Superimposed Pattern of the Southern Sichuan Basin Revealed by Seismic Refl ection Profi les Across Lushan–Chishui, China

2021 ◽  
Author(s):  
G. Su ◽  
Z. Li ◽  
H. Li ◽  
D. Ying ◽  
G. Li ◽  
...  
Keyword(s):  
Sichuan Basin ◽  
Oil And Gas ◽  
Foreland Basin ◽  
Geologic Structure ◽  
Gas Accumulation ◽  
Equilibrium Profiles ◽  
Oil And Gas Resources ◽  
The Sichuan Basin ◽  
Seismic Reflection Profiles ◽  
Superimposed Basin

Abstract The Sichuan Basin is a typical intracraton superimposed basin. It is rich in oil and gas resources in the different sets of sedimentary sequences. It underwent multistage tectonic evolution, which resulted in different types of prototype basins. However, there are still many different opinions on the types and superimposed patterns of the Sichuan Basin in different geologic periods, which largely affect the understanding of the mechanism of effective oil and gas accumulation and preservation. This paper aims to re-recognize several prototype types of the Sichuan Basin by discussing the prototype basins and their superimposed models to deepen the significance of superimposed basin evolution for hydrocarbon accumulation. The regional geological and drilling data are used for a detailed interpretation of seismic reflection profiles across Lushan–Chishui. Then, five regional unconformities are identified with the equilibrium profiles technique which is used to flatten the formation interface in different geologic periods. Based on the unconformities, the southern Sichuan Basin is divided into six tectonic layers, each of which is regarded as a prototype basin: a pre-Sinian crystalline basement (AnZ), a marine rift cratonic basin (Z–S), a marine intracratonic sag basin (P2l–T2l), a marine–continental downfaulted basin (T3x1–T3x3), a continental depressed basin (T3x4–J), and a foreland basin (K–Q). The different prototype basins are vertically superimposed to form a “layered block” geologic structure of the multicycle basins. Affected by the late-stage tectonic transformation, the geologic structure of vertical stratification underwent a strong transformation, which had a profound impact on oil and gas accumulation with the characteristics of early accumulation and late adjustment.

An introduction to seismic exploration of the Micang-Dabashan foothill belt in the Sichuan Basin

2018 ◽  
Vol 6 (4) ◽  
pp. SM39-SM50
Author(s):  
Jingbo Wang ◽  
Zhongshan Qi ◽  
Penggui Jing ◽  
Tianfa Zheng ◽  
Yanqi Li ◽  
...  
Keyword(s):  
Sichuan Basin ◽  
Oil And Gas ◽  
Seismic Exploration ◽  
Small Scale ◽  
Marine Strata ◽  
Piedmont Zone ◽  
Migration Imaging ◽  
Imaging Results ◽  
Platform Margin ◽  
The Sichuan Basin

Geologic studies indicate that the platform-margin reef-shallow facies in Permo-Triassic marine strata in the Micang-Dabashan foothill belt in the Sichuan Basin are favorable exploration targets for oil and gas exploration. However, the typical dual-complexity problem (complex surface condition and subsurface structure) brings a great challenge for seismic technology targeting of those potential oil and gas reservoirs. To overcome this problem, varieties of advanced seismic acquisition and processing methods have been used to improve the imaging quality of piedmont seismic data since 2000. Some improvements have been achieved: The reflection waves from the far offset and deep layer can be acquired in shot gathers from limestone outcropped areas, and the signal-to-noise ratio (S/N) of reflection and diffraction waves in the stack section has been enhanced significantly so as to reveal amounts of valuable geologic information. The resolution and the S/N of seismic migration imaging for the strong fold zone in marine strata have been improved partially, so that the structure of the step-fault zone and the enveloping of gypsum rock are clearer than those revealed by the old seismic section. Even so, actual drilling data demonstrate that the subsurface structures of the foothill belt are far more complex than those revealed by the current seismic imaging results. Therefore, postdrilling evaluation for the validity of seismic techniques implemented in the Nanjiang and Zhenba piedmont zone has been carried out. The results indicate that the current acquisition scheme and processing workflow cannot completely fulfill the requirements of high-precision velocity modeling and migration imaging of complex structures (such as footwalls of thrust fault and small-scale fault blocks) in the piedmont zone, especially when the rugged surface and the widespread limestone outcrop appear simultaneously. Finally, we have developed some potential needs of seismic theories and techniques in the foothill belt, including seismic wave propagation, acquisition, and processing technology.

