A Unique Rigless Casing Leak Repair, Ghawar Field, Saudi Arabia

Abstract

Abstract This paper describes the successful field application of a relatively new rigless technique to repair a casing leak in a saltwater disposal well in the Ghawar field in Saudi Arabia, the first installation of its kind in the Middle East. This unique repair method utilizes an electric-line-conveyed, non-metallic, composite sleeve composed of elastomers and thermo-setting resins reinforced with fibers. A description of the technology is presented, along with a brief history of its development, characteristics of the patch, and the installation procedure. The candidate selection process, candidate well history, and installation procedure for two patches are discussed, and economics are shown illustrating that this type of repair was economically superior to a rig workover. Introduction Cost effective, optimum methods of repairing tubing and casing leaks have been sought after throughout the history of oil and gas production operations. Repair alternatives have included mechanical patches of various types, and in the case of tubing leaks, outright replacement in cases of severe damage. For casing patch installation, tubing often must be removed to allow access to the casing. This typically requires a workover rig or pulling unit at significant expense. It also typically results in a significant period of downtime since it requires killing of the well, mobilization and demobilization of the rig, and sometimes a stimulation or cleanup treatment to remove formation damage inflicted by the kill fluid and/or the solid plugging material carried into the well by the kill fluid. The degree of corrosion resistance of the patch or replacement tubulars must be considered, as does the resulting inside diameter as it relates to tool sizes for future surveillance and intervention activities. And finally, the overall cost must be evaluated, for the initial installation and including operating costs over the life of the well. Problem Description Uthmaniyah Well ‘A’ was drilled and completed in 1991 as a vertical, tubingless, open hole Arab-D seawater injection well with 7" liner from 2015’ to 7125’ and 6" open hole below that to TD at 7495'. In 1995 the well was switched to produced (salt) water disposal, and in February 1999 a casing leak was confirmed which was allowing crossflow of water from the higher pressured Arab-C to the lower pressured, open hole Arab-D interval below (Figure 1). Temperature and flowmeter surveys were conducted, which indicated that during shut in, dump flooding was occurring at a rate of 1000 barrels per day. Casing diagnostic logs were run in June 1999. The casing leak was pinpointed in the Arab-C at a depth of 6990’ and an area of significant exterior corrosion was also noted at 6394’ to 6398'. Exterior corrosion of casing and liners is not uncommon in the Ghawar Field when the primary cement job does not provide full cement coverage. The overall cement bond in Well ‘A’ was quite good for the 7" liner, with the exception of localized areas of poor cement bond at the above-noted depths, and the general condition of the liner was also very good. In terms of reservoir management, the end result of such casing leaks is that injected water does not reach the intended interval (Arab-D), but instead is partially lost to the shallower Arab-C. Since the Arab-C is not a producing interval, it has become overpressured relative to the Arab-D, the primary producing interval in Ghawar Field. Repair Alternatives The traditional repair for a casing leak like this has been a rig workover where the tubing (if present) is pulled from the well and a scab liner is placed over the leak. The open hole section typically is filled with calcium carbonate chips to limit fluid losses and to protect the injection intervals from damage during the workover. Cementing of the scab liner is typically difficult with no squeeze pressure obtained.