Special design considerations are required in a number of more complex cases. Some of the issues to address are discussed below and the casing designer will need to check the latest relevant industry experience.

- HPHT well
- Squeezing salt well
- Steam well
- Horizontal well
- Slim hole well
- Permafrost well
- Gravity structure
- Reservoir compaction environment
- Deep-water well
- Gas-lift well

HPHT well

In High Presure High Temperature (HPHT) environments, high differential pressures often lead to the use of high strength, thick-walled, and occasionally non-standard, casing.

High temperatures…

Squeezing salt well

When a hole is drilled through a salt formation, and subsequently casing is set, the salt will gradually move and make contact with the casing. The following paragraphs describe the loading on the…

Steam well

The design of steam wells is complicated by the fact that the axial stress exceeds the yield strength in compression during heating and exceeds the yield strength in tension during subsequent cooling.…

Slim hole well

For a slim hole casing design all the design loads, inclusive burst, collapse, and tensile load requirements, should be determined as for all other wells. For a fixed influx volume and assuming a…

Gas-lift well

Casing designs for wells in which gas-lift completions are to be installed are based upon different design load cases from standard wells. They have to be treated differently from standard wells in…

Gravity structure

With time, a concrete gravity platform structure will induce considerable deformation within the supporting soil. The casing, particularly the marine conductor, will have, at least in part, to follow…

Deep-water well

Deep-water wells present two problems for the casing designer, casing setting depth, and environmental loading above the seabed.

Firstly, these environments have lower fracture gradients than…

Permafrost well

The consequences of permafrost thaw resulting from increased surface temperatures during drilling and production, affect casing design in a number of ways.

Permafrost is a permanently frozen soil.…

Reservoir compaction environment

Production of hydrocarbons will, in time, lead to a reduction in reservoir pore pressure if pressure is not maintained by a drive mechanism. The resulting increase in effective stress leads to…

Horizontal well

There are a number of areas in horizontal well casing design that may differ from a standard well. These mostly relate to the casing loading, although there can be instances where the capacity of the…