Effect of Proppant Damages on Fracture Conductivity and Long-Term Recovery in Shale Gas Reservoirs

Shale gas production for the Appalachian basin was 33 billion cubic feet per day in 2022 according to the U.S. Energy Information Administration (EIA). Horizontal wells with efficient and effective hydraulic fracture stimulation enabled economic recovery in shale gas reservoirs. However, ultimate gas recovery is still low due to the dynamics of fracture conductivity with respect to stresses, geochemistry, and interactions with formation rocks. Laboratory studies of individual factors affecting fracture conductivity were reported, but an impact on long-term well performance and recovery is still lacking. In this paper, we will (a) first understand the physics and mechanisms of proppant crushing, proppant diagenesis, and proppant embedment through a critical review of all published laboratory and field data; (b) then develop correlations and mathematical equations to quantify the change of fracture conductivity with stress and time; (c) build the equations into an advanced reservoir simulation model to investigate the impact of fracture conductivity dynamics on long-term gas recovery; and (d) conduct a systematic and comprehensive analysis to obtain new understandings and insights on optimized well stimulation and increased long-term recovery in shale gas reservoirs. Based on our simulation of a 40/70 mesh proppant (15 md·ft), a 10 year production is reduced by 13.2% of the base case when multiphase flow, proppant crushing, proppant diagenesis, and proppant embedment are incorporated. At a lower initial fracture conductivity of 0.4 md·ft, the 10 year gas production is reduced by 80% when these factors are considered. Proppant embedment and proppant crushing should be considered during the proppant selection.