Types of Rigs Needing Decommissioning Services
The process of removing an oil or gas rig that is no longer needed is known as decommissioning. There are different types of rigs and some of them are easier to cut up and remove than others. Many rigs are based offshore, typically in the North Sea and a lot of them have been there for decades. Older oil and gas rigs are rooted to the sea bed and have to be cut up before they are moved offshore. Newer rigs often have floating platforms, which means that they can be untied from the seabed and floated back to the mainland for decommissioning there. All decommissioning of rigs involves cutting them up and putting the pieces into safe storage until they are needed to build another rig. Most of the pieces have been in contact with noxious substances, which is treated like hazardous waste and so they have to be stored in a safe facility.
Fixed Rigs
The fixed oil or gas rig is generally the older type of rig built before the mid nineteen nineties. A fixed rig is one that is constructed on legs made of steel or concrete, which are then fixed or anchored directly into the seabed. On top of the legs is a deck or platform holding crew quarters, the drilling rigs and facilities for production. Fixed rigs are immobile because they were designed for long term use. Most fixed platforms work better in water depths up to 520 metres. Older rigs are often more difficult to decommission than more modern structures. Specialist decommissioning services are needed to dismantle fixed offshore rigs.
Jack-up Platforms
A jack-up rig is a platform that is designed to be jacked up above the surface of the water and has legs that can be lowered in the same way as jacks are lowered. A jack-up platform is usually located in water up to a depth of 120 metres, although some of the larger platforms of this type may be used in depths up to 170metres.
Semi-Submersible or Floating Platforms
Floating or semi-submersible platforms are those rigs that have columns that are buoyant enough for the platform to float on the surface of the water but with enough weight in them to ensure that the rig stays upright. Floating platforms are essentially structures that are designed to be moved from place to place, this type of platform is easier for decommissioning services because it can be moved before cutting. These platforms are kept in place by what is known as dynamic positioning or by the use of a mix of chains and wire or polyester rope. Floating platforms may operate in water depths of between 200 and 10,000 feet.
Types of Rigs that may Require Platform Decommissioning
There are a number of different types of oil and gas rigs. The removal of outdated or faulty rigs is known as platform decommissioning, which involves taking the rig apart, removing it from the site, and cutting up the pieces. Most rigs are situated offshore, many of them in the North Sea. Decommissioning a rig requires the expertise of skilled contractors, while there are many different rigs, the most common ones are a fixed platform rig, semi-submersiible platforms, jack-up and tension leg platforms.
The fixed platform is often the most common and usually the older type of rig. The platform is built on concrete or steel legs that are rooted into the seabed. The deck or platform contains the drilling rigs, quarters for the crew and also some facilities for production. The fixed rig is meant for extended use and could be standing for many years before anyone thinks about platform decommissioning. Fixed platforms are usually found in fields where the water is around 520metres deep.
Jack-up and tension leg platforms are used in different depths of water. As the name implies the jack-up platform can be jacked up above the surface of the water. The Jack-up platform is generally used in water that is 120metres deep, but depending on the size of the rig legs, could be up to 170metres. The jack-up rig is probably the easiest to move for platform decommissioning contractors because it is actually designed to be shifted from one place to another Tension leg platforms are generally platforms that are designed to float and upwards movement is prevented by the manner in which the platform is attached to the seabed Tension leg platforms are typically found in waters that may be up to 2000 metres deep. Tension leg platforms can pose a problem for the platform decommissioning contractor, largely due to the depth of water they need to work in.
The semi-submersible platform is erected on certain kinds of columns that are weighty enough to keep the rig in an upright position, but have sufficient buoyancy for the platform to float. Like the jack-up rig, the semi-submersible platform is designed to be shifted from one place to another. Sometimes ballast is used to shift the platform down or up and changing the buoyancy rate in the columns. When drilling and production are being carried out the rig is fixed to the seabed using a combination of wire and polyester rope and chains. Such rigs operate in depths between 60 and 3050 metres of water. Platform decommissioning contractors who may be required to remove the rig may find it easier than a fixed platform because it is designed to be moved.
Working on an Oil Rig
A job on an oil rig can be very tough. It is physically and mentally demanding and workers often have to put up with extreme conditions because of the nature of the job. The type of jobs available on an oil rig would include subsea engineering, drilling, scaffolding or painting for example. Workers on an oil rig can expect to earn quite a good salary coupled with living quarters of the highest standard. Most oil companies will also pay the travel expenses of their workers. If you want to get a job on an oil rig, then you will be pleased to know that there are many entry level positions available as well as a number of senior positions. Most people in senior positions on an oil rig have worked their way up from the bottom.
Because oil rigs are offshore, it is necessary for workers to stay on the rig for periods of time. Shifts can be about twelve hours but workers will work for about two weeks on with three weeks off. There are some positions on the rig which would not get so much time off but in general, most jobs will allow for around half of the year off.
