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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