Abstract
Cased-Hole Expandable Liners can be used for many different applications, including corrosion remediation, casing damage repair, perforation isolation, and to seal off water encroachment. The standard expandable liner design includes a carbide anchor at the bottom to hold the liner in place, as well as elastomer bands at the top and bottom of each joint to provide a seal. By designing a specialized liner system, in which the entire liner is wrapped with elastomers, greater sealability and pressure integrity is achieved.
In this particular application in the East Texas Basin, watered-out perforations needed to be isolated to facilitate fracturing and producing a deeper zone in the wellbore. Several approaches were considered and it was eventually decided to install a single trip 38 ft elastomer-wrapped expandable joint to isolate perforations in 5-1/2 in. 17.0 lb/ft casing and maintain a seal during the fracturing operations. Elimination of the end connections and beveling the ends of the liner meant that it could be rated at the pressure limitation of the pipe body, rather than that of the connections. In addition, further studies indicated that wrapping the entire expandable liner section with elastomers provided added support and sealability.
This paper will discuss the problems associated with the water encroachment through the perforations, the design of the elastomer-wrapped expandable liner system, and the engineering study that led to its rating being sufficient to withstand the high pressure frac job. It will go on to describe the liner installation and the ensuing well stimulation, which yielded very satisfactory results.