Structural Styles Features And Their Relation With Oil And Gas In Liaozhong Depression And Its Adjacent Areas

Based on the information of regional geology, earthquake and drilling data, started from the structural interpretation of seismic data and combined with the results of previous research, structural and evolutional features of the trunk fracture zones in Liaozhong Depression are studied. And on this basis, the characteristics of structural styles are summarized in Liaozhong Depression and its adjacent areas, and origins of the structural styles are analyzed. Finally combined the factor of hydrocarbon accumulation, relation between the structural styles with oil and gas is analyzed.The trunk fracture zones in Liaozhong depression control monolithic tectonic framework of the depression, and divide the depression into eastern uplifting, central sag, and western uplifting. Liaozhong 1 fracture zones crossed the whole Liaozhong sag from the south to the north. There are differences in nature of the fracture breaking stress along the strike direction. And nature of the fracture breaking stress mainly includes elongation, strike-slip, and their complex. Nature of Liaozhong 2 fracture zones breaking stress in the north of Liaozhong sag shows strike slip, and their lines of dip are variety along the fracture strike direction, which reveals ribbon effect of strike slip fault. Liaoxi 3 fracture zones breaking stress in the north of Liaodongwan show elongation.There are several types tectonic styles developed in Liaozhong depression and its adjacent areas, such as elongational tectonic styles, strike-slip tectonic styles, complex tectonic styles, diapire tectonic styles and reversed tectonic styles that related to fracture.The main activity periods of the trunk fracture zones in Liaozhong depression: â‘ The strong extension period: in sedimentation period from Kongdian formation to member 3 of Shahejie formation, Liaozhong 1 fault, Liaozhong 2 fault, and Liaoxi 3 fault were mainly characterized by extension motioning. â‘¡The right strike-slip activity period: in sedimentation period from member 3 of Dongying formation to the member 2, because of the right strike-slip activity of the Tan-Lu fault zone the three trunk fracture zones were subjected to exploitation and renovation in different degree. â‘¢The inverse activity period: in the end of Dongying sedimentation, regional uplifting of the basin occurred, so there were inverse activities of faults in some areas. â‘£Weakly strike-slip activity or extension period: in sedimentation period from Guantao formation to Pingyuan formation, Liaozhong 1 fault and Liaozhong 2 fault were mainly characterized by weakly strike-slip motioning, and Liaoxi 3 fault was mainly characterized by weakly extension motioning.Multiple types tectonic styles, resulted in extension motioning and strike-slip motioning of the trunk fracture zones in Liaozhong depression, form a variety of traps. The deep traps related to extension activities of faults, and the shallow traps related to strike-slip activities of faults. The trunk fracture zones in Liaozhong depression, connecting source rocks with traps, can be used as vertical migration channels of oil and gas.