Study On Influence Factors And Logs Evaluation Methods Of Porosity For Shale Gas Reservoir

In the thesis the influencing factors of shale reservoir porosity was analyzed and the shale gas reservoir porosity evaluation model was established by combining the conventional logging data and core experimental data of the Wufeng Formation and the Longmaxi Formation in the JY1 in Jiaoshiba area.The control variable method was used to compare and to analyze the influence degree of TOC and R₀ on the porosity of shale gas reservoir in the study area,and to analyze the influence of diagenesis and tectonic action on the porosity of shale gas reservoir according to the core interpretation.The conclusion are:?1?the porosity of shale reservoirs in the study area decreases first and then increases with the change of organic carbon content;?2?the porosity of samples with the same organic carbon content increases with the increase of organic matter thermal maturity;?3?the porosity of shale reservoirs decreases sharply under the influence of compaction;cementation also reduces shale porosity;dissolution increases shale porosity;?4?the effect of tectonic action is small.The porosity evaluation model was established by multivariate linear regression by using the conventional three-porosity logging data and the TOC of the Wufeng Formation and the Longmaxi Formation of the JY1,and the porosity was evaluated in this interval,which was more than 90%in agreement with the experimental data.