In the San Juan Basin, the Mesaverde formation was originally stimulated with nitroglycerin in the 1950's. In the late 80's, Prima recompleted wells, sidetracked, redrilled and hydraulically refractured wells. 14 openhole wells sidetracked and refraced, with 100% success rates. Incremental rates of 609 mcfd/well achieved, with an average FOI of 25. Operator estimated 2 bcf incremental reserves per well, with only $383,000 investment.
A performance analysis technique is presented which can be used to identify recompletion candidates in producing gas fields. Through geological description and a field case history, it is demonstrated that p/z versus cumulative production curves can be diagnostic tools in identifying inefficient completions or wellbore damage in a stratified reservoir system. It is also shown that these wells can be recompleted or redrilled to add significant incremental reserves which would have otherwise been abandoned.
Previous theoretical work presented in the literature demonstrated that layered gas reservoirs producing without crossflow display non-linear p/z versus cumulative production curves. This paper presents field data which support that observation and concludes that the absence of this behavior in a stratified reservoir environment may be indicative of a recompletion candidate due to wellbore damage in one or more of the layers. A field case history is presented involving wells producing from the Mesaverde Group in the San Juan Basin of New Mexico. Wells which were originally completed with nitroglycerin were selectively recompleted to yield significant incremental reserves. These wells were identified by their linear p/z behavior in an area where theory and historical performance indicate a non-linear p/z curve should be present. The results of the recompletion program are presented.
Author(s): T.L. Hower, Intera Bergeson; M.K. Decker, Prima Oil & Gas Co.
Paper Number: SPE 24307