Wu L.,China University of Petroleum - East China |
Wu L.,Petrochina |
Chen Q.,China University of Petroleum - East China |
Pang F.,Oil & Gas Survey Center |
Shi P.,Research Institute of Shaanxi Yanchang Petroleum Group
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2015
Located in the eastern part of the Yangtze plate, the tectonic deformation of the Lower Yangtze is of geological significance. Based on the regional geological data, seismic data, well logging, and geophysical data, the stratigraphy and faults are finely interpreted, and two regional geological profiles are established throughout the study area, namely Suqian-Shaoxing profile and Lianyungang-Suzhou profile. The Lower Yangtze region is divided into 6 level one tectonic deformation units, followed by Subei-Jiaonan orogenic belt, Subei thrust area, north and south thrust belt, Sunan thrust area, Zhebei thrust area, and Jiangnan orogenic belt, and it can be further divided into 14 level two tectonic deformation units, which clearly represent the Mesozoic-Cenozoic tectonic deformation of the Lower Yangtze region. There are three typical tectonic deformation styles out of the two profiles, including compression, extension, inversion, which can be divided into 5 sub-classes and 10 small classes. © 2015, Jilin University Press. All right reserved.
Su X.,China University of Geosciences |
Yin J.,China University of Geosciences |
Zhu Y.,Oil & Gas Survey Center |
Wang P.,Oil & Gas Survey Center |
And 4 more authors.
Geological Bulletin of China | Year: 2015
Among the Mesozoic global oceanic anoxic events, the Posidonienschiefer (Posidonia shale) facies in southern Germany represents the earliest one, which is well-known all over the world. Up till now, the Posidonia shale facies has been found at 4 localities in the Qiangtang Basin, including drill holes and outcrops. In Qiangtang Gas Hydrate Scientific Well QK-5, a more than 150 m black shale sediment sequence was discovered, which yielded the Early Jurassic Cleviceras elegans-Bositra buchii assemblage. The locality of Posidonia shale facies in Well QK-5 is the northernmost one, on the northern side of the “middle uplift zone” of the Qiangtang Basin, while the other three are spread in areas from Shuanghu to Sewa, on the southern side of the “uplift zone” of the basin. Actually, there is few evidence to indicate that the basin had ever been separated by a uplift during Early Jurassic. In addition, the Bailongbinghe Formation (Sowa Formation) in northeast Qiangtang, formerly thought of belonging to the Late Jurassic age, is proved to range from Early to Middle Jurassic by the Toarcian and Early Callovian ammonite successions. The discovery of Posidonia shale facies in the Qiangtang Basin is helpful to further understanding the Mesozoic sedimentary and evolution history of the basin. Considerable stratigraphic thickness and distribution area of the carbon-rich Posidonia shales in the basin would provide a very optimistic outlook for shale gas exploration. ©, 2015, Science Press. All right reserved.
Dai K.,Dagang Oilfield Company |
Dai K.,China University of Petroleum - Beijing |
Liu C.,Chinese Academy of Geological Sciences |
Xiao D.,Dagang Oilfield Company |
And 7 more authors.
Earth Science Frontiers | Year: 2016
The study of the tectonic deformation and evolution of the eastern section of North Qaidam is comparatively weak, particularly the paleotectonic stress characteristics and its transformation mechanism is not clear. In this paper, systematic observation and analysis on stress-response structures (e.g. folds, joints, slickensides) and profile measurements were carried out in Olongbluke. Results indicate that compressive stress direction in the Caledonian was NE. There were two phase of compressional tectonic events in the late Hercynian-Indosinian, of which the early stress direction was SN and the late stress direction was NW. During the Early to Middle Jurassic, the stretching direction was approximately EW. Then, compressive stress direction changed into NE after the Late Jurassic. Based on balanced cross-section and the strata extension ratio of Ounan depression, the tectonic evolution of Northeast Qaidam can be divided into four stages. During Cambrian to Early Ordovician, the Ounan sag was under retroarc extensional environment and turned into retroarc extrusion, which resulted in the formation of the NW trending anticline. During the Permian to the Triassic, the whole uplifting of Olongbluke area resulted in the stratigraphic missing. Intracontinental extention within the Early to Middle Jurassic and extrusion inversion within the Cretaceous, the Olongbluke area was in an inherited uplifting and had not fully deposited. In Late Himalayan Epoch, tectonic deformation was intensified and surrounding mountain was uplifted rapidly caused by reverse faulting. Basement curled structural pattern was widely distributed within this phase. © 2016, Editorial Office of Earth Science Frontiers. All right reserved.
Bao S.,Oil & Gas Survey Center |
Lin T.,Oil & Gas Survey Center |
Nie H.,Sinopec |
Ren S.,Oil & Gas Survey Center
Earth Science Frontiers | Year: 2016
Through observation (Quantang Shaoyang, Beishan Longhui County), measured profile (Jianxincun Lianyuan County and Qixingjie Lianyuan County), sampling and laboratory analysis such as adsorbed gas content, geochemical parameters and reservoir parameters etc. of Longtan & Dalong Formations of Permian in the Xiangzhong depression, we established a composite section of lithology-rock mineral-geochemical-physical properties-gas-bearing properties of Longtan & Dalong Formations of Permian. The kerogen maceral of the Dalong Formation and Longtan Formation was mainly exinite, vitrinite and inertinite content is less. Samples with total organic carbon greater than 2% accounted for more than 40% of the total longitudinal samples, mainly distributed in the bottom of Dalong Formation and the top of Longtan Formation. The thermal maturity is between 1.10%-2.22%, with an average of 1.42% and is at mature to high mature stage. The micro-reservoir types are mainly mineral micro-pores and micro-fracture, followed by organic matter micro-pore. The mineral micro-pores mainly include interparticle residual micro-pores, interparticle dissolution micro-pores, intraparticle dissolution micro-pores and intraparticle micro-pores. Parameters such as thickness of the shale, total organic content, maturity and gas content, oil & gas showing, indicated that the most favorable member for shale gas accumulations is the bottom of the top of Longtan and Dalong Formations with about 80 m thickness which may have good shale gas exploration potential. It is worth noting that shale gas accumulation conditions such as geochemical parameters, mineral composition, reservoir parameters and gas content etc. of the Permian shale in the Sichuan Basin is similar to those in the Xiangzhong depression. They have late peak period of hydrocarbon generation and shallow uplift.The giant Puguang gas field is sourced from the Permian shale. It is needed to pay attention to the transitional facies of shale gas exploration and research of the Permian shale in Sichuan Basin. © 2016, Editorial Office of Earth Science Frontiers. All right reserved.