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ABSTRACT. Israel's structural bodies: anticlines-synclines and horstgräben (blocks) have been tested by more than 30 wildcats (deepest4000m) in the course of the past few years. The anticlinal tests usually started in the Upper Cretaceous crests. They reached or penetrated the pelagic Jurassic limestone-dolomite (1000-1500m thick) in Central-Northern Israel, while in the Negeb upland drilling encountered limy, marly, sandy epicontinental series or continental sandstone of Jurassic-Triassic and (at Sinaf) of Paleozoic age. However, no fluid producers were found. The only oil field - Heletz (and Brur) - is thought to lie in a tilted half-horst structure bordering on the Mediterranean Neogene graben of Ashkelon. True, larger anticlinal gas accumulations, expected to become exploitable, are now being tested at Zohar. But, this and other showings of this peculiar well may be attributed to lateral migration deriving from the structures and source-beds of the Dead Sea graben, only a few miles from Zohar. Good and partly very good shows were, however, frequently discovered in fractures and joints of Jurassic limestone. Sealed by an Infracretaceous shale cover, they must once have formed quite substantial oil accumulations originating, in the writer's opinion, during the Lower-Mid Tertiary orogeny.
The source-beds are possibly of pre-Jurassic age. Graben-structures were drilled in down-sunken (Engedi, Massada) and uplifted blocks (Jordan near Tiberias), and at Debora (an uplifted half-antiche next to the Tabor graben). Apart from the producing areas, all the graben-block wildcats mentioned are rich in excellent and "live oil", or waxy and viscous shows. Oil and such other shows are thought to have originated by lateral migration from Upper Cretaceous and/or Oligocene-Neogene downwarped and down-sunken graben Sediments sealed by marine or continental Neogene-Quarternary cover beds.
In view of past drilling experience, testing of graben structures in coastal and off-shore areas, as well as in inter-mountain depressions (Jordan-Dead Sea and Tabor-Esdraelon), seems to hold greater prospects than anticlinal testing.
This concept should dominate our line of thought in further oil exploration. Yet, recovering of the semi-liquid hydrocarbons in the highly fractured Jurassic limestone of the anticlines must be considered and economical methods worked ont.
RESUME. Les éléments structuraux en Israël (anticlinaux, synclinaux et blocs horst-graben) ont été investigués, au cours des dernières années, par plus de 30 "wildcats" dont le plus profond fut de 4.000 m. Les puits anticlinaux ont généralement débuté sur des crêtes d'âge Crétacé supérieur. Dans la partie nord-centrale d'Israël, ils ont atteint ou pénétré les couches pélagiques calcaires dolomitiques du Jurassique dont l'épaisseur est de l'ordre de 1.000 à 1.500 m. Au contraire, dans les hautes t
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