摘要
基于反时外推的概念,我们利用有限元方法发展了弹性波叠前反时偏移算法,并在去年用这种方法对有偏移距的合成地表记录进行偏移。在本文中,我们用此方法对合成地表数据和合成VSP数据同时进行偏移。使用地表数据兼VSP数据偏移结果得到改善,偏移成像被准确地收敛于反射点的真实深度。偏移深度剖面上的另一改善是通过引入“调整场”显示技术而达到的,它将偏移剖面的垂直和水平分量结合起来。以往偏移剖面上使得每单一位移分量的偏移成像变得模糊不清的噪音现在在“调整场”偏移深度剖面上被很好地消去。随即,偏移成像更加清楚地勾划出反射点。为展示利用地表数据兼VSP记录和引入“调整场”显示技术所得的改善。这里给出二个合成实例:一个是弹性半空间上二个弹性层;另一个是弹性半空间上倾斜与水平的组合层。
Based on the concept of reverse-time extrapolation, we have developed the pre-stack reverse-time migration method for elastic waves by means of the finite element method and applied it to migrate offset synthetic surface data last year. In this paper we apply the method to migrate both the synthetic surface data and the synthetic VSP (vertical seismic profile) data simultaneously. The migration results are improved by using both the surface data and VSP data: the migration images are accurately converged to the true depth of the reflec -tors.Another improvement in the migrated depth section is made by introducing 'modified field' display technique, which combines the vertical and the horizontal component migrated sections. The noise in the previously migrated section, which blurs the migration images in each individual displacement component, is now well eliminated in the ' modified field' migrated, depth section. Consequently, the migration images delineate the reflectors more clearly.
Two synthetic examples, one with two elastic layers over an elastic half-space and the other with a composite elastic dipping and horizontal layer over an elastic half-space, are presented to show the improvement by using both the surface data and VSP data and by introducing ' modified field ' display technique.
出处
《石油物探》
EI
CSCD
北大核心
1990年第3期22-34,共13页
Geophysical Prospecting For Petroleum