IRAQ - Nahr Umr/Zubair Development.

Another SC on offer involves the Nahr Umr and Zubair reservoirs of North and South Rumaila, Luhais and Subba fields. The planned production capacity of this project is 330,000 b/d.

Rumaila was one of the causes of conflict between Iraq and Kuwait in 1990. It is about 80 km long, extending about 3.6 km into Kuwait's territory. The latter extension is to be developed by Kuwait on a large scale.

South Rumaila was found by BPC in 1953, following the discovery of the adjacent Zubair field. This large, gentle, anticlinal structure was later found to be trending from south to north and was divided into two parts, North Rumaila and South Rumaila. The northern part of the field was discovered in 1954 after additional seismic surveys were conducted. The southern part was put on stream in 1954. South Rumaila in 1990 had at total of 208 wells, including 133 producers. But its Middle Cretaceous reservoir was beginning an irreversible decline.

North Rumaila was confirmed as a commercial discovery in 1958 but BPC decided not to develop it. In 1961 Baghdad revoked the rights of IPC and its subsidiaries over all non-producing discoveries. INOC then took over a partial development of North Rumaila with Soviet help, and this went on stream in 1972. IPC and its subsidiaries were nationalised on June 1, 1972, with South Rumaila kept as part of INOC's operations. A further development of North Rumaila was completed years later. Its oil and that of South Rumaila are used in a blend of crudes called Basra Light. The mix was in 1990 exported mainly through IPSA pipeline to the Red Sea terminal near Yanbu' (1.65m b/d). Saudi Arabia closed IPSA pipeline after Iraq's invasion of Kuwait in August 1990, as the UN imposed sanctions on Iraq. South Rumaila in 1990 had 443 wells, including 303 producers.

Installations at both North and South Rumaila were heavily damaged by US-led attacks in early 1991. A partial rehabilitation of these areas after March 1991 proved to be a difficult task, with many wells having been on fire and the southern part was affected by the UN buffer zone (UNIKOM) separating Iraqi and Kuwaiti border areas. There are several small fields near Rumaila which, together with West Qurna, Nahr Umr and Majnoon to the north and north-east, and the Zubair/Luhais/Subba group, are part of the "Great Rumaila Triangle".

The Yamamah reservoir, an Early Cretaceous formation beneath North and South Rumaila and possibly Zubair, is more than 4,000 metres deep. It contains high quality oil, of the 37-40 DEG. API range with low sulphur. This, too, is to be developed under on SC basis.

Zubair is a giant, with 4.5 bn barrels in proven reserves, but a smaller anticlinal accumulation than Rumaila. The field was discovered in 1949 by BPC and went on stream in 1951. Production has come from three reservoirs: a shallow Oligo-Miocene heavy oil reservoir in the Lower Fars and Upper Ghar (20 DEG. API and 5.5% sulphur); a Mid-Cretaceous Mishrif limestone (23 DEG. API, 3.5% S); and a Lower Cretaceous Zubair sandstone (36 DEG. API, 1.9% S). The latter formation is 3,500 metres deep and is 55 metres thick, containing over 1.5 bn barrels of proven 36 DEG. API oil with 1.9% S. A development of the third reservoir by SOC has raised the field's capacity from 70,000 to 230,000 b/d, through the drilling of 50 producing wells and 40 water injection wells. The development has included installation of a 70,000 b/d GOSP at Rafidhiyah, the rehabilitation and expansion of four older GOSPs each to a 40,000 b/d capacity, 19 additional storage tanks and 300 km of new pipelines. The field by 1990 had 110 wells, with 56 producers. Its axis is parallel to S. Rumaila and is closer to Basra.

Luhais, close to Zubair found in 1961 by BPC, was developed by NIOC and went on stream in 1978 at 50,000 b/d of 32.5 DEG. API oil. It was expanded to over 100,000 b/d. Its reservoirs are Mishrif and Zubair, both to be developed further. It has a lower Nahr Umr zone yet to be tapped. In 1990 the field had 21 wells, including 12 producers, and a degassing station. Firms negotiating the SC for this this include Machinoexport and CNPC. Its capacity target has been set at 30,000 b/d.

