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Completion systems are the components necessary to complete the well after it is drilled and prepare it for production. There are many completion options available to oil and gas producers. Today’s cased-hole completion systems vary from relatively simple single-zone low-pressure/low-temperature (LP/LT) designs to complex high-pressure/high-temperature (HP/HT) applications that were unthinkable with the technology available 50 years ago. Many of the basic components appear similar to those used in the past, yet they have been vastly improved, and their performance has been optimized to suit numerous environments.
Factors that affect the design of completion systems
There are several keys to designing a successful completion system and selecting components that are fit for purpose for both the downhole environment and application. Consideration must be given to the various modes under which the completion must operate and the effects any changes in temperature or differential pressure will have on the tubing string and packer. Ultimately, the system must be both efficient and cost-effective to achieve production and financial goals. A key factor in the completion design is the production rate.
Other factors that must be considered as part of the completion design:
- Flow control equipment
- Equipment metallurgy
- Equipment standards and grades such as ISO and API
- Understanding the impact of force and length changes to the tubing string
- Operational mode of the well (production, shut-in, injecting, treating)
Systems for specific completion types
The appropriate equipment depends on the type of completion as well as downhole conditions.
- Single-string low pressure/low temperature (LP/LT) wells
- Single-string medium pressure/medium temperature wells
- Single-string high pressure/high temperature (HP/HT) wells
- Multiple-zone single-string selective completions
- Dual-zone completion using parallel tubing strings
- Big-bore/monobore completions
Noteworthy papers in OnePetro
Burton, Aaron, and Sergey Kotov. 2013. Unconventional Completions – Wellbore Completions and Fracturing. https://webevents.spe.org/products/unconventional-completions-wellbore-completions-and-fracturing
Waters, George. 2013. Completion of Hydrocarbon Bearing Shale Reservoirs. https://webevents.spe.org/products/completion-of-hydrocarbon-bearing-shale-reservoir-spe-distinguished-lecturer
Allen, T. and Roberts, A.P. 1993. Production Operations, fourth edition, I and II.
Factors and Conditions Which Cause Seal Assemblies Used in Downhole Enviornments to Get Stuck. Baker Oil Tools—Engineering Tech Data Paper No. CS007.
Patton, L.D. and Abbott, W.A. 1985. Well Completions and Workovers: The Systems Approach, second edition, 57–67. Dallas: Energy Publications.