(576d) A Novel Approach of Enhanced Gas Recovery Using Carbon Dioxide for Shale Gas Supply Chain Network in Unconventional Reservoirs

Shale gas is one of the most important resources to improve the energy independence of the United States by supplying natural gas, and natural gas was produced and supplied locally by processing shale gas with the recent advances in horizontal drilling and hydraulic fracturing. Over the past decade, improved practices of reservoir stimulation and production have made shale gas a viable energy resource [1]. However, shale gas production by hydraulic fracturing technique includes technological and environmental issues [2]: (1) sharp decrease of shale gas production rates at a shale well; (2) increase in carbon dioxide (CO₂) emission rates by generating electricity at power plants. To achieve the economic and environmental benefits of the shale gas production, the maximum amounts of produced shale gas and reduction of CO₂ emission should be guaranteed.

Many studies have developed shale gas supply chain network (SGSCN) in an economically viable manner [2-5]; however, they did not consider handling CO₂ emission and decreased shale gas production rates after a few years of production. Enhanced gas recovery using CO₂ (EGR-CO₂), which is a technique to increase the shale gas production rates while decreasing CO₂ emissions, has gained much attention as a new approach to solve these issues simultaneously. When a huge amount of CO₂ is injected into a shale well after completing hydraulic fracturing jobs, the shale gas production rates will be increased by replacing shale gas with injected CO₂ at shale rocks. More specifically, CO₂ is injected into the shale rocks at a higher pressure than the initial pressure of shale gas in the fracture; CO₂ has a higher adsorptivity than shale gas in shale rocks, enabling it to liberate the adsorbed shale gas in place [1, 6-7]. The shale rock has the potential to store a huge amount of CO₂, which is captured from flue gas emitted at power plants generating electricity by natural gas separated from shale gas. According to these connections, EGR-CO₂ should be considered in determining optimal SGSCN configuration.

Motivated by these considerations, we focus on the development of a novel framework to apply CO₂-EGR in SGSCN model; this application will allow us to simultaneously increase shale gas production rates and decrease CO₂ emission rates. SGSCN consists of three main parts: (1) water network for ensuring the freshwater supply and wastewater treatment; (2) shale gas network for separating shale gas and generating electricity; (3) CO₂ network for ensuring the separating CO₂ and injecting CO₂ into a shale well. Based on this developed framework, the optimal SGSCN configuration will be determined by maximizing the overall profits considering EGR-CO₂ and no CO₂ injection (CO₂ emission penalty). The proposed model has been applied two case studies to illustrate its superiority over existing approaches.

Literature cited:

[1] Li, X. and D. Elsworth, Geomechanics of CO2 enhanced shale gas recovery. Journal of Natural Gas Science and Engineering, 2015. 26: p. 1607-1619.

[2] Gao, J. and F. You, Shale gas supply chain design and operations toward better economic and life cycle environmental performance: MINLP model and global optimization algorithm. ACS Sustainable Chemistry & Engineering, 2015. 3(7): p. 1282-1291.

[3] Cafaro, D.C. and I.E. Grossmann, Strategic planning, design, and development of the shale gas supply chain network. AIChE Journal, 2014. 60(6): p. 2122-2142.

[4] Lira-Barragán, Luis Fernando, et al. "Optimal water management under uncertainty for shale gas production." Industrial & Engineering Chemistry Research 55.5 (2016): 1322-1335.

[5] Arredondo-Ramírez, Karla, José María Ponce-Ortega, and Mahmoud M. El-Halwagi. "Optimal planning and infrastructure development for shale gas production." Energy Conversion and Management 119 (2016): 91-100.

[6] Godec, M., et al., Potential for enhanced gas recovery and CO2 storage in the Marcellus Shale in the Eastern United States. International Journal of Coal Geology, 2013. 118: p. 95-104.

[7] Pei, P., et al., Shale gas reservoir treatment by a CO2-based technology. Journal of Natural Gas Science and Engineering, 2015. 26: p. 1595-1606.