TY - JOUR
T1 - Multiple atmospheric noble gas components in hydrocarbon reservoirs
T2 - A study of the Northwest Shelf, Delaware Basin, SE New Mexico
AU - Kennedy, B. M.
AU - Torgersen, T.
AU - Van Soest, M. C.
N1 - Funding Information:
Arthur L. Bowsher, Consultant, Roswell, New Mexico is gratefully acknowledged for coordinating sample collection, collecting and providing well information, many useful discussions, and his continued interest in our project. H. Hiyagon assisted in sample collection and analysis, Ron Broadhead provided interest and valuable discussion, and Lynn Brandvold measured core sample concentrations of Li, K, U, and Th. Acknowledgment is due to the following operators for their willingness to provide samples: Yates Petroleum Corp., Cities Service Co., Memorial Exploration, Mesa Petroleum Co., and Carl Schellinger. We also acknowledge Chris Ballentine and two anonymous reviewers and the patience of the GCA editorial staff. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences under contracts DE-AC03-76SF00098, UCB34P32-158, and DE-FG02-95ER14528.
PY - 2002/8
Y1 - 2002/8
N2 - The Northwest Shelf of the Delaware Basin, SE New Mexico is the site of several large and productive oil and gas fields. The most productive reservoirs are located in the late Pennsylvanian Morrow and early Permian Abo formations. Production from the latter more important play is predominately from fluvial Abo red beds of the Pecos Slope Field. The oxidizing conditions implied by the reddish color of the formation require an external hydrocarbon source. To test the existing migration model for the region and constrain the location of potential hydrocarbon sources, we measured the elemental and isotopic composition of noble gases produced along with the hydrocarbons. We found the hydrocarbons to be highly enriched in radiogenic 4He, 40*Ar and nucleogenic 21*Ne [F(4He) = 44,000-250,000; 40Ar/36Ar = 400-3145; 21Ne/22Ne = 0.044-0.071]. The greatest enrichments occur in the Pecos Slope gas fields. The hydrocarbons also contain three independent nonradiogenic noble gas components each with an atmospheric isotopic composition. One component is most likely air-saturated water (ASW). The second component is enriched in the heavy noble gases [F(130Xe) > 8.5] and is derived from the hydrocarbon sources. The third component is enriched in Ne [F(20Ne) > 0.8] that we believe is degassed from sources within the reservoirs. This component is correlated with but decoupled from the dominant source of radiogenic 4He and 40*Ar. Very high concentrations of 4He (up to ∼1% by volume) in the Pecos slope reservoirs require a source external to the reservoirs, such as the underlying Precambrian basement granites and sedimentary equivalents. Structural buckles cutting through the Pecos field may act as high flux vertical pathways for the radiogenic 4He. If the hydrocarbons in the Pecos slope fields have migrated northward from the deeper Delaware Basin, as suggested by compositional trends, then perhaps the buckles also play an important role in the distribution and filling of the Pecos slope reservoirs.
AB - The Northwest Shelf of the Delaware Basin, SE New Mexico is the site of several large and productive oil and gas fields. The most productive reservoirs are located in the late Pennsylvanian Morrow and early Permian Abo formations. Production from the latter more important play is predominately from fluvial Abo red beds of the Pecos Slope Field. The oxidizing conditions implied by the reddish color of the formation require an external hydrocarbon source. To test the existing migration model for the region and constrain the location of potential hydrocarbon sources, we measured the elemental and isotopic composition of noble gases produced along with the hydrocarbons. We found the hydrocarbons to be highly enriched in radiogenic 4He, 40*Ar and nucleogenic 21*Ne [F(4He) = 44,000-250,000; 40Ar/36Ar = 400-3145; 21Ne/22Ne = 0.044-0.071]. The greatest enrichments occur in the Pecos Slope gas fields. The hydrocarbons also contain three independent nonradiogenic noble gas components each with an atmospheric isotopic composition. One component is most likely air-saturated water (ASW). The second component is enriched in the heavy noble gases [F(130Xe) > 8.5] and is derived from the hydrocarbon sources. The third component is enriched in Ne [F(20Ne) > 0.8] that we believe is degassed from sources within the reservoirs. This component is correlated with but decoupled from the dominant source of radiogenic 4He and 40*Ar. Very high concentrations of 4He (up to ∼1% by volume) in the Pecos slope reservoirs require a source external to the reservoirs, such as the underlying Precambrian basement granites and sedimentary equivalents. Structural buckles cutting through the Pecos field may act as high flux vertical pathways for the radiogenic 4He. If the hydrocarbons in the Pecos slope fields have migrated northward from the deeper Delaware Basin, as suggested by compositional trends, then perhaps the buckles also play an important role in the distribution and filling of the Pecos slope reservoirs.
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U2 - 10.1016/S0016-7037(02)00883-9
DO - 10.1016/S0016-7037(02)00883-9
M3 - Article
AN - SCOPUS:0036691141
SN - 0016-7037
VL - 66
SP - 2807
EP - 2822
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
IS - 16
ER -