Evaluation of Downhole Multi-Cycle Sleeve Technology for Re-Frac Completions in Southwest Manitoba

Abstract

Abstract A new down hole multi-cycle sleeve completion system that was run in a well allowed the operator to re-frac all previously stimulated zones along the horizontal section of a wellbore with relative ease. The technology utilizes sleeves that can be closed and opened for the life of the well and re-defines the way re-frac completions can be done. Risks are significantly reduced and efficiencies improved compared to other re-completion techniques Coiled tubing (CT) equipped with a resettable frac plug bottom hole assembly (BHA) was deployed in a well that was originally fractured from the toe interval back to the heel. Unlike conventional completion systems where the frac sleeves are left open after each stage, these particular sleeves were closed immediately after each frac was complete. Once all the stages were stimulated, CT was then moved back down the well to re-open all the sleeves from the toe to the heel and allow the well to produce. This method is described as the Shift-Frac Close (SFC) sequence and is discussed in more detail in the paper. Both the original and re-completion were done in this nature. Well details along with original and re-frac designs will also be discussed in the paper The subject well consisted of 25 stages along the HZ section. The original completion from start to finish took ~ 56 hours to complete where each interval was fractured successfully with fairly small tonnages and low rates. After poor production results the operator decided to re-frac all intervals with a more aggressive frac design placing more sand in each interval at faster rates and higher bottom hole sand concentrations. It was estimated that the re-frac completion took ~38 operating hours. This represents significant improvement when compared to other systems where trying to re-complete a well may require drilling out ball seats, re-perforating and/or using risky isolation or diversion techniques. In addition, being able to close the sleeves after each frac has shown added benefits in the prevention of proppant flow back. This was noted in both the original stimulation and re-completion performed on this particular well that in turn saved money in potential sand cleanouts and possibly eliminated the use for resin coated sands. The paper documents this first ever application of executing re-fracs through re-closeable sleeves, and discusses the importance of sleeve reliability and longevity. Having the flexibility with this completion system also allows customers the option to frac intervals out of sequence, which has been hypothesized to reduce effective fracture spacing and effectively tap into a natural fractured network (Sharma et al 2013).