蒙脱石伊利石化对含油气盆地地层压力影响的定量研究

Evaluation of the Contribution of Illitization of Smectite to the Geopressure in Oil-Bearing Basin

异常高压带是含油气系统研究和资源勘探领域的热点之一。本文以东营凹陷为例,定量研究了粘土矿物成岩作用对地层压力聚集的贡献。在系统分析粘土矿物组成、成岩物理化学条件的基础上,模拟计算了蒙脱石伊利石化的动力学过程,计算了脱水造成的体积变化和硅钙释放量。指出脱水作用造成的体积变化不是形成异常高压的重要因素,但硅钙的释放可能对封隔层的形成起着非常关键的作用,对地层异常压力的积聚和保持有重要贡献。

Overpressure is an important issue in the research and exploration of petroleum system. Based on the case study of Dongying Basin, we evaluated quantitatively the contribution of illitization of smectite to the geopressure during diagensis processes. Clay component and physical-chemical parameters of digenesis were analysed using XRD and basin modeling,respectively, and the results are used in the dynamic chemical simulation of illitization processes. Furthermore, the volume increase due to dehydration and release of Si, Ca attributed to illitization were calculated by integrating relative geological information. According to the obtained results, it is suggested that the expanding of water in smectite because of dehydration does not contribute to the increase in geopressure significatively, and that the release of Ca and Si plays an important role in the overpressure seals, which is of great significance for the accumulation of overpressre in Dongying Basin.