Abstract: Clay minerals of ittite/mont morillonite mixing layer, kaolinite, illite etc. and carbonate mineral of calcite etc. exist in Cao 104 reservoir in Le’an oilfield. Various sensitivity in these minerals may damage the reservoir in the different stages of oilfield exploration and development. The experiment study indicates that strong water sensitivity and moderate salt sensitivity exist in the reservoir. So attention should be paid to the compatibility between injected water and the formations in the period of water injection development. In addition, the reservoir has weak alkali sensitivity and no earth acid sensitivity, so earth acid can be used for acidizing stimulation.