ROV. However, in high-power applications, most of the electric power drives a high-power electric motor, which drives a hydraulic pump. The pump is then used for propulsion and to power equipment such as torque tools and manipulator arms where electric motors would be too difficult to implement subsea. Most ROVs are equipped with at least a video camera and lights. Additional equipment is commonly added to expand the vehicle’s capabilities. These may include sonars, magnetometers, a manipulator or cutting arm, water samplers, and instruments that measure water clarity, water temperature, water density, sound velocity, light penetration, and temperature.


The ROV has a wide range of capabilities that include:

Pre-spud surveying of the seabed and underwater acoustic positioning systems

Overseeing conductor cementing and wellhead installation operations

Assisting with landing of the BOP on the wellhead

BOP intervention by acting as an additional safeguard for operating emergency well shut-in procedures via the Blowout Preventer Actuating Tool (BOP-AT)

Daily surveys to establish the integrity of all subsea components of the drilling operations, namely the riser, LMRP, BOP and wellhead.

Daily checks of “bullseyes” on the wellhead and BOP to ensure there is no displacement from vertical of the seabed structures.




ROVs are commonplace on all rigs these days, especially in deepwater drilling. With exploration moving into water depths beyond that which can be usefully achieved by divers, the ROV becomes an increasingly important tool. Almost all ROV personnel are employed directly by ROV operators or contractors. There are a number of large internationally based ROV survey companies as well as many smaller operations.


A team comprising ROV pilots and technicians operates the ROV units. While both positions require certification in Hyperbaric Operations specific to operating ROV’s offshore, flying an ROV competently is not the only skill required of a pilot. ROVs are highly complex mechatronic (robotic) devices and working offshore in remote locations means assistance by qualified factory trained technicians is unavailable. It is advantageous for the ROV pilot to hold appropriate technical and practical skills because they will have to be responsible for onsite repair and maintenance of the ROV unit under their care. A qualification in one (or more) of the following nationally recognized trade skills (with post training employment) are considered to be essential pre-requisite qualifications for entry into an ROV training course: Electronics, Hydraulics, Electrical and Mechanical. Tertiary qualifications in an appropriate discipline, and significant relevant industrial experience may also help your chances of securing a spot in an offshore ROV team once your certification course has been completed.


The ROV team consists of at least two, but quite commonly three, personnel on each dayshift and nightshift. They will work out of a unit on the deck close to where the ROV docking station is located. The atmosphere inside the ROV unit is quite unlike any other office on the rig, with serene underwater vistas showing on all the computer screens. In shallow waters there can be quite an aquarium affect showing on their monitors, especially in tropical waters. Added to this, there’s usually a coffee-making machine, stereo and mood lighting – all essential elements of the ROV experience!


Casing and Cementing Operators


While the drill crew is in charge of drilling the actual well, specialist casing and cementing crews perform the running and cementing of the casing strings after each section has been drilled.


The well is drilled in stages whereby it is drilled to a certain depth, cased and cemented, and then the well is drilled to a deeper depth, cased and cemented again, and so on. Each time the well is cased, a smaller diameter casing is used. The widest type of casing is called conductor pipe, and it is usually about 30 to 42 inches in diameter. The next size in casing string is the surface casing, which can run several thousand feet in length. Intermediate casing is then run to separate challenging areas or problem zones, including areas of high pressure or lost circulation. The last type of casing string that is run into the well, and therefore the smallest in diameter, is the production casing, which is run directly into the expected reservoir zone. In an effort to save money, sometimes a liner string is run into the well instead of a casing string. While a liner string is very similar to casing string in that it is made up of separate joints of tubing, the liner string is not run the complete length of the well. A liner string is hung in the well by a liner hanger, and then cemented into place.


casing diagram


Casing is run from the rig floor, connected one joint at a time by casing elevators on the traveling block and stabbed into the previous casing string that has been inserted into the well. Hanging above the drill floor, casing tongs screw each casing joint to the casing string.

Casing is run into the well and officially landed when the weight of the casing string is transferred to the casing hangers, which are located at the top of the well and use slips or threads to suspend the casing in the well.


casing RIH


A rounded section of pipe with an open hole on the end, a guide shoe is connected to the first casing string to guide the casing crew in running the casing into the well. Additionally, the outside of the casing has spring-like centralizers attached to them to help position the casing string in the center of the well.

