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西湖凹陷超压普遍发育,成因机制复杂,目前研究未见深入.从产生超压的主要因素入手,采用定性分析与定量计算相结合的方法,基于超压层段的测井响应特征、速度与垂直有效应力、沉积速率与孔隙度演化史、压力演化史与生烃强度史耦合的初步判断,再通过定量的计算综合分析了西湖凹陷超压的成因机制.研究表明:不均衡压实作用和生烃作用是西湖凹陷超压形成的主要机制,但在不同的区带有一定的差异.其中保俶斜坡带以不均衡压实作用为主,经过估算生烃作用贡献率为23%~57%,平均达到41%;而在中央背斜带超压形成机制有两种模式,大部分是以生烃作用为主的增压模式,贡献率为51%~78%;个别井位研究显示以不均衡压实作用为主的增压模式.在三潭深凹超压的形成中,不均衡压实作用与生烃作用相当,生烃作用增压稍强于不均衡压实作用增压,生烃作用的平均贡献率为60%左右.
The overpressure in Xihu sag is generally developed and its mechanism is complicated, but no deep research has been done at present.According to the main factors of overpressure generation, the method of combining qualitative analysis with quantitative calculation is used to calculate the overpressure of the overpressured zone based on logging response characteristics, Vertical effective stress, sedimentation rate and porosity evolution history, pressure evolution history and hydrocarbon generation intensity history, and then analyzed quantitatively the formation mechanism of overpressure in Xihu Sag. The results show that the imbalanced compaction and Hydrocarbon generation is the main mechanism of overpressure formation in the West Lake Sag, but there are some differences in different zones, of which the unbalanced compaction effect is the main slope of Baoji slope, and the contribution rate of hydrocarbon generation is estimated to be 23% -57 %, With an average of 41%. However, there are two modes of overpressure formation in the central anticline, most of which are supercharged modes with a contribution rate of 51% -78%. Some well positions In the formation of Santan deep overpressure, the unbalanced compaction is similar to that of hydrocarbon generation, and the supercharging of hydrocarbon generation is slightly stronger than that of unbalanced compaction , The average contribution rate of hydrocarbon generation About 60%.