Effective fracture treatment distribution to stimulate and obtain production from all perforation clusters is a key goal for success in unconventional reservoirs. The objectives of this work were to assess the impacts of multi-cluster stage perforating design parameters and execution uncertainties on treatment slurry distribution, production, ultimate recovery, and offset well interference for unconventional reservoirs.

A stochastic perforation breakdown and slurry injection model and a conceptual reservoir simulator were used to investigate treatment slurry distribution, production, and ultimate recovery impacts. The design parameters in the analysis were clusters per stage, cluster spacing, maximum proppant concentrations, perforation diameter, and number of perforations per cluster for both fixed- and variable-shot cluster designs. Uncertainties evaluated included perforation breakdown percentage, perforation shot phasing for non-oriented carriers, perforation hole diameter growth from erosion, and formation permeability.

As part of the analysis, the authors defined and used a new dimensionless quantity—the Slurry Distribution Number (Nsd)—that potentially fills a gap as no standard industry definition exists for perforation cluster efficiency. Nsd successfully correlated perforating design changes with slurry distribution outcomes. The authors used the results to identify strategies to mitigate uncertainty impacts, obtain more predictable outcomes, and achieve improved production results.

Novel information is presented that can assist perforating design optimization for unconventional reservoirs. In addition to introducing Nsd, the authors show perforation carrier phasing and shot phasing within the casing are generally not the same for decentralized carrier systems. The authors demonstrate how to model the perforation breakdown and stage stimulation process using a combination of published geomechanics, perforation erosion, and perforation flow resistance models. Lastly, the authors describe future study opportunities for perforating uncertainties and design parameters.

Keywords:
hydraulic fracturing, Artificial Intelligence, friction, Efficiency, Upstream Oil & Gas, time step, recovery, perforation flow area, standoff, covariance
Subjects:
Drilling Operations, Casing and Cementing, Hydraulic Fracturing, Well & Reservoir Surveillance and Monitoring, Reservoir Characterization, Reservoir Fluid Dynamics, Reservoir Simulation, Formation Evaluation & Management, Unconventional and Complex Reservoirs, Information Management and Systems
Copyright 2020, Society of Petroleum Engineers
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