  Hydraulic fracturing stimulates fracture swarm in reservoir formation though
pressurized injection fluid. However restricted by the availability of
formation data, the variability embraced by reservoir keeps uncertain, driving
unstable gas recovery along with low resource efficiency, being responsible for
resource scarcity, contaminated water, and injection-induced earthquake.
Resource efficiency is qualified though new determined energy efficiency, a
scale of recovery and associated environmental footprint. To maximize energy
efficiency while minimize its' variation, we issue picked designs at reservoir
conditions dependent optimal probabilities, assembling high efficiency
portfolios and low risk portfolios for portfolio combination, which balance the
variation and efficiency at optimal by adjusting the proportion of each
portfolio. Relative to regular design for one well, the optimal portfolio
combination applied in multiple wells receive remarkable variation reduction
meanwhile substantial energy efficiency increase, in response to the call of
more recovery per unit investment and less environment cost per unit nature gas
extracted.
