Perforating cemented casing is a staple for completing wells in every major basin in North America. The objective is to provide a highly conductive pathway between the wellbore and the target formation for both the stimulation and production fluids. New technology, statistical analysis, experimentation and trial-and-error are all used to find the optimal method for creating this pathway. Diagnostics like proppant tracers, downhole cameras, distributed temperature sensing (DTS), distributed acoustic sensing (DAS) and perforation friction pressure analysis can also be used to help evaluate the successes associated with the different methods for perforating.
New technology in creating consistent hole perforations in a horizontal wellbore, without the need for mechanical centralization or positioning systems, has recently been developed. This method of perforating employs a specialty shaped charge that allows for more control in the distribution of entry hole diameter (EHD) across a given cluster. This provides operators a more predictable and consistent pathway from the wellbore to the formation.
Not only is a consistent hole desirable in a standard multi-cluster stage treatment, but other recent completions trends can also benefit from increased precision in perforating. High density perforating (HDP) is being used in order to create more transverse fractures along the length of the well. A consistent hole allows for more precise estimations of pressure drop across each cluster in these mostly limited-entry or extreme limited entry (XLE) completions. Additionally, near-wellbore (NWB) perf sealing pods are being used to divert treatments from initially open clusters to bypassed or partially open clusters in an attempt to force perf cluster efficiencies higher and distribute stimulation fluids and proppant more evenly. Having a consistent hole for every perforation is ideal in attempting to seal the perforations in the NWB region with a fixed diameter pod. SPE 189900 (Senters, et al 2018) provides more detail on diversion optimization. Engineered completions design is employed in an attempt to selectively perforate rock within a stage with similar mechanical properties to drive stimulated cluster efficiencies higher. Perforating similar rock with a consistent hole shaped charge only stands to improve the chances of distributing the treatment more evenly throughout the clusters.
This paper will provide insight into the recent trends in perforating which show an increase in the amount of consistent hole shaped charges versus conventional shaped charges like deep penetrating and large hole. Diagnostic data accompanies entry hole diameter statistics and friction pressure calculations for the consistent hole shaped charges in order to demonstrate how they differ from conventional shaped charges. Finally, proppant tracer diagnostics will highlight several case studies where consistent hole shaped charges or other recent perforating methods were employed.