地震约束建模的强非均质碳酸盐岩储层波阻抗反演

Impedance inversion of strongly heterogeneous carbonate reservoir based on amplitude-constrained modeling

塔里木盆地深部碳酸盐岩储层以次生溶蚀孔、洞、缝为主,空间分布具有极强的非均质性。传统的"相控建模"、"岩溶建模"和"碳酸盐岩储层相控建模"方法均不能准确刻画储层分布特征。为此,提出地震约束建模方法:首先基于线性反演去除资料的AVO效应获得纯纵波数据,然后结合测井信息计算相对波阻抗,并进一步转化为绝对波阻抗属性定量质控波阻抗反演质量。采用的建模方法本质上属于确定性建模,流程包括纯纵波数据提取、相对阻抗计算、振幅约束低频建模、波阻抗反演等。ZG8井区的实例分析证实:基于纯纵波振幅约束建模的反演方法可以避免传统插值建模方法受井资料影响大的局限,克服了常规融合层速度等建模方法精度不高的缺陷,准确反演了强非均质储层的分布规律。

Deeply buried carbonate reservoirs in the Tarim Basin are secondary dissolution pores and fractures which are dominated by visible dissolution caves,holes,and fractures,and characterized by strong 3D heterogeneity.They cannot be explicitly modeled by conventional facies-controlled,surfacekarst modeling methods,and the storage facies controlled modeling method.Therefore an amplitudeconstrained modeling method is proposed to solve this problem.First pure P-wave data are obtained with AVO effects removal.Then a colored inversion is conducted with logging data to achieve relative impedance.Finally a cross-matching is carried out with logging data to get absolute impedance for inversion constraint.This method is essentially realized in the deterministic framework and mainly contains pure P-wave data calculation,relative impedance computation,amplitude-constrained low frequency model construction,and impedance inversion.Field data tests in the ZG8 area suggest that the proposed method could avoid well data effects existed in the conventional interpolation method,and overcome the precision deficiency of processing velocity.The secondary carbonate reservoir with strong heterogeneity could be more finely delineated.