|Threaded oil-well pipe or casing after expansion shows Von Mises stresses at maximum deformation. Red indicates highest stresses, not failure. Enventure engineers use nonlinear FEA from Ansys Inc. to find the load required to expand the pipe during installation and its properties after expansion.|
|Ansys is also used to calculate maximum contact pressures after expansion.|
A new oil and gas-well drilling system from Enventure Global Technology LLC, Houston, uses expandable pipe or casing that allows drilling wells deeper than standard equipment. Solid Expandable Tubular (SET) technology eliminates telescoping of casings that often limits drilling depth. Well holes must be shored up with casing pipe, but using traditional methods means each deeper section must have a smaller diameter than the casing above it. The line of pipe eventually resembles a telescope.
After drilling below the last casing using the SET method, a new casing atop an expansion cone is placed into the new hole section. Fluid pumped at high pressure below the cone forces it up the pipe, expanding the casing as it rises. Expandable tubes almost entirely eliminate the need to telescope pipes, making it possible to reach deeper oil and gas.
When looking for the right combination of material, fluid pressures, and manufacturing methods, engineers at Eventure simulated the expansion process using nonlinear finite-element analysis in software from Ansys Inc., Canonsburg, Pa. "Drilling companies want to know which tube properties are guaranteed, and how they are measured," said Kevin Waddell, vice president of technology at Enventure. "FEA significantly reduced the time required to conduct thorough simulations and analyses."
The pipe is made by electric-resistance welding and heat treating to increase ductility. This allows pushing the steel into its plastic region during expansion without rupturing. Cold working also increases fracture toughness.
-- Paul Dvorak