Choosing the best natural gas drying solution

Abstract

Before being ready to be transported in the pipes, natural gas must be purified from acid gases and dehydrated to improve the efficiency of its transportation in pipes and reduce the pipe corrosion. Usually, absorption towers are used to dispose Hydrogen Sulfide, whereas dehydrating towers are used to get rid of water. The study aims to improve natural gas dehydration process using glycol (TEG) through the use of heteroglycols (EG, MEG) and compare them both in terms of dehydrating tower size, glycol losses, energy required to reprocess glycol, changing annual costs and environmental impact by calculating the emission rate of BTEX gases (benzene, toluene, ethylbenzene and xylene). Moreover, it aims to study the effect of increasing the number of dehydration stages by examining the case of Deir Attia Gas Well.

The study concluded that in the case of the Deir Attia Well (with a flow rate of 150000 m3/sec), during dehydration, diethylene (DEG) is the least expensive in terms of annual costs and the (EG) solution is the least polluting. Besides, At average or low flow rate, it is preferable to use  the least polluting solution (EG) during treatment processes, as there was no significant difference in costs when using cheap solutions. It was also found that by increasing the number of dehydration stages by one, the rates of BTEX gases decreased significantly.