Diagenetic evolution of deep sandstones and multiple-stage oil entrapment: A case study from the Lower Jurassic Sangonghe Formation in the Fukang Sag, central Junggar Basin (NW China)

Cao, Binfeng; Luo, Xiaorong; Zhang, Likuan; Sui, Fenggui; Lin, Haifei; Lei, Yuhong

doi:10.1016/j.petrol.2017.02.019

Cited by 55 publications

(28 citation statements)

References 30 publications

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“…The negative 13 C values could be attributed to a variety of sources and/or processes, such as the derivation of carbon from thermal maturation of organic matter during burial [10,47,48].…”

Section: Isotope Analysis and Origins Of Carbonate Cementmentioning

confidence: 99%

Origin and Distribution of Carbonate Cement in Tight Sandstones: The Upper Triassic Yanchang Formation Chang 8 Oil Layer in West Ordos Basin, China

et al. 2017

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Two generations of carbonate cement as Type I (microcrystalline calcite and dolomite) and Type II (mainly Fe-calcite and Fedolomite) are recognized in Chang 8 sandstones, Ordos basin. Carbonate cement in Chang 8 sandstones is closely related to the dissolved carbon from thermal maturation of organic matters. Carbonate cement in the loosely packed framework grains precipitated shortly after deposition, and late-stage ferroan calcite and ferroan dolomite formed with progressive burial. The early diagenetic carbonate cement is partially to completely replaced by late-stage ferroan calcite and ferroan dolomite. Carbonate cement is much more commonly observed in sand bodies adjacent to Chang 7 source rocks. With increasing distance from the Chang 7 oil layers, the carbonate cement content gradually decreases. However, some tight carbonate cemented zones also occur at the sandstone-mudstone interfaces. Dissolution of Ca-feldspars by organic acids-rich fluids, together with clay mineral transformations such as illitization of smectite, would provide Ca 2+ and Mg 2+ ions for carbonate cementation. Organic acids and CO 2 rich fluids would charge into the reservoirs with the hydrocarbons, and when the CO 2 and acids were buffered by the framework grain dissolution, carbonate cement would precipitate with a decrease in CO 2 concentration.

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“…The negative 13 C values could be attributed to a variety of sources and/or processes, such as the derivation of carbon from thermal maturation of organic matter during burial [10,47,48].…”

Section: Isotope Analysis and Origins Of Carbonate Cementmentioning

confidence: 99%

Origin and Distribution of Carbonate Cement in Tight Sandstones: The Upper Triassic Yanchang Formation Chang 8 Oil Layer in West Ordos Basin, China

et al. 2017

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“…As mentioned before, the Fukang coal field is rich in coalbed methane, which formed from the coalification process. Meanwhile, geological data show that quartz albitophyre intrusive bodies, which have been formed in the Carboniferous period (Cao et al., 2017; Gong et al., 2017), located in the Tianshan piedmont, are distributed in the south and southeast of the coal field. Moreover, albite has been found in the No.…”

Section: Discussionmentioning

confidence: 99%

Mineralogical characteristics and sources of alkali metals in the No. 6 coal seam from the Fukang mining area of the Zhunnan coalfield, Xinjiang province, Northwest China

Liang

Zhang

2019

Energy Exploration & Exploitation

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Minerals in coal are of great significance in determining coal properties, washing, combustion, gasification, and liquefaction. The content of alkali metals in coal is an important factor determining corrosion and/or erosion in combustion boilers. Eleven coal samples were taken from the No. 6 coal seam of the Fukang mining area, Zhunnan coalfield, Xinjiang province, China. X-ray fluorescence, inductively coupled plasma-mass spectrometry, low-temperature ashing-X-ray diffraction, and electron probe microanalyzer were used for analyzing the minerals, major elements, and trace elements of the coal. The results indicated that the minerals mainly consist of dawsonite, dolomite, albite, calcite, kaolinite, quartz. The average content of Na2O in the ash of the No. 6 coal seam samples was 10.91%. Na mainly occurs in the form of organic compounds in the No. 6 coal seam, then in the form of inorganic minerals, such as dawsonite and albite. Na in surface and underlying strata was brought into the coal by water and combined with organic matter, resulting in relatively high Na contents in the upper and bottom parts of the coal seam and relatively low Na contents in the middle part.

