CASING DESIGN FOR SPECIAL APPLICATIONS
Today, the wells drilled by the petroleum and other energy development industries cover a wide range of drilling conditions. Highly deviated and even horizontal wells are being drilled to complete reservoirs which otherwise could not be produced economically. Wells are being drilled and completed in widely disparate environments from below freezing conditions in the permafrost zones of Alaska and Canada, to thermal energy recovery projects up to 500 °F: and steam injection projects between 300°F and 400°F, to the extremely high collapse pressure conditions arising from massive salt domes in various parts of the world.
Severe drilling and borehole conditions place additional requirements on casing design. As a result, it is often difficult to meet API requirements for principal design loads such as collapse, burst, and tension. In the following sections the current practices used in designing casing for highly deviated wells and the severe collapse loads that arise from the swelling of salt formations in very deep wells and thermal wells, are reviewed.