Syndepositional Fault Analysis And Its Effect On Sedimentary System In Xingouzui Formation, Jianghan Basin

Jianghan is a faulted basin, developing in Cretaceous-Tertiary, East China. Xingouzui formation is one of the most important hydrocarbon reservoirs. The filling pattern and structure are closely related to hydrocarbon generation, migration and accumulation. Up to now, there is not much research on syndepositional fault or its relationship with reservoir and hydrocarbon resources rock.With the guidance of Structure Geology, Applied Sedimentology, Basin Analysis and Sequence Stratigraphy, added with seismic and well log interpretation, cores, the structure-stratigraphy framework and sedimentary system distribution are established. Main syndepositional faults are recognized and their assemblage patterns are summed up, both horizontally and vertically. So, the syndepositional faults are divided into four groups horizontally and into five patterns vertically. By calculating the Growth Index and tectonic subsidence modeling, if Houganglongwan Fault is taken as a boundary, the active intensity of syndepositional faults in western basin is intenser than the eastern basin. In SQXXII, the NE aligement faults are intenser, but in SQXXIII, the NW, NNE aligement faults are intenser.The reconstruction of the palaeogeomorphology is based on the stripped strata resumption, compaction resumption and palaeobathymetry adjustment. The results tell us that the palaeogeomorphology features during SQXXIII, SQXXII, and SQXXI are much the same as features in Xingouzui period, only with partly difference. This illustrates that syndepositional faults have homochronous effect on palaeo-geomorphology during the active state. According to the cutting depth, the developmental scale, developmental phase and the effects on palaeogeomorphology, syndepositional faults in Jianghan basin are divided into three hierarchy:Basin Margin Syndepositional Faults-controlling the development of a depression; Intrabasinal Syndepositional Faults-controlling the development of a sag; Intrabasinal Syndepositional Faults-controlling the development of a secondary sag.Combined the palaeogeomorphology background, provenance types, faults assemblage patterns, seismic-well sedimentary system interpretation, seismic attribute analysis, sand content, sand thickness and core description, there are six filling patterns for syndepositional faults’controlling effects on sedimentary system.During Xingouzui stage, East China was experiencing the SN-NE force of compression, consequently, the NNE, NE sysdepositonal faults came out. The regional structure activity led to the reactivation of some basement faults. Also, in early Palaeocene, volcanic activity was common, and this caused some small scale snydepositonal faults.Guided by hydrocarbon bearing system theory, combined with the relationship between syndepositional faults and reservoir & hydrocarbon resources rock, three favorable places for prospecting are supposed:Wancheng area; Zongkou Panchang syncline and the rim area; Zhanggou-Pengchang fault area.