Marginal reserves in the Gulf of Mexico (GOM) shelf can be developed using old completion technology in new ways. Tubing-less completions or monobores are one of those technologies. Several monobores have been performed in the GOM, but usually, they were not the primary completion technique. Most were performed out of necessity, either because liners were stuck above the zone of interest or drill pipe was stuck across the interval.

Large cost savings can be realized by utilizing monobores as the primary completion without impairing the completion efficiencies. By eliminating the high day rates of a conventional platform rig, a single frac packed completion can be performed for less than $ 500,000.

This paper describes a technical review of two 4-½″ monobore completions that were performed in Eugene Island (EI) 273 to recover marginal reserves. The monobore completions were planned as the primary completion technique. However, several changes were made to the monobore completion as compared to conventional frac packing technology. For example, we utilized oriented, limited entry perforating (0°/180° phased and 0.25″ diameter entry holes, 4 shots per foot (spf) and no annular pack.

Many key learnings were identified during the completions and several changes were made prior to the second completion. These changes resulted in an overwhelming success both mechanically and financially. The second well, EI 273 Well C-1ST, was performed in less than 5 days at a cost of $ 465,000. The completion efficiency is 88 % and maximum sustained production was 20,000 mcfd.

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