南美奥连特盆地东部斜坡带构造变形物理模拟

Physical Modeling on Structural Deformation in the Eastern Slope of the Oriente Basin, Southern America

南美奥连特盆地东部斜坡带发育大量与正断层反转活动有关的断背斜构造,也是非常有利的油气聚集区。文章主要应用比例化物理模拟实验方法,以奥连特盆地东部斜坡带为模拟对象,来分析早期正断层的陡缓程度、倾向组合以及断层间距等因素对正断层复活反转过程中断背斜构造形成的影响。模拟结果表明,当早期正断层均向挤压端倾斜时,如果陡倾角正断层更靠近挤压端,则陡、缓正断层都易发生反转,并形成断背斜构造。但当缓倾角正断层更靠近挤压端时,则该断层会吸收绝大部分的挤压量,而相对远离挤压端的陡倾角正断层不易发生反转。当早期正断层倾向相对时,距离挤压端更近的陡倾角正断层会吸收一定的挤压量,从而发生反转并形成背斜构造。而相对远离挤压端的缓倾角正断层是否发生复活反转则主要受断层间距的影响,距离越小越有利于断层反转。上述认识对在奥连特盆地东部斜坡带寻找与早期正断层反转有关的断背斜圈闭具有一定指导意义。

Faulted anticlines caused by inversion of early normal faults are commonly developed in the eastern slope zone of theOriente Basin, southern America. These faulted anticlines are favorable traps for hydrocarbon accumulation. Using scaled physicalmodeling, this study addresses the influence of dip angles, combinations and distances between early normal faults on the formation offaulted anticlines in the eastern slope zone of the Oriente Basin. Results show that when early normal faults dip toward the compressionend and the steep dip angle fault is relatively closer to the compression end, normal faults with steep and gentle dip angles are easy toreact and invert, and then faulted anticlines would form in hanging walls. In contrast, if the normal fault with gentle dip angle is closerto the compression end, it would absorb the majority of compression strains, and the steep dip-angle fault which is far away to thecompression end is difficult to invert. If early normal faults dip toward each other, the steep dip-angle fault which is closer to the compression end would invert and form faulted anticline in hanging wall. Whether the gentle dip fault inverts is affected by the distancebetween normal faults. The shorter the distance, the fault with gentle dip angle is more likely to invert. These results provide useful datato locate favorable traps resulted from inversion of early normal faults in the study area.