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ENM200 Subsurface

Petroleum Geology:

Dynamic Earth

- An introduction to Geology and

Petroleum Geology for non-

geologists entering the Oil and Gas

Industry

Dr Bryan T Cronin (ext.cronin1@rgu.ac.uk)

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Objectives of Petroleum Geology course

Half of Subsurface Module, ENM200

Academic lecturer: Dr Bryan Cronin

Petroleum Geology: 3 components:

- Our Dynamic Earth (5+ hours teaching)

- Petroleum Geology (5+ hours teaching)

- Online activities.

Assessed work half of the assessed work in this module will be on Petroleum Geology

Exam you will have to do two questions from the Petroleum Geology part of the module (which has three in total, 2 x Petroleum Geology and 1 x Formation Evaluation)

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Why study Petroleum Geology?

The processes of formation, accumulation and storage of hydrocarbons are all geological

Petroleum Geology: Finding OilReservoir Engineering, Well Engineering,

Production and facilities : Getting it out

Safety, the environment and decommissioning: Cleaning up during and afterwards

LECTURE 2

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Field Development: where does the geology come in?

1. Exploration: seismic character, external reservoir body geometry, seal and trap configuration, HC pathways

2. Appraisal: STOIIP (stock tank oil initially in place), rates of recovery, aquifer (size and pressure)?

3. Planning: Optimum depletion plan, Platform#? Well#?

4. Development: Injection and production, completions and workovers?

5. Management: Infills, workovers, enhanced recovery, reinjection, monitoring and surveillance

i.e. we need reservoir description a knowledge of the geology from the start (1), then the need intensifies (2), then a more complete picture is both

necessary and possible (3-5)

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Introduction to Petroleum Geology

1. Dynamic Earth (plate tectonics)

2. Crustal Composition (atoms-minerals-

rocks)

3. Geological time, correlation + maps

4. Rock Deformation and synthesis

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1. Our dynamic earth

An introduction to geology

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Global Earthquake Zones

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Global Volcano Zones

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50 Ma in the future ...

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2. Crustal Composition

From atoms to rocks

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Oil and Gas Reservoir Lithologies

Type Mineralogy Origin Main Porosity

Sandstone SiO2 Detrital Matrix

Limestone CaCO3 Biogenic Matrix

Chalk CaCO3 Biogenic Matrix

Dolomite MgCO3 Diagenetic Matrix/Fracture

Others Various Various Fracture

(Basement, shales, etc)

CA

RB

ON

AT

ES

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Robert Gordon University 41Halite planes and cleavage

Robert Gordon University 42Quartz crystal seen on SEM

Robert Gordon University 43Clay structure

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The Rock

Cycle

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Rock Cycle:

Graphic

Representation

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Weathering of different materials

Erodability

of minerals

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Ice-wedging

(Mechanical

Weathering)

Robert Gordon University 48Quartz Sandstone

(note matrix: no overgrowth)

Robert Gordon University 49Quartz in cordierite sillimanite gneiss

Robert Gordon University 50Clean sandstone under SEM

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Muscovite in Kyanite Schist, XPL, Shetland

minerals in an metamorphic rock

Robert Gordon University 52Zircons in Biotite, from Biotite-Kyanite Schist,

Ross of Mull, Scotland (PPL) can date the rock

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Zoned plagioclase crystal from Cornish Granite:

Igneous rock under the microscope

Robert Gordon University 54Bioclastic Sandstone

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Rock Textures

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Where are igneous rocks found?