川西彭州地区雷口坡组潮坪相薄储层辨识机理研究

Strategy for identifying thin reservoirs in tide-flat facies in the Leikoupo Formation,Pengzhou,Western Sichuan

川西彭州地区三叠系雷口坡组雷四上亚段潮坪相薄储层识别难度极大。围绕如何从复合地震强反射中区分并识别上、下两套储层面临的地球物理难题,采用先“分”后“合”的研究思路,基于实际地层结构及不同储层叠加样式建立正演模型,利用全波场波动方程正演模拟技术,剖析了不同主频条件下薄储层的地震响应特征,通过波形差异化分析,从复合地震响应中“剥离”出了两套储层所引起的地震响应特征及变化规律,明确了两套储层在不同频带下的地震识别标志和识别方法,为该区强反射界面干扰下两套薄互层储层辨识机理分析及精准预测奠定了基础。基于不同频带下薄储层辨识机理的分析结果,定性预测了薄储层平面展布,提出了深层潮坪相薄储层识别和预测难题的解决方案,为该区地震资料品质评价、面向薄储层的地震采集技术设计、地震资料处理及薄储层预测提供了依据和指导。

The identification of reservoirs in the upper submember of the Lei-4 member in the Triassic Leikoupo Formation(Pengzhou area,western Sichuan)is challenging.This study is focused on establishing a strategy to identify and distinguish between the upper and lower sets of reservoirs using composite seismic reflection data.The approach followed the concepts of“dividing”and then“merging”.A model was established on the basis of the actual structure of the formation and the different reservoir superposition styles.Subsequently,the characteristics of the seismic response of thin reservoirs with different dominant frequencies were analyzed using the forward modeling of the full-wave field wave equation.Subsequently,by analyzing the differential waveform,the characteristics of the seismic response and the disturbances caused by the two sets of reservoirs were“stripped”from the compound seismic response.In practice,the two sets of reservoirs were separated based on seismic identification marks in different frequency bands.The proposed method facilitated the effective identification and accurate prediction of the two sets of thin interbedded reservoirs in the study area under the interference of strong reflection interface.By implementing this method,the distribution of the thin layers was predicted qualitatively.In this study,methods for the identification and prediction of thin reservoirs in deep tidal-flat facies were also proposed.Furthermore,this work provided a basis and guidance for the evaluation of seismic data quality,the design of seismic data acquisition and processing,and ultimately the prediction of oriented thin layers.