滨里海盆地东缘速度建模方法研究与应用

Research and application of the velocity modeling method for the eastern margin of the Pre-Caspian Basin

滨里海盆地东缘阿克若尔地区石炭系碳酸盐岩顶面低幅度构造具有较大的油气勘探潜力,由于上覆下二叠统地层分布复杂,横向速度变化大,使得石炭系低幅度构造成图存在很大难度;为了解决研究区构造快速成图的问题,通过3种速度建模方法对比,优选出分频层速度反演方法,建立研究区的速度模型,解决了分频层速度反演受常规层速度反演方法横向连续性的限制问题,对下二叠统碳酸盐岩异常体的速度刻画更为准确;同时,分频层速度反演方法与井—震速度谱协同速度建模方法和常规井约束层速度反演相对比,提高了研究区下伏石炭系低幅度构造的深度域成图精度,取得了较好的效果。

The low-amplitude structures on the top of the Carboniferous carbonate rocks in the Akzor area on the eastern margin of the Pre-Caspian Basin show considerable potential for oil and gas exploration.However,the complex distribution of overlying Lower Permian strata and significant changes in lateral velocities pose high challenges for the mapping of the Carboniferous low-amplitude structures.To achieve the rapid mapping of the structures in the study area,this study selected the frequency-division interval velocity inversion method to build the velocity model for the study area after comparing three methods for velocity modeling.The velocity model built in this study,solving the problem that the frequency-division interval velocity inversion is constrained by the lateral continuity of conventional interval velocity inversion methods,yielded more accurate velocity characterization of anomalies in the Lower Permian carbonate rocks.Moreover,compared to the collaborative velocity modeling method based on well-seismic velocity spectra and the conventional interval velocity inversion method constrained by log data,the frequency-division interval velocity inversion method effectively improved the depth-domain mapping accuracy of the underlying Carboniferous low-amplitude structures in the study area,boasting high performance.