The purpose of this paper is to summarize the available geological knowledge of a major part of offshore Iran, and the Persian Gulf. The part played by geophysical surveys is briefly considered. Direct application of geophysical results as well as deduction made therefrom, integrated with the scattered well and other available information, have been utilized in developing the geological history-structural geology and to some extent stratigraphy of this continental shelf area. These have been supplemented and illustrated by stratigraphic cross sections, facies and isopachous maps. A list of oil fields in the Persian Gulf and surrounding areas and wildcats drilled in offshore Iran is also presented.
BRIEF OUTLINE OF GEOPHYSICAL SURVEYS IN OFFSHORE IRAN Geophysical investigation of the Iranian sector of the Persian Gulf commenced on January 6, 1958. In 1963- 1964 a major portion of the area (District-I) was shot for 200 per cent stack seismic reflection reconnaissance survey followed by more detailed seismic reflection work. Most of the area has now been covered by seismic reflection surveys supplemented locally by gravity and very little refraction work.
The original seismic reflection data lacked continuity and failed to provide clear-cut results of the deeper important parts of the section. There appear to be two structural trends, one oriented approximately along a younger northwest/southeast direction and the other in a north/south direction. The former trend typifies the by P. MINA Head, Afiliated Companies AIffairs Group, National Iranian Oil Company M. T. RAZAGHNIA Exploration Manager, Iran Pan American Oil Co. Y. PARAN Head of Oil Afairs Coordination, National Iranian Oil Co. 56n structures in the southwest Iran mainland where most of the production has come from Tertiary. Recently oil in commercial quantities has also been found in the Mesozoic (Cretaceous). The latter trend follows the structures on the Arabian mainland where Mesozoic (Cretaceous and Jurassic) is the prolific producer.
It thus became increasingly critical to distinguish the variations in structural trends between the Tertiary horizons and those below the regional Upper Cretaceous unconformity. In effect, methods to overcome the near-surface reverberations and multiple reflections and the lack of energy returns had to be employed to obtain more reliable data in order to define and delineate the anomalies below the above-mentioned unconformity. Increasing use has been made of multiple coverage recording in analog form. Lengths of seismic cable, reaching 10,000 feet, were effectively employed in some seismic reflection surveys. A higher degree of dip resolution and multiple attenuation was attained by the use of long cable and six fold stacking technique.
A further improv
