基于波形的波阻抗特征识别技术在川西气田储层预测中的应用

川西坳陷陆相砂岩储层波阻抗分为高、中、低3类,其中储层预测的主要目标是具有低波阻抗特征的高孔渗砂岩储层.通过对储层波阻抗特征、地震资料分辨率、模型正演等的分析,提出了基于波形的波阻抗特征识别技术.该技术首先通过地震反射波峰、波谷振幅属性的一、二维匹配特征,判断地震强振幅异常的反射极性,识别波阻抗特征;然后再根据地震相特征,判别河道或三角洲砂岩储层,排除非储层陷阱;最终识别出高阻抗致密砂岩与低阻抗高孔渗砂岩.该技术不受地层埋深的限制,在合兴场气田浅层蓬莱镇组进行了低阻含气砂体识别,得出该套储层砂体越厚,孔渗性越好,含气丰度越高,振幅越强的认识,钻井命中率在90%以上;在丰谷气田深层须家河组进行了高阻抗砂体识别,得出一呈透镜体的反射＂异常＂为低孔渗致密砂体,砂体越厚,孔渗性越差,振幅越强的认识,预测该砂体不利于天然气的储集.

The application of impedance characteristic recognition technology based on waveform in reservoir prediction of gas fields in west Sichuan

The Impedance characteristic of sandstone reservoir continental facies in west Sichuan depression can be classified by three kinds, low impedance porous reservoir which has better effect in gas exploration is the most favorable target of seismic reservoir prediction.Through analyzing the impedance characteristic of reservoir and the resolving power of seismic data and positive model etc. , The impedance characteristic recognition technology based on waveform is advanced, it is emphasize that with analysis of wave peak and wave trough amplitude matching relation in 1-D and 2-D, the polarity of abnormal strong reflection can be realized, the impedance characteristics will be identified, at the same time, we also can recognize the sandstone reservoir belong to river or delta according as seismic facies, exclude the possibility of shale, identify high impedance compact rock and low impedance porous rock, it is very good for reducing the risk of exploration. The burial depth does not limit the technology, and it has been used in the practice in the continental facies reservoir prediction successfully in several gas fields in west Sichuan.