The U.S.S.R.'s Tengiz oil field near the northeast coast of the Caspian Sea in western Kazakhstan has posed the Soviet Union's most difficult problems in evaluating and developing a supergiant reservoir.
Tengiz probably will not be developed enough to permit an accurate determination of reserves until 1995, Soviet geologists say. However, it's possible the timetable could be advanced if a joint venture between Moscow and Chevron Corp. goes into operation and includes Tengiz (OGJ, June 11, p. 18).
Preparing the pre-Caspian basin field for relatively small first stage production of 60,000 b/d has been enormously costly and technologically challenging.
Construction of a plant to process Tengiz crude with its high hydrogen sulfide content in dissolved gas is far behind schedule, and wells remain shut in until the plant is complete. Inefficiency and shortages of equipment and materials are widespread, Soviet sources report.
Soviet industry is unable to manufacture high quality pipe and equipment required to handle the extremely sour, corrosive Tengiz crude, forcing costly purchases from western firms at a time when Moscow is scraping the bottom of its hard currency reserves.
In 1987, Occidental Petroleum Corp. and Italy's Montedison SpA signed a memorandum of intent to form a joint venture to develop and operate a massive petrochemical complex in Tengiz field. Japan's Marubeni Corp. agreed to participate in the enterprise.
LAGGING THE PACE
Compared with Tengiz, placing the Volga-Ural area's largest field - Romashkino - and western Siberia's super-giants - Samotlor and Urengoi - on large scale production was fast and easy.
What's more, Romashkino, Samotlor, and Urengoi were developed with relatively little foreign assistance. Moscow has been forced to turn to Communist and western nations for extensive aid in bringing Tengiz on stream.
The U.S.S.R. discovered Romashkino in 1948 and began commercial production in 1952. By the early 1960s, it was the U.S.S.R.'s most prolific oil field.
Western Siberia's Samotlor is a 1965 discovery in a remote, roadless, swampy area plagued by extreme winter cold and summer flooding. Yet Samotlor by 1974 was producing more than 1.2 million b/d and became the U.S.S.R.'s leading oil field.
Urengoi, apparently the world's largest gas field, was discovered in 1966 astride the Arctic Circle, far from population centers and surface transportation. Developed in 1978, Urengoi produced more than 2 tcf in 1980 and the following year became the U.S.S.R.'s largest gas field by a wide margin.
In sharp contrast, Tengiz, although lying in a desert area, is close to a crude oil pipeline, a railroad, and towns. It is only 100 miles southeast of the Guryev refinery.
THE COST OF DELAY
Early this spring, the Moscow newspaper Rabochaya Tribuna (Worker's Tribune) reported that work delays on Tengiz facilities had cost the U.S.S.R. 3 million tons (21.9 million bbl) of crude oil, along with large volumes of natural gas, sulfur, ethane, and propane.
It placed the value of the loss at 148 million rubles.
To speed construction of the Tengiz oil and gas processing plant, the U.S.S.R. brought in 80 brigades of Hungarian workers. They are paid three to four times as much as their Soviet counterparts, and Hungary will receive oil products in partial exchange for projects they complete.
Kazakhstan officials have angrily objected to the higher pay granted to the Hungarians.
But Rabochaya Tribuna pointed out that the Hungarians are highly skilled, whereas Soviet workers flown to Tengiz area construction projects for short tours of duty are likely to be former farm-hands, miners, "and even artists."
EQUIPMENT PROBLEMS
The Soviets admit many deficiencies and "unresolved problems" in drilling deep pre-Caspian basin holes such as those in Tengiz field. They say the shortcomings have slowed drilling and reduced well quality.
The Soviet magazine Neftianik (Oil Worker) criticized chronic shortcomings of corrosion resistant blowout preventers and casing, suitable casing string equipment, ball cocks, and other items. It said development and introduction of modern drilling technology for conditions in the pre-Caspian basin are lagging badly.
Even so, it said, "The increase in oil reserves in Tengiz and adjacent fields was achieved despite failure to meet goals for exploratory drilling."
Early this year, drilling of 18 Tengiz development wells was in progress. One well was projected to 19,685 ft, another to 21,352 ft.
Deepest Tengiz hole went to 17,759 ft, but even it did not reach the bottom of the Carboniferous reservoir.
No. 54 well in the salt dome sector of Tengiz is in the planning stage and is projected to 22,966 ft. The Soviets believe holes that deep will establish a still greater pay thickness, originally estimated at almost 3,000 ft and later increased to "more than 1,600 m" (5,249 ft).
DRILLING PACE QUICKENS
Despite the problems, the U.S.S.R. is stepping up drilling activity in the western Kazakhstan area, especially in the Tengiz district.
A rig manufactured by the Uralmash plant in Sverdlovsk may be used for drilling in Tengiz and other pre-Caspian depression fields. The BU-8000 rig is designed to drill to 8,000 m (26,246 ft).
Fifty-six drilling brigades and 88 rigs were available to the Pre-Caspian Oil Drilling Association by the beginning of this year. Since 1986, the number of pre-Caspian basin drilling brigades has increased by 90% and in western Kazakhstan, including Tengiz field, by 120%.
During 1986-89, the Pre-Caspian Oil Drilling Association started exploratory drilling in 19 areas, and the plan for increasing oil reserves was exceeded. New subsalt oil pools were found in Korolevskoye field just north of Tengiz and in other areas of western Kazakhstan.
The Soviets hope to complete geological exploration of the Korolevskoye structure in 1992.
Copyright 1990 Oil & Gas Journal. All Rights Reserved.