Diagenetic and porosity evolution of conglomerate sandstones in Bayingebi Formation of the Lower Cretaceous, Chagan Sag, China–Mongolia frontier area

Wei, Wei; Zhu, Xiaomin; Tan, Mingxuan; Xue, Ming; Guo, Dianbin; Su, Hui; Wang, Pengyu

doi:10.1016/j.marpetgeo.2015.08.011

Cited by 41 publications

(16 citation statements)

References 34 publications

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“…Figure shows the well correlation based on the borehole cores description and the regional sedimentology (Li et al, ; Yang et al, ; Wei et al, ). The Lower Cretaceous interval can be divided into (1) coarse sandy channel sandstone in the lower part, (2) fine‐medium grained, fining‐up sandstone to mudstone in the middle part and (3) coarse sandy channel, coarsening‐up sandstone and conglomerate in the upper part.…”

Section: Resultsmentioning

confidence: 99%

“…The basal K1b1 Member (unconformably overlying Permian basement), was dominated by nearshore subaqueous fan sandstone and conglomerate facies. The overlying K1b2 Member developed several fan deltas along the margins of the Western sub‐sag, where a high‐gradient slope was formed and sediment supply increased from the uplifted sediment from the source areas around the sag (Xu et al, ; Li et al, ; Yang et al, ; Wei et al, ). The K1b2 Member comprises fan delta conglomerates, sandstones and lacustrine mudstones, with a maximum thickness of 700 m. Moreover, the K1b2 Member is also the major hydrocarbon source unit of the Chagan Sag, including dark lacustrine organic mudstones was deposited in the basin centre.…”

Section: Geological Settingmentioning

confidence: 99%

“…It is therefore crucial to understand diagenetic evolution in reservoir sandstones. Mineral composition, sorting and grain size (Posamentier and Allen, ; Morad et al, ), controlled by sedimentary facies not only control reservoir quality, but also affect the types and extent of diagenetic alterations (Taylor et al, , ; Ketzer et al, ; Reed et al, ; Morad et al, ; Wei et al, ). These changes may be detected by the occurrence of specific eogenetic alterations, which have an important impact on mesogenetic alterations, and hence on reservoir quality.…”

Section: Introductionmentioning

confidence: 99%

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Facies controls on the distribution of diagenetic alterations in fan delta deposits: a case study from the Lower Cretaceous sandstone, Chagan Sag, Inner Mongolia, China

et al. 2016

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By integrating diagenesis and sedimentary facies, the distribution of diagenetic alterations and their impacts on reservoir quality were investigated within a lacustrine fan delta depositional environment in the Lower Cretaceous of the Western sub‐sag in the Chagan Sag, Yin‐E Basin, northern China. Core observation and analyses of petrography and geochemistry of the sandstones revealed that the eogenetic alterations display spatial and temporal distribution patterns associated with sedimentary facies, including distributary channels of a fan delta front (DC), distributary bays (DB) and sheet sands (SS) and mouth bar (MB) (SS and MB are collectively referred to as S). Percolation of meteoric waters occurring in high permeability DC sandstones resulted in leaching of feldspar, the formation of kaolinite, as well as mechanical infiltrated clays around detrital grains. Conversely, the DB deposits containing abundant ductile lithic fragments were subjected to mechanical compaction and thus the development of a pseudomatrix. During a long burial residence time (the Early Cretaceous period) in a lacustrine environment, abundant early carbonate cements were precipitated, especially in the distal S sandstones. The sandstones lacking eogenetic cements were subjected to stronger mechanical compaction. Additionally, eogenetic alterations have an important impact on the distribution of the mesogenetic alterations. Sandstones containing few eogenetic cements or thin or discontinuous infiltrated clay rims around the detrital grains were subjected to quartz cementation. However, during the hydrocarbon generation stage, the most efficient percolation of meteoric waters and organic acid dissolved feldspar minerals and carbonate cements, resulted in DC sandstones having more intragranular and intergranular porosity. Owing to high matrix contents and early calcite cement contents, the DB and S sandstones had lower permeability and were rarely dissolved. During the late mesogenetic stage, late carbonate cements occurred in all sedimentary facies and iron and magnesium ions were released from the transformation from kaolinite to illite or to chlorite. The results from this study show possible diagenetic evolutionary pathways in the reservoir sandstones within the fan delta depositional environment, which in turn provides some insights into the controls on reservoir potential. Copyright © 2016 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Facies controls on the distribution of diagenetic alterations in fan delta deposits: a case study from the Lower Cretaceous sandstone, Chagan Sag, Inner Mongolia, China

