Productivity of blast-fractured wells in liquid-rich shale gas formations

• We investigate the productivity of natural gas liquid wells completed by blast-fracturing.
• An analytical solution was derived for wells in liquid-rich shale gas formations.
• Well productivity was found non-linearly affected by the number of fractures and fracture penetration.
• Increasing the amount of explosives will not improve well productivity proportionally.

The explosive stimulation by blast-fracturing was first used in well stimulation with pronounced results in the booming Pennsylvania oil field in 1865. The advent of hydraulic fracturing in the 1950's caused explosive stimulation of oil wells to decline dramatically. Because the hydraulic fracturing process consumes a huge amount of water and imposes a threat to the ground water resources, it is highly desirable to revisit the feasibility of replacing hydraulic fracturing with blast-fracturing in the oil and gas well completion processes. This paper presents an analysis of well productivity of different types of well architectures to be completed with the blast-fracturing stimulation in liquid-rich shale gas formations.Compared to the hydraulic fracturing, blast-fracturing creates radial fractures with fracture-orientations independent of formation stress anisotropy. This eliminates the requirement of in-situ stress orientation that is necessary for designing multi-hydraulic fracturing horizontal wells. An analytical model was developed in this investigation to predict the initial productivity of vertical wells, horizontal wells, and radial-lateral drain holes. Case studies indicate a good agreement between the result given by the models and field observation. Sensitivity analyses with the analytical model indicate that the initial productivity of blast-fractured wells increases non-linearly with the number of radial fractures and fracture penetration. The benefit of increasing fracture depth levels out as the amount of explosives increases. This paper presents well completion engineers a theoretical base and useful data for revolutionizing their well completion technology in developing liquid-rich shale gas basins.