International
Saudis plan huge gas processing complex Persian Gulf nation could be important source of light hydrocarbons and ethylene derivatives by latter part of decade By 1980, Saudi Arabia could become a major source of light hydrocarbons, ethylene, and ethylene derivatives. Work has begun on a huge processing complex to remove ethane and heavier hydrocarbons from natural gas. The gas is produced along with crude oil and has up to now been flared (burned). Processing also will remove sulfur gases, carbon dioxide, water, and other unwanted compounds from the gas. The complex, to be owned by the Saudi Arabian government, is being built by Fluor Corp. under the direction of Aramco Services Corp., part of the giant Aramco oil production combine. Construction will peak in 1978 on a series of gathering systems, gas-oil separators, gas processing plants, pipelines for both gas (methane) and the natural gas liquids, and a fractionation center.
Proposed complex will involve units at seven locations • Natural gas liquids plant •Petrochemical complex • Fractionation plant and shipping terminal
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C&EN May 31, 1976
Enormous product quantities will be produced by units in the complex, Malcolm Huvall of Aramco told a meeting of the Natural Gas Men of Houston earlier this month. Some 6 billion cu ft of raw gas a day will be processed when all units now planned or being designed and constructed are completed. Useful products to be recovered include, on a daily basis, 600 million cu ft of ethane (about 380,000 bbl); a combined 200,000 to 400,000 bbl a day of propane, butanes, and heavier hydrocarbons; and 7000 tons of sulfur. To support these processing facilities, some 4000 Mw of electricity and 14 million lb per hour of steam will have to be generated, Huvall says. Pipelines will total 2000 miles in varying sizes up to 40 inches in diameter. Auxiliary facilities will include a microwave communications system, computer control installations, residential areas, and extensive port and terminal facilities. Huvall doesn't disclose total cost of all these facilities. Industry sources put it in the range of several billion dollars if all auxiliaries are included. Fluor has said its contract is valued at $4 billion. Ethane produced by these facilities will all be used in Saudi Arabia for either manufacture of ethylene and other chemicals at a proposed complex at Jubail or as a supplemental fuel for various other manufacturing operations. No ethane will be exported. The 600 million cu ft of ethane a day accounts for about 20% of current world production, Huvall estimates. Although some of the other gas liquids might be used internally in Saudi Arabia, much will be exported. Port facilities adjacent to a central fractionation-terminal complex at Juaymah on the Arabian Gulf will be built to handle refrigerated tankers. The whole current Saudi Arabian gas program has been divided into four phases, depending on the kind of operation involved. Initially, crude oil and the associated gas will be gathered to gas-oil separator plants. Present plans call for 39 such plants to be fed through 400 miles of onshore and 100 miles of offshore pipelines. More than 70 compressors driven by electric motors totaling more than 500,000 hp will move the separated gas to five natural gas liquids (NGL) processing centers located at Abqaiq, Berri, Safaniya, Shedgum, and Uthmaniyah. At the NGL centers, the sour, wet gas at about 200 psig will first pass through sweeteners containing diglycol amine to remove hydrogen sulfide and carbon dioxide. Sulfur recovery units will vary in size between 500 and 1000 tons a day.
These units are designed to meet stringent limits on sulfur dioxide concentrations in stack gases. Sweetened gas next will be compressed from about 150 psig to 475 psig by four 32,000-hp steam turbines. This pressure will cause the gas to flow through the rest of each NGL unit up to the final residue gas compression facilities. Gas will come out of the compressors at about 280° F. Four direct refrigerated chill-down trains will bring the temperature to —88° F. Three stages of propane and one stage of ethane refrigeration will be used. Liquid hydrocarbons dropped out during the chilling will go first to a demethanizer and then to surge spheres (storage units) before the liquids pipeline. Each of the NGL centers will take in on average 1.5 billion cu ft a day of raw sour natural gas. Output will average 600 million cu ft a day plus liquids. The final step at each of the processing centers will be to compress the residue gas to 700 psig, normal pipeline transmittal pressure. Ethane plus natural gas liquids produced at each plant will be pumped to a central fractionation plant at Juaymah. Pipelines will operate against a 550-psig back pressure-surge volume installation in the receiving area. This pressure will allow for single-phase pipelining of the product liquids. At the central fractionation plant, up to 700,000 bbl a day of liquid products from the NGL centers will be separated into ethane, propane, butanes, and natural gasoline (five-carbon compounds and heavier). The center will have three parallel trains, each designed to handle 230,000 bbl a day. These will be supported by six 500,000 lb-per-hour and three 300,000 lb-per-hour package boilers. Since the fractionation plant is on the coast, seawater cooling and seawater boiler-feed water will be used. Other facilities, in the rough planning stages, include another, smaller fractionation center on the west coast of the Arabian Peninsula in an area called Yanbu. Liquids initially would come from a natural gas liquids complex at Khurais. As part of the construction of the gas program, a vast increase will be made in port facilities. Currently Huvall puts imports at some 8000 tons of material daily through ports at Dammam and Ras Tannura. During the two years of major construction, imports are predicted to increase to 28,000 tons daily. To handle this load, Dammam will be expanded, and barge terminals will be added at Jubail and Al' Uqayral' Uqayr. Bruce F. Greek, C&EN Houston
