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RESERVOIR GEOLOGY OF THE CERRO NEGRO STEAM INJECTION AREA, ORINOCO OIL BELT, VENEZUELA
Author(s) -
Antonio Santos C.,
Frontado Luis
Publication year - 1987
Publication title -
journal of petroleum geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.725
H-Index - 42
eISSN - 1747-5457
pISSN - 0141-6421
DOI - 10.1111/j.1747-5457.1987.tb00208.x
Subject(s) - geology , sedimentary depositional environment , fluvial , facies , delta , sedimentary rock , geochemistry , sequence (biology) , stratigraphic unit , petroleum reservoir , geomorphology , paleontology , structural basin , aerospace engineering , biology , engineering , genetics
Several very favourable areas were defined in the Orinoco Oil Belt, after intensive geological, exploration and evaluation studies were conducted between 1970 and 1982. The Cerro Negro project area was selected as the first to be investigated. Subsequently, a small part of this area, covering 5.9 hectares (14.5 acres), and containing about 159,000 cu. m (1 MM** brl) STOIIP of 8 to 11° API, in the objective sand, was chosen in which to initiate the Cerro Negro Steam Injection Project (PIVCN), which is now under development. The Early Miocene Oficina Formation, whose sands constitute the reservoir rock, show a fluvial to deltaic sequence at the base (Morichal Member), a transgressive sequence in the middle section (Yabo‐Jobo Member), and finally a closing prograding sequence (Pilón Member) at the top. Qualitative analyses of the sedimentary section indicate optimum textural, mineralogical and depositional conditions which determined the final configuration of a sequence with excellent reservoir porosity and permeability. The distributary channel facies show the best petmphysical parameters †, (φ35%, φ So :* 30%, S w : 5%, V sh :* 6%, K: 50,000md). These values yield an oil content of 2,300 STB/acre‐ft. in the objective sand, namely unit 0–15 of the Morichal Member. Oil entrapment is primarily stratigraphic, and no oil/water contacts or gas caps have been found in the PIVCN project or in the whole of the much larger Cerro Negro area.