A lot of people will get a job on an oil rig at entry level and this means they will not need any previous experience on the rigs. Types of jobs that are available at entry level include painters, roustabouts, medics, scaffolders or materials men and women. You could also look for a position as part of the catering or cleaning crew or as a radio controller.
Some jobs on the oil rigs will require you to have certain skills or experience such as subsea engineering, drilling or being part of the deck crew. However once you have a foot in the door on an oil rig, it is possible for you to move up through the ranks.
The payment for someone starting out as a roustabout on an oil rig will be approximately £200 per day and while this is not huge when you consider the amount of work it involves, it is still a good salary for an entry level position. With the possibility of advancement and so much leave available, it is very attractive for a lot of people. If you were to work your way up and become a driller then you could expect to be earning up to about £60,000 per year. Senior positions pay up to about £150,000 per annum.
Engineering Economics
As with everything in life, engineering projects cost money. When engineering companies, such as Claxton Engineering, set out to quote on a project, they have to take a variety of factors into consideration. This is not easy to do and requires special training.
Engineers follow an economics course during their training at university. They have to learn the cost of time and the cost of offering various alternatives. Importantly, they also have to learn what it would cost to do nothing about a situation. It is their job to weigh up all the options and present a solution that is viable – especially in monetary terms. If they come to a decision that it would be best to leave good enough alone, they must also be aware of what that decision is going to cost their client.
Engineers are taught how to solve problems using, amongst others, science, logic, biology and even art. They are tasked to find viable alternatives to existing problems and to then design and manufacture the solution. Examples of this are when bridges have to be built over vast chasms or rivers, or when a road needs to go through a mountain.
Other issues that engineers have to face are improving transportation, making more eco-friendly fuel and building structures that are lightweight, but incredibly strong and durable. This includes building aeroplanes, space shuttles and finding a viable alternative energy sources.
With the issue of cost comes the consideration of revenue. How much money will the client make after investing in this project? Sometimes the answer is nothing as the project is for public benefit, paid by public funds or taxes. Other times there could be great profits to be made from a project e.g. new, more economic aeroplanes. These alternatives have to be seriously considered before embarking on the project.
No matter what the problem, companies such as Claxton Engineering have the responsibility to quote on the most cost effective way of solving the problem. However, they cannot compromise on safety or the security of the end users. Viable solutions do not mean a loss of life or injury to people. If the project cannot be run responsibly, the engineer is tasked to find other alternatives to the problem.
Engineering touches our everyday life all the time. Just staying at home you are experiencing the knowledge and skill of one or more engineers. Boiling your kettle or switching on your fireplace are all examples of engineering feats. Driving on a road in your car is also due to the skill of an engineer.
Enjoying life and the daily innovations in almost every sphere of life is a testimony to the great work done by engineers.
Digging Deeper - HPHT Wells Gain Momentum
Oil wells and pipelines are popping up in places in the world that at one time would be inconceivable. Deep in the waters of the Gulf of Mexico and West Africa, high pressure high temperature wells are pumping oil from deep within the earth’s core, thousands of feet below the ocean's surface. This relatively new technology is allowing oil companies to reach places that were once out-of-the-picture. Formulated and coined the name HPHT wells, this specialized well was effectively only a pipe dream, excuse the pun. Wells of this nature only truly became a practical means of accessing oil in the mid to late 90's. Through revolutionary design advance HPHT wells gained the ability to fully withstand great depths, extreme pressures, and intense temperatures. Threaded and coupled joint connectors, partnered with solid steel casing deep sea oil wells are able withstand unbelievably harsh conditions.
These days HPHT wells are able to withstand pressures in access of 10,000 psi and temperatures reaching well above 300 degrees Fahrenheit, conditions that are associated with such great depths and so close to the Earth's core. Ultra-HPHT and extreme-HPHT, such as that designed and operated by Claxton Engineering, are able to handle pressures greater than 12,000 psi. This fresh well design is meant to aid in the drilling of the deep trenches of the North Sea. As these wells gain popularity, revolutionary design improvements make them more affordable and practical; oil companies aren't going to be holding back on where they choose to drill next.
While these improvements raise the bar in safety and guards against disaster, disasters do happen, on occasion. As we witnessed this summer in the Gulf of Mexico, when disaster strikes, it strikes hard and swift. The result of a busted pipeline or a leaky well is devastating to local flora and fauna populations, water quality, and local economies. Reparations for such travesties against nature and humanity continue to be loosely enforced, never truly compensating those who lost livelihoods to the hands of a multi-national corporation that has very much else on the mind but profit.
Why are these players in the oil industry able to continue their increasingly aggressive efforts to extrapolate a dwindling resource for the Earth? Digging deeper and deeper into the ocean floor disaster will almost inevitably return, possibly, to a point of disarray that is un-repairable. Of course, the answer is to the question? Why is this able to continue? Are huge profit margins and an international dependence on a limited resource? Increased safety measures on existing HPHT wells is one thing; but safety measures to increase drill depths and the overall number of deep ocean oil wells across the globe is hardly an effective way to prevent future accidents.