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PROSPECT EVALUATION - COURSE OUTLINE Day 1

OBJECTIVES COURSE OVERVIEW SOURCE ROCKS & THE PETROLEUM SYSTEM

Day 2 TRAPS RESERVOIR ROCKS AND DEPOSITIONAL ENVIRONMENTS

Day 3 FLUIDS SEALS

Day 4 BASIN TYPES PLAY TYPES

Day 5 VOLUMETRICS PROSPECT RISKING CONCLUSIONS AND RECAP

EXERCISE 1 Burial history and source rock maturity EXERCISE 2 Britannia reservoir correlation EXERCISE 3 Play analysis (Exploration battleships) DAILY EXERCISE Technical terms & definitions

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An understanding of the origins of hydrocarbon accumulations The Petroleum System.

An understanding of a simple classification of Play Types and how the characteristics work in practise - using real field examples.

What parameters need to be measured and how to calculate volumes of hydrocarbons

Ranges of typical parameter values for hydrocarbon accumulations - using Play Type characteristics

How to apply risking in Prospect Analysis.

PROSPECT EVALUATION - OBJECTIVESSomething to take with you

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PROSPECT EVALUATION - COURSE OVERVIEW

Scale of Exploration Targets leading to Discovery:

Sedimentary Basin >>10,000 sq km

Petroleum System >>1,000 sq km

Play Type >> 100 sq km

Prospect 10 sq km

Drill for Discovery

Increasing Expenditure

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Definitions:

Petroleum System: a volume of rock within a sedimentary basin that encompasses a pod of active source rock and all the elements and processes to form and preserve a hydrocarbon accumulation

Play Type: a group or trend of prospects with basically the same set of geological characteristics.

Prospect: a potential hydrocarbon accumulation of a specific play type (yet to be drilled)

Field: a proven hydrocarbon accumulation that can be economic or un-economic, developed or undeveloped, producing or decommissioned

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PROSPECT EVALUATION - COURSE OVERVIEW

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Hydrocarbon Play Types Where to find Oil and Gas within a working Petroleum System

4 Basic Criteria: TRAP RESERVOIR LITHOLOGY & DEPOSITIONAL ENVIRONMENT SOURCE ROCKS & FLUID TYPE SEAL LITHOLOGY Hydrocarbon column height

Other Factors. TIMING STRUCTURAL SETTING OF SEDIMENTARY BASIN STRATIGRAPHIC AGE/BURIAL DEPTH

PROSPECT EVALUATION - COURSE OVERVIEW

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A TRAP is a 3 dimensional geological object in which hydrocarbons are retained. Size and shape are very important for detection, development and economy.

Hydrocarbons are less dense than water. After expulsion from the source rock in the subsurface, buoyancy effects cause the HCs to rise toward the surface via permeable rocks or via fractures (excess pressure).

HCs will thus be lost (surface seeps) unless entrapped by a combination of geometry of a sealing unit (cap rock) over a reservoir.

There are many types of traps and a simplified classification by shape and origin provides a useful synopsis for play/prospect characterisation.

PROSPECT EVALUATION - COURSE OVERVIEW

TRAPsurface

subsurface

seal

reservoir

source rock

TRAP

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Type Mineralogy Origin Main Porosity

Sandstone SiO2 Detrital Matrix

Limestone CaCO3 Biogenic MatrixChalk CaCO3 Biogenic MatrixDolomite MgCO3 Diagenetic Matrix/Fracture

Others Various Various Fracture(Basement, shales, etc)

PROSPECT EVALUATION - COURSE OVERVIEWRESERVOIR LITHOLOGY

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PROSPECT EVALUATION - COURSE OVERVIEWRESERVOIR DEPOSITIONAL ENVIRONMENT

Controls on the size, shape and production characteristics of reservoir bodies

Major effects on reservoir quality distribution: Porosity Permeability Net to Gross Ratio Connectivity/Compartmentalisation

Identification in the subsurface, use of well logs, cores and cuttings

ContinentalEolianAlluvial fanFluvialLacustrineGlacial

MarineMarginal/ParalicShelfSlopeBasin

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Hydrocarbons - a continuum of increasingly complex compounds of hydrogen and carbon, with many accessory components, including sulphides, CO2 and heavy metals.

Light Compounds Heavy compounds

PROSPECT EVALUATION - COURSE OVERVIEWSOURCE ROCKS & FLUID TYPE

GAS OILCOMPLEX FLUIDS

diphasicmonophasic monophasic

e.g. condensate

Gas hydrates (frozen methane)Non-commercial today

Bitumen Tar

Poor economy to non-commercial

AT SUBSURFACE P/T CONDITIONS

Commercial Hydrocarbon Fluids

Liquids

Solids

transportable

Tanker

Pipeline transportable

Need nearbymarket

Gas difficult to store

Liquids easy to store

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PROSPECT EVALUATION - COURSE OVERVIEWOTHER IMPORTANT FACTORS

SEAL LITHOLOGYImportant for trap capacity to contain a hydrocarbon column.Major rock characteristic extremely low permeability.Common seals: Shales, Tight Carbonates, Marls, Evaporites (e.g.

anhydrite super seal of Middle East) and Halite.

TIMINGTrap must be in place before migration occurs

STRUCTURAL SETTING OF SEDIMENTARY BASINControl on occurrence and distribution of play types.

STRATIGRAPHIC AGE AND BURIAL DEPTHControl on reservoir properties, fluid composition and production

characteristics

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PROSPECT EVALUATION COURSE COVERAGE

PLAY TYPE CHARACTERISTICS

PROSPECT ANALYSIS AND RISKING

TOOLS AND METHODS, PLUS EXAMPLES FROM OIL AND GAS FIELDS AROUND THE WORLD

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PROSPECT EVALUATION - COURSE OVERVIEW

COURSE OVERVIEW

PROSPECT EVALUATION - COURSE OUTLINEPROSPECT EVALUATION - OBJECTIVESSomething to take with youPROSPECT EVALUATION - COURSE OVERVIEWPROSPECT EVALUATION - COURSE OVERVIEWPROSPECT EVALUATION - COURSE OVERVIEWPROSPECT EVALUATION - COURSE OVERVIEW TRAPPROSPECT EVALUATION - COURSE OVERVIEW RESERVOIR LITHOLOGYPROSPECT EVALUATION - COURSE OVERVIEW RESERVOIR DEPOSITIONAL ENVIRONMENTPROSPECT EVALUATION - COURSE OVERVIEW SOURCE ROCKS & FLUID TYPEPROSPECT EVALUATION - COURSE OVERVIEW OTHER IMPORTANT FACTORSPROSPECT EVALUATION COURSE COVERAGEPROSPECT EVALUATION - COURSE OVERVIEW COURSE OVERVIEW