This work presents the interaction of the different forms of extraction of natural gas either by unconventional methods such as gas shale, offshore extraction and by conventional means of extraction of associated natural gas, where different technologies of enhanced oil & gas recovery such as the injection of heat and the injection of carbon dioxide are taken into account with the intention of improving the extraction of natural gas remaining from the wells; the extraction of non-associated natural gas, as well as importation is also considered. Traditionally, only economic aspects have been contemplated for the design of such processes, this has generated important safety problems when the processes are already in operation. Recently, the inherent safety aspect of processes has been involved since the design stage, particularly for the physical layout of industrial facilities. However, safety from the point of view of occupational health of personnel and people who live near to the facilities has not been adequately addressed, this can be assessed through an analysis of occupational health in these processes; that is, how harmful a process is compared to all processes considered, determining which parts of the process and which chemicals are hazardous to the health of workers who are in constant contact through the skin, eyes, inhalation during their work hours. Furthermore, the environment is also important, a consideration of CO
2 emissions is included to evaluate the impact in the surrounding environment. In addition, the costs associated with the entire process are taken into account, from extraction to distribution of natural gas.
Finally, the objective function consists in maximizing profit which involves the sale of petroleum and natural gas, and the different capital and operational costs; the minimization of the total fresh water used in gas shale extraction, conventional extraction of natural gas associated and non-associated, and the minimizing of total emissions in gas shale, offshore extraction, in conventional extraction of natural gas associated and non-associated, and the emissions generated during importation. The proposed model is a Mixed Integer Linear Programming problem and it was implemented in the software GAMS, where the solver DICOPT was used to solve a case study from Mexico. Results show that there is very important to consider the interaction between different ways of extraction due to the recent increase of energy demand in the world, but also is important to take into account the occupational health of workers, as well as the environment.
