Hybrid plays of Upper Triassic Chang7 lacustrine source rock interval of Yanchang Formation, Ordos Basin, China

Jiang, Shu; Chen, Lei; Wu, Yue; Jiang, Zhenglong; McKenna, Elinda

doi:10.1016/j.petrol.2017.09.033

Cited by 19 publications

(6 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A large number of n‐alkanes and acyclic isoprenoid alkanes were detected in the samples, and the main carbon peak was distributed from nC 15 to nC 33 . However, most of them were concentrated between nC 23 and nC 33 , and only a small number of samples have main carbon peaks at less than nC 20 (S. Jiang, Chen, Wu, Jiang, & Elinda, 2017; Mansour, Gentzis, et al, 2020; Peters & Moldowan, 1991). In addition, the odd–even predominance (OEP) ranged from 0.62 to 6.94, with an average of 2.31; and the OEP in the eastern area was significantly lower than that in the western area.…”

Section: Resultsmentioning

confidence: 99%

The organic geochemical characteristics from the Palaeogene lacustrine source rock in the Nyima Basin, Central Tibet, and their geological significance

et al. 2021

View full text Add to dashboard Cite

The Lunpola Basin is a fault‐depression type residual Palaeogene continental basin, and it is the only basin located in Tibet in which industrial oil has been discovered. In recent years, as research has progressed, quantities of oil shale and asphalt were discovered in the adjacent Nyima Basin, which shows a good prospect for exploration. In this study, the organic geochemistry, n‐alkanes, biomarkers, and maturity parameters of the samples were analysed using gas chromatography (GC) and mass spectrometry (MS). The organic geochemistry revealed that the Niubao Formation has a high organic matter abundance (total organic carbon content of 0.15–8.43 wt% and hydrogen index of 31.25–1721.15) and is dominated by type I–II2 kerogen. The GC and MS analyses indicate that the oil shales of the Nyima Basin have a high organic matter abundance and a good hydrocarbon production potential, and the main organic matter sources were aquatic algae and terrestrial plants, as evidenced from the unimodal/bimodal distributions of the n‐alkanes. Besides, the high phytoalkane, gammacerane, homohopane, and gypsiferous mudstone contents in the Nyima Basin indicate a deep, hypoxic, well‐stratified, saline lacustrine sedimentary environment. Under warm climatic conditions, accelerated continental weathering increased nutrient input, leading to water‐mass eutrophication and algal blooms in the water column, while arid conditions and intensified evaporation induced saline stratification, leading to enhanced preservation of organic matter and the formation of high‐quality source rock layers in this lake basin. Therefore, the Eocene global greenhouse effect may have been the main reason for the formation of the large sets of oil shales in the Nyima Basin.

show abstract

Section: Resultsmentioning

confidence: 99%

The organic geochemical characteristics from the Palaeogene lacustrine source rock in the Nyima Basin, Central Tibet, and their geological significance

et al. 2021

View full text Add to dashboard Cite

show abstract

“…Suboxic slowed the breakdown of organic matter sediments in lower parts, which facilitates the preservation of organic matter. Under low closure degrees, on the other hand, the bottom water gradually converges with the warm water at the top, damaging the original environment [24,[55][56][57][58][59]. Meanwhile, there was less sedimentary organic matter with lower abundance as they further underwent dilution and oxidative decomposition [60][61][62][63].…”

Section: E Influence Of Waterbody Closure Degree On Enrichment Of The...mentioning

confidence: 99%

Influence of Organic Matter on Gas-Bearing Properties and Analysis of Sedimentary Mechanism of Organic Matter Enrichment: A Case Study on the Yangtze Region of Southern China during the Early Cambrian

