000 02539nab a2200205 4500
005 20260520000223.0
008 260224s2009 xxu
245 0 0 _aHydrogeochemistry and gas compositions of the Uinta Basin
_bA regional-scale overview
260 _a
_b
_cagos. 2009
270 _a23/09/2009 ; 23/09/2009
300 _a31 p. ; 1087-1118
520 _aThe geochemistry of formation fluids (water and hydrocarbon gases) in the Uinta Basin, Utah, is evaluated at the regional scale based on fluid sampling and compilation of past records. The deep formation water is dominated by Na-Cl type where halite dissolution has the greatest effects on water chemistry. Its distribution and composition is controlled by both the lithology of geological formations and regional hydrodynamics. The origin of the saline waters in the southeastern basin is interpreted to be a mix of ancient evaporatively concentrated seawater with meteoric water recharged in the geological past, which has experienced water-rock interactions. At the basin scale, three-dimensional mapping of the dissolved solid contents further reveals that (1) in the northern Uinta Basin bordering the Uinta Mountains, significant flushing of the deep basinal brines up to 6-km (3.7-mi) depth by meteoric water has occurred, and (2) in the central basin groundwater discharge areas along the Green River Valley, regional upwelling of saline waters from 2- to 3-km (1.2- to 1.8-mi) depth is occurring. Moreover, gas composition and water-gas stable isotope characteristics in the central to southeastern basin indicate the presence of a deep, thermogenic, and regionally continuous gas deposit. In particular, gases sampled in this region from the Wasatch Formation and Mesaverde Group indicate a similar source rock (type III kerogen of the deeply buried, thermally mature Mesaverde Group in the central to northern basin) as well as migration from the Natural Buttes gas field toward the southeastern basin. Evidence for biogenic methane formation is observed only in the upper Green River Formation in the central to northern Uinta Basin. Here, the organic-rich, immature Green River shales experience meteoric water invasions and formation fluid chemistry, and stable isotope compositions are diagnostic of microbial methanogenesis.
581 _a8
773 0 _tAAPG Bulletin
_g93
942 _cARTICULO
100 1 _aZhang, Ye
_941978
100 1 _aGable, Carl W.
_941979
100 1 _aZyvoloski, George A.
_941980
999 _c170501
_d170501