Residual Oil Zone Screening with

Basin Evolution Modeling

CO2 Conference

Midland, Texas

4–7 December 2017

Matt Burton-Kelly

Geologist

Energy & Environmental Research Center

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Current Project funded by U.S. Department of Energy

Objectives:

• Identify and characterize the presence

and extent of potential residual oil zones

(ROZs) in the Williston Basin and

Powder River Basin.

• Estimate residual oil in place and CO2

storage potential.

• Determine feasibility of CO2 enhanced

oil recovery in identified ROZs.

• Develop repeatable methodology for

sedimentary basins to be included in a

best practices manual.

• “To see if we could.”

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Provides a complete record of the

evolution of a petroleum system,

including:

• Deposition and erosion.

• Pressure and compaction.

• Heat flow analysis.

• Petroleum generation.

• Fluid pressure, volume,

temperature analysis.

• Reservoir volumetrics.

• Structural evolution.

• Generation, migration, and

accumulation of hydrocarbons.

Basin Evolution Modeling – Schlumberger PetroMod

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Synthetic Tilting Dome Model

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ROZ Process Definition

“ROZs are zones that used to be full of oil but have been naturally waterflooded.”

This definition requires:

• A high-saturation (paleo)trap.

• Natural waterflooding.

Oil “traffic” alone doesn’t count without an

accumulation.

source

Basin evolution modeling could be used to

identify (paleo)traps and naturally

waterflooded zones.

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PetroMod Output and Grid

300 Ma

200 Ma

100 Ma

75 Ma

50 Ma

0 Ma

Unit A

Unit A

Unit A

Unit A

Unit A

Unit A

Hydrocarbon Mass: 0

Hydrocarbon Mass: 10

Hydrocarbon Mass: 8

Hydrocarbon Mass: 2

Hydrocarbon Mass: 11

Hydrocarbon Mass: 7

Change: +10

Change: -2

Change: -6

Change: +9

Change: -4

Raster Output, One Layer per

Property per Time Step

(e.g., hydrocarbon mass)

Cell-by-Cell

Oil saturation output is less trustworthy than mass

with large cells, so an alternative was needed.

*Ma = Millions of years ago.

Mass

Time

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Local Grid Refinement Structural Deformation Model

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Potential ROZ Hydrocarbon Mass Curves

A High-Mass (Paleo)Trap

Natural Waterflooding

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Non-ROZ Hydrocarbon Mass Curves

A High-Mass (Paleo)Trap

Natural Waterflooding

“Paleo-ROZs”

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Calculating Potential ROZ Mass

𝑇𝑜𝑡𝑎𝑙𝑡=0 and 𝑀𝑜𝑏𝑖𝑙𝑒𝑡=(𝑚𝑎𝑥,0) are derived from PetroMod

output. 𝑆𝑜𝑐 is a rock property input to PetroMod, taken from

lab analysis (oil % irreducible with respect to water).

Green terms are known at each step.

• 𝑇𝑜𝑡𝑎𝑙𝑡=0 = 𝑀𝑃𝑍𝑡=0 + 𝑅𝑂𝑍𝑡=0

• 𝑅𝑂𝑍𝑡=𝑚𝑎𝑥 =100 ×𝑀𝑜𝑏𝑖𝑙𝑒𝑡=(𝑚𝑎𝑥,0)

𝑆𝑜𝑐

• 𝑅𝑂𝑍𝑡=0 = 𝑅𝑂𝑍𝑡=𝑚𝑎𝑥 −𝑀𝑜𝑏𝑖𝑙𝑒𝑡=(𝑚𝑎𝑥,0)

• 𝑀𝑃𝑍𝑡=0 = 𝑇𝑜𝑡𝑎𝑙𝑡=0 − 𝑅𝑂𝑍𝑡=0

Automated Process, per Cell, per Formation

t =

𝑇𝑜𝑡𝑎𝑙𝑡=0

𝑅𝑂𝑍𝑡=𝑚𝑎𝑥𝑀𝑜𝑏𝑡=(𝑚𝑎𝑥,0)

𝑅𝑂𝑍𝑡=0

𝑀𝑃𝑍𝑡=0

𝑀𝑃𝑍𝑡=0: Main Pay Zone at timestep = 0 Ma

𝑅𝑂𝑍𝑡=0: Residual Oil Zone at timestep = 0 Ma

𝑀𝑜𝑏𝑖𝑙𝑒𝑡=(𝑚𝑎𝑥,0): Oil that left the cell between

the timestep with maximum hydrocarbon

mass and 0 Ma.

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Output/ExampleOne Williston Basin Formation

Mass over Time

Mass at t = 0

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Output/Example

Some Potential ROZs…

Some Unflooded Traps…

Many Cells (not shown) Never Contain

Appreciable Amounts of Oil

Mass Curves for 100 Random Grid Cells

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Output/Example

Potential ROZ Mass at t = 0

• 𝑇𝑜𝑡𝑎𝑙𝑡=0 = 𝑀𝑃𝑍𝑡=0 + 𝑅𝑂𝑍𝑡=0

• 𝑅𝑂𝑍𝑡=𝑚𝑎𝑥 =100 ×𝑀𝑜𝑏𝑖𝑙𝑒𝑡=(𝑚𝑎𝑥,0)

𝑆𝑜𝑐

• 𝑅𝑂𝑍𝑡=0 = 𝑅𝑂𝑍𝑡=𝑚𝑎𝑥 −𝑀𝑜𝑏𝑖𝑙𝑒𝑡=(𝑚𝑎𝑥,0)

• 𝑀𝑃𝑍𝑡=0 = 𝑇𝑜𝑡𝑎𝑙𝑡=0 − 𝑅𝑂𝑍𝑡=0per Cell…

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Takeaways• “To see if we could” – Could we?

o Theoretically, yes.

• Scale and detail of input models are

important:

o Automated facies modeling (neural

networks) may help attenuate purely

structural hydrocarbon migration and

locate stratigraphic traps.

o Tradeoff between detail, time spent

building model, and PetroMod

simulation time.

• This method will work at any scale and any

type of ROZ, but beware—Garbage In,

Garbage Out.

• Large effects from

o Inputs that affect generation and

migration masses (T, TOC, HI).

o Irreducible oil saturation (𝑆𝑜𝑐)

*MTT = Mass through time, the method described here.

THANK YOU!

Extra Animations

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CONTACT INFORMATION

Energy & Environmental Research Center

University of North Dakota

15 North 23rd Street, Stop 9018

Grand Forks, ND 58202-9018

www.undeerc.org

701.777.5297 (phone)

701.777.5181 (fax)

Matt Burton-Kelly

Geologist

mburtonkelly@undeerc.org