Interpretation of AVO anomalies
Interpretation of AVO anomalies
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DOI：
10.1190/1.3467825
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发表时间：
2010-09
期刊：
影响因子：
3.3
通讯作者：
D. Foster;R. G. Keys;F. D. Lane
中科院分区：
文献类型：
--
作者：
D. Foster;R. G. Keys;F. D. Lane
我们研究了岩石和流体性质的变化对振幅随炮检距变化的AVO响应的影响。在斜率截距域中，来自湿砂和页岩的反射落在我们称之为流体线的趋势上或附近。来自含气或轻烃砂的地形的反射落在近似平行于流体线的方向上;来自含气和轻烃砂的底部的反射落在流体线的相对侧的平行方向上。地震数据的极性标准决定了这些来自含烃砂顶部的反射是在流体线之下还是之上。通常，砂和页岩的岩石性质不同，因此来自砂/页岩界面的反射也从流体线移位。这些趋势与流体线的距离取决于P波速度VP和S波速度VS之比的对比度。该比率是孔隙流体可压缩性的函数，并且意味着与流体线的距离随着可压缩性的增加而增加。来自湿砂的反射比与烃有关的反射更接近流体线。孔隙度的变化影响声阻抗，但不显著影响VP/VS对比，因此，孔隙度的变化使AVO响应沿着近似平行于流体线的趋势移动，这些观测对于解释流体、岩性和孔隙度之间的AVO异常是有用的。
We investigate the effects of changes in rock and fluid properties on amplitude-variation-with-offset AVO responses. In the slope-intercept domain, reflections from wet sands and shales fall on or near a trend that we call the fluid line.Reflectionsfromthetopofsandscontaininggasorlight hydrocarbonsfallonatrendapproximatelyparalleltothefluidline;reflectionsfromthebaseofgassandsfallonaparallel trendontheopposingsideofthefluidline.Thepolaritystandard of the seismic data dictates whether these reflections from the top of hydrocarbon-bearing sands are below or above the fluid line. Typically, rock properties of sands and shales differ, and therefore reflections from sand/shale interfaces are also displaced from the fluid line. The distance of these trends from the fluid line depends upon the contrast of the ratio of P-wave velocity VP and S-wave velocity VS. This ratio is a function of pore-fluid compressibility and implies that distance from the fluid line increases with increasing compressibility. Reflections from wet sands are closer to the fluid line than hydrocarbon-related reflections. Porosity changes affect acoustic impedance but do not significantly impacttheVP /VScontrast.Asaresult,porositychangesmove theAVO response along trends approximately parallel to the fluidline.TheseobservationsareusefulforinterpretingAVO anomaliesintermsoffluids,lithology,andporosity.