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“…According to the data collected from 35 scanning electron microscopy (SEM) (S4800, Hitachi) observations and 60 X-ray diffraction (XRD) analyses of clay minerals, we obtained the distribution characteristics and origins of the authigenic minerals and clay minerals F I G U R E 1 Location of the study area and main wells in the Jimusar Sag, modified according to (Kuang et al, 2012); (a) location of the Junggar Basin in China; (b) location of the Jimusar Sag in the Junggar Basin; (c) the structural framework and main location of wells of the Jimusar Sag [Colour figure can be viewed at wileyonlinelibrary.com] (B. Cao, Luo, et al, 2017;Higgs, Crouch, & Raine, 2017). The XRD method used a Bruker D2 Phaser Diffractometer (230 V, 45 KVA from 4 to 60 2θ, step size of 2 per minute).…”

Section: Research Methods Of Diagenesismentioning

confidence: 99%

Effects of diagenesis on natural fractures in tight oil reservoirs: A case study of the Permian Lucaogou Formation in Jimusar Sag, Junggar Basin, NW China

et al. 2020

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Compared with conventional reservoirs, tight reservoirs experience more intense diagenesis; thus, their properties are extremely poor. Nevertheless, natural fractures with high‐strength can appear in these reservoirs and could play an essential role in the accumulation and production of tight oil. In this study, we focused on the effects of different diagenetic processes in the formation and transformation of natural fractures to determine the effects of natural fractures on tight reservoirs. Various observation techniques and analysis methods were applied (i.e., observations of cores, cast thin sections, scanning electron microscopy; field emission scanning electron microscopy; and X‐ray diffraction analysis). We clarified characteristics of the fractures and distribution patterns based on core descriptions and microscopic observations and explained the diagenetic stage and evolution sequence of reservoirs. Past studies regarding carbon and oxygen isotope analysis and basin simulation were considered. This study also reviewed the fracture formation time, source of fracture fillings, and oil charging time. We obtained insight into the coupling relationship of fracture states, diagenetic sequences, hydrocarbon charging, and, in particular, the controlling effect of diagenesis on natural fractures. The results revealed that formation, preservation, and destruction of natural fractures in tight reservoirs were closely related to diagenesis. Compaction and cementation in the reservoirs decreased the porosity and altered the petrophysical properties of the reservoir. They also provided favorable conditions for the development of tectonic fractures, while dissolution did not. The influences of dissolution and cementation on natural fractures depended on the duration for which these processes were active. Compaction and cementation formed related types of diagenetic fractures, while dissolution increased the effectiveness of natural fractures. The purpose of this study was to evaluate the influence of diagenesis on the formation, controlling effects, and effectiveness of natural fractures, as well as the effects of natural fractures on tight reservoirs through geological history. This study is expected to provide guidance for future exploration and development of tight oil and gas with similar geological origins.

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Diagenetic evolution of deep sandstones and multiple-stage oil entrapment: A case study from the Lower Jurassic Sangonghe Formation in the Fukang Sag, central Junggar Basin (NW China)

Cited by 55 publications

References 30 publications

Origin and Distribution of Carbonate Cement in Tight Sandstones: The Upper Triassic Yanchang Formation Chang 8 Oil Layer in West Ordos Basin, China

Origin and Distribution of Carbonate Cement in Tight Sandstones: The Upper Triassic Yanchang Formation Chang 8 Oil Layer in West Ordos Basin, China

Mineralogical characteristics and sources of alkali metals in the No. 6 coal seam from the Fukang mining area of the Zhunnan coalfield, Xinjiang province, Northwest China

Effects of diagenesis on natural fractures in tight oil reservoirs: A case study of the Permian Lucaogou Formation in Jimusar Sag, Junggar Basin, NW China

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