Pazargad - World's Largest Crude Oil Storage Barge
Authors: Feizy G. , McDonald J.E. 
Published: December 2007

Pazargad, world's largest crude oil storage barge, has been serving the Cyrus Field in the Persian Gulf for more than fifteen months. Experience gathered over this period has revealed certain operational type problems. More importantly, however, this experience has proven the successful application of a floating, self-contained storage, desalting and crude exporting facility.

Introduction

Pazargad, with 1,000,000 barrels nominal capacity, is the world's largest crude oil storage barge (figure 1). She is operated by Iran Pan American Oil Company for the National Iranian Oil Company and Amoco Iran Oil Company. The barge is located in the Cyrus Field about 45 miles west of Kharg Island in the Persian Gulf (figure 2).

The Cyrus Field commenced production in April 1967, from six wells at a rate of about 2 5,000 BOPD (figure 3). 19-degree API gravity crude is produced from the Burgan Sand at approximately 7,500 feet. The crude contains a very tight emulsion which makes desalting desirable for maximum marketability. Present production ranges between 25,000 and 30,000 BOPD. Produced crude is gathered at the production platform which has a current capacity of 35,000 BOPD. Oil platform which has a current capacity of 35,000 BOPD. Oil and gas are separated at that point and the crude is then pumped through a submarine line to storage. Initially, a 40,000 dwt captive tanker, the Persian Commander, served as storage. Crude is transferred from storage through a submarine line to an export tanker about 3,800 feet away. The export terminal is designed to safely accommodate tankers up to 35,000 dwt under maximum ten year storm conditions. Tankers of 72,000 dwt have been successfully moored and loaded during favorable weather conditions.

During the 41 months the captive tanker was in service, Cyrus production was limited to an average of about 10,000 BOPD because of insufficient storage capacity on the tanker and lack of desalting facilities. Various alternative schemes were considered for increasing storage and providing desalting facilities. These included a pipeline to desalting, storage and export facilities on Kharg Island, submerged storage in the field and use of a large rental (captive) tanker. The barge Pazargad was selected as best suited for the programmed Cyrus Field operations.

PAZARGAD Pazargad replaced the captive tanker on October 2, 1970. The barge is rated at 133,000 dwt equivalent to a working storage of about 880,000 barrels of Cyrus crude. She is 505 feet long, 150 feet wide and 82 feet high with a maximum permissible draft of 72 feet. Pazargad was designed and built permissible draft of 72 feet. Pazargad was designed and built by Mobil Oil Corporation and chartered to IPAC through a lease rental type agreement. The barge was constructed in Rotterdam and towed to the Persian Gulf via the Cape of Good Hope by the tug Arctic, one of the largest tugs in the world.

Pazargad is secured to a single-buoy mooring system (figure Pazargad is secured to a single-buoy mooring system (figure 4) designed to transmit a mooring force of 360 metric tons under 100 year storm conditions. The mooring lines consist of two 16-inch diameter nylon ropes 300 feet long. The buoy is connected to four chains each of which is attached to a four-pile anchoring jacket (figure 5). Water depth is approximately 140 feet

Two rubber hoses attach to the bottom of the mooring buoy extending from the submarine lines on the sea floor. One connects to the production line for incoming crude and the other connects to the export line. Both the incoming and the export crude streams pass through a concentric manifold within the buoy. The produced crude comes on board through the starboard floating hose. The export crude leaves Pazargad via the portside floating hose. These hoses are 570 feet in length.