25 mi

25 km

N

Desorption Work Performed

Cuttings Core

oil gasoil & gas

Oil & Gas Fields

Kansas Geological Survey CBM Program

AcknowlegmentsAcknowledgments I would like to thank the Kansas Geological Survey for providing funding for this project as a part of my Masters research. I would also like to specifically thank Jim Stegeman of Colt Energy,and Devon Energy for providing log data, Larry Brady and Diane Kamola for insight, and Patricia Acker for graphical support.

Poster available online at:http://www.kgs.ku.edu/PRS/Publication/2003/ofr2003-28/index.html

Locations of core and cuttings samples desorbed for gas content from eastern Kansas.

Typical desorption characteristics for coal from Montgomery and Labette counties. In general, coals have higher gas contents in Montgomery County as opposed to Labette County. This may be due to the up-dip nature of coal deposits in Labette County or the fact sampling has been more limited within the county.

Gas in place per section (one square mile) assuming a constant thickness in coal and given an average gas content of 130 scf/ton for the Mulky, 200 scf/ton for the Weir-Pittsburg and 150 scf/ton for the Riverton.

The Kansas Geological Survey plans on continuing the research of Middle Pennsylvanian coalbed methane resources throughout eastern Kansas. Masters thesis work for the Bourbon arch is in progress, while thesis work for the Forest City basin and along the Nemaha ridge will start in the near future.

-70 -60 -50 -40

-70 -60 -50 -40

?

?

?MICROBIAL

GAS

MIXED GAS

?

-260

-240

-220

-200

mat

urat

ion

THERMOGENICGAS

13C METHANE (ppm)

-180

-160

-140

dD

ME

TH

AN

E (

pp

m)

0.01

0.1

1

10

100

WE

TN

ES

S (

%)

maturation

mixing

MICROBIALGAS

THERMOGENICGAS

0.5 1.0 1.5 2.0 2.5

SOURCE ROCK MATURITY (Ro %)

? ?

Cass Co. Tebo and Up Neutral coals at ~600' & ~700’ depth

MG Co. Croweburg coal at 1134' depth

Cass Co. Tebo & Up Neutral coalsat ~600' & ~700' depth

MG Co. Croweburg coalat ~1100’ depth

eastern Kansas conventional gas (from Jenden et al., 1988)analysis of coalbed desorption gas

25 mi

N

Thayer

Silver City

Kingston Irish Valley

Mapleton NE

Olathe

Logsdon

Pomona

Pomona

Tucker

Sallyards

Thayer

Silver City

Kingston

Mill Creek

Irish Valley

N.E. Mapleton

Olathe

N.W. McLouth

Pomona

Tucker

Welch-Mohr

Sallyards

Brewster

Neosho Falls

Clinesmith

Elk City

Neosho Falls

Elk CityBrewster

Schrader

EastonPaola-Rantoul

Welch-Mohr

Brewster

Clinesmith

Elk City

Neosho Falls

Easton

Thayer

Silver City

Kingston

Welch-Mohr

Schrader

Mill CreekTucker

PomonaPomona

McLouth NW

Sallyards

Logsdon

Irish Valley

Mapleton NE

Olathe

Neosho Falls

Neosho Falls

Easton

Clinesmith

Paola-Rantoul

Elk City

Elk City

Brewster

Brewster

Mill Creek, SchraderSilver City, Thayer, Brewster, Elk City,

Mapleton NE, Neosho Falls, Olathe,Clinesmith, Easton, McLouth NW, Pomona, Sallyards, Welch-Mohr

Kingston, Brewster, Irish Valley, NeoshoFalls, Paola-Rantoul, Tucker.

Logsden

Schrader

U. PENN

M. PENN

MSSP

L. ORD

Cass Co.sample

Montgomery (MG) Co. sample

Paola-Rantoul

LV Co. Mineral coalat ~800’ depth

LV Co. Riverton coalat ~1100’ depth

LV companysample (fromBosticet al., 1993)

Leavenworth Co. Riverton coalat ~ 1100’ depth

oil oil & gas gas

Oil & Gas Fields

Mill Creek

McLouth NW

Logsdon

Gas Isotope Analysis

d

ReferencesAitken, J. F., 1994, Coal in a sequence stratigraphic framework: Geoscientist, Vol. 4, no.5, p. 9-12.

