压制孔隙影响的流体敏感因子优选及其在烃类检测中的应用

The optimization of sensitive fluid factor removing the effect of porosity and its application to hydrocarbon detection

尼日尔三角洲盆地S区块发育深水扇沉积,高孔含水砂岩表现为振幅"亮点"和远道增强的AVO异常,其特征与油层类似,基于常规方法开展烃类检测存在多解性。针对该问题,笔者提出一种新的流体因子敏感性定量分析和优选方法,能够压制孔隙度造成的流体识别假象,达到"突出流体、压制孔隙影响"的目的。分析结果表明,λ/μ具有对流体性质敏感性高、对孔隙度敏感性低的特征,是本区开展烃类检测的最佳敏感流体因子。实际应用结果表明,利用该方法能够有效区分真"亮点"油层和假"亮点"水层,预测结果与已钻井更加吻合,有效提升了烃类检测成功率。

The deep-water turbidite sandstone reservoirs in Niger Delta basin have great oil-gas exploration potential.Drilling results in S Block area indicate that high-porosity water sandstones show "bright spot" and class II-III AVO anomaly,which are similar to features of oil sandstones.It is critical to remove the effect of porosity while fluid detection is conducted.However,conventional analysis method seldom considers the effect of porosity,and the selected fluid factor is sensitive to both hydrocarbon and porosity,which leads to inaccurate detection result.Therefore,in this study,a new quantitative evaluation method based on fluid and porosity substitution is proposed to choose the most sensitive fluid factor,which can highlight hydrocarbon and suppress the effect of porosity.The analysis result shows that λ/μ is the most suitable elastic parameter in this area and can be used to detect hydrocarbon.The real data application result shows that λ/μ can effectively distinguish "bright spot" water sandstones from oil sandstones,and the predicted results are well consistent with the drilling data,which proves the feasibility of this method.