Zhang

Wei

et al. 2022

Geofluids

View full text Add to dashboard Cite

Shale gas exploration requires studies on the enrichment mechanism of sedimentary organic matter. The Lower Cambrian shale is taken as a study object to analyze the effect of organic matter on gas content using TOC content and porosity analyses, isothermal adsorption experiments, and FIB-HIM scanning electron microscopy observations. Then, we selected typical wells to determine the presence of excessive silica in the siliceous minerals by quantitative calculations. Besides, we analyzed the genesis of excessive siliceous minerals using elements including Al, Fe, and Mn, thus speculating the controlling factors of the redox environment and biological productivity. Results show that total organic carbon content controls the content of free and adsorbed gas, while shale gas mainly exists in organic pores and is developed in large numbers and with high roundness, showing the characteristics of “small pores inside big pores.” In the Lower Yangtze region during the Early Cambrian, the excessive siliceous minerals were of hydrothermal origin, and there were frequent hydrothermal activities due to its closeness to plate boundaries. These activities can intensify the reducibility of the waterbody’s bottom and improve the biological productivity on its surface, resulting in the enrichment of this matter. Most excessive silicon in this region is biogenic, while only a small part is of hydrothermal and biogenic mixed origin. The enclosed waterbody of the Upper Yangtze region was far from plate boundaries and close to the semiclosed “gulf,” resulting in its delamination. The waterbody’s surface was abundant with oxygen, thus increasing the biological productivity, while the high reducibility at the waterbody’s bottom was conducive to preserving sedimentary organic matter.

show abstract

“…Affected by high-frequency climate change, continental shale reservoirs with characteristics of frequent facies change, a complex lithology, and strong heterogeneity have diverse sedimentary environments. Shale oil in China is mainly distributed in continental lacustrine basins as follows: Cretaceous of the Songliao Basin (Cao et al 2017), Paleogene of the Bohai Bay Basin (eastern China) (Chao et al 2017;Chen et al 2017;Lu et al 2015), Triassic of the Ordos Basin (Cui et al 2019;Lai et al 2016;Sun et al 2020;Jiang et al 2017;Yao et al 2009;Wei et al 2019), Jurassic of the Sichuan Basin (central China) (Li et al 2018;Wang Responsible Editor: Santanu Banerjee et al 2018), and Permian of the Junggar Basin (western China) (Zhang et al 2019a, b, c;Luo et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Diagenesis and reservoir space types of alkaline lake-type shale in Fengcheng Formation of Mahu Sag, Junggar Basin, China

et al. 2021

View full text Add to dashboard Cite

Using observations and descriptions of drilling cores, image logging, microscopic section, argon ion polishing field emission scanning electron microscopy, X-ray diffraction, and whole-rock trace element analysis, the study of shale reservoir diagenesis and space types in the Fengcheng Formation of the Mahu Sag was conducted. Considering the trace element contents and their ratios (Sr/Ba, V/Ni, Th/U, V/(V + Ni), U/Mo, and Sr/Cu), the Fengcheng Formation is formed in a dry and hot continental lacustrine basin with a paleoenvironment of saltwater and anoxic/lean oxygen conditions. The shale reservoirs of the Fengcheng Formation with the characteristic of multisource mixed sedimentation include terrigenous clastic, volcaniclastics, and carbonate rocks. Currently, the Fengcheng reservoir of the Mahu Sag is in the middle of diagenetic-stage B. The principal factors for reservoir densification are compaction, dissolution, carbonate mineral cementation, and clay mineral cementation. The Fengcheng Formation develops multiple reservoir storage space types, such as rock fractures, stylolites, and micro–nanoscale pore-throat systems. The macroreservoir space types include tectonic, induced, bedding, and dissolution–expansion fracture types. The microreservoir space types include microfractures, stylolites, and micro–nanoscale pore throats. The research showed that the Fengcheng Formation has tectonic fracture-pore systems (tectonic fracture-type reservoirs) and stylolite-matrix pore-tectonic microfracture systems (shale oil reservoirs), forming the shale oil preponderant charging channel network. Reservoir space type and its spatial distribution are the principal factors for shale oil accumulation of the Fengcheng Formation in the Mahu Sag.

show abstract

Hybrid plays of Upper Triassic Chang7 lacustrine source rock interval of Yanchang Formation, Ordos Basin, China

Cited by 19 publications

References 29 publications

The organic geochemical characteristics from the Palaeogene lacustrine source rock in the Nyima Basin, Central Tibet, and their geological significance

The organic geochemical characteristics from the Palaeogene lacustrine source rock in the Nyima Basin, Central Tibet, and their geological significance

Influence of Organic Matter on Gas-Bearing Properties and Analysis of Sedimentary Mechanism of Organic Matter Enrichment: A Case Study on the Yangtze Region of Southern China during the Early Cambrian

Diagenesis and reservoir space types of alkaline lake-type shale in Fengcheng Formation of Mahu Sag, Junggar Basin, China

Contact Info

Product

Resources

About