We study the effects of asymmetric cost on the cooperative behavior in the snowdrift game on scale-free networks. The asymmetric cost reflects the inequality in mutual cooperation and the diversity of cooperators. We focus on the evolution of cooperation and the inequality in wealth distribution influenced by the degree of asymmetry in cost, related with cooperators' connections. Interestingly, we find that when cooperators with more neighbors have the advantage, cooperative behavior is highly promoted and the rich exploits the poor to get richer; while if cooperators with less neighbors are favored, cooperation is highly restricted and the rich are forced to offer some payoff to the poor so that the wealth is more homogeneously distributed. The wealth distribution in population is investigated by using the Gini coefficient and the Pareto exponent. Analytical results and discussions are provided to better explain our findings. The asymmetric cost enhances the leader effects in the decision making process by heterogeneous wealth distribution, leading not only to very high cooperator density but also to very stable cooperative behavior.

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The Upper Ordovician Wufeng‐Lower Silurian Longmaxi shale is widely distributed in the Sichuan Basin and its periphery, which is the key stratum for marine shale gas exploration and development (E&D) in China. Based on sedimentary environment, material basis, storage space, fracability and reservoir evolution data, the reservoir characteristics of the Wufeng‐Longmaxi shale and their significance for shale gas EE&D are systematically compared and analyzed in this paper. The results show that (1) the depocenter of the Wufeng (WF)‐Longmaxi (LM) shale gradually migrates from east to west. The high‐quality shale reservoirs in the eastern Sichuan Basin are mainly siliceous shales, which are primarily distributed in the graptolite shale interval of WF2‐LM5. The high‐quality reservoirs in the southern Sichuan Basin are mainly calcareous‐siliceous and organic‐rich argillaceous shales, which are distributed in the graptolite shale interval of WF2‐LM7. (2) Deep shale gas (the burial depth >3500 m) in the Sichuan Basin has high‐ultrahigh pressure and superior physical properties. The organic‐rich siliceous, calcareous‐siliceous and organic‐rich argillaceous shales have suitable reservoir properties. The marginal area of the Sichuan Basin has a higher degree of pressure relief, which leads to the argillaceous and silty shales evolving into direct cap rocks with poor reservoir/good sealing capacity. (3) Combining shale gas exploration practices and impacts of lithofacies, depth, pressure coefficient and brittle‐ductile transition on the reservoir properties, it is concluded that the favorable depth interval of the Wufeng‐Longmaxi shale gas is 2200∼4000 m under current technical conditions. (4) Aiming at the differential reservoir properties of the Wufeng‐Longmaxi shale in the Sichuan Basin and its periphery, several suggestions for future research directions and EE&D of shale gas are formulated.