Concepts for CO2 EOR in the Bakken

Formation

19th Annual CO2 Flooding Conference

Midland, Texas

December 13, 2013

James Sorensen, John Harju, Steve Hawthorne,

Jason Braunberger, Gavin Liu, Steve Smith, and Ed Steadman

© 2013 University of North Dakota Energy & Environmental Research Center.

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Program Partners

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Bakken Extent and Stratigraphy

Pronghorn

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The Bakken is a Tight Oil Formation

• While oil may be produced directly from its shales, a vast

majority of Bakken oil production is from low-permeability

siltstones, sandstones, and carbonates in the “Middle Member”

which lies between two oil-rich shale layers.

Middle Bakken Core

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North Dakota Bakken Production History

• Vertical wells in 1950s and 1960s saw limited success.

• Late 1980s and early 1990s saw better results from

horizontal wells in the upper shale member, but were still

economically unattractive.

• Success in early 2000s in the Middle Bakken in Montana’s

Elm Coulee Field spurred renewed interest in North Dakota

Bakken.

• In mid-200s improvements in well drilling, completion, and

stimulation combined with better understanding of geology

and high-price environment led to sustainable production in

North Dakota.

• North Dakota Bakken annual production has gone from

7.4 Mmbo in 2007 to over 219 Mmbo in 2012.

Well drilling into the Bakken in the 1950s. Photo courtesy of Lynn Helms, North Dakota Dept. of Mineral Resources.

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Bakken Production History

1960 – Early verticals ♦ IPs around 150 to 450 bpd

♦ Typical cumulative production = 85,000 bbl/well

1990 – Early horizontals ♦ IPs around 230 to 500 bpd

♦ Typical cumulative production = 145,000 bbl/well

2005 – Recent multistage ♦ IPs over 1500 bpd not uncommon

♦ Typical cumulative production unknown, too early to tell

♦ 500,000 bbl/well?

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Current Trend in Bakken & Three Forks

Well Configuration

1320’

Middle Bakken and

Three Forks wells on

320 acre spacing.

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How Do We Get More Oil Out of the Bakken?

• The more we understand

about the Bakken

Petroleum System, the

more oil we recognize in it.

• Currently, only a 3%–10%

recovery factor.

• Small improvements in

recovery could yield over a

billion barrels of oil.

• Can CO2 be a game

changer in the Bakken?

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CO₂

How Does CO2 Interact with a Bakken

Reservoir?

We need to understand:

• Rock matrix

• Nature of fractures (macro and micro)

• Effects of CO2 on Bakken oil

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Reservoir Characterization & Modeling

Simulations to provide guidance on:

• Can we get incremental oil?

• Which schemes might work best?

• How much CO2 will it take?

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Project Study Fields

• Compare thermally

mature to immature

– Characterize core from

Bailey and Murphy

Creek (mature) vs.

Rival and Grenora

(immature).

– Static and dynamic

modeling of Bailey and

Grenora.

• Evaluate 2009 CO2

huff ‘n’ puff in Elm

Coulee area.

– Apply lessons learned

in that test to potential

future injection tests.

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Reservoir Evaluation Methodology

Geologic description of the core from three wells

Analyze a suite of core plugs for matrix properties and fractures

Correlate lab data with logs and perform multimineral petrophysical analysis (MMPA)

Construct geological model of the reservoir system to support dynamic simulations of potential EOR schemes

Analyzing production rate as related to completion techniques for several key wells

Detailed study completed for Corrine Olson, Burbank, and Rogne wells

Understanding the Matrix

Optical Microscopy (OM)

Thin-Section Analysis

Scanning Electron Microscopy (SEM)

High-Magnification Backscatter

Electron (BSE) Image Analysis

Energy-Dispersive X-Ray Spectroscopy (EDS)

Quantitative Elemental Analysis

and Mineral Determination

Helium Gas Porosimeter

Porosity Determination

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Understanding Natural Flow Pathways

• Analysis of macrofractures

– Fracture properties

♦ Measure aperture, length, and orientation

• Microfractures studied by SEM:

– Morphologies of each lithofacies

♦ Identified microfractures

♦ Open vs. closed

– Fracture properties

♦ Measure aperture and length

• Utilize macrofracture and microfracture data to help populate fracture properties in the static geologic model.

0

2

4

6

8

10

12

14

10,660 10,670 10,680 10,690 10,700 10,710 10,720 10,730

Fra

ctu

re I

nte

nsit

y,

#/f

t

Measured Depth, ft

All and O+PO FI vs. Depth, Dunn Co. Well

# AllFracs

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Ultraviolet Fluorescence (UVF)

Analysis of Microfractures

Middle Bakken thin section in plane-polarized light compared to UVF.

