This document is an expanded abstract.

Summary

Removing mercaptans from sour natural gas is becoming an important issue with the global trend towards more stringent specifications for commercial gases. Amines have been extensively used on account of their ability to meet severe H2S and CO2 specifications and high acid gas selectivity over hydrocarbons. Amines however have limited mercaptans removal capability, an additional treatment step is generally required to achieve stringent specification on total sulfur in the treated gas.

For more than 10 years, TOTAL works on the natural gas sweetening process for high sulfur comprising gas. Targeting to unlock the potential value for such a kind of difficult-to-treat gases in a profitable and energy efficient way, TOTAL successfully developed a new series of hybrid solvents technologies, HySWEET®. In 2018, a significant milestone will be achieved after the first HySWEET® process implementation in ADNOC Gas Processing’s Habshan 32/33 units. This paper will present the HySWEET® challenging development pathway and the benefices that can be achieved in both green field and brown field gas processing projects.

Introduction

More than 40% of proven natural gas or associated gas reserves are currently identified as sour gases containing CO2, H2S and/or other sulfur compounds, representing over 2600 trillion Cubic Feet (TCF). Dedicated treatments must be used to achieve the required specifications (trade, security, transport ...). Various technologies (e.g. amine) have been developed and optimized for several years to remove acid gases from natural gas. This problem has evolved, especially in Europe, Russia and the Middle East, because of the appearance of more stringent specifications for total sulfur compounds, especially mercaptans (RSH) and carbonyl sulfide (COS). It becomes challenging, nowadays, for oil and gas companies to develop these sour gas fields in a profitable way. Indeed, the physico-chemical properties of mercaptans allow only very limited reaction with amines at normal operating conditions. The use of a classical aqueous amine solution is generally not enough to reach mercaptan specifications on produced gas. Hence, additional treatments are required to eliminate these compounds with a non-negligible impact on plant CAPEX and OPEX.

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