Banca de DEFESA: REBECA SEABRA DE LIMA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : REBECA SEABRA DE LIMA
DATE: 05/08/2022
TIME: 14:30
LOCAL: videoconferência https://www.youtube.com/channel/UCCBwJxTIfyeGmQSqDLK6duw
TITLE:

The Conduit-Seal System in Neoproterozoic Mixed-Carbonate-Siliciclastic Caves from Salitre Formation, Una-Utinga Basin, Northeast Brazil

KEY WORDS:

Caves; Conduit-Seal System; Carbonate; Analogous

PAGES: 135
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

Kartisification processes in carbonate reservoirs are well defined in the literature and relevant for oil and gas exploration. However, the development of mixed-carbonate-siliciclastic reservoirs can sometimes be difficult to understand. The studied caves presented in this work comprise two main approaches: stratigraphic and structural. The main objective is to understand the behavior of a conduit-seal system in a mixed-carbonate-siliciclastic plataform in the Lapinha and Paixão caves, located at Una-Utinga Basin, Bahia, Northeast Brazil. The study is based on micro to macro scale analyses, through Light Detection and Ranging (LiDAR) surveys, Unmanned Aerial Vehicle (UAV) images, stratigraphic profiles, gamma spectrometry, Uniaxial Compressive Strength (UCS) using Schmidt hammer, structural field mapping and laboratory data analysis, petrographic and
petrophysical analyses. The stratigraphic results comprise the definition of three sedimentary facies described in a vertical columnar section of 22 m in Lapinha and 10 m in Paixão, as well as in thin sections. At the bottom of sections, the lime mudstone facies (Lm) comprises 10% of siliciclastic sediments, which characterizes Lm as the most soluble facies, responsible for the development of most cave passages. Heterogeneous calcarenite facies with carbonate and siliciclastic intercalations may present a conduit or seal behavior, depending on siliciclastic sediments variation (ca. 30-50%). The mixed limestone facies with siliciclastic sediments, about 50% of siliciclastic content, can be characterized as a sealing facies due intense chemical compaction. In addition to the stratigraphic control, it was possible to identify in these caves a structural control, based on quantitative analysis, associated with stratigraphic data. The conduit facies (Lm and/or CaLm) present great density and intensity of fractures indexes, while the sealing facies (LmTs), the opposite. In conclusion, siliciclastic sediments along the described sedimantary facies controls karstification processes at different scales in a mixed carbonate-siliclastic platforms. Thus, Lapinha and Paixão caves can potentially be analogues of mixed carbonate-siliciclastic reservoirs, using the stratigraphic and structural patterns described in the present work. The conduit-seal system in a mixed carbonate-siliciclastic platform may be interesting for characterization of these mixed reservoirs and for the prediction of oil and gas.

COMMITTEE MEMBERS:
Externo à Instituição - ANDERSON DE MEDEIROS SOUZA - IFPB
Externo à Instituição - CLÁUDIO PIRES FLORÊNCIO - PETROBRAS
Externo à Instituição - FABIO LUIZ BAGNI - PETROBRAS
Presidente - 1161652 - FRANCISCO PINHEIRO LIMA FILHO
Externo à Instituição - SÉRGIO VIEIRA FREIRE BORGES - IFRN