低阻页岩气层含气饱和度计算新方法

发布时间：2018-11-17 18:00

【摘要】：四川盆地涪陵地区焦石坝页岩气田的产层为上奥陶统五峰组—下志留统龙马溪组,其底部一般发育厚度20 m左右、有机质含量和含气丰度均高的优质页岩气层,但是该层段却不具有最高的电阻率数值,较低的电阻率往往会导致利用电法测井信息的Archie等公式计算获得的含气饱和度远远低于实验分析值。为提高页岩气层关键参数的计算精度,开展了寻求利用非电法测井信息计算含气饱和度的方法研究。在深入分析该区页岩气层低阻成因的基础上,剖析了传统电法测井求取含气饱和度的局限性,阐述了利用中子—密度孔隙度重叠计算含气饱和度的可行性。根据页岩气层中子、密度等孔隙度测井响应特征,采用岩心实验刻度,利用密度测井值、密度孔隙度、密度与中子孔隙度的差值,以及通过优化最佳叠合系数的双孔隙度重叠等多种方法建立了页岩气含气饱和度计算模型。该新方法有效避开了电法测井中的低阻因素的影响,从根本上解决了优质页岩气层段含气饱和度计算数值偏低的问题,在实际应用中见到了良好的效果,为该区页岩气储量的准确计算提供了技术支撑。
[Abstract]:The Jiaoshiba shale gas field in Fuling area, Sichuan Basin, is produced by upper Ordovician Wufeng formation and Lower Silurian Longmaxi formation, with a high quality shale gas reservoir with a thickness of about 20 m and high organic matter content and gas abundance. However, the interval does not have the highest resistivity value, and the lower resistivity often leads to the gas saturation calculated by using the Archie formula of electrical logging information is far lower than the experimental analysis value. In order to improve the accuracy of calculating the key parameters of shale gas reservoir, the method of using non-electric logging information to calculate the gas saturation is studied. On the basis of deep analysis of the causes of low resistivity of shale gas reservoirs in this area, the limitation of traditional electrical logging in obtaining gas saturation is analyzed, and the feasibility of calculating gas saturation by using neutron density porosity overlap is expounded. According to the response characteristics of shale gas reservoir neutron and density logging, the core experiment calibration is used, and the difference between density logging value, density porosity, density and neutron porosity is used. The calculation model of gas saturation of shale gas is established by optimizing double porosity overlap of optimum overlap coefficient and so on. The new method effectively avoids the influence of low resistivity factors in electrical logging, and solves the problem of low gas saturation calculation in high quality shale gas reservoir. It has good effect in practical application. It provides technical support for accurate calculation of shale gas reserves in this area.
【作者单位】：中石化胜利石油工程有限公司测井公司;
【基金】：中国石油化工股份有限公司科研项目“四川盆地及周缘页岩气测井评价技术研究”(编号:G0800-12-zs-246)
【分类号】：P618.13

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