Solid Expandable Tubular Technology: The Value of Planned Installation vs. Contingency
Narrow pore pressure/fracture gradient windows often necessitate additional casing strings to reach deeper objective depths. Operators are constrained by the number of strings of conventional casing that they can run through subsea or surface wellhead equipment. Planning solid expandable tubulars into the well design allows the operator to run additional casing strings and drill to deeper objectives. Using a solid expandable tubular system in the upper sections of the well design preserves hole size from the onset and allows more casing strings to be run without having to push casing points to the frac-gradient limit. Preserving hole size contributes to drilling efficiency, reduces equivalent circulation density (ECD), and minimizes risk associated with small hole size in deeper sections of the wellbore. Another application for solid expandable tubulars is with surface stack technology. Early surface stack systems were designed around a subsea stack blowout preventer (BOP) system placed on top of a 13-3/8 in. drilling riser. After setting the 13-3/8 in. riser, only one or two casing strings could be run through the riser, which precluded reaching deeper geologic objectives. This paper will look at two case histories. The first case history compares two deepwater offset wells in Mississippi Canyon. One well used expandable casing as a contingency, and the other well incorporated the casing as part of the base design. The second case history will evaluate a well where solid expandable tubular technology allowed up to three additional casing strings to be run in a surface stack application. This paper discusses how combining solid expandable tubular technology with surface stack technology has pushed the technical limits of surface stack drilling into deeper water and deeper formations.