Project Location: Austin, Texas
Client: Marathon Oil Company, Houston, Texas
Dates: December 1999 to February 2000

Structural casings are commonly used as one of the foundation components for offshore wells in the oil industry. The design of these casings must consider drilling and production loads (life-cycle loads) in static and cyclic modes. The practices for the design of these casings for offshore platforms are outlined by the American Petroleum Institue in recommendations from API RP 2A.

Modern concepts of soil-structure interaction were developed by LCR&A in order to study the response of structural casings. The new method developed for Marathon Oil Company considers the lateral resistance of the soil as a nonlinear function of the deflection of the casing while analyzing the effects of various axial loads placed at different levels above the wellhead (using p-d effects). A commercial software was developed by engineers from LCR&A and results from this new program compared very well with results obtained from very complicated and costly finite-element models prepared by other consulting firms.