Ten Years' Experience with Sour Gas Production in Germany
Authors: Ockelmann Helmuth , Blount Floyd E. 
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

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The sour-gas production in West Germany and especially the problem of tubing string plugging by precipitation of elemental problem of tubing string plugging by precipitation of elemental sulfur is described. The main trouble results from elemental sulfur dissolved or chemisorbed in the sour gas. It is intensified by the lack of condensable higher hydrocarbons in German sour gas.

Remedies against sulfur plugging are critically examined. Up to now, only liquid sulfur solvent have been found suitable for economic sour-gas production under German conditions.

Different solvents, their properties, their advantages and disadvantages are mentioned. Experience in Germany with the two main types of sulfur solvents, e.g. high boiling aliphatic hydrocarbons and aqueous alkali sulfide solutions are described and discussed. Both processes applied in Germany have their distinctions and draw-backs. Additional problems may rise with decreasing reservoir pressure and influx of formations waters.

Introduction

Throughout the world, natural gases are produced. Gas reservoirs are found in various geological formations, and the gas quality may change from field to field. Beside sweet gas reservoirs, fields with so-called "sour gas", e.g. natural gas containing hydrogen sulfide (H2S) have been discovered As long as it is possible to satisfy the demand for natural gas with available sweet gas, nobody will be interested in producing sour gases, especially those with large amounts of H2S. Production and handling are more difficult, and the gas has to be Production and handling are more difficult, and the gas has to be sweetened before it can be sold to consumers. Therefore, it is understandable that larger sour gas facilities were first developed exclusively in countries with insufficient energy supply especially without large sweet gas reserves. Thus, first in Canada and France sour gas fields with high H2S content were completed. Later on, West Germany, USA, USSR, and other countries followed. This paper reports exclusively on experiences and problems present in West German sour gas fields. Besides other components as hydrocarbons, nitrogen, etc., sour gases contain especially chemically sour reacting components as H2S and carbondioxide (CO2). In addition to H2S, other sulfur components are often also of importance, e.g. carbonoxi-sulfide (COS), mercaptanes (RSH), carbondisulfide (CS2), and elemental sulfur (S). As the amount of H2S and the Proportion of H2S and CO2 may vary considerably, a large number of sour gas varities is possible. Of special significance is the amount of hydrocarbon condensates present in the wellstream, as these reduce the severeness of sulfur troubles experienced in sour gas production considerably. Table 1 shows examples of analyses of sour gases.