The two most popular fracture placement methods in unconventional shale with multiple stages fracturing completion are wireline plug-n-perf and pinpoint perforating / fracturing using coiled tubing. The debate regarding which method is better is still unresolved, as each method has its performance and economic advantages, which make the selection decision very challenging for practitioners and decision makers.
In the Antelope Shale reservoir in Monterey Formation, each of these two fracture placement methods were implemented for multi-stage fracturing in 4 vertical offset wells to evaluate the benefits and associated risks, and to identify the preferred method for a full field development plan. The plug-n-perf method had multiple clusters perforated with wireline for each frac stage, whereas the coil tubing method utilized sand-jets to create pinpoint perforation holes with single cluster.
In this paper, we discuss the lessons learned and results from application of both fracture placement methods in Antelope Shale using key performance and economic indicators, including time efficiency, cost, production, fracture geometry and zonal coverage. The multitude of operational events experienced during these completion executions demonstrated both the associated benefits related to improved efficiency (efficient completion execution without trouble, record number of completions in single day, etc.) and disadvantages in terms of delayed operation (perforation guns not firing, CT parting, multiple fishing operations during drill out of plugs, ineffective perforation cutting, depth control of CT, etc). The results from various diagnostics such as microseismic, tiltmeters, Diagnostic Fracture Injection Test (DFIT), tracers, etc. were used to compare the effective pay zone coverage with multiple fracture stages, fracture geometry and well productivity for both fracture placement methods.
For multi-stage fracturing completions in tight rock, an understanding of risks, rewards, and economic impact of both methods is crucial to completion and stimulation strategy.