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Title: Generation and expulsion of petroleum and gas from Almond Formation Coal, Greater Green River Basin, Wyoming

Abstract

Petrographic and geochemical studies of coal from the Almond Formation in the Greater Green River basin demonstrate that the coal contains important volumes of stored liquid petroleum, as well as methane. Modeling indicates that at the basin center, most of the oil generated in the coal has been thermally cracked to gas, whereas at the basin flank the oil-to-gas reaction has barely proceeded. Several new concepts are presented about the mechanism of petroleum generation in coal based on (1) natural maturation trends gleaned form examination of Almond coal samples from different burial depths and (2) similar maturation trends observed in hydrous pyrolysis experiments using immature Almond coal samples. These new concepts show that the oil in the coal was generated during the alteration of desmocollinite and liptinite macerals to exsudatinite (waxy oil) and inertinite solid residue; that the waxy oil was initially stored in porous structures and subsequently in vesicles as the coal matured under increasing temperature; that primary migration of the oil occurred as the generation of a sufficient volume of exsudatinite microfractured the vitrinite-semifusinite vesicles, interconnecting vesicles and pores; and that the thermal cracking of exsudatinite generated a sufficient volume of gas to fracture the vesiculated coal asmore » pore pressure increased and allowed migration of hydrocarbons out of the coal.« less

Authors:
 [1];  [2];  [3]
  1. Universidad industrial de Santander, Bucaramanga (Colombia)
  2. Univ. of Wyoming, Laramie, WY (United States)
  3. Bringham Young Univ., Provo, UT (United States)
Publication Date:
OSTI Identifier:
433073
Resource Type:
Journal Article
Resource Relation:
Journal Name: AAPG Bulletin; Journal Volume: 81; Journal Issue: 1; Other Information: PBD: Jan 1997
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; 02 PETROLEUM; 03 NATURAL GAS; WYOMING; SEDIMENTARY BASINS; COAL DEPOSITS; GREEN RIVER FORMATION; STRATIGRAPHY; PETROLEUM DEPOSITS; METHANE; PRODUCTION; THERMAL CRACKING

