基于变系数Δlg R技术的陆相烃源岩总有机碳含量测井评价

Log Evaluation on the TOC of Continental Source Rocks based on Variable Coefficient Δlg R Model

利用变系数Δlg R技术评价陆相断陷湖盆烃源岩,提高低有机质丰度、强非均质烃源岩总有机碳含量(TOC)预测精度。松辽盆地C地区XI组烃源岩富含泥岩、贫有机组分、非均质强,一方面导致通过有限的分析测试数据表征地下烃源岩有机质丰度的方法可靠性差;另一方面造成烃源岩层呈现高自然伽马、中高声波时差、中低电阻率的特殊测井响应。采用变系数Δlg R技术评价烃源岩TOC,针对模型参数多变、TOC预测公式通用性差的问题,采用针对单井厘定模型参数的方法,改善了TOC预测效果。应用效果表明,变系数Δlg R技术预测TOC的平均相对误差为16.6%,比传统Δlg R技术和多元回归方法分别低15.6%和13.2%。变系数Δlg R技术为强非均质地层烃源岩TOC测井评价提供了有效方法。

Using variable coefficientΔlg R to evaluate the source rocks in continental faulted lake basins can improve the accuracy of the TOC of the source rock with low organic matter abundance and strong heterogeneity.The source rock of the XI formation in the C block in the Songliao basin is rich in mudstone,poor in organic matter and strong in heterogeneity.On the one hand,insufficent data lead to poor reliability of characterizing the organic matter abundance of the underground source rock;on the other hand,the source rock shows special logging responses-high GR,medium to high AC and medium to low resistivity.Δlg R instead of variable model parameters and common TOC prediction formula can improve the accuracy of the TOC of the source rock,by only selecting model parameters for a well.Application results show that the average relative error from the variable coefficientΔlg R is 16.6%,15.6%than that of the conventionalΔlg R and 13.2%lower than the multiple regression method.Variable coefficientΔlg R is an effective method for evaluating the TOC of the source rock with strong heterogeneity.