Hydrocarbon generation can yield high fluid pressures in sedimentary basins as the conversion of solid kerogen to hydrocarbons can result in an increase in fluid volume. To quantify the relationship between gas generation and overpressure in source rocks, a set of equations for computing the pressure change due to gas generation has been derived. Those equations can be used to quantitatively estimate overpressure generated by type III kerogen in source rocks by considering gas generation and leakage, gas dissolution in formation water and residual oil, thermal cracking of oil to gas, and hydrocarbon episodic expulsion from source rocks. The equations also take consideration of other factors including source rock porosity, transformation ratio, total organic carbon (TOC), hydrogen index, and compressibility of kerogen, oil, and water. As both oil and gas are taken into account in the equations, they can also be used to estimate the evolution of overpressure caused by hydrocarbon generation of type I and type II kerogen source rocks. Sensitivity analyses on the type III kerogen source rock indicate that hydrogen index is the most influential parameter for overpressure generation, while TOC and residual gas coefficient (β: ratio of residual gas over the total gas generated) have a moderate effect. Overpressure can be generated even if the gas leakage/loss in the source rock is up to 80% of the total gas generated. This suggests that the internal pressure seal of the source rock is not a critical factor on the pressure change as long as the source rocks are capable of sealing liquid oil. The equations were applied to evaluate the overpressure in the Eocene–Oligocene Enping Formation source rocks due to hydrocarbon generation in the Baiyun Depression, the Pearl River Mouth Basin by considering the source rock properties, hydrocarbon generation history, and hydrocarbon expulsion timing. Two episodes of overpressure development due to gas generation and release were modeled to have occurred in the Enping Formation source rock since 16 Ma. The overpressure release at 10.2–5.3 Ma via hydrocarbon expulsion was apparently related to the Dongsha phase of tectonic deformation, whereas the pressure release at 2–0 Ma was due to pressure generation that was exceeded the fracture‐sealing pressure in the source rocks. 相似文献
Cao, Y., Shih, C., Bashkuev, A. & Ren, D., September 2015. Revision and two new species of Itaphlebia (Nannochoristidae: Mecoptera) from the Middle Jurassic of Inner Mongolia, China. Alcheringa 40, XX–XX. ISSN 0311-5518.
Two new species of Itaphlebia Sukatsheva, 1985, Itaphlebia longiovata and I. amoena (Nannochoristidae Tillyard, 1917), are described and illustrated from the Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, China. Previously described Middle Jurassic nannochoristid genera, Chrysopanorpa Ren in Ren et al., 1995 and Protochoristella Sun, Ren & Shih, 2007b, together with Stylopanorpodes and Netropanorpodes Sun, Ren & Shih, 2007a (originally assigned to Mesopanorpodidae) are revised and considered to be synonyms of Itaphlebia. The following tentative species synonymies are proposed: Protochoristella formosa and Stylopanorpodes eurypterus = Itaphlebia ruderalis (Ren in Ren et al., 1995), comb. nov.; Netropanorpodes sentosus = I. jeniseica Novokshonov, 1997a, syn. nov.; and Protochoristella polyneura = I. multa Novokshonov, 1997a, syn. nov. Netropanorpodes decorosus is transferred to Itaphlebia. These new species, new material and the new combinations broaden the diversity of the Itaphlebia in mid-Mesozoic ecosystems and provide new characters enabling amendment of the generic diagnosis.
YiZi Cao [easycaoyinzi@aliyun.com], ChungKun Shih [chungkun.shih@gmail.com] and Dong Ren [rendong@mail.cnu.edu.cn], College of Life Sciences, Capital Normal University, Xisanhuanbeilu 105, Haidian District, Beijing, PR China 100048; Alexei Bashkuev [fossilmec@gmail.com], Borissiak Paleontological Institute, Russian Academy of Sciences, Profsoyuznaya st. 123, Moscow 117997, Russia.相似文献
Liu, X.H., Li, Y., Yao, Y.Z. & Ren, D., April 2016. A hairy-bodied tettigarctid (Hemiptera: Cicadoidea) from the latest Middle Jurassic of northeast China. Alcheringa 40, xxx–xxx. ISSN 0311-5518
Extant tettigarctids are also known as hairy cicadas because they are covered by long and abundant hairs. This character had not been reported in fossil species of Tettigarctidae because previous examples were poorly preserved or lacked long hairs. Hirtaprosbole erromera gen. et sp. nov. (Tettigarctidae) with a hairy body, from the latest Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, China, is described here. This new species provides evidence that tettigarctids with long dense hairs had appeared by the latest Middle Jurassic and lived at high altitudes.
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