四川盆地五峰-龙马溪组低阻页岩含水饱和度测井评价

Water Saturation of Low Resistance Shale in the Wufeng-Longmaxi Formation of Sichuan Basin Logging Evaluation

四川盆地五峰-龙马溪组页岩气层段,是有机质含量高、含气丰度高的优质页岩气层,但该层段却不具有高的电阻率,较低的电阻率会导致利用电法测井信息的Archie、Simandoux、双水模型等公式计算获得的含水饱和度远远高于实验分析值。为提高页岩气层含水饱和度的计算精度,在深入分析该区页岩气层测井响应特征及低阻成因的基础上,全面剖析了传统电法测井求取含水饱和度的局限性,改进形成了适应该区低阻页岩的含水饱和度测井评价技术方法。结果表明:利用声波时差、有机碳含量等非电法测井信息计算含水饱和度,避免了传统电信息计算低阻页岩层的含水饱和度导致的偏差,在研究区应用效果更加显著,为该区页岩气储量的准确计算提供了技术支撑。

The shale gas section of the Wufeng-Longmaxi Formation in the Sichuan Basin is a high-quality shale gas formation with high organic matter content and high gas-bearing abundance,but this section does not have high resistivity,and the lower resistivity often leads to the water-bearing saturation obtained by using the Archie,Simandoux,and double-water model formulas of electrical logging information to be much higher than the experimental analysis value.In order to improve the calculation accuracy of water saturation in shale gas formations,the limitations of traditional electric logging for water saturation were comprehensively analyzed on the basis of in-depth analysis of logging response characteristics and low-resistance causes of shale gas formations in this area,and the technical method of water saturation logging evaluation adapted to low-resistance shales in this area was improved.The results show that by using non-electrical logging information such as acoustic time difference and organic carbon content to calculate the water content saturation avoids the deviation caused by the traditional electrical information to calculate the water content saturation of low-resistance shale formations,which is more effective in the study area and provides technical support for the accurate calculation of shale gas reserves in the area.