The Spanish Mediterranean new-field discovery

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(Amposta Marino), found by a consortium led by Shell, is scheduled to produce 40,000 BOPD by October 1972. Oil reserves are estimated at ½ billion bbl. Oil is 19° API with 5% sulfur and a pour point of 75°F. The field appears commercial and will help to reduce Spain's daily import of 410,000 bbl. Amposta Marino produces from porous, fractured dolomites of late Mesozoic age (Neocomian-Aptian) which are capped by the probable source beds of Miocene clays. The Miocene itself tested subcommercial(?) gas from several shallow sandstones and 37° API oil and gas from a basal carbonate which becomes biogenic on the flanks of tilted fault blocks. The field is on a relatively stable marine platform (not in a delta model) which accumulated thick (10,000 ft) Mesozoic carbonates The early Tertiary was a period of emergence during which the easternmost fault blocks were stripped down to the Paleozoic rocks. In Miocene time, the area sank and marine clays, as well as evaporites of the Mio-Pliocene, were deposited in a basin between the mainland and the Balearic Islands. As exploration continues, the Tertiary and not the Mesozoic is postulated to become the main target. A drifting away of the Balearic Islands from the Spanish mainland is proposed by some to accommodate the geologic history.

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