Citation Formats

Garcia-Gonzalez, M., Surdam, R.C., and Lee, M.L. Generation and expulsion of petroleum and gas from Almond Formation Coal, Greater Green River Basin, Wyoming. United States: N. p., 1997. Web.
Garcia-Gonzalez, M., Surdam, R.C., & Lee, M.L. Generation and expulsion of petroleum and gas from Almond Formation Coal, Greater Green River Basin, Wyoming. United States.
Garcia-Gonzalez, M., Surdam, R.C., and Lee, M.L. 1997. "Generation and expulsion of petroleum and gas from Almond Formation Coal, Greater Green River Basin, Wyoming". United States. doi:.
@article{osti_433073,
title = {Generation and expulsion of petroleum and gas from Almond Formation Coal, Greater Green River Basin, Wyoming},
author = {Garcia-Gonzalez, M. and Surdam, R.C. and Lee, M.L.},
abstractNote = {Petrographic and geochemical studies of coal from the Almond Formation in the Greater Green River basin demonstrate that the coal contains important volumes of stored liquid petroleum, as well as methane. Modeling indicates that at the basin center, most of the oil generated in the coal has been thermally cracked to gas, whereas at the basin flank the oil-to-gas reaction has barely proceeded. Several new concepts are presented about the mechanism of petroleum generation in coal based on (1) natural maturation trends gleaned form examination of Almond coal samples from different burial depths and (2) similar maturation trends observed in hydrous pyrolysis experiments using immature Almond coal samples. These new concepts show that the oil in the coal was generated during the alteration of desmocollinite and liptinite macerals to exsudatinite (waxy oil) and inertinite solid residue; that the waxy oil was initially stored in porous structures and subsequently in vesicles as the coal matured under increasing temperature; that primary migration of the oil occurred as the generation of a sufficient volume of exsudatinite microfractured the vitrinite-semifusinite vesicles, interconnecting vesicles and pores; and that the thermal cracking of exsudatinite generated a sufficient volume of gas to fracture the vesiculated coal as pore pressure increased and allowed migration of hydrocarbons out of the coal.},
doi = {},
journal = {AAPG Bulletin},
number = 1,
volume = 81,
place = {United States},
year = 1997,
month = 1
}
  • Organic petrological and geochemical studies demonstrate that the Almond Formation coals contain great unrecognized volumes of stored gas and oil. Oil is generated during maturation of hydrogen-rich vitrinite (desmocollinite) and liptinite macerals into exsudatinite (waxy oil) and inertinite solid residue. The waxy oil is initially stored in pores and vesicles. As the coal thermally matures, stored hydrocarbons are expelled from the pores and vesicles. This phase change causes a significant volume increase, which may overcome the storage capacity of these coals, fracturing them and allowing primary migration of hydrocarbons. Kinetic modeling, based on hydrous pyrolysis experiments, indicates that at themore » basin center, most oil generated and expelled from Almond coals has been thermally cracked to gas, whereas at the basin flank the oil-to-gas reaction is unimportant. During hydrous pyrolysis these coals expel up to 0.17 barrels of oil and 404 cubic feet of gas per ton of coal, indicating excellent generative capacity. Calculations of the volume of Upper Cretaceous coals in the Greater Green River at vitrinite reflectances between 0.9 and 1.7 percent indicate that these coals may have generated 24 billion barrels of oil and 66 trillion cubic feet of gas. 39 refs., 51 figs., 11 tabs.« less
  • Resistivity variations in two cores from the Laney Shale sandstone interval correlate with differences in the type and morphology of zeolite cements present in the sandstones. Resistivity of the Laney Shale sandstones varies from 12 to 30 ohm-meters. and shows a significant lateral difference in two wells spaced 6 miles apart. Mean sandstone porosity (27%) is the same in both cored intervals and does not correlate with differences in resistivity response. Thin section, x-ray diffraction, scanning electron microscopy, and whole rock chemical analysis show that variation in the content of the zeolites analcime and clinoptilolite is the most significant mineralogicalmore » difference between the two cores. The sodium zeolite, analcime, shows a trend of increasing abundance with depth through the higher resistivity sandstone interval. The blocky analcime cement increases sandstone resistivity by decreasing the abundance of conducting pathways. Lower resistivity sandstones contain the sodium-potassium-calcium zeolite, clinoptilolite. Clinoptilolite occurs as a microcrystalline cement in the form of small prismatic crystals that line pores. The clinoptilolite crystals have a much higher surface area to volume ratio than do the larger analcime crystals. This produces a greater abundance of conducting pathways, via ion exchange surfaces, on clinoptilolite crystals. Zeolite cements in the Laney Shale sandstones formed at shallow burial depths, most likely from the interaction of migrating sodium-rich, high pH connate brines with volcaniclastic grain components.« less
  • The report names and describes the Godiva Rim Member of the Green River Formation in the eastern part of the Washakie basin in southwest Wyoming and the central part of the Sand Wash basin in northwest Colorado. The Godiva Rim Member comprises lithofacies of mixed mudflat and lacustrine origin situated between the overlying lacustrine Laney Member of the Green River Formation and the underlying fluvial Cathedral Bluffs Tongue of the Wasatch Formation. The Godiva Rim Member is laterally equivalent to and grades westward into the LaClede Bed of the Laney Member. The Godiva Rim Member of the Green River Formationmore » was deposited along the southeast margins of Lake Gosiute and is correlated to similar lithologic units that were deposited along the northeast margins of Lake Uinta in the Parachute Creek Member of the Green River Formation. The stratigraphic data presented provide significant evidence that the two lakes were periodically connected around the east end of the Uinta Mountains during the middle Eocene.« less
  • Coal exploration drill holes, measured sections, and underground mine data have been analyzed to reconstruct the depositional setting of the Rock Springs Formation. Extensive coal deposits up to 22 ft thick that developed on top of delta-front sandstones extend for 15 mi along depositional dip, and 36 mi along depositional strike. These coal deposits are referred to as type A coal seams. Coal deposits 1-17 ft thick that developed in upper delta-plain-fluvial environments are less than 20 mi in length. These deposits are referred to as type B coal seams. Type C seams are persistent, thin coal deposits 1-8 ftmore » thick, developed on top of delta-plain-fluvial deposits less than 25 mi in length, and they mark the delta-lobe abandonment phase. Approximately 15 major coal zones exist in the Rock Springs Formation. A model for predicting coal-seam thickness and continuity is believed to be applicable to additional exploration in the Green River basin and in other Cretaceous coalbearing basins in the Western Interior.« less
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