Incorporation of Neutrally Buoyant Proppants in Horizontal Unconventional Wells to Increase Propped Fracture Area Results for Substantially Improved Well Productivity and Economics

Abstract

Hydraulic fracturing stimulation of unconventional wells employing large volumes of sand in low viscosity fluids provides propped fracture conductivity in less than 25% of the created fracture area, primarily because of poor sand transport mechanics. The remaining unpropped area is at best only marginally productive using the conventional sand/slickwater hydraulic fracturing process alone. Near-neutrally buoyant proppants (NBPs, ASG 1.055) have proven to be highly effective in accessing production from fracture area that is otherwise left unpropped. Fracture models illustrate the propped fracture area of designs incorporating NBPs is improved to over 85% of the created fracture area. Production simulations of typical slickwater and sand frac designs supplemented with NBPs at 3% by weight of sand distributed evenly throughout the slurry stages show cumulative production increases of 20% to greater than 50% compared to the large volume slickwater/sand treatments without NBPs. Efforts have been directed to justification of the incremental expense involved with the NBP applications and assessment of the associated value-added economic metrics, including the value of the realized incremental production vs. time, the payback time for recovery of the incremental costs, and Return on Investment (ROI). For example, in a 2018 trial of NBP wells in the Middle Bakken formation of North Dakota, the production uplift observed for NBP wells achieved payback of the incremental costs in an average of 26 days; the 1-year cumulative oil production of the NBP wells averaged 69,632 barrels greater than control wells, resulting in a 25% uplift compared to the offset control wells. The Year 1 Return on Investment (ROI) for the drilling and completion costs of the first Middle Bakken well with NBP was 97% versus 64% for the sand-only control wells. Controlled multi-stage horizontal completions of wells with sand-only have been evaluated against wells utilizing NBPs in the application have been executed within several unconventional plays, including the Permian and Williston basins. The performance of the NBP wells have consistently validated the production uplift predictions of the production simulation models. The case studies analyzed herein expand the economic assessment of the NBP stimulation designs by including production analyses quantitative comparison of Net Present Value, production decline rates, and projected EURs of the NBP wells and non-NBP offset wells.