In the last few years, there has been a significant increase in gas production to meet the global energy demand. To date, most of the recoverable gas potentials are situated in offshore concessions, and mostly in deep water. Therefore, the need to consider the environmental and technical challenges to establish and maintain any offshore gas production facility are important to the success of the field development and operation.
The use of remote technology has been used in the subsea sector of the oil and gas industry for many years; however, the scale at which it has been used in the past against the needs for the future is becoming a major consideration to the development and operation to any subsea gas production fields. Remotely Operated Vehicles (ROV) is one of the most advantageous remote tools to any deepwater operation. Introduced to the offshore industry over 25 years ago the ROV has developed from a simple observation vehicle into a sophisticated underwater work platform (Work Class ROV) reaching depths of 4000mtrs and beyond. The numbers of tasks that WROV can perform cover are many and varied and are referred to as "ROV intervention operations". Typical examples of intervention tasks are subsea production system; valve actuation, component replacement, control umbilical connection. With the majority of these tasks undertaken by the ROV, and some intervention tool specifically designed for the task.
Intervention accounts for 2 - 3 % of the total cost of offshore oil production, it frequently paces other operations on the critical path during oil field construction and operation because the operation of very costly equipment (such as supply vessels, drill rigs, and derrick barges) depends on the success of ROV operations. Making these operations more efficient and reliable will produce a large cost saving ripple effect throughout the aspects of the offshore operation.
Introduction
For many years subsea production designs did not typically incorporated provision for remote intervention as water depths allowed the use of divers to undertake the intervention operation; installation, inspection, maintenance, work over and recovery. The emergence of well-engineered and reliable work class remotely operated vehicles, combined with the need to complete subsea wells in water depths inaccessible to divers ensured that ROV intervention capability had to be considered and incorporated into the subsea production system design. So today deep water subsea production systems cater for ROV intervention which contributes to improving access to the deep water fields and hence the overall economics of subsea developments.
ROV Development
Perhaps the most significant in the evolution of subsea intervention has been the development of ROV's. When initially introduced, ROV's were observation vehicles used for underwater inspection and video documentation.
The next step was to add a manipulator arm to slightly larger vehicles to accomplish light work tasks, such as debris removal, or attachment of lift lines.
ROV's have now proliferated, and are available in a wide range of capabilities from observation only to heavy work tasks using additional tools such as follows.
