Oil and gas well intervention involves many activities. It is often done to provide maintenance to facilities, which can extend their production life. Well parts will eventually have to be repaired or replaced. During a light intervention, tools are lowered into the well. Specialized equipment maintains the pressure at the surface, while sensors monitor the conditions deeper down. Production may stop entirely if a heavy intervention is required, such as when major pieces of equipment need to be replaced.
Routine procedures for light work include using wireline, slickline, or coiled tubing so not to block a well. Pumps, valves, or temperature/pressure/flow measurements downhole can often be made without disrupting operations as well. In more extreme cases, crews must remove wellheads, pressure barriers, and other equipment for more thorough access and to remove heavier components. Heavy interventions can be done to plug up a well or reconfigure it.
Not intervening can mean production falls and the well will eventually no longer have commercial viability. Operators also have cost concerns with the work done, but reducing the costs of light intervention can prevent wells from being shut in and abandoned. The complexities of the process include finding suitable vessels to conduct the work, hard-to-handle riser pipes, and the tendency of steel coiled tubes to become fatigued and damaged.
Wireline, tractors, coiled tubing, and hydraulic workover well interventions can improve performance, and each serves a specific series of applications.
Additionally, vessels can be used for intervention processes. Ships include diving capabilities, oil spill containment, and a full range of abilities to maintain and fix wells throughout the world. The more capable a vessel or facility is, the better able it is to apply the proper procedures and implement contingency plans for the specific well and its condition.
Risk of Well Intervention Accidents
Accidents and injuries may be caused by:
- Chemicals used to block or clean wells.
- Issues with high-powered tubing used for repairs.
- Equipment and accidents on platforms.
- Helicopter incidents that occur between the platform and shore.
- Lack of skill and understanding of using heavy-duty equipment.
The high degree of skill needed means that well intervention specialists must be trained, competent, and aware of what they are doing. Any level of negligence can have a profound impact on human life and the economic well-being of the corporation.
Well Control Regulations
The Bureau of Safety and Environmental Enforcement issued the 2016 Well Control Rule that covers various topics, from blowout preventers to manufacturing, repair, maintenance, and reporting standards. Intervention systems are considered a form of well control and are thus included in the regulations. The bureau also called for intervention units to be assessed via a compliance worksheet. The guidelines put forth by the organization apply to riser systems with a control system on top of the wellhead; Riserless Intervention Systems that incorporate the control package, pressure control, and wireline lubricator atop the wellhead; and Open Water Subsea Pumping Systems.