Bostic, J., Brady, L., Howes, M., Burchett, R., and Pierce, B.S., 1993, Investigation of the coal properties and the potential for coal-bed methane in the Forest City basin: U.S. Geological Survey, Open-File Report 93-576, 44 p.

Flores, R. M., 1993, Coal-bed related depositional environments in methane gas producing sequences: AAPG Studies in Geology Series, no. 38, p. 13-37.

Ham, W. E., and Wilson, J. L., 1967, Paleozoic epeirogeny and orogeny in the central United States, in Symposium on the chronology of tectonic movements in the United States: American Journal of Science, Vol. 265, no. 5, p. 332-407.

Jenden, P.D., Newell, K.D., Kaplan, I.R., and Watney, W.L., 1988, Composition and stable isotope geochemistry of natural gases from Kansas, Midcontinent, U.S.A.: Chemical Geology, v. 71, p. 117-147.

McCabe, P. J., 1984, Depositional models of coal and coal-bearing strata. In: Rahmani, R. A. & Flores, R. M., (eds) Sedimentology of coal and coal -Bearing sequences: International Association of Sedimentologists, Special Publication, 7, p. 13-42.

McCabe, P. J., 1991, Geology of coal; Environments of deposition, in Gluskoter, H. J.,Rice, D.D., and Taylor, R. B., eds., Economic Geology, U. S.: Boulder, CO, Geological Society of America, The Geology of North America, Vol. P-2, p. 469-482.

McCabe, P. J., and Parrish, J. T., 1992, Tectonic and climatic controls on the distributionand quality of Cretaceous coals. In: McCabe, P. J. & Parrish, J. T. (eds) Controls on the Distribution and Quality of Cretaceous Coals, Geological Society ofmerica, Boulder, Special Paper, 267, p. 1-16.

Moore, G. H., 1979, Pennsylvanian paleogeography of the southern mid-continent, in Hyne, N. J., ed., Pennsylvanian sandstones of the mid-continent: Tulsa Geological Society Special Publication 1, p. 2-12.

Saueraker, P. R., 1966, Solution features in southeastern Kansas: The Compass, Vol. 43, no 2, p. 109-128.

Staton, M. D., 1987, Stratigraphy and depositional environments of the Cherokee Group (Middle Pennsylvanian) central Cherokee basin, southeastern Kansas: unpublished masters thesis, University of Kansas, 102 p.

Conclusions· Thicker and laterally extensive coals develop toward the end of the transgressive systems tract and beginning of the highstand

systems tract.

· The Mulky coal is associated with marine carbonate sediments, which explain its tendency to be a carbonaceous shale or high-

ash coal.

· The geometry, orientation and associated depositional environments of the Weir-Pittsburg coal is interpreted as a mire

on a coastal plain environment.

· The Riverton coal is interpreted to have accumulated in raised and low-lying mires above marsh and lake environments associated with the karstic Mississippian limestone lows. The Riverton coal thickens into Mississippian lows and thins on highs.

· Based on preliminary gas isotopic analysis, Cherokee basin coal gas samples represent a mixed thermogenic and microbial origin.

· Preliminary desorption data indicates that coals of the centralpart of the Cherokee basin have higher methane contents than coals at the margins of the basin.

13Lower plot of methane dD vs. methane d C, suggests that natural gases in eastern Kansas are derived from three different origins (thermogenic, microbial carbon dioxide reduction and microbial). Of the conventional gases sampled in the Cherokee basin most have intermediate compositions that suggest a mixed thermogenic and microbial origin. Coal gases sampled in Montgomery County and Cass County also have intermediate compositions.

13Upper plot of wetness vs. methane d C supports a mixing of microbial and thermogenic gases. Most Cherokee basin samples plot below the thermogenic gas arrow and in the mixed gas field suggesting a microbial and thermogenic origin. Coal gases sampled in Montgomery County, Leavenworth County and Cass County also have mixed origins.

