Basin and Petroleum Systems Modelling: Applications for Conventional and Unconventional

Petroleum Exploration Risk and Resource

Assessments

By Dr Bjorn Wygrala Schlumberger

21-22 November 2013

4. Reservoir in Petroleum

Systems Modeling

Education Days Moscow 2013

2

1. Opening Session: Industry Challenges and Opportunities

Conventional Petroleum Systems

2. Deepwater and Salt

3. Structural Complexity

4. Reservoir in Petroleum Systems Modeling

Theoretical Aspects

5. Temperature and Pressure

6. Petroleum Generation and Migration

Unconventional Petroleum Systems

7. Shale Gas/Oil

8. Gas Hydrates

9. Closing Session: Petroleum Systems Modeling in Context

3

Local Grid Refinement (Model-in-Model) Method

Regional Model Input

Results

Conclusion

Local Model Component distribution

PaleoAccumulation Analysis

Water Washing, Gravity Segregation, Biodegradation

Application of MDT-DFA Data Introduction

Pemex Case Study

Conclusions

Overview

4 4

Regional Model

• Full 3D, pressure, temperature calibrated model of Kuwait.

Overview

5

Reservoir-in-Petroleum-Systems Modeling Concept

• Key Features:

• Complete 3D Kuwait regional geologic model with included Petrel reservoir data model of

major

• oil field (Local Grid Refinement)

• Approximate area of reservoir data model is 1000km2

• Study will enable determination of reservoir pressure/temperature (PVT) and charge history

• This will provide boundary conditions for oil property and distribution analysis

6

Method

Local Grid Refinement (LGR): Use highly refined grid in local areas of interest to improve simulation accuracy

Overview

7

Overview

Field shown in low

resolution as used

in regional model

Field shown in high

resolution as used

in local model

8

Regional Model

Goal:

– Explanation of charge history of the field: covering the kitchen

areas of the petroleum system.

– Loss of resolution in the field area: distribution of charge to the

structures of the field cannot be covered but general amount of

available mass for migration and entrapment.

– Timing of charge depends on structural evolution of the entire

area not only on field scale.

Regional Model

9

Input

– Regional maps of 1200 m lateral resolution

– 43 Layers

– Thermal History:

• 76 Wells

– VRo, BHT

• Generation of heat flow maps to cover lateral and temporal shifts.

Regional Model

10

– Pressures and Porosity

• 60 Wells

– Measurements on core samples and log data

– Fluid Compositions

• PVT Data from more than 300 production well samples

– Source Rock Data

• New generated kinetics for Najmah, Sargelu and Makhul source rocks.

• Literature data for Kazhdumi source rock

Regional Model

11

Results

Regional Model

Charge area of the field is very

large, covering also regions in a

greater distance with proven

source rocks.

Large amount of accumulated

hydrocarbons need at least more

than one source beside the

Makhul.

Source rocks in the direct vicinity

of the field are immature.

Lateral long-distance migration

from kitchen areas can provide

additional charge.

12

– Charge History

Regional Model

Multiple charge episodes lead to

mixing within the reservoirs.

1st Step

Source rock tracking with limited

number of components helps to

identify the different source rocks

2nd Step

High resolution 14-component

kinetic reactions of the identified

sources are used to model fluid

properties.

Results

13

Results

– Two separate petroleum systems.

• Jurassic-Paleozoic, Sub-Gotnia System with Najmah, Sargelu and Qusaiba sources

• Cretaceous System with Makhul and Kazhdumi source rocks

– Gotnia is considered as an effective Seal

• Gotnia is a thick salt/anhydrit succession considered to be present all over the study area

• High overpressures below the Gotnia evaporates indicates no seal breach in recent

times.

• No evidence of faulting of Gotnia in the past.

– Geochemical Analysis indicates oil mixing in the cretaceous reservoirs

• Generated mass of the Makhul in the model area is not sufficient to fill known fields

• Makhul and Kazhdumi source rocks are very similar in depositional environment.

• Both source rocks are mature and are generating hydrocarbons

• Lateral fill and spill paths from the Dezful Embayment can be modeled

Regional Model

14

Local Refined Model

Input and Goal

– 100 m lateral resolution – Boundary Conditions, No. of layers as in Regional

Model

– In-Situ migration modeling with model-in-model grid refinement can describe

distribution of charge from the low-resolution regional model to the field

structures

Local Model

15

– Distribution of 14 components for each source rock: 28 components with

source rock tracking.

– Full pressure and temperature calibrated

– Detailed charge history of the field (from regional model) and redistribution

of charge in the local model

– Distribution of heavy oil in wells and heaviest component C60+ in model was

compared to explain heavy oil occurrence from charge modeling.

– Heavy Oil can not only be found at the OWC but in some areas of the field

also in structural and stratigraphic higher reservoirs.

