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Lecture 14

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Should we drill Alpha?. Should we drill Beta?. Beta. Alpha. Lecture 14. Prospect Analysis. Objectives & Relevance. Objective: Introduce the types of considerations necessary to get a prospect ready for management approval. Relevance: - PowerPoint PPT Presentation
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FWS 2005 L14 – Prospect Analysis Courtesy of ExxonMobil Lecture 14 Lecture 14 Alph a Bet a
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Page 1: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Lecture 14Lecture 14

Alpha

Beta

Page 2: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Objectives & Relevance

• Relevance:Demonstrate some the tasks that go into

determining the size of the ‘prize’ and the risk associated with a prospect

• Objective:Introduce the types of considerations

necessary to get a prospect ready for management approval

Page 3: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Overview of Prospect Analysis

Given the geologic framework and the results of our data analysis, our next task is to analyze and assess viable prospects:

• Analyze prospect elements• Source, Migration, Reservoir, Trap, Seal

• Consider the most-likely scenario

• Consider other cases - the range of possibilities

• Assess the prospect• What volumes of HCs can we expect?

• Will it be oil or gas?

• Risk the Prospect

• What is our level of confidence that all the prospect elements work?

Page 4: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Outline

1. Define prospect elements

2. Estimating trap volume

3. HC Type

4. Assessment

5. Risk

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Page 5: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Outline

1. Define prospect elements

2. Estimating trap volume

3. HC Type

4. Assessment

5. Risk

A “Kitchen”Where Organic

Material Is Cooked

A “Container” From Which Oil & Gas Can Be

Produced

“Plumbing” To Connectthe Container to the Kitchen

CorrectlyPlacedWells

Page 6: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

A Real HC System

Brent Sandstoneacts as a reservoir

Unconformity

Heather ShaleSognefjord Shale

both organic poor

FaciesChange

Draupne Shaleorganic rich

serves as a source rock

Gas Generation

Gas Generation

Oil Generation

Oil Generation

Immature

Immature

Immature

Immature

HC Generation & Expulsionoil & gas from the Draupne, gas from coals in the BrentHC Migrationinto Brent carrier beds and up faults

HC Fill & Spill

FaultLeakPoint

OilSpillPoint

late gas displaces early oil

Page 7: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Alpha Beta

Reservoir

Seal

Source

Basement

Overburden

18 Ma

Most-Likely Scenario

OilGeneration

OilMigration

OilFill & Spill

Sea Water

Page 8: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Alpha Beta

Reservoir

Seal

Source

Basement

Overburden

10 Ma

Most-Likely Scenario

OilGeneration

OilMigration

OilMigration

Sea Water

Page 9: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Most-Likely Scenario

Reservoir

Seal

Source

Basement

Overburden

Present

Alpha Beta

OilGeneration

GasGeneration

Oil & GasMigration

OilMigration

Sea Water

Page 10: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Most-Likely Scenario

Map of the Reservoir Unit

Alpha Beta

Oil

Oil

18 Ma

Page 11: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Most-Likely Scenario

Map of the Reservoir Unit

BetaAlpha

OilOil

10 Ma

Page 12: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Most-Likely Scenario

Alpha Beta

Oil Oil

Gas

Map of the Reservoir Unit

Present

Page 13: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Exploration’s Task

To EMDCor EMPC

DropArea

Drill Wildcats

ConfirmationWell

Identify Opportunities

ProcessSeismic Data

CapturePrime Areas

InterpretSeismic Data

AcquireSeismic Data

AssessProspects

Success

Success

Failure

Uneconomic1. Volume2. HC Type3. Assessment4. Risk

Page 14: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Outline

1. Define prospect elements

2. Estimating trap volumes

3. HC Type

4. Assessment

5. Risk

Let’s start an exercise

Page 15: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Exercise 12 – Parts 1 - 6

We will do some quick estimates using a series of simplifying

assumptions

Page 16: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

How can we get a rough estimate of the cross-sectional area?

Base 1

Height 1

Consider This ….

Let’s say our trap in cross-section view looks like this….

Base 2

Height 2

Page 17: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

From Area to Volume

Volume of a Cone = 1/3 Π r2 * h

Consider the trap to be approximately ½ a cone

Alpha

Beta

r

h

r r

Page 18: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Outline

1. Define prospect elements

2. Estimating trap volumes

3. HC Type

4. Assessment

5. Risk

• DHI Analysis• AVO Analysis• HC Systems Analysis

Page 19: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Oil or Gas???

• Should there be a difference in seismic response (AVO) between an oil-filled reservoir and a gas-filled reservoir?– Model response with different rock & fluid

properties

• If there should be a difference, which fluid type does the seismic data support?– Extract amplitudes from near- and far-angle

stacks

• From our basin modeling & HC systems analysis, which fluid type should we expect– What did the source generate– What did the trap leak or spill

Qu

an

titativ

eQ

ualita

tive

Page 20: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Model Seismic Responses - Input

10% Porosity

Gas

Oil

Brine

20% Porosity

30% Porosity

Page 21: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Model Seismic Responses - Output

10% Porosity10% Porosity

OffsetOffset OffsetOffsetOffsetOffset30% Porosity30% Porosity20% Porosity20% Porosity

Page 22: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Model Seismic Responses - Output

-0.4

-0.2

0.0

0.2

0.4

-0.3 -0.2 -0.1 0.0 0.1 0.2 0.3

Intercept

Slo

pe

GasOilBrineShale

10%

20%

30%

AVO Crossplot

Page 23: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Questions???

