Mar 2008, Volume 2 Issue 1
    

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  • Issues concerning global warming today
    REN Zhenqiu
    2008, 2(1): 27-30. https://doi.org/10.1007/s11707-008-0009-x
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    The global weather of today is growing significantly warmer; this is an indisputable fact. However, the scientific community has not yet reached consensus on the causes of global warming and its possible consequences. This paper introduces the causes of global warming and summarizes its results, which both involve a series of huge and complex system issues. Our top priority is to pinpoint the main reason and the interrelated links between causative factors by adopting a macro-approach, or comprehensive comparison analysis. Its physical mechanism was then determined and its digital model established after quantitative study.
  • The paleoclimatic records and the relevance with the formation of hydrocarbon source rocks: A case study of Huanghekou depression, Bohaiwan basin
    LIU Zhanhong, LI Sitian, XIN Renchen, XU Changgui, CHENG Jianchun
    2008, 2(1): 73-82. https://doi.org/10.1007/s11707-008-0010-4
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    Bohaiwan basin, covering an area of 200 000 km2, is one of the most important oil-bearing basins in Eastern China. Rifting processes formed the basin, and two evolution phases can be recognized. The rifting phase developed in Paleogene, and post-rifting phase occurred in Neogene. More than 200 oil fields have been found in the onshore and offshore area in Bohaiwan basin in recent years. The distribution of the oil fields is closely related to the rich hydrocarbon depressions, and the Huanghekou depression is one of these rich hydrocarbon depressions. A number of large and medium-sized oil and gas fields have been found in this area, such as BZ25-1, BZ34 etc., and the hydrocarbon was mainly from the Huanghekou depression. The formation of rich hydrocarbon source rocks depended on the tectonic setting of rapid subsidence, favorable paleoclimatic conditions and paleolimnology environments. The effects of paleoclimatic condition on hydrocarbon source rocks are the focus of this paper.
  • Comparison between control factors of high quality continental reservoirs in Bohai Bay basin and Ordos basin
    ZHENG Junmao, YOU Jun, HE Dongbo
    2008, 2(1): 83-95. https://doi.org/10.1007/s11707-008-0002-4
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    Bohai Bay basin, a typical extensional rift basin, and Ordos basin, an intra-craton down-warped basin, represent two important basin types in China. Because of their respective features, the main control factors for their high quality reservoirs are different. In Bohai Bay basin, the sandbody shows great variety in types and severely separated distribution and its high quality reservoirs are mostly controlled by the vertical secondary pore and vertical abnormal pressure. On the other hand, the sandbody in Ordos basin features a relative lack of variety, good continuity, indistinct vertical zone, and its reservoirs are mainly controlled by the diagenetic differentiation caused by different sedimentation inside the sandbody. Therefore, in the Bohai Bay basin, the exploration should be based on the analysis of sedimentary facies and the favorable diagenetic zones and formations. The focus in Ordos basin, however, should be put on the relatively high permeability sandstones in a generally low permeable sandstone background.
  • Evidence of the transgression lake of the Subei basin during Late Cretaceous and Paleocene and its geological significance
    FU Qiang, LI Yi, ZHANG Guodong, LIU Yurui
    2008, 2(1): 114-119. https://doi.org/10.1007/s11707-008-0004-2
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    Based on analysis of the well drilling core from Subei basin, the authors conclude that during the Late Cretaceous and Paleocene, Subei basin was linked with the sea and the deposit was affected by transgression. The cause of marine transgression may be that since Late Cretaceous and Paleocene tension power had predominated ground-stress conditions of the East China Sea and developed a series of half-graben-like basins filled by a huge thick sediment of the Early Tertiary in the shelf of Huabei–Bohai gulf, Subei–South Yellow Sea and East China Sea. Consequently, seawater transgressed from the East China Sea to the Yellow Sea and linked half-graben-like basins on the shelf to the sea within a short period. During the sedimentation of the Late Cretaceous Taizhou Formation and Paleocene Funing Formation, the Subei basin had formed the ostracoda-enriched dark shale, including predominantly the whole basin E1f2 Formation and E1f4 Formation and local K2t2 Formation, which became the main source rocks of the basin. The evidence of paleontology, minerals in rocks and geochemistry can help confirm the environment of the lake basin that developed during the Late Cretaceous and Paleocene. We generally designate this environment as “near sea lake basin” and the sea-transgressed layer and member as “transgression lake basin”. Whereas, it is generally called “inland lake and river alluvium plain” during the sedimentation of the Eocene Dainan Formation and Sanduo Formation. This research is not only significant to the paleogeographic reconstruction of the Subei basin during the Late Cretaceous and Paleocene, but also important in understanding the development and distribution of the source rocks and evaluating the potential of oil and gas generation.
  • Sedimentary charateristics and hydrocarbon accumulation in Northeast Sichuan basin
    TANG Liangjie, LI Lei, LI Rufeng, LI Jianming, WU Xiling
    2008, 2(1): 120-125. https://doi.org/10.1007/s11707-008-0001-5
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    Northeast Sichuan basin is a Mesozoic–Cenozoic basin in the northern margin of the Yangtze plate which has a complex tectonic background and hydrocarbon accumulation history. By means of the analysis method of wave processes, major cycles of sedimentary wave process in this basin have been studied. The results show that there are five-order cycles corresponding to 760, 220, 100, 35 and 20 Ma respectively, two first-order sedimentary cycles (220 Ma) and four second-order sedimentary cycles (100 Ma). The authors find that the second-order sedimentary cycles are well matched with reservoir formation cycles through studying the relationship between second-order sedimentary cycles and reservoir formation cycles, and divide three reservoir formation cycles in this basin.