Multicomponent and source-free converted-wave reverse time migration for VSP
Multicomponent and source-free converted-wave reverse time migration for VSP
复制标题
DOI：
10.1190/segam2018-2994695.1
复制
发表时间：
2018-08
期刊：
影响因子：
--
通讯作者：
Yue Du;Y. Li;Jizhong Yang;A. Cheng;X. Fang
中科院分区：
文献类型：
--
作者：
Yue Du;Y. Li;Jizhong Yang;A. Cheng;X. Fang
由于其几何形状，VSP 具有检测和监测钻孔周围物体的优势。多组分 VSP 可以添加有关井筒附近地下弹性特性的丰富信息。然而，由于波物理学的复杂性，弹性波成像一直具有挑战性。近地表结构的不确定性也会影响图像精度。在本文中，我们利用弹性图像条件和标量波动方程进行 VSP 逆时偏移 (RTM) 来对复杂结构进行成像。我们还提供了一种使用无源转换波 (SFCW) RTM 成像进行 VSP 的替代方法，以避免复杂的覆盖结构。通过多个数值示例，PP、PS 和 SFCW 图像展示了对井眼周围复杂沉积层进行成像的能力。同时使用 PP 和 PS 图像可以为复杂的地下提供良好的解释，但它们依赖于相对正确的速度模型。 SFCW 图像是面向目标的，对于复杂的上覆层速度问题具有鲁棒性，但对于远离钻孔的区域缺乏照明。
VSP has advantages to detect and monitor the objects around the borehole due to its geometry. Multicomponent VSP can add rich information about the elastic properties of the subsurface near wellbore. However, the elastic wave imaging has been challenging due to the complexities in wave physics. The uncertainties in near surface structure will also affect the image accuracy. In this abstract we utilize the elastic image conditions with scalar wave equations for VSP reverse-time migration (RTM) to image the complex structures. We also provide an alternative way of using the source-free convertedwave (SFCW) RTM imaging for VSP to avoid the complex overburden structures. With multiple numerical examples, the PP, PS and SFCW images demonstrate the ability to image the complex sediment layers around the wellbore. Using both PP and PS image can provide a good interpretation for the complex subsurface but they rely on a relatively correct velocity model. The SFCW image is target oriented and is robust for the complex overburden velocity issue, while it has a lack of illumination for the areas further away from the borehole.