Production of Wet Natural Gas Containing Corrosive Components: Four Case Histories

Abstract

Abstract In petroleum production, the problem of corrosive media attacking metallic structures is almost ubiquitous. Particularly severe environments are encountered in the production and transport of wet natural gas containing corrosive components, such as hydrogen sulphide and carbon dioxide. When exploring new gas fields, it is therefore a prerequisite to take into account the corrosivity of the respective fluids in all stages of the field development, in material selection, field layout, and facilities design. In preparation of the subsequent production phase, reliable corrosion monitoring programmes have to be selected, established, and implemented, as necessary. Furthermore the financial aspects always play an important role thus posing a real challenge for the engineer forced to seek a compromise between economics and design. This paper gives a comprehensive overview of these considerations regarding four different OMV gas fields, two of them in Austria and two in Pakistan, which were successfully developed and brought on stream between 1967 and 2003. These fields do not only vary in their geographical position, but also in gas compositions, production start, and the location of gas dehydration units. One major aspect dealt with in each of these cases, was material selection including metallic as well as non-metallic and composite materials. Where the initial decision was made in favour of carbon steel, different methods of corrosion protection, the application of corrosion inhibitors, corrosion monitoring, and intelligent pigging are discussed in the paper. Comparing the various methods of resolution that have been worked out for all four case histories, experience gained in more than three decades of production and transportation of wet corrosive natural gas is presented. Furthermore, results of the ongoing corrosion monitoring measurements in operation in the mature gas fields are discussed under the aspect of the remaining facility lifetimes.