Optimal Water Management in a Macroscopic System That Includes a Shale Gas Exploitation System

According to the US Energy Information Administration (EIA), about 200 shale gas resource opportunities have been identified in five geologic provinces in eastern Mexico. Prospective regions include 1) Paleozoic shale gas in Chihuahua region; 2) Cretaceous shale gas in the Sabinas Burro-Picachos region; 3) Cretaceous shale gas in the Burgos Basin; 4) Jurassic shale gas in Tampico-Misantla; and 5) unspecified shale gas potential in Veracruz. Technically recoverable shale resources have been estimated at 545.2 trillion cubic feet of natural gas and 13.1billion barrels of oil and condensate. However, the exploitation of shale gas in Mexico is still under investigation because of its potential impacts on technical, environmental (water footprint) and social aspects.

This work presents a mixed-integer nonlinear program (MINLP) to assess the water impact in any of the macroscopic geologic regions where a shale gas exploitation system is technically feasible. The model allows finding the optimal distribution of water in a hydrological region that involves different users: domestic, industrial (including shale gas exploitation) and agricultural; conventional and unconventional water sources (rainwater storage system) are considered. In particular, water withdrawals and wastewater discharges arising from a shale gas distribution system are included. The formulation has been applied to a case study for a shale gas exploitation system in the Burgos basin, located in Tamaulipas, Mexico. The water impact is estimated by using the AWARE methodology, which evaluates the demand for water with respect to the total area of the region analyzed. The model parameters are taken from national geographic databases, which have been analyzed using the ESRI ArcGIS geographic information system. The model is solved by using the GAMS® modeling environment. Results provide the selection of a distributed treatment system that minimizes the levels of pollution in the water bodies and reduces the consumption of fresh water.