碳酸盐岩溶蚀窗的形成及地质意义

设计了温度压力同时变化的溶蚀模拟实验,得到了一组近似箱状曲线的溶蚀率变化曲线。溶蚀作用在开始阶段随温度、压力的上升,溶蚀率上升,在60～120℃（13～31MPa）形成一个高峰箱顶。该曲线表明,在一定深度（溶蚀窗）范围内,CO₂对碳酸盐岩的溶蚀能力保持在较高的水平。而当深度进一步增加时,溶蚀能力急剧下降,当埋深相当于4 000 m左右时,溶蚀能力达到最低,此时的溶蚀能力仅比常温下略高一些。该溶蚀试验结果对于深埋溶蚀作用的理解及有利储层的预测有着重要的意义。

Dissolution window of carbonate rocks and its geological significance

Box-shaped variation curves of dissolution rates of carbonate rocks in CO₂ aqueous solution were obtained from simulated dissolution experiments designed with simultaneously changing temperature and pressure. It shows that the dissolution of carbonate samples increases with rising temperature from the very beginning and then forms a box-like plateau when the temperature reaches 60-120℃and pressure reaches 13-31 MPa.The curves indicate that the dissolution rate of carbonate rocks in CO₂ aqueous solution remains high within a certain burial depth range（the so-called dissolution window） of the carbonate rocks.When the depth is beyond the upper bound of the range,the dissolution rate declines rapidly and reaches the lowest point（only a little bit higher than that at room temperature） at the depth of about 4 000 meters（150℃,41 MPa）.The experiment and its results bear great significances for a better understanding of carbonate reservoirs and a more accurate prediction of favorable exploration targets.