Peatlands in coastal plains develop above and behind open and back barrier shorelines, on estuaries, above infilled lagoons, and atop interfluves (Flores, 1993). Sustained growth and preservation of peat requires protection from marine influence. A gradual increase of base level will raise the water table aiding in the growth of mires. Continued transgression will eventually bury the peatland, protecting it from marine processes. Low-lying peatlands are prone to tidal effects and form brackish mires, while fresh water peatlands form in elevated areas and migrate across the low-lying mires to form protected raised mires (Flores, 1993).

The karst topography on top of the Mississippian limestones provided many low-lying areas where lakes and marshes developed. Low-lying mires formed across lows as the water table rose during a gradual transgression. Raised mires developed above the low-lying mires and sustained their own water table while building upward (McCabe, 1991). Margins of raised mires are typically steep and pinch out into marginal marine sediments. Continued transgression eventually buried and compacted the peat formed in the mires. As a result, Riverton coals will tend to thicken into Mississippian lows where peat developed from both raised and low-lying mires.

0

50

100

150

200

250

0 10 20 30 40 50 60 70 80 90

Ga

sC

on

ten

t(s

cf/

ton

)

632.9' -633.8'Summit coal

730.7'-731.1'Mulky coal

778.0'-778.9'Croweburg coal

786.0'-787.3'Fleming coal

820.0'-821.2'Scammon coal

838.5'-839.1'Tebo coal

924.0' -925.0'Weir-Pitt coal

1078.0' -1079.0'Rowe coal

1134.5'-1135.5'Riverton coal

Summit

Rowe

Scammon

CroweburgMulky

FlemingTebo

Riverton

Weir-Pitt

TIME (square root of hours since bottom hole time of core)

Typical Desorption Characteristics of Montgomery Co. Coals

0

200

400

600

800

1000

1200

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Mulky

Weir-Pitt

Riverton

Thickness (ft)

OG

IP (

mm

cf)

OGIP per Section

0% 20% 40% 60% 80% 100%

Ash (moisture free wt%)

0% 3% 5% 8% 10% 13%

Sulfur (moisture free wt%)

13000 13500 14000 14500 15000 15500 16000

Btu/lb (moisture ash free)Proximate Analysis

0% 2% 4% 6% 8%

Summit

Excello

Shale

Mulky

Bevier

Croweburg

Tebo

Weir-Pitt

Rowe

Neutral

Riverton

Moisture (wt%)

0 100 200 300 400

Summit

Excello

Shale

Mulky

Bevier

Croweburg

Tebo

Weir-Pitt

Rowe

Neutral

Riverton

Gas Content (MAF scf/ton)

The ASTM Book of Standards (2002) describes the process of proximal analysis on coals. To report analytical results on a dry (moisture free) basis, moisture content needs to be determined first. Testing for moisture entails calculating the weight loss of a sample when heated. Determining ash content involves burning the sample and weighing the residue. Ash is an important indicator of clastic input, likely derived from marine invasion during peat development. Calculation of sulfur entails mixing part of the sample with Eschka mixture, the sulfur dissolves in hot water and precipitates as barium sulfate. The barium sulfate is filtered, ashed, and weighed. Sulfur content is an indicator of coal quality. The graphs above show a relationship between ash and sulfur, where ash content increases with sulfur content. Like ash, coals with higher sulfur contents reflect a marine influence. Once calculations for moisture and ash content are obtained the calorific value (Btu/lb) can be determined on a moisture ash free basis. Calculating the calorific value involves burning a sample in an adiabatic oxygen bomb calorimeter. Observation of temperature before and after combustion represents the calorific value. The calorific value provides a basis to determine rank of coals. For example, coals such as the ones above have calorific values greater or equal to 14,000 Btu/lb and are classified as high-volatile A bituminous.

0

20

40

60

80

100

120

0 10 20 30 40 50 60 70 80 90

Ga

sC

on

ten

t(s

cf/

ton

)

382'-382.11'Iron Post coal

420'-421'Fleming coal

630.4'-631.4'Dry Wood coal

695.9'-696.5'Rowe coal

766.7'-767.7'Neutral coal

840.2'-841.2'Riverton coal

TIME (square root of hours since bottom hole time of core)

Rowe

Dry WoodFleming

RivertonNeutral

Iron Post

Typical Desorption Characteristics of Labette Co. Coals

Riverton Depositional Model

Depositional Models

Weir-Pittsburg Depositional Model