1. SPE-179967 What Factors Control Shale Gas Production Decline Trend: A Comprehensive Analysis and Investigation HanYi Wang, The University of Texas at Austin

2. Slide 2 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Presentation Outline  Introduction  Unique Mechanisms of Shale Gas Production and Decline  Methodology and Modeling Approach  Results, Analysis and Interpretation  Conclusions and Discussions

3. Slide 3 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Problem Statement Why decline trend different for different shales ? Can DCA give us useful information to guide completion designs or optimize field development ? Arps （ 1945 ）：

4. Slide 4 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Adsorption Gas

5. Slide 5 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Matrix Apparent Permeability and Its Evolution

6. Slide 6 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Fracture Networks and Pressure Dependent Conductivity

7. Slide 7 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Non-Stimulated Reservoir Volume (Non-SRV) Horizontal Wellbore Hydraulic Fracture IdealReality Sub-optimal Completion Design (Stress Interference ) Reservoir Heterogeneity (Brittle/Ductile)

8. Slide 8 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Methodology and Modeling Horizontal Wellbore Hydraulic Fracture Natural Fractures

9. Slide 9 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Base Case Simulation K=100 nd constant matrix permeability constant fracture conductivity

10. Slide 10 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Impact of Adsorption gas Remove all initial adsorption gas in place (From 60% to 0%)

11. Slide 11 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Impact of Matrix Permeability

13. Slide 13 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Impact of Non-Stimulated Reservoir Volume

14. Slide 14 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Impact of Non-Stimulated Reservoir Volume

15. Slide 15 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Impact of Fracture Networks Density and Conductivity

16. Slide 16 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Impact of Fracture Networks Density and Conductivity

17. Slide 17 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Impact of Fracture Networks Connectivity

18. Slide 18 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Field Data Interpretation

19. Slide 19 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Conclusion and Discussion  Adsorption gas increase production and decreases production decline rate, but play a more important role in early transient flow stage  Even though higher matrix permeability contributes to higher production rate, it also leads to steeper production decline trend in bounded SRV  The evolution of shale matrix apparent permeability during production can increase overall production, but has limited impact on production decline trend  When SRV is surrounded by Non-SRV, production rate declines more gradually

20. Slide 20 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Conclusion and Discussion  The density, conductivity and connectivity of fracture networks have dominant impacts on gas production and its decline trend  Pressure/stress dependent fracture conductivity does impair the overall production, but it actually reduce production decline rate  If the fractures are sparsely distributed in the SRV and not hydraulically well connected, then these fractures have negligible influence on well performance  The reason for much higher production decline rate in unconventional reservoirs than that in conventional reservoirs is due to larger contact area

21. Slide 21 SPE179967 What Factors Control Shale Gas Production Decline Trend HanYi Wang Problem Statement Time dependent rock deformation

22. Thank You Slide 22 Q/A