伽马拟声波曲线构建技术在储层预测中的应用

The application of GR pseudo- acoustic curve construction technology in reservoir prediction in Xiaohaotu.

小壕兔工区的气藏属于典型的岩性气藏,砂体薄,岩性横向变化大。砂岩含气后,速度、密度、波阻抗明显降低,呈现出类似于泥岩的特征,声波曲线不能很好地反映地层的岩性。为此,采用拟声波曲线波阻抗反演方法,对该地区砂体的分布特征和展布规律进行了描述。首先,通过统计分析找出对地层岩性变化敏感的测井曲线——伽马测井曲线;然后利用信息融合技术将声波测井曲线和伽马测井曲线构建成伽马拟声波曲线;最后,利用宽带约束地震反演技术进行了储层反演。对伽马拟声波曲线的反演结果与声波曲线的反演结果进行了对比, 伽马拟声波曲线的反演结果在分辨率和与钻井岩性的匹配精度上都有较大的提高。用反演结果对砂体的分布特征和展布规律进行了描述,结果与地震振幅属性预测结果大趋势一致,但在局部刻画上更细致。

Thin sand body and drastic lateral variation of lithology characterize lithologic gas reservoir in Xiaohaotu area. The velocity, the density and the impedance of gas bearing sandstone is getting lower than usual, its cgaracteristics tend to be similar to those of mudstone. Acoustic curve can not reflect the characteristic of the strata effectively. Therefore, a pseudo-acoustic curve is introduced to de- scribe the distributed law and characteristic of the sand Firstly, the GR curve sensitive to the lithology is searched by statistics and analysis. Secondly, integrating the acoustic curve with GR curve, a pseudo-acoustic curve is formed by information modulating; Finally, GR curve is used to construct a pseudo-acoustic curve to constrain the impedance inversion in reservoir prediction. The inversion result of pseudo-acoustic has higher quality in both resolution and matching for drilling lithology in comparison to that of acoustic impedance inversion. Although both inversion results have similar trend in amplitude attribute predicting, pseudo-acoustic impedance inversion expose more informations in local part.