21. risk assessment of petroleum system, plays, prospects

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21.

Risk Assessment of

Petroleum System, Playsand Prospects

by: Awang Harun Satyana

INDONESIAN PETROLEUM ASSOCIATION (IPA)

REGULAR COURSE, SOLO – CENTRAL JAVA, 4-8 JUNE 2012



Society of Petroleum Engineers (SPE)American Association of Petroleum Geologists (AAPG)World Petroleum Council (WPC)Society of Petroleum Evaluation Engineers (SPEE)

Risk : the probability of loss or failure

As “risk” is generally associated with the negative

outcome, the term “chance” is preferred for general

usage to describe the probability of a discrete event

occurring.

2007 definition

Uncertainty : the range of possible outcomes in a series

of estimates. For recoverable resource assessments, the

range of uncertainty reflects a reasonable range of

estimated potentially recoverable quantities for an

individual accumulation or a project.

Risk and Uncertainty



Play Assessment – Projection of undiscovered potential

for family of prospects, taking into account shared(regional) geologic controls

ISSUES: Regional trends can overlook local complexities.

Prospect Assessment – Projection of undiscovered

potential for individual prospects, taking into account

(local) feature-specific complexities

ISSUES: Multiple, stand-alone evalutions can overlook shared regional

controls. Often only top prospects are evaluated.

Integrated Assessment – Projection of undiscovered

potential for family of prospects, taking into account both

shared (regional) controls among prospects and (local)

specific complexities of individual prospects

Assessment Scale – Definitions and Issues

Hood and Stabell (2006)



Prospect Generation

Wildcat Drilling

Discovery, Appraisal,

Field Development

Field

Recovery

Abandonment

Optimization Enhanced

Decline, +

+ +

Basin Analysis

Play Assessment

Prospect

Assessment

Reserves

Assessment

Exploration

Appraisal

Development

Production

Assessment through the Upstream

Sykes et al. (2006)



“A group of leads and prospects, and possiblyoil and/or gas fields, all having similar geologic

origins -- a family of geologically similar traps.”

PLAY CHARACTERISTICS: ATTRIBUTES OF

CONSTITUENT PROSPECTS & FIELDS

• Common Source Rock, HC-type, migration history;

• Similar Reservoir Rock (depositional origin, production characteristics);

• Similar Structural configuration, trap type, structural history;

• Generally trapped by common master seal;

• Prospects form a coherent lognormal Field-size Distribution

Rose (2006)



Risk Assessment (1)

• Risk assessment assigns a probability of success.

• In our assessment process, we evaluate four different concepts of exploration as a function of the degree of knowledge about the specific

project: basin framework, petroleum system framework, play, and prospect.

• Basin Framework Is there a volume of sedimentary rocks capable of

containing potential ingredients of a working “hydrocarbon machine”:

source, reservoir, trap and seal, and proper timing and migration? This

assessment is a screening device only, and does not include economic

considerations.

• Petroleum System Framework The petroleum system framework is

defined as a volume of sedimentary rocks containing hydrocarbons and

charged by a single source rock. The definition requires manifestations of

hydrocarbons (seeps, shows, or a producing well) and is applicable in many

frontier basins only by analogy. Recognition of an active petroleum system

also serves only as a screening device because it carries no volumetric

(and therefore, no economic) value.Otis and Schneidermann (1997)



Risk Assessment (2)

• Play In our definition, the play is the elemental part of a petroleum system,and is recognized as having one or more accumulations of hydrocarbons

identified by a common geological character of reservoir, trap, and seal;

timing and migration; preservation; a common engineering character of

location, environment, and fluid and flow properties; or a combination of

these. Individual plays, therefore, have unique geological and engineering

features, and can be used as a basis for economic characterization. In our

assessment process, we evaluate four different concepts of exploration as a

function of the degree of knowledge about the specific project: basin

framework, petroleum system framework, play, and prospect.

• Prospect Prospect represents an individual, potential accumulation. Each

prospect is perceived as belonging to an individual play, characterized by

risk components and a probabilistic range distribution of potential

hydrocarbon volumes within its trap confines.

Otis and Schneidermann (1997)



Risk Assessment (3)

• Within the evaluation process, the risk considered is geologic risk; i.e., therisk that a producible hydrocarbon accumulation exists. We consider a

producible accumulation to be one capable of testing a stabilized flow of

hydrocarbons. Geologic risk is assessed by considering the probability that

the following four independent factors of the play concept exist.

– (1) Presence of mature source rock (Psource )

– (2) Presence of reservoir rock (Preservoir )

– (3) Presence of a trap (Ptrap)

– (4) Play dynamics (Pdynamics ) or the appropriate iming of trap formation

relative to timing of migration, pathways for migration of hydrocarbons from the

source to the reservoir, and preservation of hydrocarbons to the present day.

