Cased hole vs openhole completions

[msy]

Hi everybody,

I read somewhere, that the current trend is a move away from openhole completions, what are the advantages and disadvantages of the the two completions type? What are the current and future technologies that can reverse the trend?

Thanks
Regards
Salim

[maftab]

Open hole versus perforated. The open hole method is initially cheaper, since perforating costs are eliminated. This method permits testing of the zone as it is drilled, eliminates formation damage by drilling mud and cement, and allows for incremental deepening as necessary to avoid drilling into water. This last factor is important in thin, water-drive pay sections where no more than a few feet of oil zone penetration is desired. On the other hand, the perforated completion offers a much higher degree of control over the pay section, since the interval can be perforated and tested as desired. Individual sections can, in general, be isolated and selectively stimulated much more easily and satisfactorily. There is considerable evidence that hydraulic fracturing is more useful in perforated completions. API Bulletin D6 indicates productivity ratios of perforated wells are about 50% higher than those of similar open hole completions.6 This superiority is apparently due to uniform treatment over the entire pay section plus the stimulation benefit gained from penetration of the perforations themselves. The improved zonal control is also of value when remedial measures, such as water or gas exclusion, are undertaken.

With perhaps a few exceptions in low pressure or thin water-drive pay areas, benefits of the perforated completion overshadow those of the open hole type. This advantage has been made possible by modern perforating and stimulation techniques and advances in drilling muds, cementing materials and methods, as well as other aspects of petroleum technology.

regards,
Nadeem