This report has been written to describe the basic understanding of the petroleum system on the N’SANO field offshore Cabinda in Angola. The N’SANO field was discovered in 1992 and is located on Block 0 offshore of Cabinda province in Angola. The Block 0 is mainly divided into three source rock Megasystems which are associated with three distinct geologic packages. The Bucomazi formation is the most prolific source rock in the Area A of Block 0. The source rocks for the Bucomazi are kerogen of type I and type I-II, the migration is mostly fault related (vertical), the reservoirs are sandstones of synrift and postrift age, sealed by transgressive marine shales of Cenomanian-Eocene age.
Key words: Petroleum geology; source rock; reservoir rock; migration; trap; seal
Table of Contents
1. Introduction
1.1 Objectives
2. Regional Geology
2.1 Stratigraphy
3. Petroleum System - N’SANO Field
3.1 Source Rock
3.2 Migration
3.3 Reservoir rock
3.3.1 Upper Pinda Reservoir
3.3.2 Vermelha Reservoir
3.3.3 Likouala Reseroir
3.4 Seal
3.5 Trap
4. Prospectivity Impact on Block 0 - NSANO Field
5. Conclusion
6. References
Objectives and Research Focus
This report aims to provide a comprehensive understanding of the petroleum system in offshore Cabinda, with a specific focus on the geological characteristics and prospectivity of the N’SANO field located in Block 0, Area A.
- Analysis of the geological evolution and stratigraphic framework of the offshore Angolan basins.
- Evaluation of source rock quality, hydrocarbon maturation, and migration pathways.
- Examination of reservoir characteristics across the Upper Pinda, Vermelha, and Likouala formations.
- Assessment of structural and stratigraphic traps and sealing lithologies in the N’SANO field.
- Determination of the overall petroleum system prospectivity within Block 0.
Excerpt from the Book
3.1 Source Rock
Source rocks are rocks containing organic material, mainly derived from Algae, Bacterial and Land plant. Potential source rocks are normally evaluated by the high concentration in organic matter, which is expressed as a percentage of TOC (Total Organic Carbon) value.
There are three known types of source rocks (Fig 3), 1. Kerogen type I (mainly algae derived), 2. Kerogen type II (mixed algae and bacteria), and 3. Kerogen type III (mainly landplant). Sedimentary rocks formed from sediments rich in organic matter, once buried as a result of both sedimentation and subsidence, are exposed to increased temperature and pressure envelope. As a result of increased temperature and pressure, a biogenic decay aided by a bacteria and abiogenic reactions (in the organic matter) takes place in the shallow subsurface areas. Methane, carbon dioxide and water are given off, leaving the kerogen. When kerogen reaches the deeper subsurface, temperature and pressure are further increased, transforming the kerogen into petroleum (Fig 4).
Summary of Chapters
1. Introduction: Outlines the discovery and location of the N’SANO field and establishes the primary research objective of developing an understanding of its petroleum system.
2. Regional Geology: Describes the tectonic evolution of the offshore Angolan basins and the distinct stratigraphic packages found in Cabinda.
3. Petroleum System - N’SANO Field: Provides an in-depth technical analysis of the source rocks, migration processes, reservoir rock properties, sealing mechanisms, and trap types specific to the field.
4. Prospectivity Impact on Block 0 - NSANO Field: Evaluates the prospectivity of the area by synthesizing the interplay between depositional, diagenetic, and structural factors for hydrocarbon accumulation.
5. Conclusion: Summarizes the findings, highlighting the Bucomazi formation as the primary source and the trap-reservoir combinations that enable production.
6. References: Lists the academic and technical literature used to support the geological and petroleum engineering arguments presented in the report.
Keywords
Petroleum geology, source rock, reservoir rock, migration, trap, seal, N’SANO field, Block 0, Bucomazi formation, hydrocarbons, Pinda reservoir, offshore Cabinda, organic matter, kerogen, tectonics.
Frequently Asked Questions
What is the core subject of this report?
The report provides a detailed overview of the petroleum system in the N’SANO field, located offshore Cabinda in Angola, focusing on the geological components necessary for hydrocarbon exploration.
Which key geological areas does the study cover?
The study focuses on the petroleum system within Block 0, specifically analyzing the geological characteristics of Area A where the N’SANO field is situated.
What is the primary objective of this research?
The objective is to synthesize existing geological data to develop a robust understanding of the source, migration, reservoir, and trap dynamics that characterize the N’SANO field.
Which scientific methodology is employed?
The author utilizes a comprehensive analysis of stratigraphic columns, geochemical logs, burial history graphs, and technical geological literature to evaluate the petroleum system elements.
What topics are discussed in the main body?
The main body covers the regional tectonic history, detailed source rock properties, primary and secondary migration pathways, specific reservoir characteristics (Pinda, Vermelha, Likouala), and the classification of traps and seals.
Which keywords define this work?
Key terms include petroleum geology, source rock, reservoir rock, migration, trap, seal, and the Bucomazi formation.
How is the migration of hydrocarbons described in the N’SANO field?
Migration is primarily characterized as fault-related vertical movement, though the report acknowledges significant lateral migration occurring within the Presalt along the Chela formation.
What distinguishes the Pinda reservoir from the others?
The Pinda reservoir is identified as a complex, stratified sequence of dolomites and sandstones formed through multiple depositional and diagenetic episodes, distinct from the other reservoir units in the field.
- Quote paper
- Ataliba Miguel (Author), 2012, Petroleum Geology Offshore Cabinda, Munich, GRIN Verlag, https://www.hausarbeiten.de/document/270708
