先存断层产状及其组合关系对反转构造变形影响的离散元数值模拟研究

反转构造在我国含油气盆地中广泛发育,对于油气勘探具有重要意义.本文采用离散元颗粒流方法研究了先存正断层的陡缓程度、倾向组合关系和距离挤压端的远近等因素对断层的反转构造发育及其反转量的影响.模拟结果显示,先存断层的产状及其距离挤压端的远近会影响先存断层的反转次序、反转量,进而影响盖层内反转构造的发育.当先存正断层倾向指向...

Discrete Element Modelling of the Impacts of Attitudes and Geometric Parameters of Pre-existing Faults on Inversion Structures

Inversion structures are widely developed in China’s marine and continental basins,which are of great significance for oil and gas exploration.Using discrete element modeling,we investigated the influence of dip angles,dip directions and relative distances between pre-existing faults and the shortening boundary on the formation of inversion structures.The modelling results show that these factors have a great impact on the inversion order,inversion amount,and the kinematics of the inversion structures.When the pre-existing normal faults dip towards the shortening boundary,if the gently-dipping normal fault is closer to the shortening boundary,the inversion structures are mainly developed along the gently-dipping fault instead of the steeply-dipping fault;if the steeply-dipping fault is closer to the shortening boundary,the inversion structures are developed along both the steeply-dipping and the gently-dipping faults.When the pre-existing normal faults dip away from the shortening boundary,the inversion structures are developed along both the steeply-dipping and the gently-dipping faults,independent of the distance between the pre-existing fault and the shortening boundary.When the two pre-existing faults are dipping towards each other,the inversion structures are mainly developed along the gently-dipping fault instead of the steeply-dipping fault in the model containing a gently-dipping normal fault closer to the shortening boundary;the inversion structures are developed along both the steeply-dipping and the gently-dipping faults in the model containing a steeply-dipping fault closer to the shortening boundary.In models where both the gently-dipping and the steeply-dipping faults are inverted,the fault closer to the shortening boundary has a larger amount of inversion.The similarity between the modelling results and the seismic section in the central inversion zone of the Xihu Depression further demonstrates that the fault closer to the shortening boundary has larger amount of inversion.