利用相邻地震反射能量组合特征排除“亮点”陷阱——以川西坳陷德阳向斜为例

川西坳陷内中浅层岩性气藏勘探中,地震振幅亮点异常是储层识别的重要依据,但越来越多的钻井证实“亮点”异常,也可能是泥岩、薄互层、致密砂体等众多非储层带来的陷阱。以川西坳陷德阳向斜内,典型完钻井井震分析为基础,总结出不同物性砂体地震响应特征,建立起“顶部强波谷、底部强波峰”、相邻波峰反射能量“上弱下强”的优质储层识别模式,同时利用相邻波峰反射能量“上强下弱,双强”等特征来排除振幅“亮点”陷阱,提高基于地震反射能量的储层预测精度,该方法具有简单、直观,易实现等特征,同时经钻井证实,预测结果准确可靠。

Using Adjacent Seismic Reflection Characteristics of the Energy Mix to Exclude “Bright Spot” Trap:Taking Deyang Syncline in Western Sichuan Depression as an Example

During the shallow lithologic gas reservoir exploration in the western Sichuan Depression,seismic amplitude “bright spot” anomaly is an important basis for the reservoir identification.However,more and more drilling wells confirmed that the “bright spot” anomaly may be a trap resulted from the non-reservoir such as mudstone,thin-interbedded layer,dense sandbody.Based on the typical drilled well seismic analysis in the Deyang syncline,western Sichuan Depression,this paper summarized the seismic response characteristics of sandbody with different physical properties,and established a high quality reservoir identification model with features of “strong trough top,strong peak bottom” and “weak top and strong bottom” of adjacent peak reflection energy.At the mean time,seismic amplitude “bright spot” trap can be excluded by using the characteristics such as “strong top and weak bottom,double strong” of adjacent peak reflection energy,improve the reservoir prediction accuracy which is based on seismic energy reflection.This method is simple,intuitive,easy to realize,moreover,it is accurate and reliable which has been proved by the drilling results.