The well completion typically includes the perforations, sand exclusion system, (liner), tubing, wellhead, tubing accessories, packers, associated safety equipment and Xmas tree.
The perforations, gravel pack etc. provide the 'inflow system' into the well structure, while the tubing with flow controls, safety devices for isolating the reservoir, the Xmas tree and, where necessary, artificial lift or pressure boosting facilities, provide the 'outflow system' (well conduit) within the well structure.
1. General completion design considerations
Well and completion design must take into consideration the following requirements:
- artificial lift needs
- well service/maintenance options.
- reservoir: fluid volumes, sand exclusion, number of zones, stimulation requirements, etc.
- future requirements: secondary recovery, injector, etc.
- operating conditions: pressure/temperature, corrosion, scale, wax, etc.
- government legislation: safety requirements, annulus vent/flare restrictions (downhole gas separation), etc.
- surface facility constraints: pipelines, process equipment, etc.
- company safety and environmental considerations.
- data gathering requirements: permanent downhole monitoring, etc.
- maintainability, accessibility, intervention frequency, etc.
- standardisation of equipment.
Production operations input into well design
- regulations governing the provisions of subsurface safety valves;
- statutory requirements on maintenance of equipment and its frequency.
- sand control
- well killing
- sampling
- safety equipment
- corrosion inhibition
- well spacing
- flow control