Natural gas is expected to make-up an increasing larger share of the worldwide energy supply. Many of the new gas fields are increasingly sour. The need to ensure safe production from these new fields means more emphasis on adequate materials selection and corrosion control. This paper provides an overview of the procedures that have been used over the past 16 years to manage sour gas corrosion risks at the Fairway Field, offshore Alabama. It covers the design, implementation, operation and monitoring of the corrosion control and asset integrity programs. The sour gas pipeline was inspected after 15 years in service, and found to be in practically "as new" condition. The produced water disposal pipeline experienced a leak, caused by internal corrosion, after 14 years in operation. Several factors that can affect the success or failure of a corrosion management program are discussed, in particular the ability of the corrosion control system to adapt to varying operational conditions, and to recover from unanticipated upsets.
Natural gas is expected to make a large contribution to satisfy the world's increasing energy demand in the coming decades. A large percentage of the new gas reserves that that will be brought into production over this period are sour. The reservoir pressures and temperatures are also progressively increasing as the search for gas expands into deeper and more difficult territories. The oil and gas industry has a good record of successfully, and safely, producing hot sour gas, as demonstrated by the many years of experience in the Canadian, US, and other fields around the world. Corrosion management played a crucial role in enabling the development and production of these fields. Nevertheless, although uncommon, corrosion related failures do occur, with often catastrophic consequences in terms of loss of human life, environmental damage, and economic losses. To meet the challenges presented by the rapid growth in sour gas developments, the corrosion community needs to identify and apply the factors that contribute to the successful management of sour gas corrosion risks. In this context, this paper summarizes the learnings from 15 years of operation of one offshore sour gas field in the US. These learnings are of general application to other highly corrosive gas production and transportation situations. The Fairway Field is a sour gas field located offshore Mobile Bay, Alabama. The name derives from its location, on the shipping fairway to the Port of Mobile. Water depth is 20 to 30 feet. The field was discovered in the early 1980s, and brought into production in 1991. The field development involved five well jackets with minimum facilities: wellhead, test separator, and gas coolers. Four of the jackets are connected through subsea flowlines, 2,000 to 10,000 feet in length, to a central facilities platform (CFP). Another well jacket is connected to the CFP through a surface bridge. At the CFP the produced gas and gas are separated, and sent to the Yellowhmamer Gas Plant through 16-inch (for gas) and 8-inch (for water) diameter, 16-miles long pipelines.
