Structural Characteristics Of Zhenwu Fault Zone

Structures in Subei basin are broken and fragmented in that tectonic movements in Subei Area were frequent ever since the Mesozoic era, which caused overlap and composition of multi-stage basins. Structures in zhenwu fault zone, the southern boundary of Gaoyou Sag in subei basin, are complicated. Under the influence of zhenâ‘ fault, there is not only similarity but also dissimilarity in activity among faults in various levels. Therefore, study on the structural characteristics, evolutionary history and origin of faults in zhenwu fault zone has great theoretical value on the guidance of oil & gas exploration.Under the guidance of theories on structural geometry, kinology etc., structures and strata on typical profiles were carefully interpreted on the basis of seismic profiles, well logging data and other geological data. Geometric characteristics and law of activity of faults in Zhenwu fault zone were analyzed; structural evolution and genesis of the fault zone were also studied.Zhenwu fault zone were divided into four sections on the basis of geometrical characteristics of faults analyzed. Strike, shape and occurrence on profile of main faults, faults complex and distribution of low-order faults are all different in different sections.Evolution characteristics and law of activity of faults in zhenwu fault zone were summarized by calculating average activity rate of faults in each period and analyzing structural evolution history reflected in appropriate depth profiles selected. Main faults in zhenwu fault zone are active in a long period while low-order faults are usually active at one time and distribute intensively. It is proved that zhenâ‘¡fault is composed of three secondary faults by finding proofs in stratigraphic thickness and fault dip. Evolution models of zhenâ‘¡fault and zhenwu fault zone were also summarized.Accommodation zones in zhenwu fault zone were found, classified and graded by signs of geometrical characteristics, thickness and depth of strata as well as active characteristics of faults. Reasons that lead to the formation of accommodation zones in zhenwu fault zone were also analyzed.It is summarized that the inheritance from the occurrence of boundary fault is origin of faults near to the boundary fault. Faults on the concave side of the boundary fault tend to fill up the bend before it develops alone the boundary fault. Stress concentration at the end of main fault, uneven distribution of horizontal stress and long-term growth of accommodation zones are all causes that lead to the formation of low-order faults in zhenwu fault zone.