DOI: 10.1306/05191009179
Scopus记录号: 2-s2.0-78651403927
论文题名: Oil generation as the dominant overpressure mechanism in the Cenozoic Dongying depression, Bohai Bay Basin, China
作者: Guo X. ; He S. ; Liu K. ; Song G. ; Wang X. ; Shi Z.
刊名: AAPG Bulletin
ISSN: 0149-1891
EISSN: 1558-9621
出版年: 2010
发表日期: 2010
卷: 94, 期: 12 起始页码: 1859
结束页码: 1881
语种: 英语
Scopus关键词: Acoustic travel-time
; Active faulting
; Bohai Bay Basin
; Calcareous mudstone
; Calcite precipitation
; Cenozoic
; Density log
; Dongying depression
; Effective pressure
; Effective stress
; Fine-grained sediment
; Geothermal gradients
; High pressure
; Low density
; Matrix porosity
; Microfractures
; Oil bearings
; Organic-rich source rock
; Over-pressures
; Overpressure
; Overpressured source
; Pressure coefficients
; Prolific oil
; Reservoir rock
; Reservoir sandstones
; Sedimentation rates
; Shahejie formation
; Source rocks
; Total Organic Carbon
; Vertical stress
; Vitrinite reflectance
; Carbonate minerals
; Compaction
; Diseases
; Electromagnetic logging
; Hydrocarbons
; Organic carbon
; Radioactivity logging
; Sedimentology
; Stress analysis
; Rocks
; acoustic array
; active fault
; calcareous soil
; Cenozoic
; depositional environment
; Eocene
; kerogen
; mudstone
; oil production
; oil shale
; overpressure
; pore pressure
; sedimentation rate
; source rock
; Bohai Bay
; China
; Dongying Depression
; Shandong
Scopus学科分类: Energy
; Earth and Planetary Sciences
英文摘要: The Dongying depression in the Bohai Bay Basin is a young, prolific oil-producing basin in China. The gray to black mudstones, calcareous mudstones, and oil shales of the Eocene Shahejie Formation (Es3 and Es4) are the major source rocks that are primarily dominated by type I kerogens with a high total organic carbon of up to 18.6%. The Es3 interval is characterized by a sedimentation rate of up to 500 m/m.y. Widespread overpressures are present in the Eocene Es3 and Es4 intervals in the depression, with pressure coefficients up to 1.99 from drillstem tests. Among the sonic, resistivity, and density logs, only the sonic-log displays an obvious response to the overpressure from which the top of the overpressure can be clearly identified. Acoustic traveltime versus effective vertical stress analysis of more than 300 wells in the Dongying depression suggests that the acoustic traveltime of the normally pressured and overpressured mudstones is reduced with increasing vertical effective stress. Pore pressures are accurately predicted in the Dongying depression using an Eaton (1972) exponent of 2.0 by comparing the predicted pressure coefficients with measured pressure coefficients. Disequilibrium compaction has been previously proposed as the sole cause of the high-magnitude overpressures in the Eocene strata of the Dongying depression because of rapid deposition of fine-grained sediments. However, our data indicate that the overpressures are caused by oil generation from the source rocks within the Es3 and Es4 intervals. The overpressured sediments display a normal compaction as evidenced from the overpressured mudstones exhibiting no anomalously low density, the apparent lack of correlation between mudstone densities and effective vertical stress, and the overpressured reservoir sandstones showing no anomalous high-matrix porosities or anomalous geothermal gradient. The depths to the top of the overpressure intervals range from 2000 to 3000 m (6562-9843 ft) following closely source rock depths. All the overpressured reservoirs and source rocks have a minimum temperature of approximately 87°C, and overpressured source rocks generally have vitrinite reflectance (Ro) values of 0.6% or higher. Overpressures are not found in the strata within which the Ro values are less than 0.5%. The overpressured reservoirs in the Es3 and Es4 intervals are predominantly oil saturated or oil bearing. Organic-rich source rocks with overpressures are capable of generating hydrocarbons and thus can maintain an abnormally high pressure. The calcite precipitation in the calcareous mudstones may have caused a significant reduction in porosity and permeability to form an effective pressure seal. The presence of widespread microfractures in the source rocks may relate to episodic expulsion of hydrocarbons or overpressure dissipation. Overpressures in the reservoir rocks are generated by the fluid transmission from the overpressured source rocks through active faulting and fracturing. Copyright © 2010. The American Association of Petroleum Geologists. All rights reserved. URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-78651403927&doi=10.1306%2f05191009179&partnerID=40&md5=6a3b72117fef112255756fbad2f8861b
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/13460
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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Recommended Citation:
Guo X.,He S.,Liu K.,et al. Oil generation as the dominant overpressure mechanism in the Cenozoic Dongying depression, Bohai Bay Basin, China[J]. AAPG Bulletin,2010-01-01,94(12)