Banca de DEFESA: VITÓRIA COSTA MEIRELLES GÓES

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : VITÓRIA COSTA MEIRELLES GÓES
DATA : 20/01/2020
HORA: 09:00
LOCAL: Auditório B do Instituto de Geociências
TÍTULO:

POTENTIAL HYDROCARBON GENERATOR AND PALEO ENVIRONMENTAL INTERPRETATION OF THE BARREIRINHA FORMATION, SOUTH AMAZONAS BASIN, BRAZIL.

PALAVRAS-CHAVES:

Keywords: Organic geochemistry, palinofacies, depositional paleoenvironment, Barreirinha Formation.

PÁGINAS: 60
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
RESUMO:

ABSTRACT

The present work aimed to evaluate the potential for hydrocarbon generation and the conditions of the depositional paleoenvironment of the Barreirinha Formation, Amazon Basin, from the characterization of organic geochemistry and palinofacies analysis. For this, 60 outcrop samples were collected along the southern compartment of the basin, near the city of Itaituba, state of Pará, where there are indications of the outcropping of the black shales of the Barreirinha Formation. The total organic carbon (TOC) contents found in the collected samples vary between 0.04% and 6.59%, thus constituting a big difference in the production and preservation conditions of the organic matter. The values of insoluble residue (IR) do not vary (around 99%) denoting a predominantly silicy-sedimentation (shales with low carbonate associated). Regarding sulfur, the values ranged from 0.05 to 5.72%, showing a deposition in marine environments. The parameters provided by the Rock-Eval pyrolysis also reflect the variations in the depositional conditions of the geological formation under study. The potential for hydrocarbon generation ranges from low to excellent, emphasizing that the samples with the highest generating potential (S2) values have higher TOC contents. This characteristic is justified by the good quality of the organic matter, since such samples have high values of Hydrogen Index (IH) and low values of Oxygen Index (IO), conforming type I / II kerogen. On the other hand, samples with low potential are those with lower TOC values and higher IO values, configuring type II kerogen. Regarding the free hydrocarbon values present in the samples (S1), the low values of S1 (<0.5 mg HC / g rock) indicate that there was little natural generation of hydrocarbons by the rocks under study. This fact is due to the low degree of thermal maturation, as indicated by the values of Tmax (<440ºC) and production index (IP <0.1).Except for some samples from the IT05 outcrop that showed Tmax values (> 440 ° C) indicating that these samples underwent thermal maturation due to the effect of intrusive rocks. Through analysis of total petroleum hydrocarbons, the contribution of algalic organic matter is made explicit by the aquatic-terrestrial ratio (ART). Still in this analysis, the ratio between Pristane and Fitane isoprenoids indicate differences between anoxic and toxic environments, corroborating the interpretation of variations in the depositional paleoenvironment of the Barreirinha Formation. The evaluation of saturated biomarkers allows us to state that the organic matter present in the samples has marine origin with terrestrial contribution and low thermal maturation. Palinofacial analysis shows that there is a predominance of amorphous organic matter (MOA) in the samples, with moderate amount of palinomorphs and subordinate amounts of phytoclasts.

MEMBROS DA BANCA:
Presidente - 4315399 - ALEXANDRE BARRETO COSTA
Interno - 2349838 - MARIA DO ROSARIO ZUCCHI
Externo à Instituição - CONSUELO LIMA NAVARRO DE ANDRADE - UEFS