沾化凹陷构造—热演化研究

根据镜质体反射率利用EASY%Ro动力学模型对济阳坳陷沾化凹陷进行热演化模拟,通过对沾化凹陷四个洼陷20口井的单井热史模拟分析了该区新生代的热演化状况.研究表明,沾化凹陷在地质演化过程中其古地温是逐渐降低的,沙河街组沉积时期地温梯度为3.8~4.8℃/100m,此后其地温梯度缓慢降低至现今的2.9~3.6℃/100m.并且其内部的各洼陷之间的热演化历史存在差异,在整个新生代演化历史中,埕北洼陷的平均古地温梯度最高,其次是孤南—孤东洼陷,桩西—五号桩地区最低,而渤南洼陷则介于它们之间.新生代以来,沾化凹陷岩浆活动(构造-热事件)十分强烈,且这种岩浆活动受基底断裂的控制.各洼陷热演化特征有一定的差异是由于它们处于不同构造部位并且受不同方向和不同发育时间的断裂控制而造成的,也即构造作用和岩浆活动双重作用的结果.

Tectonic-thermal evolution of Zhanhua Sag

The thermal evolution of Zhanhua Sag in Jiyang Depression is simulated by EASY%Ro kinetic model according to vit-rinite reflectance. The thermal evolution state of the sag during the Cenozoic period is analyzed based on the simulation of thermal evolution history of 20 wells in four subsags in Zhanhua Sag. The result indicates that the geotemperature gradient of the sag is decreasing in geological evolution; it is 3.8-4.8 ℃/100m in the sedimentary period of Shahejie Formation; the geotemperature gradient is decreasing since then and now it is 2.9-3.6℃ /100m. There is difference in the thermal evolution history of the four subsags. During whole Cenozoic, the average geotemperature gradient of Chengbei subsag is the highest, Next is Gunan-Gudong subsag, that of Bo-nan subsag is the third, and the lowest average geotemperature gradient is in Zhuangxi - Wuhaozhuang area. Since Cenozoic period, the magmatic activity (tectonic-thermal event) in Zhanhua Sag is very strong and it is controlled by basement fracture. There is difference in the thermal evolution character of different subsags because they are in different locations of the structure and are controlled by the fractures which are in different directions and developed in different period.