A major challenge faced by many natural gas developments in the MENA and CIS regions is transporting raw, wet, sour gas from wells to the Central Processing Facility (CPF). The presence of H2S or CO2 and H2O in raw wellhead fluids creates a highly corrosive environment, which dictates the use of expensive corrosion resistant materials such as nickel alloys or stainless steel.

Petrofac designed, built and commissioned a sour gas processing plant in the CIS region, which includes remote, unmanned Gas Treatment Units (GTUs). The GTUs are located up to 16 km away from the CPF, and receive sour raw gas from the wells for treatment using conventional TEG dehydration. The main function of gas dehydration is to dry the gas, thereby eliminating one of the components that causes corrosivity of the gas. This avoided the requirement for cladding the large bore, sour gas transfer pipelines with corrosion resistant alloys (CRA), which would have resulted in high costs, mitigating schedule and construction challenges involved in the installation of CRA pipelines.

Dealing with raw, wet, sour gas is a global challenge faced in many plants worldwide, and has been a major cost and schedule challenge due to the use of corrosion resistant materials. The development solution illustrated in this document depicts an innovative method for transporting sour gas for treatment without the use of large bore CRA pipelines, and can reduce costs of construction and procurement substantially. Similar applications can be made in large scale natural gas processing plants where sour gas and H2O combinations exist, provided that thorough cost analysis is performed to determine the technical and financial viability of the option.

GTU operating data in the form of online water content measured by dew point analysers are documented in this report. Laboratory analysis of the dry sour gas and lean TEG are also included, with the results demonstrating the successful performance of the GTU design.

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