Structural Features And Their Relationship With The Petroleum And Gas In Hulin Basin

Based on the abundant first-hand materials, the structural features, geodynamic environment features, basin evolution and their relationship with oil and gas in Hulin Basin are studied by field geological survey, geological interpretation of seismic profiles, balanced cross sections and subsidence-burial history analysis. The main progresses are made as follows:Hulin Basin is a typical binary structure,including pre-Mesozoic basement and Mesozoic-Cenozoic cover. The basement is composed of the Proterozoic and Paleozoic, mainly granitic plutons and metamorphic rocks. The cover is composed of Mesozoic-Cenozoic sedimentary rocks, the sedimentary sequence from bottom to top including Nanshuangyashan, Datushan, Peide, Qihulin, Xiayunshan, Shangyunshan,Zhushan,Dongshan,Hulin,Fujin and Daotaiqiao formations.Nine deep faults were recognized in Hulin Basin, based on gravity and geomagnetic interpretations, and the NE-trending faults are most important large-scale faults, which controlled the structural framework and volcanic activities in basin.Based on characteristics of basement, buried depth and thicknesses, types of sediments, and geophysical characteristics, the basin can be subdivided into 6 tectonic units(grade I), including 3 rises and 3 rifts:Yunshan sag area、Yingchun uplifted area、Qihulinhe sag area、central uplifted zone、Muleng-Xingkai sag area、Jinyinku uplifted area.Qihulinhe sag is one of six tectonic units(grade I). The deep fault FQ8 controlled the boundary of the sag and formed a series of NE oriented normal faults. By the fault size, development level and the fault effect during the development of fault can be divided into three levels, namely boundary faults, main faults and secondary faults. The results of tectonic interpretation show that the structural morphology of the studied area is relatively simple, mostly single-slope and depression, locally fault blocks and faulted nose.The evolution history of Hulin basin can be classified as:In late Jurassic, the basin is dominated by regional extension and rifting. Faulting and massive volcanic eruption contributed to coarse clastic which deposited quickly in the early stage; In early Cretaceous, the basin experienced a stage of regional rifting and depression. Qihulin and Yunshan formations represent the most flourished depression development. In latest Cretaceous, there is a tectonic inversion due to effects of Pacific tectonic activities. The rift basin begin to entirely uplift and to be eroded. In the Middle-Late Paleogene, the basin entered to a stage of regional rifting and depression again.According to the analysis of petroleum geology, the relationship between structural evolution and the accumulation of oil and gas is briefly introduced in the paper.