Development of Degradable Seal Elements for Fully Degradable Frac Plugs

Abstract

Abstract Demand for hydrocarbons is continuing to grow, leading to an increase in the stage count of hydraulic fracturing in unconventional reservoirs. The plug-and-perf system is a typical stimulation method that uses frac plugs for zone isolation. Conventionally, the plugs must be milled out to recover the flow path for hydrocarbons after fracturing is complete. Fully degradable frac plugs would eliminate the need for milling out, and this in turn allows for longer wellbores in the lateral direction, lower costs, and reduced risk in well completion. A key material for fully degradable frac plugs is a sufficiently degradable rubber with good sealing properties for the seal elements of the plugs. This paper presents the fundamental properties of degradable rubbers developed in a comprehensive materials study. The degradation behaviors of the degradable rubbers were investigated under various temperature and fluid media conditions. The mechanical strength was compared with that of conventional nitrile rubber. Nonlinear, three-dimensional multi-body contact analysis and qualification testing were integrated to estimate the sealing performance of seal elements made of the degradable rubbers.