Local Model

Main Reservoirs on Regional Surface

Reservoir 4S: C60+ Masses

Reservoir 3SL: C60+ Masses

Reservoir 3SM: C60+ Masses

Reservoir 3SU: C60+ Masses

Burgan Field 4th Sand Reservoir Filling History

present 10 Mabp 25 Mabp 39 Mabp

22

Paleo-Accumulation Analysis

– Charge through time and redistribution on high resolution Grid

– Comparison with known Heavy Oil occurrences in the field.

Local Model

Strong correlation of heavy oil

wells and paleo-OWC.

Tilting of structures in geologic

past is leading to remigration

and flushing of paleo-OWC

Additional charge from second

source is filling structures and

lead to preservation of heavy

oil in higher reservoir levels

Water Washing

– Water Drive could be modeled by differential burial and different compaction

of the sediments

– good lateral hydrodynamic communication of the reservoirs are indicated by

hydrostatic pressure conditions throughout carrier.

– Strong lateral water drive could cause depletion in water-soluble compounds

Local Model

24

Component Distribution

– Present Day Distribution of

C60+ components in the model,

representing potential mass

and distribution of heavy oil in

the field.

– HO layers from well-logs were

imported as picks and

compared to modeled

component distribution,

displayed as geobody.

– Present Day C60+ does

correspond to some but not all

HO Wells

Local Model

26

Biodegradation

– Reservoirs are cool and do not

reach sterilization

temperatures of 80°C.

– Biodegradation models show

reduced activity and

degradation rates since

deepest burial and later uplift

– Shallow accumulations show

strong indications of

Biodegradation in GC-MS

– Cretaceous reservoirs are not

consistent, showing wide

range of non degraded to

strongly affected oils

Local Model

27

Calibration of Petroleum Systems Models with

MDT-DFA Data

MDT (Modular Dynamic Formation Tester)

DFA (Downhole Fluid Analysis)

28

Downhole Fluid Analysis (DFA)

on the MDT

Sample

Modules

Pump

DFA

Tools

Pump

IFA

LFA

Fluid

Entry

Contamination

Phase change

GOR

Composition

CO2

Density

Viscosity

Asphaltene

H2S in field trials

Fault Block Migration

29

Disequilibrium

Heavy Oil

Gradients

Water

Washing

Biodegradation

Biodegradation

Tar Mat

Connectivity

Asphaltene

Deposition

Gas Charge

CO2 62%

CO2 61%

CO2 27%

CO2 11%

CO2 2%

GAS

OIL

CO2

DFA

GOR & Asphaltene

Gradients

Cubic & FHZ EoS

&

Reservoir Context

DFA Work Flow

Measure & Analyze

Fluid Gradients

30

Examples of Applications of MDT-DFA Data

30 30 30

2. Reservoir Architecture Compartments, sealing

barriers, baffles

1. Compositional Grading (Heavy Ends)

One Oil Column: Shell, Deep Water GoM

Different Fault

Blocks

Different GOR

(colours)

Hibernia

Area Map

31

Calibration of Petroleum Systems Models with MDT-DFA Data

Section of field utilized for 5 well MDT study Veracruz study area

32

Reservoir in Petroleum Systems Modeling

– Local grid refinement (LGR) in Petroleum Systems Modeling can help to

investigate problems of different scales within one petroleum system.

– LGR in Petroleum Systems Modeling needs to be able to work with

thermal, pressure, geomechanics and different fluid flow methods

(Flowpath, Darcy, Hybrid, Invasion Percolation) in the different parts of

the model.

– Full scalability from petroleum systems to reservoir scale models is

possible. Large petroleum systems can be modeled without losing

information of the prospect/field geometries.

– Migration modeling in local refined grids can help to evaluate field scale

remigration processes on geologic timescales

– Source rock tracking can be used to describe lateral large distance

migration

Conclusions 1

33

Petroleum Systems Modeling Results and Reservoir Processes

– Charge histories of the field in the case study strongly affects the distribution

of components.

– Occurrence of heavy oil at the OWC can be explained as a combination of

different processes: Water Washing, Gravity Segregation, Charge and

Biodegradation

– Water washing and gravity segregation in combination with the charge

history can explain best the observed distribution of heavy oil above the

original OWC.

Conclusions 2

34

Using MDT-DFA Data to bridge the gap between reservoir and

basin scale process modeling

– Petroleum Systems Modeling can provide essential data such as reservoir

charge and pressure-temperature (PT) histories

– These can then help to understand and predict petroleum property

distributions within fields and in different compartments in fields.

– MDT-DFA data can provide essential high-resolution calibration data for

petroleum systems models.

– Both methods provide important important benefits to each other to improve

both reservoir and basin scale understanding and predictions of petroleum

property distributions.

The authors would like to thank the Kuwait Oil Company for the permission to publish this work.

Conclusions 3