Well interventions involve an activity or set of activities designed to change or manage wells' production. Hence, during the life of a well, well intervention is used both proactively and reactively to achieve most-optimum production levels. The scope of well intervention ranges from replacing failed mechanical equipment down-hole, to changing the flow dynamics and production profiles and repairing wellheads. Younger wells may require managed production profiles, whereas older wells need more cleaning and equipment change-out activities to maintain production levels. Well intervention is used both offshore and onshore; offshore use includes more logistical issues and challenges, and a specialized vessel may be required for well intervention.
Well intervention can be carried out with or without a drilling rig. The rig used in well intervention activities, whether offshore or onshore, is called a work-over rig, although a standard drilling rig is also utilized. Work-over rigs and drilling rigs have some major differences. Work-over rigs are smaller than conventional rigs, and they do not include pressure control equipment (usually) or mud pumping and storage equipment.
Rig-less well interventions are widely used due to their economic benefits and mobility. Onshore, these well interventions can be achieved using trucks or snubbing units, whereas in offshore applications, they require a specialized vessel / lift boat or a drilling rig. Generally, the more deviated and horizontal the well, the heavier the technology required.
The scope of well intervention is divided into three distinct segments: 1) deployment or conveyance methods; 2) down-hole tools and services; and 3) deployment methods that provide a way to place a tool in a well. Down-hole tools and services are required to carry out a job in a wellbore.
It is convenient to divide well interventions into three separate families of services, as shown below.
- Well Intervention
- Deployment Methods
- Coiled Tubing
- Work-over Rig
- Production Management & Enhancement
- Offshore Stimulation
- Onshore Stimulation
- Data Acquisition & Logging
Depending on technical complexity and a number of other variables, such as well type and age, offshore vs. onshore, space and cost, the value ladder below can be used to illustrate the deployment methods and down-hole tools and services.