Abstract

This paper focuses on the evolution of an advanced completion design utilizing solid particulate diverters resulting in a dramatic increase in the number of fracture initiation points as validated with radioactive (RA) tracers. The ultimate goal of this strategy is to increase capital efficiency by placing a dense fracture network more contained within the producing formation. The information contained in the paper should be of great benefit to completion engineers working across a variety of unconventional oil and gas basins.

It is generally proven that larger proppant volumes and more frac stages result in higher oil and gas recoveries, i.e., bigger is better. Practically, the number of stages for a 9,500 ft lateral (typical for the Bakken) is limited to 40 or 50 stages due to operational and cost limits. For advanced completion designs (complex fracture networks), the goal is not to just increase the stage count but to increase the number of initiation points (perforation clusters) that are effectively stimulated increasing the contacted fracture surface area. Considerations when executing this strategy include, but are not limited to: proppant transport, screen out risk, stress shadowing and geo-mechanical variability along the wellbore.

With volatile oil prices, continued innovation is necessary to sustain the unconventional shale success. In pursuit of better well performance AND lower capital costs, Liberty Resources has moved to a completion design that incorporates a high density perforating strategy and a focus on diversion methods to effectively stimulate each cluster. Solid particulate diverter was utilized to increase perforation cluster efficiency. Production performance is encouraging, and RA proppant tracers show that cluster stimulation efficiencies in excess of 85% can be achieved.

The unconventional shale revolution that began 15 years ago has successfully returned the United States to being a world leader in oil and gas production and technology. Completion designs have evolved significantly from the first early Barnett Shale completions and are now quite diverse. Variations in design are driven by the uniqueness of each basin's geologic and reservoir properties as well as operator bias. This diversity in completion methodologies has contributed significantly to technology advancement; the status quo is continually tested with new innovations. The Williston Basin was one of the first unconventional shale oil successes and it continues to contribute to the advancement of horizontal fracturing technology.

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