Continental Shale Gas Reservoir Sensitivity Experimental Research of Chang 7 of Yanchang Formation in Xiasiwan Area

An experimental study has been conducted on sensitivity of the continental shale gas reservoir of Chang 7of Yanchang Formation in Xiasiwan area,using X-ray diffraction,field emission scanning electron microscope,nitrogen adsorption and core displacement experiment.The results show that the reservoir is characterized by medium weak or weaker salt sensitivity,water sensitivity and alkali sensitivity,weak-no acid sensitivity and medium to strong or strong stress sensitivity.The main factors affecting the reservoir sensitivity are the mineral components,reservoir property and reservoir pore structure.Due to the particularity of shale reservoir,some key experimental technologies and methods were improved in the sensitivity experiments.①The complete pore throat size distribution curve was formed by combining the mercury injection capillary pressure curve with the nitrogen adsorption method to obtain BJH pore size distribution curve function.②The sample oil removal in the sensitivity experiments was implemented by conventional washing oil and high temperature(150-200℃)baking method.③The pulse gas permeability tester was adopted,which is most suitable for shale gas reservoir sensitivity experiments at present.The permeability values before and after the sensitivity experiment were obtained,using the gas displacement method instead of the conventional liquid displacement method.The sensitivity of the reservoir characteristics data of the shale was obtained by the improved sensitivity experiment,which satisfies the purpose and requirements of this experiment.