A Comprehensive Model for Real Gas Transport in Shale Formations with Complex Non-planar Fracture Networks

Area of Science:

• Petroleum Engineering
• Reservoir Engineering
• Geomechanics

Background:

• Hydraulic fracturing in shale gas reservoirs creates complex fracture networks.
• Modeling gas transport in these networks, considering various mechanisms and geometries, remains challenging.
• Predicting well performance requires computationally efficient models for arbitrary fracture networks.

Purpose of the Study:

• To develop a comprehensive model for real gas transport in complex, non-planar shale fracture networks.
• To analyze the impact of gas transport mechanisms and fracture complexity on well productivity and transient flow.
• To provide insights into optimizing shale gas production strategies.

Main Methods:

• Development of a robust computational model for real gas transport.
• Systematic analysis of gas transport mechanisms (e.g., Knudsen diffusion, slippage, desorption).
• Evaluation of fracture complexity and geometry on well performance metrics.

Main Results:

• Non-planar fractures lead to more accurate gas production estimates than simple planar fractures due to reduced interference.
• Specific flow regimes (e.g., a "hump" in transition, linear flow with slope < 1/2) indicate natural fracture presence.
• Fracture network complexity, characterized by sharpness of flow "humps", influences production behavior.
• Gas desorption and flow mechanisms extend transition periods; Knudsen diffusion and slippage dominate later production.

Conclusions:

• Maximizing fracture complexity by creating large, connected networks is key to increasing shale gas production.
• Understanding gas transport mechanisms and fracture geometry is crucial for accurate well performance prediction.
• The developed model offers a computationally efficient approach for analyzing complex shale fracture systems.