碳酸盐岩储层地震相控非线性反演技术及应用

Seismic phase-controlled nonlinear inversion of a carbonate reservoir

针对碳酸盐岩储层普遍存在的非均质性特征,采用地震相控非线性反演技术进行储层预测,以进一步提高地震预测精度。考虑到非线性最优化理论综合了约束反演与模型反演的优点,因此,首先将标准化或重构之后的测井资料与地震信息相结合,构建地震道与波阻抗关系的目标函数,然后在精确的层序地层格架和地震相模型控制下,从井旁道出发逐道外推,最后将每次得到的结果作为下一道反演的初始模型,展开迭代反演。其核心思想是将地质研究成果与地震反演相结合,使地震反演结果具有明确的地质意义和较高的可靠性。地震相控非线性反演技术在南大西洋S盆地的L油田盐下微生物灰岩储层地震预测的应用结果表明,该技术提高了复杂碳酸盐岩储层的地震预测精度,为盐下碳酸盐岩油气藏的勘探开发提供了可靠的依据。

The common heterogeneity found in carbonate reservoirs is the main factor limiting the accuracy of seismic predictions.To address this issue,a seismic phase-controlled nonlinear inversion technique was proposed in this study.It combines the advantages of constrained and model inversion.Based on a nonlinear optimization algorithm,the proposed method combines the standardized or reconstructed logging data with seismic information to reconstruct an objective function of the relationship between the seismic trace and wave impedance.Using a precise stratigraphic sequence and a seismic phase model,and starting with traces in areas next to wells,the traces were extrapolated one by one,the results of each inversion were used as the input model for the inversion of following trace.The core concept of the method is to integrate geological information into the seismic inversion,so that the boundary effects arising in the seismic inversion can be eliminated and a clear geological significance and good prediction capacity of the output can be ensured.The method was applied to the seismic prediction of a microbial limestone reservoir in the oilfield L in the S basin,South America.The method was shown to improve the prediction accuracy of complex carbonate reservoirs compared to that obtained through traditional methods.It can therefore be concluded that the proposed method provides a new basis for the exploration and development of pre-salt carbonate reservoirs in the study area.