At some point in the life of all oil and gas wells, parts will require maintenance, repair or replacement. At these times, operators turn to intervention specialists.
Interventions fall into two general categories: light or heavy. During light interventions, technicians lower tools or sensors into a live well while pressure is contained at the surface. In heavy interventions, the rig crew may stop production at the formation before making major equipment changes.
Well service personnel typically perform light interventions using slickline, wireline, or coiled tubing. These systems allow operators to minimize the possibility of potential well blockages. Operators also order light interventions to change or adjust downhole equipment such as valves or pumps, or to gather downhole pressure, temperature, and flow data.
Heavy interventions—also referred to as workovers—require the rig crew to remove the wellhead and other pressure barriers from the well to allow full access to the wellbore. These operations require a rig to remove and reinstall the wellhead and completion equipment.
Typically, heavy interventions are used to replace parts such as tubing strings and pumps that cannot be retrieved through light interventions. Some heavy interventions are performed to plug and abandon an original producing zone to reconfigure the well to produce from a secondary zone; these operations are known as recompletions.
An article in the Winter issue of Oilfield Review “Defining Intervention: Upstream Maintenance and Repair” focuses on the essentials of well intervention and describes the basic tools and methods available to operators whose wells are producing below potential.
von Flatern, R.: “Defining Intervention: Upstream Maintenance and Repair,” Oilfield Review 26, (Winter 2014/2015): 26, No. 4, 62–63.