Abstract: Skin data of instantaneous reaction or reaction after 8 hours can be gained by acidification contrast experiment u-sing reservoir cores. Skin changes over long distance has been calculated through extrapolating with two experimentdata,by which the differences before and after reaction can be attained. The differences can be used to monitor field a-cidification. skin correction method in well xl2-w3251 has been applied in the fifth oil production plant of Daqing toguide field construction,which has achieved good results.