Huang L.,China Academy of Petroleum Exploration and Exploitation |
Xu Z.-Y.,China Academy of Petroleum Exploration and Exploitation |
Wang P.-W.,China Academy of Petroleum Exploration and Exploitation |
Xiong S.-Y.,China Academy of Petroleum Exploration and Exploitation
Geology in China | Year: 2012
Guizhou depression has experienced three stages of tectonic evolution, i.e., the early Proto-Tethys rift basin and the late orogenic fold,ancient Tethys rift basin stage,and the Neo-Tethys oroganic transformation phase.With the large-scale transgression in the early Devonian, there developed platform sag and slope facies dark shale and coal-bearing coast swamp facies framework in this area,which mainly included Lower Devonian Tangding Formation black shale,Middle Devonian Luofu Formation black shale and lower Carboniferous Yanguan Formation black shale.Researches have shown that the upper Paleozoic marine shale, characterized by high abundance of organic matter,good types and high-over- mature stage of evolution, has favorable conditions for shale gas.Up to date,Upper Paleozoic shale has been found in many gas shows in Guizhong depression,which has similar geological condition to typical shale gas basins in eastern United States (Appalachian,Ford Voss and Michigan basin). According to the analogy method,the amount of Upper Paleozoic shale gas resources is preliminarily estimated to be about 12.34 1012m3 in the depression, which indicates that the area had huge shale gas resource potential.
Wang W.,China University of Petroleum - East China |
Zhou W.,China University of Petroleum - East China |
Xu Z.,China Academy of Petroleum Exploration and Exploitation
Zhongguo Kuangye Daxue Xuebao/Journal of China University of Mining and Technology | Year: 2014
Based on the demand of strategic selection of exploration areas, this study carried out the field geological survey, balance-restoring structure, and tectonic framework and evolution, and analyzed the prototype basin. The results indicate that: since the late Paleozoic, Qiannan depression has mainly experienced the following tactic movement, such as Sibao, Jinning, Guangxi, Indosinian, Yanshan, etc., as well as three stage basin evolutions and four stage basin-mountain transformation, which makes its tectonic deformation and distribution of oil and gas complicated. The depression is bounded as a triangle in shape by three discordogenic faults, namely Tongren-Sandu, Guiyang-Zhenyuan and Ziyun-Luodian. Near SN trending, Tongren-Sandu fault is protruding curvedly westward, as a west-dipping thrust fault; Guiyang-Zhenyuan fault is NW trending, and fault plane is vertical, dextral transcompression; Ziyun-Luodian fault is NW trending, and fault plane is vertical, sinistral transcompression. The depression mainly developed nearly parallelly, and within it there are roughly equally-spaced NS trending fold thrust structures, associated normal faults with EW trending; near the N-S boundary we can see a small amount of the NE and NW trending faults. The conditions of construction show that they are compressional tectonic system which was caused by EW trending stress field. Depending on the analysis of periphery outcrop as well as EW and NS seismic profiles, we can conclude that north-eastern depression is strongly uplifted and the southwest part is continuous sedimentation; it is a typical thrust-nappe tectonic system which could be clearly divided into the east root-belt, the middle-belt and the front-belt. The root-belt has the strongest deformation and the deformation weakened westwards. The south area of Changshun-Sandu has huge magnitude of the subsidence and great thickness of sedimentary strata, and the tectonic deformation is relatively weak. Therefore, it is a favorable area for hydrocarbon preservation conditions. We evaluate the hydrocarbon preservation conditions qualitatively and quantitatively in application of the tectonic intensity index and then selectet 6 explorative targets.