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Halite Filling Around Fracture

Mineralization

Within Fracture

25 μm 18 μm

21 μm

8.4 μm

SEM Analysis of Microfractures

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Data Supports Modeling

• Structural model

• Matrix petrophysical model

using multimineral petrophysical

analysis

• Fracture petrophysical model

• Dual-porosity–dual-permeability

model

• Predictive numerical modeling

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Simulation of CO2 Injection Scenarios

19

DFN From NW McGregor (Mission Canyon)

From NW McGregor (Mission Canyon)

From NW McGregor (Mission Canyon)

The size of this model is

1770 ft x 492 ft x 87 ft. Small Piece for

Preliminary Test

Simulated scenarios:

• Huff & Puff

• Injector & producer pairs

Initial dynamic simulation

results are encouraging.

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Simulation Observations

• CO2 injection may play a significant role in enhancing oil

recovery in Bakken oil reservoirs.

• The nature of the operation (Injection rate, HnP, recycle,

etc.) has a great effect on the ability of CO2 to enhance

oil production. In particular, H&P appears to be not

nearly as effective as a continuous CO2 recycle process.

• Of the scenarios run thus far, an injector-producer pair

with continuous CO2 recycle option appears to hold the

most promise for enhanced oil recovery.

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CO2 Interactions with Bakken

Rocks and Oil New Experimental Data Generated by the EERC

5000 PSI 4100 PSI 225 PSI

Ability of CO2 to Extract Oil from

Lower Bakken Shale and Middle Bakken

Phase Behavior of CO2 and Bakken Oil under

Reservoir Pressure and Temperature Conditions

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CO2 Extraction of Oil from

Bakken Rocks

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CO2 Extraction of Oil from

Bakken Rocks

Results indicate that CO2 can

effectively extract hydrocarbons

from both Middle and Lower

Bakken rock matrix.

CO2 extraction of oil from samples of

Middle and Lower Bakken rock.

5000 psi, 110°C (230°F) – examine

effect of “unit cell” rock size and matrix

lithology.

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Elm Coulee Huff ‘n’ Puff

DFN From NW McGregor (Mission Canyon)

From NW McGregor (Mission Canyon)

• In 2013 Continental Resources

joined the Bakken Enhanced

Recovery Program.

• Contribution includes data from the

2009 CO2 huff ‘n’ puff test

conducted in the Burning Tree

State 36-2 well in the Elm Coulee

area of Montana.

• These data enable us to: – Compare and contrast key

reservoir properties between the

various study fields.

– Apply lessons learned from

Burning Tree well to future pilot-

scale CO2 EOR tests.

Well location in Elm Coulee field, Montana. Photo courtesy of Montana Board of Oil and Gas Conservation.

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Programmatic Next Steps – Phase II

• Finalize project partners by early 2014.

• Select potential injection and production schemes. – Injectors and producers fracked, unfracked, combination?

– Inject into the Middle Bakken or the shales?

• Experiments to improve our understanding of

oil/CO2/natural gas phase behavior and rates of CO2

diffusion in different Bakken & Three Forks rocks under

reservoir conditions at partner locations.

• Efforts to further improve reservoir characterization. – Microfracture characterization.

– Hydrocarbon extraction data on key Bakken and Three

Forks lithofacies at partner locations.

– Integration of improved data into models.

Primary Goal Is to Conduct a Pilot Injection Test in the Field

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CO₂

Upper Bakken Shale

Lower Bakken Shale

Mid

dle

Bak

ken

L1

L2

L5

L4

L3

Field Pilot Concept: Injector-Producer

Pair in the Middle Bakken

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Field Pilot Concept: Injector-Producer

Pair in the Middle Bakken Fracked Well Unfracked Wells Experimental data and

microfracture data would be integrated into a detailed static geomodel at the near-wellbore scale.

Combination of experimental data and refined near-wellbore scale model would support simulation modeling.

Field-based injection and production data from the pilot test would be used to validate the model.

Results will guide future EOR design and operation.

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Three Forks Lower Bakken Shale

Middle Bakken

Upper Bakken Shale

Field Pilot Concept: Injector in the Lower

Bakken, Producers Above and/or Below

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Dissemination of Key Results

Bakken Decision Support System Website

http://www.undeerc.org/bakken/

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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

World Wide Web: www.undeerc.org

Telephone No. (701) 777-5287

Fax No. (701) 777-5181

Jim Sorensen, Senior Research Manager

jsorensen@undeerc.org

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Acknowledgment This material is based upon work supported by the U.S. Department of Energy

National Energy Technology Laboratory under Award No. DE-FC26-08NT43291.

Disclaimer

This presentation was prepared as an account of work sponsored by an agency of the

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