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“…The overlying Suhongtu Formation is characterized by fan delta and braided delta deposits with volcanic rocks. The Yingen Formation is dominated by shallow lake and braided fluvial deposits (Wei et al, ). Shales of the K 1 b 1 , the K 1 b 2 , and the K 1 s 1 are three intervals that were identified as potential source rocks in Chagan Sag (Ye, Yang, & Wang, ).…”

Section: Geological Settingmentioning

confidence: 99%

Geochemical characteristics, depositional environment, and controlling factors of Lower Cretaceous shales in Chagan Sag, Yingen‐Ejinaqi Basin

et al. 2017

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The Lower Cretaceous shales of Chagan Sag, Yingen‐Ejinaqi Basin, are considered as the source rocks of hydrocarbons discovered in the sag. Borehole shales from the Lower Cretaceous were subjected to comprehensive geochemical study to evaluate the quality of source rock, to reconstruct the paleodepositional environment and to determine the controlling factors of organic matter enrichment. Content of present‐day total organic carbon, and hydrogen index, averaging 1.4% and 259.2 mg hydrocarbon/g total organic carbon, respectively reveal poor to fair quality of organic matter. Average value of vitrinite reflectance (Ro) of 1.0% indicates mature organic matter. Maceral composition and biomarker analysis provide evidence for a mixed aquatic and terrigeous organic matter input. Based on Sr/Cu, Sr/Ba, and gammacerane index, we propose that organic matter was deposited in closed hypersaline under hot and arid climate conditions. The ratios of V/(V + Ni), and pristane/phytane (Pr/Ph), as well as the presence of β‐carotene suggest a stratified water column with anoxic bottom water condition. Low to moderate productivity as a result of deficient nutrient supply, the excellent organic matter preservation condition under stratified anoxic water column and high sedimentary rate controlled the quality of source rock. In addition, influence of factors such as content of clay minerals on organic matter enrichment cannot be ignored.

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“…Generalized geological map (a) and structural profile (b) of Chagan Sag showing tectonic units and study area (modified from Wei et al, ; Wei et al, ; ; Yang, ) [Colour figure can be viewed at wileyonlinelibrary.com]…”

Section: Geological Settingmentioning

confidence: 99%

The sequence stratigraphy and depositional characteristics of fan‐delta complexes in the Upper Bayingebi Member (Lower Cretaceous) in Chagan Sag, Inner Mongolia, China

et al. 2017

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The Chagan Sag is a small Early Cretaceous intracontinental passive rift subbasin in the Yingen‐Ejinaqi Basin Group generated on the Tianshan‐Xingmeng Orogenic Belt. The Lower Cretaceous strata contain the Bayingebi, Suhongtu, and Yingen formations deposited during the syn‐rift phase. The Wuliji Structural Zone bounded by a high‐dip syn‐sedimentary fault is an intensively studied area with an extent of ~300 km2 having abundant available subsurface dataset and great hydrocarbon potential. According to well‐ and seismic‐based sequence stratigraphic study, the Upper Bayingebi Member generally corresponds to a complete third‐order transgressive–regressive sequence in the Wuliji Structural Zone. The transgressive system tract gradually thins towards the north, but the regressive system tract covers the entire study area in this third‐order sequence. Further investigations reveal that tectonic subsidence and climate change are two predominant allogenic factors for controlling stratigraphic development in the Wuliji Structural Zone. During the deposition of the Upper Bayingebi Member, transverse gravity flow dominated fan‐delta complexes sourced from the Maodun Subuplift are well developed in the Wuliji Structural Zone. The retrogradational conical fan deltas are mainly located in the southern sector during the transgressive system tract stage, but the progradational Gilbert‐type fan deltas are widely developed during the regressive system tract stage. The sedimentary evolution and stratigraphic architecture are directly linked with preexisting topography, accommodation, and sediment supply. In addition, climate change and vegetation types are thought to be critical controls for fluid properties originated from feeder drainage systems and depositional processes of the construction of fan‐delta complexes in the distinct system tracts.

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Diagenetic and porosity evolution of conglomerate sandstones in Bayingebi Formation of the Lower Cretaceous, Chagan Sag, China–Mongolia frontier area

Cited by 41 publications

References 34 publications

Facies controls on the distribution of diagenetic alterations in fan delta deposits: a case study from the Lower Cretaceous sandstone, Chagan Sag, Inner Mongolia, China

Facies controls on the distribution of diagenetic alterations in fan delta deposits: a case study from the Lower Cretaceous sandstone, Chagan Sag, Inner Mongolia, China

Geochemical characteristics, depositional environment, and controlling factors of Lower Cretaceous shales in Chagan Sag, Yingen‐Ejinaqi Basin

The sequence stratigraphy and depositional characteristics of fan‐delta complexes in the Upper Bayingebi Member (Lower Cretaceous) in Chagan Sag, Inner Mongolia, China

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