中国东部地区油气层的AVO检测标志

DETECTION OF INDICATIONS FOR RESERVOIR BY AVO, EASTERN PART OF CHINA

油气层反射特征预测是油气检测的一项基础工作,它为油气检测建立正确的检测标志。油气层反射特征预测的关键是岩石物理参数的准确确定。我们利用斯伦贝谢公司长源距全波声波测井和密度测井资料整理了东部地区的岩石物理参数。根据胜利油田对浅层泥岩纵波速度的校正结果,对浅层泥岩物理参数进行了改正。然后,利用AVO技术模拟了地震资料采集和处理过程;对油气层顶面和薄油气层进行了叠前和叠后的模型研究;给出了叠后的油气层反射振幅标志,叠前的油气层AVO特征及波形特征。引用的油气层实例表明,在准确确定岩石物理参数的基础上,从AVO的观点建立叠后和叠前油气检测标志,更符合油气层反射的实际情况。完整的油气检测步骤应是:首先按AVO方法预测叠后和叠前的油气层反射特征,在地震剖面上寻找油气层反射振幅异常。然后在叠前道集记录上分析振幅随炮检距的变化特征,进一步确定油气层。

It is a fundamental work for oil/gas detection to predict the reflection characteristic of the reservoir, because it can setup appropriate indications for oil/gas detection. The key link for reservoir reflection character prediction is the correct determination for the physical parameters of' the rock. The physical parameters of the rock in the eastern part of China were examined with the data provided by the long spaced full-wave acoustic logging as well as the density logging based on the Schlumberger's technique. In line with the corrected longitudinal wave velocity of the shallow mudstone of the Shengli Oil Field,the physical parameters of the shallow mudstone were modified. The procedure of the analogue acquisition and the analogue processing of the seismic data were made by the AVO technique. The indications of the reflection amplitude of the reservoir aftei stack,the character of the reservoir in AVO and waveform before stack were given after the modelling for the top of the reservoir and the thin oil -beanng formation have been made befor and after stacking. Examples show that it woulo be more in comformity with the practice to found the indications for oil/gas detection before and after the stack has been made,but it must be a correct determination for the physical parameters of the rock. The complete procedure for oil/gas detection should be:to predict the reflection character of the reservoir before and after stack by AVO technique ,then,to search for the reflection amplitude anomaly of the reservoir on seismic section and to analyse the character of the amplitude versus the offset on the record before stack,and then,to assertain the oil - bearing formation.