"Here, injection tubing is made of a special chrome alloy to provide good corrosion resistance," says Berlin. "That's important due to the potential for saltwater to mix with CO2 in the well."
The tubing extends to depths of 6,400 ft, about 100 ft into the Mount Simon formation. There, a "packer" isolates it from a 9 5/8-in.-dia chrome casing string that extends another 600 ft, terminating in a perforated section through which the CO2 plume exits the well. To anchor the deepest casing, Schlumberger employs a custom cement capable of resisting the brine and CO2 mixture.
"We set a larger surface casing string in order to protect shallow groundwater zones," says Berlin. "Another intermediate string extends all the way from the wellhead to points above the injection zone. Both are encased in cement to isolate the well from all the subsurface formations. By the time the second well is constructed, all shallow water zones will be protected by three layers of steel, each with a layer of cement between them."
An extensive array of sensing and monitoring technology allows project team members to monitor the two installations.
"By monitoring pressures," says Berlin, "we'll know whether the CO2 is staying where we predicted it would, down near the bottom of Mount Simon."