Expandable tubular solutions have been developed and applied as a drilling solution to extend well depth while maintaining a larger borehole diameter . In this paper we review the benefits of expandable tubulars for shut-off and zonal isolation in carbonate reservoirs. Particular emphasis is given on a major Middle East Operator's experience.
Expandable open hole liner (OHL) systems, developed as a drilling solution, is based on expanding a liner across an open hole section and into the previous casing to form a liner hanger . Instead of cement, elastomer seals provide zonal isolation in open hole , .The liner is expanded to create a seal by energizing an elastomer between casing and the formation. In addition the elastomer swells in contact with water. This dual sealing mechanism provides an annular seal of any desired length. The technology is non-invasive on the reservoir. Alternative technologies either are invasive on the reservoir or have had limited success, i.e. cement, chemical squeezes or scab liners.
Expandable tubular solutions have proven successful in terms of installation reliability, isolation of fractures, swept zones and ghost holes. Also, the technology enabled inflow profile control through zonal isolation in horizontal wells. Case histories for shut-off and zonal isolation demonstrate the viability of extending the scope of expandable technology deployment for better management of carbonate reservoirs through a "drill, monitor & intervene" completion philosophy combining selectivity and shut-off in a low-cost intelligent completion solution.
A major Middle East Operator faces the challenge of increasing water production from maturing oil fields. Not counteracting water production may result in enormous treatment and handling costs. Therefore, a shift in completion philosophy from a "drill & forget" approach towards a "drill, monitor & intervene" approach is under way. Expandable tubulars and swelling elastomer technologies enable completion designs that meet zonal isolation, selectivity, shut-off and stimulation requirements across the full life-cycle of the wells.
Carbonate reservoir fields with either natural water drive or water floods would benefit from effective fracture shut-off with the objective to reduce water production, to increase oil recovery and to improve the sweep efficiency of water flood operations. Solutions for the following problems are required:
Water influx from fractures in new horizontal wells.
Early injection water break-through in single horizontal and multi-lateral producers.
Water short-cutting between water injector and producer wells via fractures. This applies to both horizontal and as well as vertical wells.