Presently, there are over 3,750 platforms installed in the OCS region of the Gulf of Mexico. Ever since platforms have been installed, there has only been 1 year in which removals outnumbered installations. As many of these platforms reach the end of their useful life (average of 20 years), the liabilities and cost associated with their removal become a major concern for oil companies. During the years between 1986 and 1999, approximately 1,414 structures were removed. Of those structures, approximately 66% were removed by explosive methods. Explosives are widely used because they are safe, reliable, and cost effective.
This paper will present the methodology of explosive usage for platform removals. Included in the paper will be a review of field data, cost comparisons with other methods, safety, and governmental regulations relative to platform removals involving explosives. The limitations regarding explosive usage will also be discussed.
Development of new products and processes involving explosive technology will be presented.
Explosives have been widely used in the oil industry from the beginning. Explosives have been used in seismic activities, perforating of formations, construction of trenches for pipelines, and the extinguishing of oil well blowouts. The first use of explosives for decommissioning and salvage of offshore structures is impossible to document. More than likely explosives were first used to sever well conductors in the mid to late 1950's. Eventually, explosives were primarily used for all platform removals in the Gulf of Mexico. During the early 1980's, there were no less than 10 companies offering explosive services for platform decommissioning. Many companies offering explosive services were actually diving and wireline operations. Environmental concerns relative to endangered species in the mid 1980's caused a drastic change in the way explosives were used offshore. Before this time, there were no rules or regulations to follow. The basic rule of thumb was, "if 5 pounds does a good job, 10 pounds does a hell of a good job". To date explosives have been used for platform removals all over the world. Since the Gulf of Mexico has the most platforms as well as the most removals this paper will concentrate on the rules, regulations, and technology that is employed in the Gulf.
The use of explosives for platform decommissioning before 1986 was not documented formally by the owners, operators, or governmental agencies. On April 15, 1986, the National Marine Fisheries Service (NMFS) sent a letter to Regional Director of the Mineral Management Service (MMS), Gulf of Mexico Outer Continental Shelf (OCS) Region. This letter expressed the concerns regarding stranding (to run ashore) events in 1985 & 1986. These strandings coincided with a number of explosive platform removals that were conducted in the State of Texas territorial waters. NMFS suggested that a correlation could exist between these stranding and the use of explosives for platform decommissioning. (Ref. 1) Consequently, MMS imposed an "unofficial moratorium" on platform removals. This was in an effort for industry to take the environmental issue seriously.