A cement slurry is then pumped into the well and allowed to harden to permanently fix the casing in place. After the cement has hardened, the bottom of the well is drilled out, and the completion process continues.


c using and drilling sequence


While the casing hands and cementers receive assistance from the drill crew when needed, these specialists will oversee all the technical aspects of the job. As you may have seen in the “Deepwater Horizon” movie, the cementing jobs are a critical part of the process safety systems of the well and the integrity of the cement bond is crucial to the safe operation of all the procedures that follow. This step in the drilling program is so critical that the company man will personally oversee the operation every step of the way to ensure total compliance with procedures and expected outcomes. The lessons learnt from the Deepwater Horizon incident show the importance of overlooking psychological bias when interpreting cement integrity well tests. The investigation into this disaster highlighted how easy it is to skew the evidence in favour of what you want the outcome to be, despite evidence indicating otherwise.


The cementing and casing programs on all offshore wells are highly technical and very detailed. They are created through a collaboration of onshore teams in the drilling department and the specialist companies that are contracted to provide the service. Every step of the process is captured in computer monitoring systems on the rig and this data is interrogated by both offshore and onshore personnel to ensure the strict procedures set out in the well plan are being followed.


Detailed well plans are drawn up in advance of the drilling of wells being commenced and they have to be signed off and approved by many departments and regulatory departments. By law, these plans have to be followed exactly as detailed, as they will be based on “best practice” and strict safety requirements. If for any reason these plans need to be changed, based on changes encountered during the drilling process that were not considered when preparing the well plan, then there needs to be a “Management of Change” document prepared. This “MoC” then needs to get approval from the highest levels in both the oil and gas companies and the third-party service providers so everyone agrees that the changes can be made without compromising the safety of the well. The cost in delays while waiting for approval can quickly add up to the millions of dollars so any deviation from “the plan” places a lot of stress on the people involved in the operation.


One last point that should be made about the casing hands and cementers is that they are advised to take out a good supply of books or movies to the rig with them. As both jobs are only performed at certain times during the drilling process, both crews are on stand-by on the rig waiting for their turn to shine. If the drilling process suffers no setbacks or delays then the casing and cementing operations will be quite fast-paced. However, quite often there are setbacks or delays that can take days, or even weeks, to resolve so the casing and cementing personnel have nothing more to do but check, and recheck, their equipment for all of this time.


 Well Testing Engineers


If hydrocarbon zones are intersected while drilling an offshore well there is likely to be a series of well tests carried out to evaluate the reservoir potential. The overall objective is to identify the reservoir's capacity to produce hydrocarbons. Test objectives will change throughout the different phases of a reservoir or oil field, from the exploration phase of wildcat and appraisal wells, through the field development phase and finally through the production phase, which may also have variations from the initial period of production to improved recovery by the end of the field lifecycle time.


The main objective in the exploration phase is to assess the size of a reservoir and state with a given certainty whether it has the properties for commercial exploitation and shall contribute to accounting for available reserves. Well testing taking place before permanent well completion is referred to as drill stem testing (DST). A DST is a procedure for isolating and testing the pressure, permeability and productive capacity of a geological formation during the drilling of a well. The test is an important measurement of pressure behavior at the drill stem and is a valuable way of obtaining information on the formation fluid and establishing whether a well has found a commercial hydrocarbon reservoir.


In a drill stem test, the drill bit is removed and replaced with the DST tool and devices are inflated above and below the section to be tested. These devices are known as packers and are used to make a seal between the borehole wall and the drill pipe, isolating the region of interest. A valve is opened, reducing the pressure in the drill stem to surface pressure, causing fluid to flow out of the packed-off formation and up to the surface.


There are two distinct phases of the DST’s and that is the “flowing” phase and the “shut in” phase.