• The probability of geologic success (Pg) is obtained by multiplying the

probabilities of occurrence of each of the four factors of the play concept.


Pg = Psource x Preservoir x Ptrap x Pdynamics




Petroleum System and Risk Analysis



Risk Assessment Computation

Probability of

HC Discovery=

Probability

of HCSource

xProbability

of ReservoirQuality

xProbability

of TrapIntegrity

xProbability of

Timing andMigration

For any Risk Factor, the “weakest”element determines the risk

< 0.30 Risk Factor contains unfavourable elements

0.30 – 0.50 One or more elements questionable

0.50 Elements unknown or no definitive data (Neutral)

0.50 – 0.70 All elements at least encouraging to favorable

>0.70 All elements well documented and encouraging to favorable

Geology Risk Factor = 1 / Probability of HC Discovery





Risk

Assessment

Checklist



For a hydrocarbon accumulation to be present and recoverable, nine

independent geologic elements must be adequate to the degree that

the Assessment Minimum volume of hc’s can be produced

Trap-Migration Timing - did the trap exist when the migration occurred?

Migration Pathways - are there paths along which the hc’s can move to the trap?

Source Maturation - is the source rock sufficiently mature to generate hc’s?

Source Richness - is there source lithology with sufficient TOC to generate hc’s?

Hydrocarbon Recovery- can hc’s be recovered from the reservoir?

Reservoir Quality - does the reservoir have suitably high N/G and porosity?

Reservoir Facies - is there a suitable reservoir lithology in the trap?

Trap Seal - is there a means for retaining hc’s in the trap?

Trap Closure - is there a geologic configuration capable of retaining hc’s?

Independent Geologic Risk Factors

Sykes et al. (2006)



BAD NEWS NEUTRAL GOOD NEWS

HIGH 0-.2 X .8- 1

MEDIUM .2-.4 .4-.6 .6-.8

LOW .4-.5 .5 .5-.6

Risk Severity

C O N F I D E N C E

Chance of AdequacyLevel of

geologic

understanding

Good quality,

definitive

data-sets

Poor quality,

ambiguous

data-sets

Negativeindications

predominate

Positiveindications

predominate

Risk Matrix

Sykes et al. (2006)



example

Petronas Carigali (2006)



BPMIGAS (2010)



Type I 1

Type II 1

Type III 1

Type IV 0.063

0 – 0.5 0.0625

0.5 – 1 0.25

1 – 2 0.5

2 – 4 0.75

>4 1

Unmatured 0.0625

Early Mature 0.5

Mature 1

Over Mature 0.125

Well 1

Field 0.5

Assessment (A+B+C+D)/4

SOURCE ASSESSMENT

Type Of Kerogen (A):

Source Rock Maturity In fetch Area TOC (B):

Source Rock Maturity (C):

Source Rock Maturity in Fetch Area Based on Well (D):

BPMIGAS (2010)



Shallow Marine Blangket Proximal 0.95

Shallow Marine Blangket Middle 0.85

Shallow Marine Blangket Distal 0.75

Coastal, Deltaic, Tidal Proximal 0.9

Coastal, Deltaic, Tidal Middle 0.8

Coastal, Deltaic, Tidal Distal 0.75

SUBMARINE FAN Proximal 0.75

SUBMARINE FAN Middle 0.675

SUBMARINE FAN Distal 0.55

Reef With Karstifikasi Process Back Reef 0.9

Reef With Karstifikasi Process Core Reef 0.8

Reef With Karstifikasi Process Fore Reef 0.7

Reef Without Karstifikasi Process Back Reef 0.9

Reef Without Karstifikasi Process Core Reef 0.8

Reef With Karstifikasi Process Fore Reef 0.7

Platform With Karstifikasi Process Proximal 0.7

Platform With Karstifikasi Process Middle 0.6

Platform With Karstifikasi Process Distal 0.5

Reef Without Karstifikasi Process Proximal 0.7

Reef Without Karstifikasi Process Middle 0.6

Reef Without Karstifikasi Process Distal 0.5

Lacustrine Deltaic Proximal 0.8

Lacustrine Deltaic Middle 0.7

Lacustrine Deltaic Distal 0.6

Alluvial Fan, Braided Stream, Meandering

Channel Proximal 0.8


Channel Middle 0.7


Channel Distal 0.6

Eolian Proximal 0.9

Eolian Middle 0.8

Eolian Distal 0.7

Fractured Basement & Fractured Porous Lava

Proximal 0.5


Middle 0.45


Distal0.4

RESERVOIR

ASSESSMENT

Reservoir Depositional

Environment Type and Position

(A) :

BPMIGAS (2010)