Tuba, a small field 39 km north of Luhais and 100 km west of Basra, was discovered in 1959 by BPC and partly developed by SOC and ONGC of India. It came on stream in Feb. 1990 to produce 20,000 b/d of 30 oil and 14 MCF/day of gas from Mishrif carbonates. Heavier oil has been extracted from Lower Cretaceous Zubair sands. The oil goes to the Luhais degassing station through a 10-inch pipeline. Its Zubair reservoir is to be developed further and its Nahr Umr pay zone is to be developed. Machinoimport, ONGC and CNPC are among companies interested in the SC.

Ratawi, found in 1948, is being negotiated for a $1.3 bn PSA by Shell, Petronas, CanOxy, Iraqi-controlled Crescent Petroleum and Escondido of Canada and the field's target is 250,000 b/d. It went on stream in 1987. The main reservoirs are Middle to Lower Cretaceous sands, which have 21 DEG. API oil. A heavier oil (17 DEG. API, 5% S) is present in the Mishrif. In addition, high- pressure gas was found at the top of the Upper Jurassic, accompanied by lighter oil. Oil in 1987 was also produced from the Lower Cretaceous Ratawi carbonates (28 DEG. API).

Al Nejma, rich in oil, gas and condensates, was found in 1989 by SOC. SOC described it as a "great national fortune". Later foreign observers said it could well be a "giant", one of the deep zones explored by SOC in the south and S-W. SOC drilled 13 wells to depths of 15,700-16,000+ ft. One of the wells yielded 3,500 b/d of 49 DEG. API oil. It was said that, like other fields where vertical migrations had been established, this could well contain different qualities of oil and gas. Baghdad in early 1990 offered it for foreign majors to develop. The is a relationship between this and an older Nejma discovery in Mosul.

Fields in the south set for development in 1990 included: Dujailah, a small heavy oil find made in 1961 by BPC, tested 2,000 b/d of 14 DEG. API oil from the top of a Mishrif reservoir; Kifl, a small discovery made by BPC in 1969 in the south-west, tested 5,500 b/d of 21 DEG. API oil with 3.5% S from the top of the Zubair sand; Samawa, a small field west of the Euphrates found in 1959 by BPC, tested 26 DEG. API oil from Upper Jurassic carbonates; Rachi, a small field near Rumaila discovered in 1956 by BPC in Nahr Umr sands, with 31 oil; Zufra, a small field not developed until 1986 because of the Iran-Iraq war, went on stream in July 1989 with a capacity of 10,000-15,000 b/d; and the Safwan & Haji, in the far south, delayed until 1987, were developed by INOC and SCOP and went on stream in 1990, with a capacity of 30,000 b/d and four wells drilled in each field.

Fields in S-E Iraq, in Misan province along the border with Iran, include structures developed in the 1970s by the Elf-ERAP partnership of France, which was later joined by Japan National Oil Corp. (JNOC) grouping Japanese interests. These fields went on stream in 1977. After suspension since the first Gulf war, they were rehabilitated by SOC and went back on stream in late May 1998.

Buzurgan, the first of Elf's finds in 1969, lies north of Basra near the Iranian border and has 2 bn barrels of proven reserves. It has two reservoirs: a Mid-Cretaceous Mishrif with 23 DEG. API oil and 3.7% S, and a Lower Cretaceous Zubair with 25 DEG. API oil. The discovery tested 3,000 b/d.

Siba, discovered in 1969 by Elf near the mouth of Shatt Al Arab, tested 6,000 b/d of 24 DEG. API oil from the Lower Cretaceous Zubair sandstone.

Jabal Fauqi is the third of the Elf discoveries in the area and lies along the Iranian border. It has two reservoirs: an Asmari limestone and a Mishrif limestone. The field went on stream in 1979, with a potentially-productive Lower Cretaceous Shuaiba reservoir found subsequently.

Abu Ghirab, discovered by Elf in 1971 along the border with Iran. It has 1.5 bn barrels of proven reserves in two reservoirs: an Oligo-Miocene Asmari with 23 DEG. API oil and 3.7% S; and Mishrif carbonates. It went on stream in 1977. Naft Khaneh, an extension of Iran's Naft-i-Shahr, was first discovered in 1909 and confirmed in the early 1930s. It came on stream in 1935 and produced 41[degree sign] DEG. API oil from a shallow Miocene Kalhor limestone, a local equivalent of the Asmari, at a depth of 500 metres. Initial recoverable reserves were estimated at 305m barrels.