During the flowing phase in exploration and appraisal wells the following information is gathered:

  •  Confirmation of discovery and productivity
  • Volumetric flow behavior and rate
  • Clean-up and rate measurement
  • Hydrocarbon properties and characteristics of the reservoir
  • Pressure
  • Gas oil ratio
  • Collection of large volume fluid samples both down hole and at the surface
  • Testing of sand production


During the “shut-in” phase, which will commonly contain at least two “pressure build up” tests, the following data can be established:

  •  Well and reservoir performance (skin, permeability, initial pressure, heterogeneity and boundaries)
  • Reservoir connectivity and proven volume
  • Flow behavior around the well bore


The following YouTube videos demonstrate the DST procedure both in open holes and cased holes. I am in no way endorsing Expro here but they had a very good video explaining the process, for which they deserve some credit.


DST open hole testing:

DST cased hole testing:


well testing


Due to the hydrocarbons being brought to the surface there will always be a flare burning during testing operations. The flare boom will either be off to the side or the back of the rig with water deluge systems suppressing the enormous amount of heat this flare generates.


Well testing engineers and technicians come from a varied background of experience in mechanical, electrical, petroleum or reservoir engineering or trade skills. Like many of the third party service providers, well testing technicians often start off in the offshore industry as roustabouts and then train in specialty fields. Well testing crews don’t generally have a permanent rotation on a rig because they are only needed at the end of the drilling of the wells so they are flown in only as they are needed. They will be scheduled to arrive on the rig several days prior to the expected completion of drilling so they can set up and test their gear before starting the DST operations.


Flaring always presents a great photo opportunity for rig workers who are starved of allowable larrikin antics.


flaring butt


While there are many other third-party service providers that work in offshore drilling operations it’s impossible to cover them all within the scope of these articles. The ones I’ve mentioned are the most common and generally always present in all drilling operations.


There’s just one more key group of contractors that work on the rig that’s of vital importance and that is the accommodation and catering crew. While they are third-party contractors they are actually employed by the drilling contractor and as such, they report directly to the OIM.


Catering Contractors


For people working offshore, a hot meal, a clean bed and freshly laundered work wear are essential comforts. With everyone working a minimum of 12-hour shifts every day it takes a very well structured support system to make sure everyone is adequately fed and has a clean room to sleep in at the end of the working day.


Some drilling contractors employ their own catering crew while many outsource the tasks to third-party catering companies. The standard that is expected is to have all cabins and bathrooms serviced daily, which nearly always includes having your bed made for you, and clean towels provided. Because of the lack of living space, and strict baggage restrictions for all personnel flying to a rig, everybody’s clothes are laundered daily to minimize the amount of clothing required. During the boom times there were usually added extras like lifestyle coaches and personal trainers making regular visits to the rig but that service disappeared once the price of oil started to drop.


The quality of meals is extremely variable, depending on the rig and location around the world. You can expect to have the cuisine of whatever country you are drilling in so this can vary from American food if you’re in the Gulf of Mexico, British food if you’re in the North Sea, Indian food if you are in many SE Asian regions, or any number of other variations. Being unskilled laborers, the catering and cleaning crew will be sourced from the closest port to where the rig is drilling.


With crew changes occurring on a daily basis, and bed space usually filled to capacity, it is necessary to have dayshift and nightshift cleaners, as well as cooks. These are generally entry-level jobs that require no experience although many of the people have experience in similar roles at onshore mining camps or similarly serviced remote work sites. While the large international contracting service providers tend to have a gender-balanced workforce these days, it’s still rare (in my experience) to see any women working these roles on rigs that use their own catering and cleaning crews. Some habits are hard to break!


While on the gender issue, it’s probably worth noting that there are generally very few women working on offshore drilling rigs. The roles that are most likely to have females represented are catering, mudloggers and MWD. I have, on many occasions, been the only female on the rig out of a POB of up to 180. While it’s rare to be the ONLY woman on board, it does occur from time to time, but generally there will be a few scattered around the facility in different roles. You generally won’t see more than half a dozen women working on a rig out of 120 to 180 workers on board. More than likely it will only be two or three.




With all the drilling contractor crews and third-party service providers now covered, it just leaves the oil and gas company’s representatives to cover in the final part of Offshore Oil and Gas PEOPLE. Part 10 will explore the main roles carried out by these oil and gas professionals and what it takes to be part of the team. Stay tuned!


If you have only just tuned into “Offshore Oil and Gas PEOPLE” then you can find the rest of the series of articles here: Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7 and Part 8.




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: