涪陵页岩气储层含气性测井评价

针对涪陵页岩气泥质含量高、电阻率测井响应识别气层存在偏差的问题,开展了含气性测井定量表征方法及应用研究。涪陵地区页岩储层的黏土矿物主要为伊利石、伊蒙混层和绿泥石;随深度增加,黏土矿物含量减少,但伊蒙混层占的比重增大。利用有机碳-密度测井曲线交会法、有机碳-铀测井曲线交会法以及声波-电阻率曲线法等三种方法计算TOC含量;对比岩心实验结果,密度曲线拟合的相关系数最高。利用测井曲线计算得到的含气饱和度、流体压缩系数、岩石弹性模量、游离气量、吸附气量等参数可以实现对储层含气量的定量表征。涪陵地区页岩气纵向、横向含气量测井评价实践表明,龙马溪组下部——五峰组页岩气储层自下而上可划分为中、高两个含气段,且该区页岩气储层横向含气量稳定,具备应用水平井开采技术等增加单井产量的地质条件。

Gas Content Ability Evaluation by logging technology in Fuling Shale Gas Reservoir

To solve the problem of recognizing gas reservoir difficulty by resistivity log response because of high shale content, the quantitative log evaluation method of gas content ability has been proposed. The clay mineral in Fuling shale reservoir is mainly illite, illite/montmorillonite mixing layer and chorite. With increased depth, the clay content decreases and the proportion of illite/montmorillonite mixing layer increase. TOC(total organic carbon) has been calculated by three methods, including intersection of TOC and density logging, radioactive logging and resistivity logging. Contrast with core experiment results, density logging curve has the best correlation with TOC. Gas saturation, fluid compressibility, elastic modulus, free gas, absorbed gas calculated by logging curves can quantitative characterize gas reservoir content ability. Based on gas content logging evaluation laterally and lengthwise, the strata, from lower part of the Longmachi Formation to the Wufeng Formation, can be divided into middle and high gas content layers. Shale gas reservoirs in the Fuling Zone extends laterally stably, and has the geological conditions to explore by chorizontal well technology which can increase the single gas well production.