多属性预测在涠西南凹陷烃源岩研究中的应用

Application of multi-attribute prediction to the Weixinan depression dominate source rock

寻找隐蔽油气藏是目前涠西南凹陷勘探的新领域,优质烃源岩描述是其中一个重要研究课题.涠西南凹陷流沙港组沉积时期为一断陷湖盆,流沙港组二段沉积阶段是湖盆发育的鼎盛时期,中深湖相泥岩或页岩发育,形成了一套良好的区域性烃源岩.油页岩是涠西南凹陷最重要的烃源岩.除油页岩外,流二段还沉积了厚套的中深湖相暗色泥岩,具备非常好的生烃能力.识别和弄清这些暗色泥岩在凹陷中的分布对定量评价涠西南凹陷的生烃潜力具有重要意义.本文尝试将地震多属性预测技术应用于优势烃源岩的研究.首先通过声波时差和电阻率曲线进行多元线性回归,拟合能够体现优势烃源岩特征的有机化学参数总有机碳TOC曲线,利用层位约束消除油页岩对属性优化的干扰作用,最后通过逐步回归的步聪法算法对多地震属性进行优化,找到最佳属性组合,实现TOC数据体的预测,揭示了流二段优质烃源岩的空间展布特征.

The subtle oil gas reservoir is a new prospecting domain in the Weixinan depression. One of the key topics is dominate source rock description. The Weixinan depression is a faulted lake basin during the deposition of Liushagong Formation. At the Liushagang 2 period, the lake basin developed and deposited a suit of widespread oil Shale. Besides oil shale as the most important source rock, there is mass of dark shale deposited in liushagang 2 Formation,which is also considered as dominated source rock. It＇s important to distinguish and make clear the distribution of dark shale within the whole basin for quantitative evaluation of the hydrocarbon-generating potential of the Weixinan depression. In this article,we try to use the multi-attribute technique to source rock research. First we create a new total organic carbon（TOC） curve from DT and resistivity log with multiple regression, then use the constraint of two horizons to eliminate the influence of oil shale on attributes optimizing. Finally, we find the optimized attribute combination with stepwise regression, and predict a new TOC volume successfully. Further analysis is carried out on the TOC volume, and reveals the distribution of dominate source rock for oil shale in liushagang 2 Formation in detail.