叠前宽角度反演方法在周返地区盐湖盆地储层预测中的应用

The Application of Pre-stack Wide-angle Inversion Method to Reservoir Prediction in Zhoufan Salt Basin

周返地区盐湖盆地发育复杂的盐韵律地层,储层密度可以对该区砂岩储层进行识别,但该区砂岩储层与非储层之间密度差异小,传统基于Aki-Richards近似公式的叠前密度反演结果精度低,无法满足对该区储层预测的要求。本文将精确Zoeppritz方程直接代入广义线性反演误差泛函,推导新的宽角度叠前反演公式,以克服近似公式对大角度叠前地震信号无法正确利用的缺点,进而提高反演结果的精度。对合成地震数据和工区实际数据的反演结果表明,该方法对密度反演结果的精度明显优于近似公式,满足周返地区盐湖盆地岩性油藏的高精度预测。

Zhoufan Salt Basin develops complex salt rhythmic strata. Density should identify the sand reservoir in this area. Unfortunately, the density difference between sand and other lithology is very small, which causes the traditional pre-stack inversion method that based on Aki-Richards equation cannot satisfy the reservoir prediction task. We substitute the Zoeppritz equation into general inversion frame and then deduct prestack wide-angle inversion formula. Our inversion formula overcomes the weakness of Aki-Richards equation which cannot apply the wide angle information accurately. In this case, the inversion accuracy is improved. The synthetic test and field data application illustrate that our density inversion result is more accurate than the traditional one and satisfy the reservoir prediction in Zhoufan Salt Basin.