The Casablanca field, the largest of four producing fields in the Spanish Mediterranean, is located about 50 km south of Tarragona. Using the Halbouty classification in AAPG Memoir 16, the field is a "paleogeomorphic trap."

The field is producing 18,000 BOPD from two wells in an "early production phase." The crude has an API gravity of 33.7°, sulfur content of 0.2%, and a GOR of 155 cf/bbl. Full field production of about 35,000 to 40,000 BOPD will start in 1983 after a platform is installed.

The reservoir is a weathered and fractured Upper Jurassic

End_Page 1005------------------------------

carbonate rock. The primary matrix porosity averages about 3%. However, weathering during the early Tertiary enlarged fractures and previously existing porous zones to a depth of 100 to 150 m below the top of the carbonate rocks. This secondary porosity, in combination with an extensive fracture network, has converted the otherwise dense carbonate rock into a commercially exploitable reservoir.

A contour map on the top of the eroded Mesozoic carbonate reservoir defines a closure 11 by 2.5 km. The field is elongated parallel to and bounded by Miocene faults with an overall configuration of a rounded limestone ridge.

The ridge is covered by middle Miocene organic rich shales, the oil source. These and younger shales cap the accumulation.

The use of a paleogeomorphic model aids the interpreter in mapping data in the Casablanca area which otherwise would seem uninterpretable, or at least difficult to interpret. The model may be of use in other carbonate areas.

End_of_Article - Last_Page 1006------------