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Title: Lagoa Feia Formation (Lower Cretaceous), Campos basin, offshore Brazil - Rift-Valley-Stage Lacustrine carbonate reservoirs

Abstract

The Lagoa Feia Formation, buried in excess of 3000 m, is the exploration frontier of the prolific Campos basin. It contains the source beds of all the basin's oil in addition to having its own potential carbonate reservoirs. The faulted margins of the basin fed a system of alluvial fans, sand flats, and mud flats. Alternating dry and rainy period regulated the size and nature of contemporaneous basinal alkaline lakes. Dry periods corresponded to contracted playa lakes with ostracod carbonates and euxinic shales; rainy periods corresponded to expanded pluvial lakes with pelecypod banks. Subaqueous intrusions of basaltic magma generated hyaloclastites with kerolitic ooids and hyalotuffs. Petrographic analysis reveals 5 diagenetic stages: (1) syndepositional alteration of lithoclasts to trioctahedral smectites; (2) early dolomitization, early silicification, and cementation by bladed-rim calcite and zeolites; (3) freshwater-vadose dissolution of bioclasts and lithoclasts, freshwater-phreatic sparite cementation, and neomorphism; (4) mixed saline-freshwater silicification; and (5) burial with compaction, late dolomitization, and partial conversion of smectites to illite. Pelecypod limestones with primary interparticle, secondary intraparticle, moldic, and moldic-enlarged porosities are the potential reservoirs. Ideal conditions for porosity generation and preservation were subaerial exposure followed by rapid lake expansion and burial.

Authors:
; ;
Publication Date:
Research Org.:
Univ. of Illinois, Urbana
OSTI Identifier:
5945506
Report Number(s):
CONF-850322-
Journal ID: CODEN: AAPGB
Resource Type:
Conference
Journal Name:
Am. Assoc. Pet. Geol., Bull.; (United States)
Additional Journal Information:
Journal Volume: 69:2; Conference: American Association of Petroleum Geologists annual meeting, New Orleans, LA, USA, 25 Mar 1985
Country of Publication:
United States
Language:
English
Subject:
02 PETROLEUM; BRAZIL; PETROLEUM DEPOSITS; EXPLORATION; RESERVOIR ROCK; CARBONATE ROCKS; CRETACEOUS PERIOD; GEOLOGIC FORMATIONS; SEDIMENTARY BASINS; SOURCE ROCKS; DEVELOPING COUNTRIES; GEOLOGIC AGES; GEOLOGIC DEPOSITS; GEOLOGIC STRUCTURES; LATIN AMERICA; MESOZOIC ERA; MINERAL RESOURCES; RESOURCES; ROCKS; SEDIMENTARY ROCKS; SOUTH AMERICA; 020200* - Petroleum- Reserves, Geology, & Exploration

Citation Formats

Bertani, R, Petrobras, T, and Carozzi, A V. Lagoa Feia Formation (Lower Cretaceous), Campos basin, offshore Brazil - Rift-Valley-Stage Lacustrine carbonate reservoirs. United States: N. p., 1985. Web.
Bertani, R, Petrobras, T, & Carozzi, A V. Lagoa Feia Formation (Lower Cretaceous), Campos basin, offshore Brazil - Rift-Valley-Stage Lacustrine carbonate reservoirs. United States.
Bertani, R, Petrobras, T, and Carozzi, A V. 1985. "Lagoa Feia Formation (Lower Cretaceous), Campos basin, offshore Brazil - Rift-Valley-Stage Lacustrine carbonate reservoirs". United States.
@article{osti_5945506,
title = {Lagoa Feia Formation (Lower Cretaceous), Campos basin, offshore Brazil - Rift-Valley-Stage Lacustrine carbonate reservoirs},
author = {Bertani, R and Petrobras, T and Carozzi, A V},
abstractNote = {The Lagoa Feia Formation, buried in excess of 3000 m, is the exploration frontier of the prolific Campos basin. It contains the source beds of all the basin's oil in addition to having its own potential carbonate reservoirs. The faulted margins of the basin fed a system of alluvial fans, sand flats, and mud flats. Alternating dry and rainy period regulated the size and nature of contemporaneous basinal alkaline lakes. Dry periods corresponded to contracted playa lakes with ostracod carbonates and euxinic shales; rainy periods corresponded to expanded pluvial lakes with pelecypod banks. Subaqueous intrusions of basaltic magma generated hyaloclastites with kerolitic ooids and hyalotuffs. Petrographic analysis reveals 5 diagenetic stages: (1) syndepositional alteration of lithoclasts to trioctahedral smectites; (2) early dolomitization, early silicification, and cementation by bladed-rim calcite and zeolites; (3) freshwater-vadose dissolution of bioclasts and lithoclasts, freshwater-phreatic sparite cementation, and neomorphism; (4) mixed saline-freshwater silicification; and (5) burial with compaction, late dolomitization, and partial conversion of smectites to illite. Pelecypod limestones with primary interparticle, secondary intraparticle, moldic, and moldic-enlarged porosities are the potential reservoirs. Ideal conditions for porosity generation and preservation were subaerial exposure followed by rapid lake expansion and burial.},
doi = {},
url = {https://www.osti.gov/biblio/5945506}, journal = {Am. Assoc. Pet. Geol., Bull.; (United States)},
number = ,
volume = 69:2,
place = {United States},
year = {Fri Feb 01 00:00:00 EST 1985},
month = {Fri Feb 01 00:00:00 EST 1985}
}

Conference:
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