Sedimentology and Ichnology of Upper Montney Formation Tight Gas Reservoir, Northeastern British Columbia, Western Canada Sedimentary Basin
Sedimentology and Ichnology of Upper Montney Formation Tight Gas Reservoir, Northeastern British Columbia, Western Canada Sedimentary Basin
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加拿大西部沉积盆地不列颠哥伦比亚省东北部上蒙尼组致密气藏沉积学和技术
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发表时间：
2016
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通讯作者：
Edwin I. Egbobawaye
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作者：
Edwin I. Egbobawaye
加拿大西部沉积盆地（WCSB）经过几十年的常规油气生产，盆地已趋于成熟，人们的注意力正转向替代油气藏系统，如Montney组致密气藏，该气藏由粉砂岩和次级层间极细砂岩组成。Montney地层资源区是加拿大主要的非常规油气藏之一，储量估计在不列颠哥伦比亚省（天然气储量= 271 TCF）、液化天然气（LNG = 126.47亿桶）和石油储量（2900万桶）。根据沉积学和遗迹学标准，在研究区间内识别出五个岩相组合：（富含有机质，波状至平行层状，黑色粉砂岩）;岩相F-2（极细粒砂岩与粉砂岩互层）;岩相F-3A（Skolithos遗迹相的生物扰动粉砂岩）;岩相F-3B（Cruziana遗迹相的生物扰动粉砂岩）;岩相F-4（微细粒砂岩）;和岩相F-5（块状粉砂岩）。在研究区域解释的Montney地层的沉积环境是较低的滨面通过近端离岸到远端离岸设置。岩石评价数据（氢指数和氧指数）显示，Montney沉积物主要含有易产气的III/IV型干酪根，其次是II型干酪根，TOC范围为0.39 - 3.54重量%，沿Montney/Doig边界沿着TOC极少达到10.9重量%。镜质组反射率和Tmax表明，Montney组的热成熟度处于“峰值气体”生成窗口范围。尽管Montney非常规“资源区带”具有经济意义，但是，最佳储集层段的位置和可预测性仍然是不确定的，部分原因是最佳储集层岩性的岩性变异性尚未得到充分表征。通过对加拿大西部不列颠哥伦比亚省东北部圣约翰堡研究区（T86 N，R23 W和T74 N，R13 W）Montney组的岩相和遗迹相分析，结合岩石地球化学评价，对Montney组致密气藏的沉积学、遗迹学和储集潜力进行了解释。
Several decades of conventional oil and gas production in Western Canada Sedimentary Basin (WCSB) have resulted in maturity of the basin, and attention is shifting to alternative hydrocarbon reservoir system, such as tight gas reservoir of the Montney Formation, which consists of siltstone with subordinate interlaminated very fine-grained sandstone. The Montney Formation resource play is one of Canada’s prime unconventional hydrocarbon reservoir, with reserve estimate in British Columbia (Natural Gas reserve = 271 TCF), Liquefied Natural Gas (LNG = 12,647 million barrels), and oil reserve (29 million barrels). Based on sedimentological and ichnological criteria, five lithofacies associations were identified in the study interval: Lithofacies F-1 (organic rich, wavy to parallel laminated, black colored siltstone); Lithofacies F-2 (very fine-grained sandstone interbedded with siltstone); Lithofacies F-3A (bioturbated silty-sandstone attributed to the Skolithos ichnofacies); Lithofacies F-3B (bioturbated siltstone attributed to Cruziana ichnofacies); Lithofacies F-4 (dolomitic, very fine-grained sandstone); and Lithofacies F-5 (massive siltstone). The depositional environments interpreted for the Montney Formation in the study area are lower shoreface through proximal offshore to distal offshore settings. Rock-Eval data (hydrogen Index and Oxygen Index) shows that Montney sediments contains mostly gas prone Type III/IV with subordinate Type II kerogen, TOC ranges from 0.39 - 3.54 wt% with a rare spike of 10.9 wt% TOC along the Montney/Doig boundary. Vitrinite reflectance data and Tmax show that thermal maturity of the Montney Formation is in the realm of “peak gas” generation window. Despite the economic significance of the Montney unconventional “resource-play”, however, the location and predictability of the best reservoir interval remain conjectural in part because the lithologic variability of the optimum reservoir lithologies has not been adequately characterized. This study presents lithofacies and ichnofacies analyses of the Montney Formation coupled with Rock-Eval geochemistry to interpret the sedimentology, ichnology, and reservoir potential of the Montney Formation tight gas reservoir in Fort St. John study area (T86N, R23W and T74N, R13W), northeastern British Columbia, western Canada.