The Development of Low-Sour Gas Reserves Utilizing Direct-Injection Liquid Hydrogen Sulphide Scavengers

摘要

The toxicity of hydrogen sulphide in hydrocarbonstreams is well known in the industry and considerableexpense and efforts are expended annually to removehydrogen sulphide to a safe level. In large productionfacilities, it is generally economical to install a regenerativesystem for treating sour gas streams. However, during thedevelopment stages of relatively small low-sour gas fields atremote and normally unmanned locations where regenerativesystems are not practical nor economical, it is necessary totreat the sour gas production with non-regenerable scavengingprocesses. In the development of its low-sour Zechstein gasreserves in the Coevorden field in the North-East TheNetherlands, the Nederlandse Aardolie Maatschappij (a Shelloperating unit, hereafter referred to as NAM) decided to adoptcontinuous direct-injection of liquid scavenging agents as thelowest overall cost process having the least environmentalimpact and the highest energy efficiency. At the inception ofthe project, the operating parameters controlling thescavenging efficiency using direct injection of liquidscavengers in this system were largely unknown.Consequently, numerous field trials using different chemistriesand different injection mechanics had to be carried out.In this paper we present the results of these fieldtrials, which ultimately led to a very successful and profitablefield development strategy. A variety of very challengingoperational problems were encountered, and solved. Referenceis made to injection nozzle blockages, fouling of glycol gasdehydration systems, severe scaling problems in productionand downstream water treatment/injection facilities,inadequate hydrogen sulphide removal efficiencies and HS&Erelated issues. A better understanding of the fundamentalrelationships between operating parameters governing direct-injectionprocesses and associated chemical development andapplication methods has been gained. Communication andintegration of experience and knowledge between theoperating unit and its chemical supplier were key successfactors in this achievement, as was the endurance andcontinuing support of field operations staff in facilitating theresolution of difficult problems.