桑托斯盆地A区块碳酸盐岩及火成岩地震预测

Seismic prediction of carbonate and igneous rocks in block A of Santos basin

桑托斯盆地A区块碳酸盐岩储层非均质性强,且被火成岩复杂化,需借助多弹性参数保证地震预测可靠性。岩石物理分析显示,纵波阻抗和横波阻抗在岩性区分上各具优势。全波形反演速度具有更多的地质细节和更高的纵向分辨率,因此利用全波形反演得到的速度信息建立初始模型,并利用宽频地震开展叠前反演。反演得到的弹性参数更加可靠,具有较高的数据驱动性。基于反演得到的纵波阻抗和横波阻抗体进行贝叶斯分类,预测了各个岩相的发育概率,从而实现了对碳酸盐岩储层发育和火成岩风险的定量预测,且预测结果得到实钻井证实。

The carbonate reservoirs in block A of Santos basion have strong heterogeneity and are complicated by igneous rocks,and multi-elastic parameters are required to guarantee the reliability of seismic prediction.The rock physics analysis shows that the P-wave impedance and the S-wave impedance have their own advantages in lithology identification.The full-waveform inversion velocity has more geological details and higher vertical resolution.Therefore,the velocity information obtained by full-waveform inversion can be used to establish an initial model,and the pre-stack inversion can be carried out using broadband seismic.The inversion-based elastic parameters are more reliable and more data-driven.Bayesian classification is performed based on the inversed P-wave impedance and S-wave impedance volumes,and the presence probability of each lithofacies is further predicted,thus realizing the quantitative prediction of carbonate reservoir development and igneous rock risk.Such prediction is verified by actual drilling.