Underground Coal Gasification (UCG)with CO2 Enhanced Oil Recovery (EOR)

in Western North Dakota

Zhengwen Zeng and Peng Pei

Department of Geology and Geologic Engineering

University of North Dakota

Outline

• Concept of UCG-EORUnderground coal gasification (UCG) coupled with CO2

enhanced oil recovery (EOR)

• Introduction to the selected site Lignite resources, oil production, topography and aquifers

• Site modeling workProcedure, current results

Concept of UCG-EOR

Surface

Syngas Production

Well

UCG Cavity

CO2 Injection Well

Process Flow of the UCG-EOR Concept

O2 Injection Well

Coal Bed

Syngas Cleaning

Water gas shift reaction

CO2 separation

Power generation using H2

Air separation unit

Oil Production Well

Injected CO2 Enhanced oil recovery Oil Reservoir

Coal Bed

CoalEOR/Sequestration

SyngasElectricity/other fuels

CO2

Our Goals• Generate power and/or syngas products via

underground coal gasification to recover the huge, unmineable lignite resources in North Dakota

• Enhance oil recovery in nearby mature petroleum reservoirs using CO2 from the underground coal gasification plants

• Sequester the CO2 eventually in the deep oil reservoirs to reduce greenhouse gas emission

Site Screening for UCG-CO2EOR

Lignite resource

Thickness (>2m) Depth (>200m) Coal quality

Vicinity to oil fields

Oil production history CO2 demand

Environmental Risks

Subsidence Aquifer

Other considerations

Topography Accessibility Infrastructures

Selected Site – Dunn County, ND

(Fischer et al, 2005)

4 townships, 144 square miles

Lignite in Fort Union Formation

Oil Production in the Selected Area

• Little Knife and many other fields are under the lignite resources in the selected area.

• Many fields are in water flooding phase (secondary production).

• There is big demand on CO2 for tertiary EOR.

Oil field Pool OOIP106 bbl

Cum. prod.106 bbl

Water inj. Start date

Little Knife Madison 4.13 1.34 12/7/1994

Blue Butte Madison 92.70 34.57 11/1/1968

Big Stick Madison 166.00 55.29 7/9/1988

Knutson Madison 19.10 4.93 1/6/2001

Rough Rider Madison 31.00 7.34 2/13/1997

T.R. Madison 42.66 11.99 11/19/2004

Candidate Oil Fields for UCG-CO2EOR

Aquifers in the Selected Area• The lignite bearing formation

(Fort Union) coincidences with the Lower Tertiary Aquifer.

• The aquifer consists of sandstone interbedded with shale, mudstone, siltstone, lignite and limestone.

• Aquifer is not highly permeable, but is an important source of water supply.

• This is a complex dual system.

(Whitehead et al, 1996)

(Fischer et al, 2005)

Aquifers in the Selected Area• Contaminants transport

mechanisms are advection, molecular diffusion and mechanical dispersion.

• Contaminants can be adsorbed on the coal and strata.

• Low-permeability sandwich layers can function as a filter and a seal to reduce spread of contaminants induced by UCG.

• Target: locations with high clay content.

(Liu et al, 2007)

Modeling the Coal Seam and Adjacent Layers

• Harmon coal sub-zones in Fort Union Formation

• Lithological interpretation logs from US Geological Survey

• Oil & gas well logs from North Dakota Geological Survey

(Flore et al, 1999)

Modeling the Coal Seam• Screen oil wells with logs penetrating the coal seams (Fort Union)• Find 38 wells with GR logs (144 sq. mile)• Identify the formations: Lignite GR=5~10; Mudstone GR20. • Create model:

– digitize interpret correlate build model

Horizon 1

Horizon 1Horizon 1

(-3100)

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SSTVD

1:1844-0.60 18.60l i th

Horizon 1 Horizon 1

Horizon 1

AM166 [SSTVD](-3100)

(-3000)

(-2900)

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SSTVD

1:1844-0.60 18.60l i th

Horizon 1 Horizon 1

Horizon 1

AM221 [SSTVD](-3100)

(-3000)

(-2900)

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SSTVD

1:1844-0.60 18.60l i th

Horizon 1 Horizon 1

Horizon 1

AM223 [SSTVD](-3100)

(-3000)

(-2900)

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-2700

(-2600)

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SSTVD

1:1844-0.40 16.40l i th

Horizon 1 Horizon 1

Horizon 1

BO77286 [SSTVD](-3100)

(-3000)

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1:1844-0.60 18.60l i th

Horizon 1 Horizon 1

Horizon 1

G169-28 [SSTVD]-0.60 18.60l i th

Horizon 1 Horizon 1

Horizon 1

G169-29 [SSTVD]-0.60 18.60l i th

Horizon 1 Horizon 1

Horizon 1

G306-2 [SSTVD]-0.60 18.60l i th

Horizon 1 Horizon 1

Horizon 1

G306-3 [SSTVD]-0.60 18.60l i th

Horizon 1 Horizon 1

Horizon 1

G306-4 [SSTVD]-0.60 18.60l i th

Horizon 1 Horizon 1

Horizon 1

GARDNER 41-9 [SSTVD]-0.60 18.60l i th

Horizon 1 Horizon 1

Horizon 1

GOVT 41X-5 [SSTVD]-0.60 18.60l i th

Horizon 1 Horizon 1

L10 [SSTVD]-0.60 18.60l i th

Horizon 1 Horizon 1

Horizon 1

L11 [SSTVD]-0.30 15.30l i th

Horizon 1 Horizon 1

Horizon 1

L12 [SSTVD]-0.60 18.60l i th

Horizon 1 Horizon 1

Horizon 1

L13 [SSTVD]-0.30 15.30l i th

Horizon 1

Horizon 1

Horizon 1

L23 [SSTVD]-0.60 18.60l i th

Horizon 1 Horizon 1

Horizon 1

L25 [SSTVD]

Model result: Coal Seam and Topography

The Harmon Coal Seam

Depth, ft Isopach, ft

Clay Content

Clay content at 10 ft below the coal seam

Coal seam

Clay Content

Clay content at 30 ft above the coal seam

Clay content at 10 ft above the coal seam

Summary

• Integrated lignite UCG-CCS-CO2EOR in Williston Basin, North Dakota is proposed.

• Candidate lignite and oil fields are screened.

• Hydrological and petroleum reservoir production conditions of the candidate fields are studied.

• Geology of the lignite and the clay seals above and beneath the coal seams are modeled.

Acknowledgements

This research is funded by:• US DOE through contracts of DE-FC26-05NT42592 (CO2

Sequestration) and DE-FC26-08NT0005643 (Bakken Geomechanics);

• North Dakota Industry Commission with five industrial sponsors (Encore Acquisition Company, Hess Corporation, Marathon Oil Company, St. Mary Land & Exploration Company, and Whiting Petroleum Corporation) under contract NDIC-G015-031;

• North Dakota Department of Commerce together with Schlumberger, IHS and American Petroleum Institute through Petroleum Research, Education and Entrepreneurship Center of Excellence (PREEC) program.

We greatly appreciate all the sponsors for their support!

Underground Coal Gasification (UCG) with CO2 Enhanced Oil Recovery (EOR) in Western North Dakota

Thanks

Contact Info:

zeng@und.edu

Peng.pei@und.edu