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Volume 33, Number 6November/December 1982

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The Keystone

The flares are going out in Saudi Arabia, but no one will miss them. Once burned, the gasses that fed the flares are today being put to use. In fact, the immense network for collecting, treating and distributing the gas is the keystone in Saudi Arabia's on-going industrial development program. Called the Master Gas System, this network is already providing fuel to generate power and desalinate water, and will soon be furnishing invaluable raw materials - feedstock — to nourish new industries.

The most ambitious energy project in history, the Master Gas System is harnessing, for domestic and world markets, immense quantities of gas released from the ground with oil in Saudi Arabia's oil fields. Designed to process up to 9,900,000 cubic meters (3.5 billion cubic feet) of gas a day, the system is furnishing fuel for items as diverse as cigarette lighters and cement plants and, by 1983, will add the equivalent of some 750,000 barrels of crude oil a day to the world's energy supply. Above all, it will provide fuel and feedstock for plants now under construction, or about to be constructed, at the new Saudi industrial cities of Yanbu' and Jubail: mainly oil refineries, petrochemical and fertilizer plants, plus a steel plant and a rolling mill.

For a product that was once a problem it is a dramatic change. Dissolved in crude oil, the gasses were brought to the surface with the oil, separated from it, and burned - since until recently, collection and processing were not economically justifiable; there simply was no market for such gas.

Aramco, which designed and built the Master Gas System — and now operates it on behalf of the Saudi government - used some gas on a small scale as far back as the early 1950s: primarily as fuel for Aramco plants, and, injected back into the ground, as a means of maintaining pressure in the Ghawar and Abqaiq oil fields. Some was also delivered to a number of local industries and power companies.

Later, in 1959, the company also began to develop a gas gathering system to recover what are called "natural gas liquids" (NGL) —a collective term used for some of the light hydrocarbon components produced with oil - and in 1961 began exporting liquefied petroleum gas (LPG). Aramco facilities, including gas processing and fractionation plants at Abqaiq and Ras Tanura, were expanded oves the years until they were capable of producing and processing 360,000 barrels of natural gas liquids a day, making Saudi Arabia the largest NGL exporter in the world.

Although economic utilization of gas had long been an objective of Saudi Arabia, a lot of gas still had to be flared until, in the mid-1970s, the rapid climb in world energy costs, coupled with the Saudi government's decision to launch a massive industrialization program, finally justified the huge investments necessary for gathering and processing gas on a large scale. Even so -when the Saudi government announced in 1975 its decision to build a greatly expanded and integrated gas system -skeptics predicted that the project would prove unprofitable because of depressed international gas prices.

The mammoth gas program, however, is paying off. Already, fuel gas gathered and processed by the system is driving seven major power generating stations and a steam power plant - producing almost all the electricity in the Eastern Province; two huge water desalination plants, a glass factory, and cement, fertilizer and lime plants. And, attracted by the prospect of ready supplies of relatively cheap fuel and feedstock, several major international firms have entered into joint ventures with Saudi government agencies - Petromin and the Saudi Arabian Basic Industries Corp (Sabic) - in setting up industries at Yanbu' and Jubail. These industries soon will be producing chemicals, refined petroleum products and manufactured goods for both export and domestic use, thereby reducing Saudi Arabia's economic dependence on crude oil exports and industrial imports.

Sales of Saudi gas, moreover, have boosted world energy supplies substantially, with more production capacity still to come on stream. By 1983, the approximate total daily capacity of the integrated gas system will be 56 million cubic meters (two billion cubic feet) of methane fuel gas; 10.6 million cubic meters (370 million cubic feet) of ethane; more than 315,000 barrels of natural gas liquids; and 3,700 tons of sulfur by-product. In general, the fuel gas and ethane will be used domestically as fuel and petrochemical feedstock and NGL and sulfur will be exported.

