On the feasibility of re-stimulation of shale wells

Abstract

As a result of advances in horizontal completions and multi-stage hydraulic fracturing, the U.S. has been able to economically develop several decades of worth of natural gas. However, a considerable concern has risen on the economic viability of shale gas development for reasons associated with the fast production declines as well as recent down-turns of natural gas prices besides rises in the costs of new technologies. Therefore, an economic analysis is required to investigate the profitability of the refracturing treatment of unconventional gas resources. Net present value of cash flows and internal rate of return are calculated for a range of gas prices considering 20 years of natural gas production from a typical unconventional shale gas reservoir. A systematic comparison is then accomplished for three scenarios: (1) re-fracturing versus no refracturing, (2) combination of re-fracturing and drilling new wells, and (3) time-dependent re-fracturing treatment. Further, this paper incorporates the cost of re-fracturing treatment, the cost of drilling a new horizontal well, the water treatment cost, as well as the current and future price of natural gas in the model. The findings of this work would help the future re-stimulation development plans of the emerging unconventional shale gas plays.

Modeling of Bulk Kerogen Porosity: Methods for Control and Characterization

“…The well productivity usually decays very fast 8,9 4 requiring re-stimulation for maximum yield, a process which is not always straightforward and 5 effective. 4,10,11 In addition, a shale play may not always be productive with current technologies 6 available, despite the fact that it is known to host gas. 12, 13 7 The environmental impact of the shale gas is also still under investigation.…”

Burial depth interval of the shale brittle–ductile transition zone and its implications in shale gas exploration and production

“…In both exploration and production of shale gas, brittleness and ductility of shale are important evaluation parameters as they are closely related to natural shale fracture (Ding et al 2012), artificial hydraulic fracturing , drilling (Eshkalak et al 2015;Zeng et al 2015), permeability (Ghanizadeh et al 2013) and gas preservation (Yarali and Kahraman 2011;Gale et al 2014;Hu et al 2015;Liu and Sun 2015;Zeng et al 2015). Brittleness is one of the most important mechanical parameters of unconventional gas shale reservoir estimation when it comes to hydraulic fracturing (Gasparrini et al 2014;Holt et al 2015) and borehole wall stability assessment and gas preservation risk (Ingram and Urai 1999;Hu et al 2014;Zhou et al 2014).…”

Mixing in a three‐phase system: Enhanced production of oil‐wet reservoirs by CO2 injection

“…Restimulation of hydraulic fracturing wells in deep shale formations using CO 2 is a promising technique to access the residual hydrocarbon after initial production has ceased to yield viable output [Eshkalak et al, 2015]. However, the leftover brine from the initial fracturing procedure is immiscible with both CO 2 and the residual hydrocarbon and might inhibit mobilization and extraction in the system.…”

“…However, current fracking practices are incredibly inefficient leaving up to 70% of the hydrocarbon behind [McGlade et al, 2013]. A recent study demonstrated the economic benefits of the restimulation treatments, including refracturing [Eshkalak et al, 2015]. This presents an opportunity to restimulate existing wells in order to enhance hydrocarbon production, thus extending their life and reducing the need for additional wells.…”

“…This presents an opportunity to restimulate existing wells in order to enhance hydrocarbon production, thus extending their life and reducing the need for additional wells. A recent study demonstrated the economic benefits of the restimulation treatments, including refracturing [Eshkalak et al, 2015]. Restimulation of deep shale formations using CO 2 is one promising technique to access the residual hydrocarbon after initial production has ceased to yield viable output.…”