U. S. DEPARTMENT OF THE INTERIOR
U. S. Geological Survey Digital Data Series 67
Geologic Studies of Deep Natural Gas Resources
Edited by Thaddeus S. Dyman and Vello A. Kuuskraa1
Version 1.0 First replication 2001
Call: (303) 202-4200
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In 1997, the U. S. Geological Survey published USGS Bulletin 2146, comprising 12 chapters dealing with geologic, geochemical, and assessment issues related to deep gas resources (Dyman and others, 1997). A primary goal of that report was to provide geology-based information that might aid in future improvements to technology for deep gas exploration and development. Chapters of this report represent a continuation of that work. The current work is funded by the U. S. Department of Energy, National Energy Technology Laboratory, Morgantown, W. Va. (contract No. DE-AT26-98FT40032), Gas Technology Institute (GTI), Chicago, Ill. (contract No. 5094-210-3366 through a Cooperative Research and Development Agreement with Advanced Resources International, Arlington, Va.), and the U. S. Geological Survey, Denver, Colo.
Chapters in the present report summarize major conclusions of this ongoing
Chapter A, Introduction, Acknowledgements,
Chapters B and C address the areal extent of drilling and the
distribution of deep basins: Chapter B provides
an update of deep drilling in the U. S. during the 1990's, and Chapter
C summarizes the distribution of deep sedimentary basins
and the potential for deep gas in the Former Soviet Union.
Chapters D and E are geochemical papers addressing source-rock issues and deep gas generation. Chapter D presents gas generation kinetic models based on laboratory pyrolysis methods and examines them for hypothetical basin scenarios based on end-member heating rates of 1 o and 10 o C/ m. y. Chapter E presents gas: oil ratios (GOR) from hydrous-pyrolysis experiments conducted on immature source rocks and summarizes how they are affected by kerogen type. The quantity of expelled oil and the gas generated during hydrous pyrolysis allows for the calculation of GOR's for a particular source rock at hydrous-pyrolysis temperatures representing different stages of oil generation.
Chapters F and G discuss assessment issues related to deep gas. In Chapter F, a probabilistic method is developed for subdividing gas resources into depth slices. This is important for deep natural gas assessments because gas plays often range across many depth intervals, and estimating the amount of gas in each interval aids in both geologic and economic analysis of the play and province. In Chapter G, the relative uncertainty of estimates of deep gas in plays in the Gulf Coast region is analyzed. More than 60 plays in the Western Gulf and Louisiana-Mississippi Salt Basins provinces are compared and analyzed for their conditional uncertainty.
Chapter H evaluates the mechanism of hydrogenation of deep, high-rank spent kerogen by water, with subsequent generation of methane-rich HC gas. The editors note with regret the untimely death, in August 2000, of organic geochemist Leigh C. Price, the author of Chapter H.
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