ABSTRACT: October Field: the Latest Giant Under Development in Egypt's Gulf of Suez

Jeffrey J. Lelek, A. S. Abdine

October field, the third largest oil field in Egypt, produced 378 MMBO from its discovery in 1977 until January 1990. It is the northernmost giant oil field in the Gulf of Suez Rift basin. Twenty wells from five platforms in approximately 190 ft (58 m) of water currently drain over 8000 ac (3238 ha). Recent successful field extensions demonstrate the viability of continuing exploration in this oil-rich area.

This structurally trapped field is a complex of rotated fault blocks typical of rift basins worldwide. A northwest-trending normal fault with an approximate throw of 4000 ft (1220 m) has trapped an 1100-ft (335-m) oil column on the upthrown eastern side. On the upthrown side, the Carboniferous through Oligocene pre-rift section dips gently to the northeast and is unconformably overlain by generally flat Miocene to Holocene clastics, carbonates, and evaporites. Severe multiple problems result from thick Miocene evaporites hampering seismic definition of the highly productive pre-rift section. These same evaporites serve as the ultimate seal in October field and throughout the Gulf of Suez. Although four layers are productive, approximately 95% of field reserves are within Carboniferous to Lower Cretaceous massive Nubia Sandstones. The remaining reserves are in more stratified Upper Cretaceous sandstones, basal Miocene rift-fill Nukhul Formation clastics, and a Lower Miocene clastic in the upper Rudeis Formation.

Several distinct reservoir accumulations exist, with the deepest and most significant original oil-water contact at -10,670 ft (-3252 m) subsea. October field oil gravities range from 14 to 34° API, with an initial solution GOR of 134 to 474 SCF/STB. The hydrocarbon source for all October field oil as well as most Gulf of Suez oil is believed to be the Campanian Brown Limestone Member of the Sudr Formation. Average reservoir parameters for the Nubia Formation are 16% porosity, 236 md permeability, 448 ft (137 m) net pay thickness, 5506 psi original reservoir pressure, and 1683 psi original bubble point pressure. The expected recovery factor is 37%.

A field study was begun in early 1990 to address gradually declining reservoir pressures recently observed. The study is being jointly conducted by GUPCO (the joint operating company of Amoco Production Company and the Egyptian General Petroleum Company) in Cairo and Amoco Production Company in Houston. GUPCO operates October field, which was producing approximately 135,000 BOPD at the beginning of 1990.

AAPG Search and Discovery Article #91000©1990 AAPG Conference-Giant Oil and Gas Fields of the Decade 1978-1988 Conference, Stavanger, Norway, September 9-12, 1990