Abstract
In the Marcellus Shale gas play in Pennsylvania and West Virginia, solid-steel expandable liners have been used over the last three years to restore casing damaged by over-pressuring during completion operations and to cover unwanted perforations to enable hydraulic fracturing. This paper describes the technology of expandable solid-steel liners and presents representative case histories in the Marcellus Shale.
Solid-steel expandable liners are expanded downhole using a pressure-driven cone that enlarges the diameter of the liner by permanently deforming it beyond its yield point but not to failure. While expanding the liner, elastomeric seals on the outside are compressed against the base casing to provide pressure integrity and anchoring.
In the Marcellus Shale, one well experienced a casing split in the lateral section during the primary cement job, and in a second well, a casing split occurred in the lateral section while pressuring open the toe fracturing sleeve. In a third well, three sets of squeeze perforations over a 1,300-ft interval had to be covered. In a fourth well, circulation for a cement job could not be established requiring the lateral liner to be perforated over its entire length in order to squeeze cement behind the casing. All of these wells required restorations of 5-1/2-in. 20 lb/ft casing to enable hydraulic fracturing.
In the first well, the casing split was repaired using a standard single-joint of expandable liner allowing the fracturing treatment to be performed using controlled screenouts (sand plugs) for fracturing-stage diversion below the expandable liner. In the second well, the casing split was repaired using two standard joints of expandable liner and the fracturing treatment was performed using drillable composite fracturing plugs (frac plugs) set below the installed liner for fracturing-stage diversion. In the third well, three separate high-performance single joints of expandable liner were used to cover the three sets of squeeze perforations over the 1,300-ft interval to enable fracturing using frac plugs set below the three single-joint expandable liners. In the fourth well, the entire lateral was relined with the solid-steel expandable liner, maintaining inside diameter (ID) sufficient for fracturing with frac plugs set inside the liner. In all these shale gas wells, solid-steel expandable liners provided reliable and robust solutions enabling fracturing to proceed as planned.
