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What is casing string & design?
What is the outermost casing string?
What is conductor casing?
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casing string. 1. n. [Drilling] An assembled length of steel pipe configured to suit a specific wellbore. The sections of pipe are connected and lowered into a wellbore, then cemented in place.
- Casing
- Tubing
- API Connection Ratings
- Proprietary Connections
- Connection Failures
- Connection Design Limits
- General References
Casing is the major structural component of a well. Casing is needed to: 1. Maintain borehole stability 2. Prevent contamination of water sands 3. Isolate water from producing formations 4. Control well pressures during drilling, production, and workover operations Casing provides locations for the installation of: 1. Blowout preventers 2. Wellhead...
Tubing is the conduit through which oil and gas are brought from the producing formations to the field surface facilities for processing. Tubing must be adequately strong to resist loads and deformations associated with production and workovers. Further, tubing must be sized to support the expected rates of production of oil and gas. Clearly, tubin...
While a number of joint connections are available, the API recognizes three basic types: 1. Coupling with rounded thread (long or short) 2. Coupling with asymmetrical trapezoidal thread buttress 3. Extreme-line casing with trapezoidal thread without coupling Threads are used as mechanical means to hold the neighboring joints together during axial t...
Special connections are used to achieve gas-tight sealing reliability and 100% connection efficiency (joint efficiency is defined as a ratio of joint tensile strength to pipe body tensile strength) under more severe well conditions. Severe conditions include: 1. High pressure (typically > 5,000 psi) 2. High temperature (typically > 250°F) 3. A sour...
Most casing failures occur at connections. These failures can be attributed to: 1. Improper design or exposure to loads exceeding the rated capacity 2. Failure to comply with makeup requirements 3. Failure to meet manufacturing tolerances 4. Damage during storage and handling 5. Damage during production operations (corrosion, wear, etc.) Connection...
The design limits of a connection are not only dependent upon its geometry and material properties, but are influenced by: 1. Surface treatment 2. Phosphating 3. Metal plating (copper, tin, or zinc) 4. Bead blasting 5. Thread compound 6. Makeup torque 7. Use of a resilient seal ring (many companies do not recommend this practice) 8. Fluid to which ...
Fowler, E.D. and Taylor, T.E. 1976. How to Select and Test Materials for –75°F. World Oil. Galambos, T.V. and Ravindra, M.K. 1978. Properties of Steel for Use in LRFD. J. of the Structural Division, ASCE, 104(9): 1459-1468. Galambos, T.V., Ellingwood, B., MacGregor, J.G. et al. 1982. Probability-based Load Criteria: Assessment of Current Design Pra...
The casing string’s displacement equation can be explained as follows: (22-16) where. EI ( x ): bending stiffness of combination of casing string, cement ring, etc., kNm 2; q ( x) : unit external force, kN/m; Dc ( x) : external diagram of casing string, m; N ( x) : axial force, kN;
Dec 21, 2018 · A casing string is an important structural component of a borehole. It maintains the borehole stability, prevents contamination of water sand, protects freshwater aquifers, seals off faults in the formation, and helps control well pressure during drilling, production and workover operations.
Apr 26, 2017 · Casing Strings There are six basic types of casing strings. Each is discussed next. Conductor Casing. Conductor casing is the first string set below the structural casing (i.e., drive pipe or marine conductor run to protect loose near-surface formations and to enable circulation of drilling fluid).
Casing strings are the series of steel pipes that line the borewell and provide structural support. The casing is placed from the wellhead down to the oil or gas reservoir. This ensures the integrity and stability of the well. In this post theory and functions of casing strings are discussed in detail. Table of content: 1. What are Casing Strings?
Dec 10, 2019 · Casing liner. Types Of Casing Used In Drilling Wells. Structural Casing or Drive Pipe. This casing string provides initial hole support close to the surface and generally varies in length from about 30 to 300 feet. The casing may be driven or hole drilled. The casing may be cemented if it is necessary to drill a hole.
