| DOI: | 10.2172/1084030
|
| 报告号: | None
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| 报告题名: | The Bakken - An Unconventional Petroleum and Reservoir System |
| 作者: | Bryant, Steven; Juanes, Ruben
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| 出版年: | 2011
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| 发表日期: | 2011-12-31
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| 国家: | 美国
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| 语种: | 英语
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| 中文主题词: | 碳氢化合物/烃类
; 石油
; 构造地质学
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| 主题词: | HYDROCARBONS
; PETROLEUM
; TECTONICS
|
| 英文摘要: | An integrated geologic and geophysical study of the Bakken Petroleum System, in the Williston basin of North Dakota and Montana indicates that: (1) dolomite is needed for good reservoir performance in the Middle Bakken; (2) regional and local fractures play a significant role in enhancing permeability and well production, and it is important to recognize both because local fractures will dominate in on-structure locations; and (3) the organic-rich Bakken shale serves as both a source and reservoir rock. The Middle Bakken Member of the Bakken Formation is the target for horizontal drilling. The mineralogy across all the Middle Bakken lithofacies is very similar and is dominated by dolomite, calcite, and quartz. This Member is comprised of six lithofacies: (A) muddy lime wackestone, (B) bioturbated, argillaceous, calcareous, very fine-grained siltstone/sandstone, (C) planar to symmetrically ripple to undulose laminated, shaly, very fine-grained siltstone/sandstone, (D) contorted to massive fine-grained sandstone, to low angle, planar cross-laminated sandstone with thin discontinuous shale laminations, (E) finely inter-laminated, bioturbated, dolomitic mudstone and dolomitic siltstone/sandstone to calcitic, whole fossil, dolomitic lime wackestone, and (F) bioturbated, shaly, dolomitic siltstone. Lithofacies B, C, D, and E can all be reservoirs, if quartz and dolomite-rich (facies D) or dolomitized (facies B, C, E). Porosity averages 4-8%, permeability averages 0.001-0.01 mD or less. Dolomitic facies porosity is intercrystalline and tends to be greater than 6%. Permeability may reach values of 0.15 mD or greater. This appears to be a determinant of high productive wells in Elm Coulee, Parshall, and Sanish fields. Lithofacies G is organic-rich, pyritic brown/black mudstone and comprises the Bakken shales. These shales are siliceous, which increases brittleness and enhances fracture potential. Mechanical properties of the Bakken reveal that the shales have similar effective stress as the Middle Bakken suggesting that the shale will not contain induced fractures, and will contribute hydrocarbons from interconnected micro-fractures. Organic-rich shale impedance increases with a reduction in porosity and an increase in kerogen stiffness during the burial maturation process. Maturation can be directly related to impedance, and should be seismically mappable. Fractures enhance permeability and production. Regional fractures form an orthogonal set with a dominant NE-SW trend, and a less prominent NW-SE trend. Many horizontal 1 direction to intersect these fractures. Local structures formed by basement tectonics or salt dissolution generate both hinge parallel and hinge oblique fractures that may overprint and dominate the regional fracture signature. Horizontal microfractures formed by oil expulsion in the Bakken shales, and connected and opened by hydrofracturing provide permeability pathways for oil flow into wells that have been hydro-fractured in the Middle Bakken lithofacies. Results from the lithofacies, mineral, and fracture analyses of this study were used to construct a dual porosity Petrel geo-model for a portion of the Elm Coulee Field. In this field, dolomitization enhances reservoir porosity and permeability. First year cumulative production helps locate areas of high well productivity and in deriving fracture swarm distribution. A fracture model was developed based on high productivity well distribution, and regional fracture distribution, and was combined with favorable matrix properties to build a dual porosity geo-model. |
| URL: | http://www.osti.gov/scitech/servlets/purl/1084030
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| Citation statistics: |
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| 资源类型: | 研究报告
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/40367
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| Appears in Collections: | 过去全球变化的重建
影响、适应和脆弱性
科学计划与规划
气候变化与战略
全球变化的国际研究计划
气候减缓与适应
气候变化事实与影响
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| 1084030.pdf（6657KB） | 研究报告 | -- | 开放获取 | | View
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| Recommended Citation: | |
Bryant, Steven,Juanes, Ruben. The Bakken - An Unconventional Petroleum and Reservoir System. 2011-01-01.
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