Quantitative prediction of oil and gas prospects of the Sinian-Lower Paleozoic in the Sichuan Basin in central China

Energy ◽  
2019 ◽  
Vol 174 ◽  
pp. 861-872 ◽  
Author(s):  
Wenyang Wang ◽  
Xiongqi Pang ◽  
Zhangxin Chen ◽  
Dongxia Chen ◽  
Tianyu Zheng ◽  
...  
Keyword(s):  
Sichuan Basin ◽  
Oil And Gas ◽  
Central China ◽  
Quantitative Prediction ◽  
Lower Paleozoic ◽  
The Sichuan Basin

Detrital zircon U-Pb ages of Paleogene deposits in the southwestern Sichuan foreland basin, China: Constraints on basin-mountain evolution along the southeastern margin of the Tibetan Plateau

2019 ◽  
Vol 132 (3-4) ◽  
pp. 668-686 ◽  
Author(s):  
Hanyu Huang ◽  
Dengfa He ◽  
Di Li ◽  
Yingqiang Li
Keyword(s):  
Detrital Zircon ◽  
Sichuan Basin ◽  
Tectonic Setting ◽  
Foreland Basin ◽  
Source Area ◽  
Orogenic Belt ◽  
Sediment Supply ◽  
Scaling Analysis ◽  
The Tibetan Plateau ◽  
The Sichuan Basin

Abstract The tectonic setting of the southwestern Sichuan foreland basin, China, changed rapidly during the Paleogene period, and records from this period may provide crucial information about the formation and tectonic processes that affected the Sichuan Basin. To constrain the provenance and to reconstruct the paleogeography of the Paleogene successions, we conducted a detailed analysis of the petrology, geochronology, and sedimentary facies of rocks from the southwestern Sichuan foreland basin. The detrital components of the three analyzed sandstone samples indicate moderately to highly mature sediment that was primarily derived from a recycled orogen provenance. Five major age populations were identified in the U-Pb age spectra: Neoarchean to Siderian (2524–2469 Ma and 2019–1703 Ma), Neoproterozoic (Tonian to Cryogenian, 946–653 Ma), Ordovician to Carboniferous (Katian to lower Pennsylvanian, 448–321 Ma), and Carboniferous to Triassic (306–201 Ma). Each of these age populations corresponds to one or several potential sources around the southwestern Sichuan foreland basin. A multidimensional scaling analysis indicated that the Paleogene zircons were mainly derived from recycled sediments of the Songpan-Ganzi terrane and the Sichuan Basin, with minor input from the Yidun terrane, Kangdian terrane, Qinling orogenic belt, and Jiangnan-Xuefeng orogenic belt. More specifically, the sediment supply from the Songpan-Ganzi terrane to the foreland basin decreased significantly from the Mingshan stage to the Lushan stage, and the Sichuan Basin simultaneously became the most important source area. In addition, there is a high correlation between the detrital zircon U-Pb age spectrum of the southwestern Sichuan Basin and that of the Xichang Basin, which may suggest that a wider and unified Paleo-Yangtze Basin existed during the Late Cretaceous-early Paleogene.

scholarly journals Characteristics of the temperature–pressure field evolution of Middle Permian system in the northwest of Sichuan Basin

2018 ◽  
Vol 36 (4) ◽  
pp. 705-726 ◽  
Author(s):  
Qiuchen Xu ◽  
Nansheng Qiu ◽  
Wen Liu ◽  
Anjiang Shen ◽  
Xiaofang Wang ◽  
...  
Keyword(s):  
Sichuan Basin ◽  
Oil And Gas ◽  
Vitrinite Reflectance ◽  
Middle Permian ◽  
Key Factors ◽  
Reduction Stage ◽  
Three Stages ◽  
The Sichuan Basin ◽  
Thermal Indicators ◽  
Oil Cracking

The Sichuan Basin is one of the richest oil and gas basins in China. The Middle Permian units (the Qixia and Maokou Formations) in the northwest Sichuan Basin have great potential for gas exploration. A new thermal history was reconstructed using the integrated thermal indicators of apatite and zircon (uranium–thorium)/helium ages, zircon fission tracks, and vitrinite reflectance data. The modeled results indicated that the northwest Sichuan Basin experienced gradual cooling, during which the heat flow at Middle Permian time (70–90 mW/m2) decreased to its current level of approximately 50 mW/m2. This study used basin modeling to reconstruct the paleo-pressure, which showed that the Middle Permian in the northwest Sichuan Basin generally developed overpressure. The pressure evolution of the Middle Permian can be divided into three stages: (1) a slight overpressure stage (T2–T3), (2) an intensive overpressure stage (J1–K2), and (3) an overpressure reduction stage (K2–present). Oil cracking and rapid tectonic subsidence are key factors that affect overpressure. The evolution of temperature–pressure has great significance with respect to hydrocarbon accumulation.

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