YEMEN - Offshore.

There is a fairly wide offshore basin in the Gulf of Aden, where a block called Sahyut stretches eastwards from Mukalla to the Arabian Sea. Another offshore area in the Gulf of Aden Basin, yet to be properly explored, runs from a point near Aden city down to the Somali coast, on the southern side of the Gulf of Aden, and is a continuation of the NW/SE trending graben of Ma'rib.

Today stable shelves at the eastern end and the middle of the Gulf of Aden's Somali coast lie opposite the coastal end of the hydrocarbon-rich Jurassic trend in Yemen. At the latter end, the south-western Yemeni coast also consists of a stable shelf. The Jurassic trend there runs to the Ma'rib/Jawf graben, across Shabwa, and to the Saudi part of Rub' Al Khali.

The offshore basin about 170 km to the east and north-east of Mukalla, in Hadhramaut, has an Eocene limestone reservoir sealed by younger and thick Mid-Pliocene sediments. These were accumulated as a result of Gulf of Aden's rifting. The Sharmah discovery there, made in 1982 by Agip, tested 43[degrees] API oil from a depth of about 2,100 metres. But that area proved to be too small for commercial exploitation. Another oil play in mid-Pliocene sediments discovered by Agip was found to be very small. Eocene shales in that area are said to have matured as a result of the depth of burial and the flow of very high heat associated with the rifting of the Aden Gulf. Although they are still organically rich, the shales cannot generate oil commercially.

There are interesting sedimentations off the strategic island of Socotra. British Gas, which got a 17,500 sq km tract (Block 38) to the south-west of Socotra near the Somali coast, studied Mesozoic and Paleozoic outcrops and their relationship to speculative petroleum systems in that region. Block 38 surrounds the smaller islands of 'Abdel-Kuri, Samhah and Darsa. BG drilled two exploration wells there which were dry and abandoned. BG's licence there expired at the end of 1996.

Reserves: The proven recoverable oil reserves in the whole of Yemen have been variedly estimated at between 700m and 3 bn barrels. Oil in place is estimated officially at 10 bn barrels.

The oil reserves are concentrated mainly in five blocks. The biggest oil reserves in place are in the Masila Block 14. They are followed by those of Ma'rib/Jawf Block 18, Jannah Block 5, East Shabwa Block 10A and Iyad Block 4. Oil reserves found in other blocks are smaller. There have been several new oil discoveries in the past seven years (see Part 2).

Reserves of natural gas have been estimated at 16.9-18 TCF. They are mostly concentrated in the Ma'rib-Jawf area and in Jannah.

The Ministry of Oil and Mineral Resources (MOMR) places oil tenders up for bid on a semi-annual basis. Contracts typically involve a 2-3 year exploration period and a 20-year PSA. The Petroleum Exploration and Production Authority (PEPA) of the MOMR authorises all licences for E&P in Yemen, subject to ratification by parliament. All contracts are signed between a company or group of companies, as contractor to the government of Yemen.