North Slope Halon Replacement Strategies

Abstract Halon 1301 has historically been used for inertion (prevention of gas explosions) and fire protection in most of the oil, gas and associated modules on the North Slope of Alaska. The Montreal Protocol, as amended in 1992, set a schedule to ban the production of certain halocarbons, including halon 1301, in the developed countries. No "drop-in" replacement is available. Alternate strategies and designs must be developed to protect personnel and facilities. Many of these are discussed in this paper. Introduction The North Slope oil fields are located on the arctic plain in the North of Alaska (Fig. 1). Prudhoe Bay is the largest oil field in the United States and the North Slope produces about 25% of America's oil. The weather and environment are very hostile to both oil production personnel and equipment during the long, cold and dark Alaska winters (Fig. 2). Most of the process equipment is housed within modules (buildings) to protect it and the operating and maintenance personnel from the weather extremes. Enclosed equipment, handling large volumes of oil and gas, creates a potentially very hazardous situation. Halon 1301 has historically been used to protect personnel and facilities for gas inertion and fire because it was effective, safe for use in inhabited spaces and relatively low cost. It is believed that halocarbons, including halon 1301, deplete the atmospheric ozone layer. The Montreal Protocol, which was enacted in 1987 and since has been signed by over 150 nations, was amended in 1992 to prohibit manufacture of halon 1301 after January 1, 1994 in developed countries. Additionally, production of chloro-fluoro-carbons (freons, etc.) is banned after January 1, 1996. The protocol was enacted to protect the ozone layer. Recycled halon can still be obtained for many critical applications, including protection of North Slope facilities, but supplies are getting scarce and costs are escalating rapidly. In the not too distant future, it will be impractical to protect the involved personnel and facilities with halon. Alternate strategies and designs must be developed soon to provide the protection required when halon can no longer be used. This paper discusses many of the new strategies and design changes. North Slope Environment And Facilities The North Slope oil fields are at the extreme north of Alaska adjacent to the Beaufort Sea. The terrain is generally flat. Relatively low amounts of moisture fall so the area is called an arctic desert. Many shallow lakes and streams (Fig. 3) are in the area because of runoff from the Brooks Range mountains to the South. Caribou, bear, ducks, geese and other wildlife are plentiful during certain times of the year (Figs. 4 and 5). The summers are short and have temperature ranges from about freezing to seventy-five degrees. The winters are long, dark and cold. Temperatures at or below minus fifty degrees are not uncommon. Occasionally, the wind blows at or above fifty miles an hour and causes the snow to be carried along. This creates a condition known as a "whiteout" and travel is restricted during the more severe of' these Wind chill temperature can fall well below minus 100 F. The sun goes down about Thanksgiving and doesn't come up until about the third week of January! Layout of the oil fields varies. Prudhoe Bay is a very large oil field jointly operated by British Petroleum Exploration (BPX) and Arco and has Gathering Centers/Flowstations and other facilities spread over about 600 square miles (Fig. 6). The other extreme is Endicott (Fig. 7). It is built on a small gravel island in the Beaufort Sea and covers perhaps a square mile. This is a more modern facility and has been designed in a much more compact way to reduce costs and minimize environmental impact. Because of the weather extremes, most of the oil and gas processing equipment is enclosed in modules. Large quantities of oil and gas are processed within these enclosed spaces (Figs. 8 and 9). Releases of either of these materials can create potentially very serious consequences. History Of Fire And Gas Protection Historically the North Slope oil and gas process modules have been protected for gas inerting and fire with halon 1301 (Slide 10). Halon 1301 extinguishes by chemical action and was used for the following reasons:It was effective for fires and inerting gas releases. P. 393