Collection of the gas begins in the kingdom's eastern oil fields, where it is separated from crude oil at or near the well heads and piped to stragetically located gas plants. At those plants, the gas is treated to remove sulfur compounds and carbon dioxide. The gas is then compressed and chilled to extract the heavier hydrocarbon components or NGL. The remaining gasses, mainly methane, are compressed and distributed for use as plant fuel for industries and power generators in the Eastern Province. What's left - ethane and NGL - is piped to east and west coast plants for fractionation into component parts by controlled vaporization and condensation in a series of columns. Ethane, the lightest component, comes off fust in gaseous form for use as fuel and feedstock for petrochemical complexes at Yanbu' and Jubail. Propane and butane, which are refrigerated and condensed for export as liquefied petroleum gas, are extracted in the second and third columns, leaving natural gasoline as the remaining product. Additional columns in the series process this product to make finished natural gasoline, also for export.

The integrated gas system comprises 34 gas-oil separator plants (GOSPs) located on the Berri, Ghawar, Abqaiq and Har-maliyah oil fields; four gas processing centers at Berri, Shedgum, 'Uthmaniyah and Abqaiq in the Eastern Province; and three NGL fractionation plants and export terminals, at Ju'aymah and Ras Tanura on the Arabian Gulf and at Yanbu' on the Red Sea. Linking these facilities are more than 2,400 kilometers of gas pipeline (1,490 miles), including the longest and most advanced in the world, running east-west across the Arabian Peninsula from Shed-gum to Yanbu'.

The total storage capacity at Ju'aymah, Ras Tanura and Yanbu' for the propane, butane and natural gasoline product streams exceeds 16 million barrels. To keep them liquid, propane and butane are stored in special 29-meter-high (95 feet) refrigerated, dome-roofed tanks, while natural gasoline, which does not have to be chilled to remain liquid, is stored in 19.5-meter-high (64 feet) floating-roof tanks at Ras Tanura and Yanbu'. The natural gas liquids are loaded for export at offshore terminals capable of handling vessels up to half a million tons. LPG is shipped to world markets in special refrigerated tankers, natural gasoline by conventional tanker.

To build the Master Gas System, many top-ranking international companies were contracted and tens of thousands of workers employed. Some 2,500 engineers and draftsmen alone were involved in the engineering phase of the project, which consumed nearly 200 million man-hours and some two million tons of imported equipment and materials.

Equipment and construction methods used were among the largest and most sophisticated in the world. Computers, for example, were used to work out precise settings for some 1,530 piles supporting a 10-kilometer-long (six-mile) pier carrying pipes to the offshore gas loading terminal at Ju'aymah. The Shedgum and 'Uthmaniyah gas plants, each covering some 121 hectares (300 acres), utilize some of the largest gas processing equipment available today, and the fractionation modules at Yanbu' are 261 meters long (856 feet) - just short of the length of three football fields.

The visual result is quite stunning: masses of gleaming steel pipes, polished aluminum spheres and shiny metal tanks and towers rising like futuristic cities from the desert sands; and giant arms reaching out to huge tankers tethered in the turquoise waters of the Gulf.

But not all of the components of the gas system are new or man-made. In fact, one is the work of nature and millions of years old - a vast underground reservoir into which excess ethane can be injected for recovery and use later by domestic industries.

Marketing the products of the gas system is being handled by Petromin, which, already responsible for the domestic distribution of petroleum products and some overseas marketing of crude, is fast establishing itself as one of the biggest NGL marketers in the world. The main overseas customer at present for Saudi NGL is Japan.

To ensure complete reliability of gas supplies to Petromin's customers, the Shedgum and 'Uthmaniyah processing plants each have four separate identical processing modules, and the Yanbu' and Ju'aymah fractionation plants each have two independent fractionation trains, only one of which will be affected by maintenance shutdowns at a time, while the others continue production.

By the beginning of October, this year, the key components of the Master Gas System: the Berri, Shedgum and 'Uthmaniyah gas plants, trans-peninsular pipeline, and fractionation plants, and marine export terminals at Ju'aymah and Yanbu' were fully operational.

With their completion, Saudi Arabia, with gas reserves estimated in excess of 2.8 trillion cubic meters (100 trillion cubic feet), is making a significant contribution to conservation of the world's precious hydrocarbon energy supplies, and has laid a strong foundation for its own future economic development based on profitable marketing of natural gas liquids abroad and the availability of relatively low-cost gas fuel and feedstocks for its ambitious plans for industrialization at home.

This article appeared on pages 20-25 of the November/December 1982 print edition of Saudi Aramco World.


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