• How can we verify this scenario?

• To what level are the traps filled with oil & gas?

• What would be the value ($) if our scenario is correct?

• How much more/less HC could there be?

• How risky is this prospect (chance that we are totally wrong)?

Many times the seismic data will give us clues!

Many times the seismic data will give us clues!

Page 24: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Seismic Line Across ‘Alpha’

Fluid Contact?Oil over Water?

Fluid Contact?Gas over Oil?

Alpha

Page 25: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Outline

1. Define prospect elements

2. Estimating trap volumes

3. HC Type

4. Assessment

5. Risk

Page 26: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Types of Assessments

• Deterministic Assessment– One value for each parameter– One final number, e.g., 200 MBO

• Probabilistic Assessment– A range of values for each parameter– A range of outcomes, e.g. 200 ± 50

MBO

Once a lead has been high-graded into a prospect, we have to assess its potential value

Page 27: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Scenarios & Probabilities

Gas Cap & Oil Leg

Alpha

40% Chance of Occurrence

Scenario 3

Scenario 1 Scenario 2

Scenario 4Alpha

Alpha

Alpha

Gas Only

Oil Only Low Gas Saturation

30% Chance of Occurrence 10% Chance of Occurrence

20% Chance of Occurrence

Page 28: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

ESTIMATES Alpha Beta

1. Gross Rock Volume

2.91 km3

2.12 km3

2. Reservoir Volume

1.02 km3

0.66 km3

3. Pore Volume

0.25 km3

0.15 km3

4. In-Place Volume

0.20 km3

0.12 km3

5. In-Place – Barrels

1280 MBO

735 MBO

6. EUR – Unrisked

288 MBO

132 MBO

7. EUR – Risked

MBO

MBO

Deterministic Prospect Assessment

To Assess a Prospect, We Assign Numbers to the Parameters related to HC Volumes

In our exercise, we have assumed the all oil case (Scenario 3)

Unrisked means everything in the HC System has worked!

Page 29: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Alpha Prospect Assessment Results

0 MOEB0 GCF0 MBOScenario 4Low Gas Saturation

288 MOEB0 GCF288 MBOScenario 3Oil Only

86 MOEB515 GCF0 MBOScenario 2Gas Only

178 MOEB97 GCF162 MBOScenario 1Oil & Gas

Oil Gas Oil-Equivalent

Assuming 100 MOEB is needed to make prospect economic

Uneconomic

Million Barrels Oil Billion Cubic Ft Gas Million Oil Equivalent Barrels

6 GCF = 1 MBO

Uneconomic

Page 30: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Probabilistic Assessment

• The Goal is to Get A Number and a Range of Possible Outcomes

• We Input a Range of Values for Each Assessment Parameter – usually minimum, most-likely, maximum

Area

2012 27

MLMin Max

HC Sat.

Thickness Net:Gross Porosity

FVF Recovery

Page 31: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Unrisked Results

Million Barrels of Oil

Alpha Prospect – Unrisked

0%

20%

40%

60%

80%

100%

0 100 200 300 400

100

Econ

om

ic M

inim

um

50% Chance of finding 200 MBO or more75% Chance of finding the economic minimum

Exc

edan

ce P

rob

abil

ity

Page 32: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Outline

1. Define prospect elements

2. Estimating trap volumes

3. HC Type

4. Assessment

5. Risk

75% Chance of Success

25% Risk

Page 33: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

9 Key Elements of the HC System

Biodegra-dation

Not Low Gas Saturation

HC Migration

Source Maturation

Source Quality

Trap Quality

Seal Adequacy

Reservoir Quality

Reservoir Presence

• A team of experts consider these key elements for each prospect.

• They rate the chance of success (COS) for each on a scale of 0 to 1

Page 34: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

COS for Alpha

• Alpha’s biggest risk is that the fault does not seal.

• There is also some risk that the trap holds low gas saturation and that reservoir quality is poor• Reservoir Presence

• Reservoir Quality

• Trap Quality

• Seal Adequacy

• Source Quality

• Source Maturation

• HC Migration

• Not Low Gas Saturation

• Biodegradation

- - - - 1.0

- - - - 0.85

- - - - 1.0

- - - - 0.8

- - - - 1.0

- - - - 1.0

- - - - 1.0

- 0.9

- - - - 1.0

}0.61

chance of success

(COS)

Some Risk

Highest Risk

Some Risk

Page 35: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Risked Probabilistic Assessment Results

0.0

0.2

0.4

0.6

0.8

1.0

0 100 200 300 400 500

Million Oil Equivalent Barrels

Alpha Prospect – Main Compartment - Risked

Gas Cap & Oil Leg

Gas Only 61 % COS

51 % Chance of Finding More

Than theEconomicMinimum

72% Chance to find any hydrocarbons58% Chance to find 100 MBOE 5% Chance to find 400 MBOE

100

Oil Only

Econ

om

ic M

inim

um

Page 36: Lecture 14

FWS 2005 L14 – Prospect AnalysisCourtesy of ExxonMobil

Exercise 14 – Part 7

In the exercise we will use • A COS of 61%• An economic minimum of 100

MBOE


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