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

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Underground Coal Gasification (UCG)with CO2
Enhanced Oil Recovery (EOR) in Western North
Dakota Zhengwen Zeng and Peng PeiDepartment
of Geology and Geologic Engineering University
of North Dakota
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Outline

• Concept of UCG-EOR
• Underground coal gasification (UCG) coupled with
  CO2 enhanced oil recovery (EOR)
• Introduction to the selected site
• Lignite resources, oil production, topography and
  aquifers
• Site modeling work
• Procedure, current results

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Concept of UCG-EOR
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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

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Site Screening for UCG-CO2EOR
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Selected Site Dunn County, ND
(Fischer et al, 2005)
4 townships, 144 square miles Lignite in
Fort Union Formation
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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.

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Candidate Oil Fields for UCG-CO2EOR
Oil field Pool OOIP 106 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
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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)
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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)
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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)
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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 GR510
  Mudstone GR?20.
• Create model
• digitize ? interpret ? correlate ? build model

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Model result Coal Seam and Topography
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The Harmon Coal Seam
Depth, ft
Isopach, ft
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Clay Content
Coal seam
Clay content at 10 ft below the coal seam
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Clay Content
Clay content at 10 ft above the coal seam
Clay content at 30 ft above the coal seam
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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.

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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!

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

• Thanks
• Contact Info
• zeng_at_und.edu
• Peng.pei_at_und.edu