This paper describes the development of a new method for driling out a shallow-set casing shoe, testing pressure integrity at the shoe, and drilling open hole below in a single drill pipe trip in a deepwater drilling environment. This methodology should reduce the cost of drilling operations, particularly in locations with shallow-water-flow potential. The development and operation of a new drillstring-integral shoe test packer system will be described that allows isolation of the bottom of a shallow-set casing string for purposes of pressure testing the shoe. This provides the operator with a method to verify shoe integrity prior to drilling into high-pressure sands, which have potential for water flow, with fewer drill pipe trips. The paper will also present a detailedcase history of how this method was applied for a major offshore operator from a floating vessel in 4,000 ft of water in the Gulf of Mexico. For this application, shoe-testing of the 30-in. casing string was critical to check for resistance to potential shallow-water-flow reaching the surface. This test operation was also performed riserless, without a means to perform the shoe pressure test other than the drill pipe string. If the shoe test proved successful, the operator could continue drilling the next wellbore section without pulling the workstring, thus streamlining the operation and saving time. Performance criteria required by the operator, the design methodology used to meet those criteria, qualification testing and field performance in initial operations, including time savings from the one-trip system will also be discussed.
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