EXPORT CRUDES FOR THE '90S CHARACTERISTICS OF NORTH SEA'S FLOTTA CRUDE UPDATED

Anne K. Rhodes Refining/Petrochemical Editor The assay of Flotta crude oil from the British North Sea has been updated (OGJ, June 6, 1983, p. 75). The inclusion of additional fields over the years has decreased the crude's gravity by 1 API and decreased its sulfur content by 0.13 wt %. Table 1 presents distillation data for Flotta. The Flotta pipeline system now combines oil from Claymore, Hamish, Highlander, Scapa, Tartan, Petronella, and Ivanhoe/Rob Roy fields.

Sept. 2, 1991

5 min read

Anne K. Rhodes
Refining/Petrochemical Editor

The assay of Flotta crude oil from the British North Sea has been updated (OGJ, June 6, 1983, p. 75). The inclusion of additional fields over the years has decreased the crude's gravity by 1 API and decreased its sulfur content by 0.13 wt %.

Table 1 presents distillation data for Flotta.

The Flotta pipeline system now combines oil from Claymore, Hamish, Highlander, Scapa, Tartan, Petronella, and Ivanhoe/Rob Roy fields.

EARLY DEVELOPMENT

The history of the system's development covers nearly 20 years. Piper oil field was discovered on Block 15/17 in January 1973 by Occidental Petroleum Corp. (OGJ, Jan. 22, 1973, p. 62). Net proved reserves as of Dec. 31, 1990, were 23 million bbl of oil.

In January 1974, planning permission was granted for the Flotta crude oil terminal in the Orkney Islands. Claymore field was discovered in May of that year. Net proved reserves for Claymore, as of Dec. 31, 1990, were 32 million bbl of oil.

Exploration continued to be successful in July of 1975, when Scapa field was discovered. As of Dec. 31, 1990, net proved oil reserves for Scapa were 9 million bbl.

Piper field produced its first oil in December 1976. The initial production rate was 50,000 b/d. In January of the following year, the Flotta terminal was inaugurated. Oil was first produced from Claymore field in November 1979, at 25,000 b/d.

In January 1981, Texaco North Sea U.K. Co.'s Tartan field oil entered Occidental Petroleum (Caledonia) Ltd.'s (Oxy's) pipeline system to Flotta, through Claymore, and in June 1982, South Piper field was discovered.

Texaco's Highlander field oil entered the Flotta system in February 1985. The following September, Scapa first produced oil at 10,000 b/d, and Chanter oil field was discovered. In November 1986, oil was first produced from the Scapa subsea template at 11,000 b/d.

Development of Chanter was approved by U.K. Department of Energy (DOE) in December 1987. The following month, East Piper oil field was discovered, later to be named Saltire. Net proved reserves as of Dec. 31, 1990, were 16 million bbl of oil.

PIPER TRAGEDY

In July 1988, Oxy's Piper Alpha platform was destroyed in a tragic explosion and fire caused by a gas leak (OGJ, July 11, 1988, p. 20). The damage shut in Piper, Claymore, and Tartan platforms and Scapa (a subsea satellite of Claymore), Highlander, and Petronella subsea fields.

Within 3 months of the fire, Oxy had begun an emergency shutdown (ESD) valve retrofit program (OGJ, May 7, 1990, p. 65). ESD valves provide a safety backup system in the event of a gas leak.

In February 1989, Claymore's gross recoverable reserves estimate was boosted by 31%, to 195 million bbl. In summer of that year, Oxy began awarding contracts in preparation for the resumption of Piper oil production, planned for the first half of 1992 (OGJ, July 3, 1989, p. 26).

Elf Enterprise (Caledonia) Ltd. plans to install a single fixed drilling and production platform in Block 15/17, about 112 mile from Piper Alpha, to produce the remaining 119 million bbl of reserves. Initial production is expected to be 75,000 b/d.

The unit, Piper B, with a design capacity of 120,000 b/d, will also handle production from Saltire and Chanter fields, which will be connected to Piper B by subsea pipelines, and from there to the Flotta terminal by a 30-in. pipeline.

In November 1989, Piper redevelopment received U.K. DOE approval, with first oil targeted for late 1992. Partners in Piper redevelopment are Elf Enterprise (36.5%), Texaco Britain Ltd. (23.5%), Lasma North Sea plc (20%), and Union Texas Petroleum Ltd. (20%).

In July and August 1989, production from Claymore and Scapa resumed, and the Flotta system was back in business (OGJ, Aug. 21, 1989, p. 51.). Oxy had added crude from the Ivanhoe/Rob Roy fields into the system through Claymore earlier that year.

ADDITIONAL FINDS

In the fall of 1989, Oxy finished its appraisal of Saltire, estimating recoverable reserves at about 100 million bbl. The following January, Saltire platform fabrication and installation contracts were awarded, with production of first oil targeted for 1992.

The P-350 million ($577.5 million) Saltire project involves a 30,000 metric ton, four-legged production platform to handle 30,000 b/d of crude and 65 MMcfd of gas from 24 wells (OGJ, Jan. 29, 1990, p. 36). In June 1990, Saltire gross proven oil reserves were estimated at 140 million bbl.

Last year brought more important events for the area. in August, a significant extension to Scapa was discovered. In October, Claymore and Scapa gross production reached 100,000 b/d, and Union Texas Petroleum's Well 15/17-24 (Westray) discovered oil.

U.K. DOE approved Saltire development plans in January 1991.

LATEST ACQUISITION

In a recent development, Ste. Nationale Elf Aquitaine acquired Occidental Petroleum Corp.'s U.K. subsidiary, Occidental Petroleum Great Britain Inc. (OGJ, May 13, 1991, p. 26).

Elf put the acquired interests into a proposed new company, Elf Enterprise (Caledonia) Ltd.; owned two thirds by Elf, and one third by Enterprise Oil plc.