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Liu Z.,Jilin University | Liu Z.,Key Laboratory for Oil Shale and Coexistent Energy Minierals of Jilin Province | Hu F.,Jilin University | Sun P.,Jilin University | And 4 more authors.
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2013

Utilizing the practical study on the continental basins, the authors divide the whole third-order sequence into four systems tracts, which are lowstand systems tract (LST), transgressive systems tract (TST), highstand systems tract (HST) and regressive systems tract (RST), named sequence type I. If LST is undeveloped in a third-order sequence, it forms the assemblages of TST, HST and RST, named sequence type II. LST occurred in the rapid declining period of lake level (base level). TST appeared with first lake flooding surface and maximum lake flooding surface. HST formed in the relative static high lake-level period. RST formed in the gradual lake-level fall stage, and the supplying rate of sediments was more than the increasing rate of accommodation space at that time. Generally, LST consists of small scale progradational parasequence sets, vertically, the sedimentary environment is shallower, and river downcutting forms in the basin margin. TST consists of retrogradational parasequence sets, and the sedimentary environment becomes deeper from bottom to up. HST consists of aggradational parasequence sets, and the sedimentary environment changes little or is in standing water. RST consists of large scale progradational parasequence sets, and the sedimentary environment becomes shallower from bottom to up. Finally, the practical study on Songliao basin has been introduced to respectively expound the distribution regularities of oil and gas reservoirs in different system tracts in depression basin and fault basin. LST develops mainly lens-shaped lithologic reservoirs in the steep slope side of fault basin and deep-water area of depression basin. TST forms mainly updip thin away type lithologic oil & gas reservoirs in steep slope belt of fault basin, and forms stratigraphic overlap lithologic oil & gas reservoirs in the gentle slope belt of fault basin and slope zone of depression basin. HST mainly consists of lens-shaped lithologic reservoirs in deep-water area. RST develops mainly stratigraphic unconformity screened oil and gas reservoirs in fault basin, and developes fault block reservoirs and fault screened oil & gas reservoirs in depression basin. Thus, in the combination of theory and the practice, the practicality of the four division about continental sequence stratigraphy has been illustrated. Source

Yuan J.-Y.,Jilin University | Zhu J.-W.,Jilin University | Zhu J.-W.,Key Laboratory for Oil Shale and Coexistent Energy Minierals of Jilin Province | Lin B.,Jilin University | And 4 more authors.
Natural Gas Geoscience | Year: 2015

The Yanji Basin is a Mesozoic fault basin. Based on cores and well logs of 20 boreholes, facies of the Tongfosi Formation are mainly fan-delta and lacustrine. Thickness of dark-colored mudstone ranges from 20 to 500m. Analyses of organic carbon, chloroform bitumen “A”, hydrocarbon generation potential, and organic matter type on more than 700 dark-colored mudstone samples show that, source rocks of the First, Second, and Third members of the Tongfosi Formation have relatively high organic matter concentration and are characterized by type-II kerogen. Results of organic maturity degree(RO)analysis on 90 dark-colored mudstone samples show that, apart from part of the third member in the Dexin Sag, most of the dark-colored mudstone of the Tongfosi Formation in the Yanji Basin is slightly mature or mature, and is interpreted as effective source rock. Thus, the Yanji Basin is a potentially productive petroliferous basin. Based on five evaluation indices, such as hydrocarbon production, facies, and trap types, a series of well blocks(i. e., Y 13 to Y 20, Yan 10 to Yan 12, and Y 1 to Y 3) are selected as priority prospects. ©, 2015, Science Press. All right reserved. Source

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