During the past decade, the combination of hydraulic fracturing and horizontal wells, has proven to be the key, to the unlocking of unconventional plays across North America and elsewhere. This efficiency has been accomplished by using two very distinct completion approaches: the Plug and Perf. method and the Open Hole Multi Stage (OHMS) completion system (typically ball activated fracturing ports).

The OHMS completion system has in general been applied to carefully selected fields and has not yet gained wider acceptance, across the industry, as a viable alternative to the more popular and extensively utilised Plug and Perf approach. This resistance to change and the reluctance to consider alternative completion approaches, are due to a number of factors, many of which reflect an operational comfort zone from which there is a hesitancy to stray. Often the disadvantages of the OHMS approach may be overemphasized, while the associated advantages are not suitably considered and vice versa for the Plug and Perf approach.

Case histories from a number of North American unconventional plays, for example the Red Oak, the Cotton Valley and the Granite Wash, will be both presented and analyzed. This analysis will focus on a number of aspects, including the hydraulic fracturing treatments, the operational efficiencies, the cost effectiveness and the overall risk reduction aspects of the OHMS vs. the Plug and Perf approaches.

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