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 the displacements that take place in the soil. The marine conductor and possibly the conductor casing therefore have to be designed such that the loads caused … Gravity structure

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 equivalent depths for land wells, or offshore wells in shallow water. As the water depth increases, fracture gradients are significantly different, particularly in the shallow sections of the well. … Deep-water 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 casing is purposely reduced. Casing loading Fpr the horizontal section itself, the stability of the formation must be determined in … Horizontal 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 compound the design problem by reducing the yield strength of the casing steel, by causing significant thermal linear expansion of the steel, and by generating high pressures in sealed annuli … HPHT 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. Soil at temperatures below freezing point may or may not contain ice, depending upon pore fluid salinity, pore pressure, and soil type. Permafrost can be continuous from … Permafrost 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 two respects: definition of the possible pressure profiles within the “live” tubing/production casing annulus (A-annulus) design of the intermediate casing to withstand the … Gas-lift well

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 reservoir compaction and deformation of the overburden. The vertical strain caused by this compaction of the producing interval is transferred to a certain extent … Reservoir compaction environment

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 single bubble of gas, the smaller annular cross section causes a greater influx height than in conventional holes. This might influence the … Slim hole 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. As such, a design is required which incorporates post yield behaviour of both casing and connections. A brief discussion of the issues involved … Steam 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 casing, and then the capacity of the casing to withstand such loading. Casing loading The plastic behaviour of salt formations may result … Squeezing salt well