Premium
GEOLOGY AND ENTRAPMENT HISTORY OF THE PORTACHUELO SALINA POOL, TALARA BASIN, PERU
Author(s) -
HayRoe H.,
Zuniga J. F.,
Montoya A.
Publication year - 1983
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.1747-5457.1983.tb00413.x
Subject(s) - geology , anticline , structural basin , petrology , sequence stratigraphy , stratigraphy , petroleum reservoir , paleontology , fault (geology) , geochemistry , sedimentary depositional environment , tectonics
Maps of pressure measurements and fluid distribution are important tools in deciphering the geology of complex reservoirs. To understand the original entrapment and present‐day distribution of hydrocarbons in the Salina Pool of Portachuelo Field, NW Peru, we used pressure and production data, in conjunction with a detailed analysis of how the pool is put together structurally and stratigraphically. In Portachuelo up to 45 Lower Eocene (Salina) sands, which can be oil‐, gas‐, or water‐bearing in different wells, have been offset by a veritable maze of normal faults. To reconstruct this jig‐saw puzzle we used “composite” electric logs that provided a close approximation of the Salina sequence prior to faulting. The Salina Pool of Portachuelo offers a challenging place to hunt for commercial oil in a 490‐m sequence of multiple thin (2–10 m) sands within small fault‐blocks. In this search it is helpful to consider the pool as a fluid system in which the reservoir geometry, defined by both stratigraphy and structure, is only one major element; the other two elements are the fluid content of the system and its internal energy, as reflected in the reservoir pressure. Because of the remarkable complexity of the reservoir geometry, it was the present‐day distribution of fluids and pressures that eventually provided the key to the pool's history of entrapment. Only after fluid and pressure variations were interpreted in terms of the structural evolution did it become clear that Portachuelo's oil originally accumulated in a well‐defined anticline. This simple distribution was destroyed by faulting, which thinned and collapsed the anticlinal crest while raising the flanks. Gas, because of its higher mobility, was more widely redistributed than oil or water.