SEISMIC ANALYSIS 0.4

LOG CHARACTERISTIC 0.5

COMBINE LOG & SEISMIC 0.7

COMBINE LOG & CORE 0.9

SEISMIC ANALYSIS KARST 0.75

LOG CHARACTERISTIC KARST 0.75

COMBINE LOG & SEISMIC KARST 0.75

COMBINE LOG & CORE KARST 0.75

SEISMIC ANALYSIS NON KARST 0.0625

LOG CHARACTERISTIC NON KARST 0.0625

COMBINE LOG & SEISMIC NON KARST 0.0625

COMBINE LOG & CORE NON KARST 0.0625

SANDSTONES 0.9

CARBONATES 0.9

CLASTIC CARBONATES 0.5

VULCANOCLASTICS 0.5

CONGLOMERATE 0.5

FRACTURED META SEDIMEN 0.4

FRACTURED METAMORF 0.4FRACTURED IGNEOUS ROCKS 0.4

COAL 0.2

OTHERS 0.2

Yes 0.99

No 0.0625

1% – 10% 0.5

10% – 20% 0.9

> 20% 0.99

Well 1

Field 0.5

1 – 3 KM 0.9

3 – 4 KM 0.7

> 4 KM 0.6

Proven 1

No Proven 0.0625

((A*B)+C+D+E+F+G+H)/7

RESERVOIR

ASSESSMENT

Assessment

Reservoir Porosity (E):

Reservoir Porosity Data From (F):

Estimated Depth Of Reservoirs

(G)

Reservoir Depositional

Environment defined by (B):

Reservoir Lithology (C):

Reservoir Fracture (D):

Reservoirs Proven In Well (H)

BPMIGAS (2010)

reservoir assessment (cont’d)



2D 0.7

3D 0.9

<1980 0.6

1980 – 2000 0.7

2000 – 2005 0.8

>2005 0.9

0 – 0.5 M 0.99

0.5 – 1 KM 0.99

1 – 2 KM 0.8

2 – 4 KM 0.7

4 – 8 KM 0.6

>8 KM 0.5

0 – 5 0.6

5 – 10 0.7

10 – 15 0.8

15 – 20 0.9

>20 0.99

<1980 0.6

1980 – 2000 0.7

2000 – 2005 0.8

>2005 0.9

<1980 0.6

1980 – 2000 0.7

2000 – 2005 0.8

>2005 0.9

Gravity

Multybeam

Sattelite Image

CSEM

IPDS

Poor 0.0625

Fair 0.5

Good 0.8

Excellent 0.9

Poor 0.0625

Fair 0.5

Good 0.8

Excellent 0.9

Assessment ((A*B)+C+D+E+F+H+I)/7

TRAP

ASSESSMENT

Trap Data Seismic Type (A) :

Trap Data Seismic Year

Acquisition (B) :

Trap Data Seismic Line Spacing

(C):

Trap Data Seismic Number of

Seismic Line (D):

Trap Data Seismic Year

Reprocessing (E) :

Trap Data Seismic Year Advance

Reprocessing (F) :

Trap Others Data Type (G) :

Trap Others Data Integrity With

Seismic Data (H):

Trap Closure Seismic Quality (I):

BPMIGAS (2010)



Very Near (0 – 2 KM) 0.99

Near (2 – 5 KM) 0.9

Middle (5 – 10 KM) 0.8

Long (10 – 20 KM) 0.6

Very Long (>20KM) 0.4

1 0.7

2 0.75

3 0.8

4 0.85>4 0.9

Vertikal 0.8

Lateral 0.8

Vertical & Lateral 0.99

Proven 1

UnProven 0.0625

No Pathways 0

Yes 0.99

No 0.0625

Yes 0.99

No 0.0625

Yes 0.99

No 0.0625

Yes 0.99

No 0.0625

Yes 0.99

No 0.0625

Assessment (A+B+C+D+E+F+G+H+I)/9

DYNAMIC

ASSESSMENT

Dynamics Migration Pathways

Position Of Trap With Respect To

Kitchen/Fetch Area (A)

Dynamics Migration Pathways

Amount Of Source Rock In The

Oil Window Within Fetch Area

(B)

Dynamics Migration Pathways (C)

:

Dynamic Migration Pathways

Connection Of Pathways to

Reservoir (D):

Dynamics Preservation /

Segregation Post Entrapment

Tectonism Or Faulting (E):


Segregation On Displacement of

Oil By Water or gas (F) :


Segregation On Biodegradation

(G) :


Segregation Thermal Cracking

(H):


Segregation Preferential Migration

Of Gas (I):

BPMIGAS (2010)



PRMS (2007)



RESOURCES & RESERVES CLASSIFICATION

PRMS (2007)

21. risk assessment of petroleum system, plays, prospects

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