Application of an extreme overbalance, sufficient to fracture the reservoir
formation, applied either Juring or after perforating was first presented
as an alternate completion technique during the 1993 Fall SPE Conference.(1
) During the ensuing two years, a number of jobs have been run by different
operators in a variety of formations with varying applications. The primar
y question asked by an operator relates to the benefit of extreme overbalan
ce (EOB) versus current perforation techniques of underbalance (UB) or mode
st overbalance for well control. Of course this question spawns a whole set
of new questions about when and how to use and the benefits and risks of t
he EOB. EOB, as used in this paper, includes extreme overbalance perforatin
g and rapid overpressured perforation extension. This paper compares and co
ntrasts UB and EOB strengths and weaknesses and provides recommendations of
when and why to use the different techniques. Field examples are provided
of successful and unsuccessful application of EOB completions.