Multi Stage Fracturing (MSF) completion systems have been continuously evolving with the goal of increasing efficiency and providing cost optimized solutions. While utilizing such systems, the primary objective is to drill a horizontal section in the prolific formation and complete the well with a conduit that allows multi stage fracturing either by ball drop sleeves in Open Hole (OH) or Plug&Perf (P&P) technique in cemented environment. A recently introduced third option called Cemented MSF has been discussed in this paper with the pros/cons of this approach and comparison with the aforementioned MSF methods.
Decision of a completion type depends on end-user preference based on performance. However, in case of excessive washouts, high doglegs, and up dip drilling directions, OH MSF completion falls into high risk category for deployment due to friction forces arise from placement need of the high number of packers across lengthy formation section. For this reason, converting to cemented liner for conventional P&P operation was recently observed in High Pressure High Temperature (HPHT) gas wells as way of mitigating the risk of deploying OH MSF completions. To address the challenges associated with, a proven and promising solution that involves utilizing cement to isolate individual stages and having cementable frac sleeves is being evaluated. This process entails cementing the clusters of ball drop, multi entry, limited entry design frac sleeves and hydraulically activated toe initiator that is operated with absolute pressure along with a landing collar to be functioned using a specialized wiping dart.
The implementation of this novel technology wherein frac sleeves are strategically positioned within the lower completion and subsequently cemented in place, adheres to the standard procedure and established deployment practices for cemented liner operations. Therefore, cemented MSF advantages over OH MSF in terms of installation is apparent. Nevertheless, the real benefit of the technology is more pronounced during the rigless fracturing operations, particularly when compared with P&P technique. The overall efficiency assessment indicates notable gains especially with establishing the injection into the first stage by activating toe sleeve before the rig move. Moreover, meeting requirements of 15,000 psi differential pressure and over 300°F temperature rating with enhanced design eliminates any application limitations, expanding the options of completion as fit for purpose approach for HPHT wells.
The novelty of this technology is the significant optimization during completion deployment and rig less frac operations without affecting production expectations. Ball drop cemented MSF completion systems is a viable alternative to conventional P&P for limited number of stages via reducing the overall capex and operational costs. In addition, minimizing the overall risk related to perforation guns and the need for multiple rig setups and dismantling during the stimulation phase.
