论文详情
为使电磁法在页岩气勘探中发挥更大作用,需要深入研究页岩储层的高总有机碳含量(TOC)、高脆性与其电性关系。在不同温度、压力和矿化度条件下对威远地区页岩气井龙马溪组页岩样品进行了复电阻率测试,分析页岩的复电阻率特性,反演提取页岩的复电阻率参数,然后根据矿物成分及含量,从岩相、脆性、矿物含量、黄铁矿等多个方面研究储层参数与页岩电阻率、极化率参数之间的关系。研究结果显示,电阻率随硅质、泥质含量的增加而减小,随钙质含量的增加而增大,电阻率和极化率、电阻率和脆性指数之间均具有良好的正相关关系,电阻率与黏土矿含量呈负相关关系。在此基础上建立了关系模型,但需要进一步补充岩样并通过实验验证模型的有效性。页岩的极化率较低,结合电镜微观分析结果初步认为,低极化与页岩的低孔隙率、黄铁矿的零星分布状态及其较差的连通性相关。研究区储层页岩的激电特征参数对采用电磁方法进行页岩气勘探开发及储层改造具有重要指导意义。
Electromagnetic methods play an important role in shale gas exploration.The high total organic carbon and brittleness of shale reservoirs require further investigation,in addition to their electrical response mechanisms.Using shale samples from the Longmaxi Formation in the Weiyuan area,the complex resistivity (CR) characteristics of shale were analyzed.The CR parameters were extracted through CR tests performed under different temperatures,pressures,and salinities.The relationships between reservoir parameters and rock resistivity and chargeability were studied with respect to a variety of characteristics,including the mineral composition and the pyrite content,lithofacies,and brittleness.Resistivity was found to be positively correlated with the calcium content but negatively correlated with the silica and shale contents.Furthermore,both resistivity and chargeability were positively correlated with the brittleness index and negatively correlated with the clay mineral content.Based on the above results,a relationship model was established.However,data from additional rock samples are required for model validation.Nonetheless,on the basis of electron microscope observations,it was hypothesized that the low chargeability could be related to the low porosity and sporadic distribution of pyrite and the poor connectivity of shale.The characteristics and understanding of the electric response of shale in the study area have important implications for the application of electromagnetic methods in shale gas exploration,development,and reservoir reconstruction.
：国家科技重大专项“不同类型页岩气资源评价方法和参数体系研究”(2016ZX05034-002)资助。