TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractWater production management starts to play a more important role as reservoirs mature. Production logging is required to identify watered out intervals in producers and thief zones in injectors. The interpretation of logs acquired in horizontal, barefoot wells in highly fractured, heterogeneous, carbonate reservoirs is challenging at least. Yet this technique has been successfully applied in Petroleum Development Oman (PDO) in the Yibal and Al Huwaisah fields (Fig. 1) and has lead to significant production improvements after the subsequent water shut off.Expandable Open Hole Clad (OHC) systems, with external seals, have been deployed to shut off water in both horizontal producers and injectors. The seal between the expanded pipe and the formation is further enhanced by elastomers with the ability to swell upon contact with formation fluids.Case histories are presented to demonstrate the viability of this new technology.

Water production management starts to play a more important role as reservoirs mature. Production logging is required to identify watered out intervals in producers and thief zones in injectors. The interpretation of logs acquired in horizontal, barefoot wells in highly fractured, heterogeneous, carbonate reservoirs is challenging at least. Yet this technique has been successfully applied in Petroleum Development Oman (PDO) in the Yibal and Al Huwaisah fields (Fig. 1) and has lead to significant production improvements after the subsequent water shut off. Expandable Open Hole Clad (OHC) systems, with external seals, have been deployed to shut off water in both horizontal producers and injectors. The seal between the expanded pipe and the formation is further enhanced by elastomers with the ability to swell upon contact with formation fluids. Case histories are presented to demonstrate the viability of this new technology. Introduction As oil fields mature, production wells experience co-production of oil and water because of aquifer encroachment and/or water injection. Controlling the water production is one of the major challenges in reservoir management. Diagnosis of the zone of water influx in horizontal well bores, however, is not always straightforward and must certainly preceed any remedial water shut off treatments. This paper starts with a discussion on the water shut off technique using expandable tubulars, followed by two case histories in which more details are provided concerning production logging, expandable clad installation and production results. Technology Overview Previously published papers have discussed the concepts of Solid Expandable Tubular (SET) technology1 and the effect of the expansion process on the system's tubulars2,3 and connectors4. The specific system used in PDO, with the required adaptations, will be reviewed in this paper. The basic principle is the down hole enlargement (expansion) of a solid pipe. Expansion is achieved with a cone that can either be pushed (typically by hydraulic force) or pulled through the pipe. SET can be applied for both well construction and remediation5. Four general types of SET products can be identified:The Expandable Cased Hole Liner (CHL) is set in a cased hole environment and is typically used to isolate perforations or damaged or corroded casing.The Expandable Open Hole Liner (OHL) is used in the well bore construction process to provide an additional liner whilst minimizing Internal Diameter (ID) loss. This provides more options in the well design process to reach the required Total Depth (TD) without compromising hole size.