Properties of Paleocene Fort Union Formation Canyon Seam Coal at the Triton Federal Coalbed Methane Well, Campbell County, Wyoming

Properties of Paleocene Fort Union Formation Canyon Seam Coal at the Triton Federal Coalbed Methane Well, Campbell County, Wyoming Charles R. Nelson; Charles R. Nelson Gas Research Institute Search for other works by this author on: This Site Google Scholar David G. Hill; David G. Hill Gas Research Institute Search for other works by this author on: This Site Google Scholar Timothy J. Pratt Timothy J. Pratt TICORA Geosciences, Inc. Search for other works by this author on: This Site Google Scholar Paper presented at the SPE/CERI Gas Technology Symposium, Calgary, Alberta, Canada, April 2000. Paper Number: SPE-59786-MS https://doi.org/10.2118/59786-MS Published: April 03 2000 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Nelson, Charles R., Hill, David G., and Timothy J. Pratt. "Properties of Paleocene Fort Union Formation Canyon Seam Coal at the Triton Federal Coalbed Methane Well, Campbell County, Wyoming." Paper presented at the SPE/CERI Gas Technology Symposium, Calgary, Alberta, Canada, April 2000. doi: https://doi.org/10.2118/59786-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Unconventional Resources Conference / Gas Technology Symposium Search Advanced Search AbstractThis paper presents results from evaluations of geochemical, petrographic and reservoir properties of Powder River Basin, Paleocene Fort Union Formation Canyon seam subbituminous coal at the Triton Federal #21C-2623 coalbed methane well in Campbell County, WY. The core analysis data reveal that at this location the Canyon seam coalbed is a multi-layered reservoir with each layer having different bulk compositional and fluid mobility properties. A very unique reservoir property of this subbituminous coal is its extremely fast gas desorption rate, which, in turn, facilitates a high early time gas production rate from the coalbed reservoir. The core analysis data indicate that the gas desorption rate is dependent on the maceral composition of the bulk coal organic matter.It was found that several commonly used coal and coalbed reservoir property analysis methods required modification to prevent or minimize errors due to subbituminous coal's propensity to undergo aerial oxidation and desiccation. The occurrence of these processes during sample handling, storage or testing causes significant (15% or greater) underestimation errors in key reservoir properties such as the in-situ gas content, moisture holding capacity, sorbed gas composition, and percent gas saturation. Effective methods for avoiding or minimizing subbituminous coal property analysis errors due to oxidation and desiccation are described in this paper. Because these error prone analysis practices have been commonly used in the past, there may be significant potential for large coalbed methane resource and reserve estimate gains in this and other Rocky Mountain region basins.IntroductionThe Tongue River Member of the late Paleocene Fort Union Formation in the Powder River Basin contains thick beds of subbituminous coal, which are reservoirs for an estimated 24 Tcf (0.68 × 1012 m3) of coalbed methane resources.1 The U.S. Potential Gas Committee has estimated that the Powder River Basin contains 9.33 Tcf (0.26 × 1012 m3) of recoverable coalbed methane resources.2 A major play area for the commercial production of these coalbed methane resources is located along the eastern flank of this basin, down-dip from large surface coal mines in Campbell County, Wyoming.1–6 In 1998, coalbed methane production from this play totaled 27.8 Bcf (0.79 × 109 m3) from about 650 wells.7The coalbed methane wells in this play are relatively shallow, typically only 250 to 1,000 ft deep (76 to 305 m), cost only about $50,000 to drill and complete, and have initial gas production rates ranging from less than 100 up to 1,000 Mscfd (2,832 to 28,320 m3/day).1–6 The use of low-cost, innovative drilling and completion practices have been critical factors in making this coalbed methane play economical.1,4–6 The average gas reserve finding cost in this coalbed methane play is about $0.25 per Mscf (28.32 m3) which compares favorably with average reserve finding costs of from $0.15 to $0.50 per Mscf (28.32 m3) for conventional on-shore natural gas resources.7,8The water production rates from these shallow coalbed methane wells average about 330 STB (52.5 m3) per day. However, the water disposal cost is generally minimal because the coproduced water quality is relatively good, typically less than 2,500 ppm total dissolved solids, enabling beneficial uses or direct discharge, under permit, into surface drainages.1,3–6This coalbed methane play is quite unique because several coal properties are strikingly different from those of commercially developed coalbed methane plays in other U.S. basins.7,8 In particular, the coal rank is much lower, the gas content is typically an order of magnitude lower, the coal moisture content is typically an order of magnitude greater, and the absolute water permeability is typically an order of magnitude greater, ranging from tens of md to more than a Darcy.4,5 Keywords: reserves evaluation, coal seam gas, gas content, oxidation, union formation canyon seam coal, analysis procedure, estimates of resource in place, upstream oil & gas, canyon seam coal, coal bed methane Subjects: Reservoir Characterization, Formation Evaluation & Management, Reserves Evaluation, Unconventional and Complex Reservoirs, Estimates of resource in place, Coal seam gas This content is only available via PDF. 2000. 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