WorldOil

Single diameter expandable casing applications continue to advance

It’s been a long-term goal-a “holy grail” of well construction-to create a well with only one diameter of casing. The savings in time, fluids, cement, hangers and other hardware, preventing constricted completions and their effect on production, and many other advantages are well documented,1 and they apply roughly in proportion to the “slimness” of the well. In other words, advantages accrue if just one string of intermediate, “telescoping” casing can be eliminated. However, the added cost of expandables can offset the savings in fluids, cement, etc., such that operators are only using the technology when they have to. But there are signs that this may be changing. We still have some time-perhaps five or more years-before we see a relatively deep well drilled with only a surface conductor and a single-diameter expandable pipe. What’s needed are improvements in: fatigue resistance; burst and collapse pressures; the speed with which the pipe expands.