储层敏感流体因子反演及烃类检测

西非尼日尔三角洲盆地发育深水扇沉积体系，钻井资料揭示，油层和水层均表现为“亮点”和远道增强的Ⅱ、Ⅲ类AVO异常，利用常规振幅和AVO方法检测烃类精度低。为此，首先分析了地震响应特征及其影响因素，通过正演模拟明确了孔隙度是引起振幅及AVO多解性的主要原因；然后，通过交会分析认识到，截距—梯度属性随孔隙度的变化规律与随含水饱和度的变化规律存在差异，进而提出了基于坐标旋转的扩展AVO属性，以降低常规AVO属性的多解性，提高油气预测精度；最后，开展面向实际储层的敏感流体因子优选，提出一种新的流体因子敏感性定量分析方法，能够优选出对流体敏感、对孔隙不敏感的流体因子，预测结果能够压制孔隙度造成的流体识别假象。分析结果表明，λ/μ（λ、μ为拉梅系数）具有对流体性质敏感性高、对孔隙度敏感性低的特征，是研究区开展烃类检测的最佳敏感流体因子。实际应用结果表明，利用扩展AVO属性和λ/μ流体因子能够有效区分真“亮点”油层和假“亮点”水层，预测结果与钻井数据更吻合，有效提升了烃类检测成功率。

Reservoir sensitive fluid factor inversion and its application in hydrocarbon detection

Deep-water turbidite sandstone reservoirs in the Niger Delta Basin have a great potential of oil and gas exploration. Drilling data from this area indicate that both oil and water layers with high porosity show "bright spots" and classes Ⅱ-Ⅲ AVO anomaly. However, it is difficult to distinguish oil from water using conventional amplitude and AVO attribute. In this study, we firstly investigated amplitude responses and their controlling factors, and found that high porosity is the key factor controlling the multiple solutions of amplitude and AVO response; then we performed a series of AVO modeling with different porosity and fluid substitution, and output the intercept-gradient crossplot whose variation with the porosity is different from that with the fluid saturation, and based on this conclusion, we introduced an exten-ded AVO attribute by rotating the axis, which can improve the precision of hydrocarbon detection; finally, after applying pre-stack inversion to further enhance the realiability of hydrocarbon detection, a new fluid factor quantitative evaluation method was proposed for selecting the best sensitive fluid factor while suppressing the effect of porosity. According to our nalysis, λ/μ is the most applicable parameter for detecting hydrocarbon in this area. And application to real data has proved that both the extended AVO attribute and λ/μ could effectively distinguish water layers from oil layers with "bright spots". The predicted results are well consistent with the drilling data, indicating the feasibility of the method.