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

Slide 2 SPE 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

Slide 3 SPE 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 ）：

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

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

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

Slide 7 SPE 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)

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

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

Slide 10 SPE 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%)

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

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

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

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

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

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

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

Slide 19 SPE 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

Slide 20 SPE 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

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

Thank You Slide 22 Q/A