Application of new-type retarded acid for sandstone reservoir in Xinjiang oilfield

In order to seek a solution to the low efficiency of acidizing methods in low permeability reservoir of Xinjiang oilfield, a new- type retarded acid called HDF has been developed. Meanwhile,the laboratory experiments on corrosion effect,scale inhibition performance and core flow have been carried out.The results show the HDF system could prolong acid rock reaction time from 1 hour to 6 hours.Besides that, when the sandstone erosion rate is close to mud acid,the retarded rate of clay minerals could be high up to 80%and the secondary precipitation could be reduced 90%.The field application in 30 wells confirms the HDF system could obviously enhance acidizing effect,especially for sandstone reservoir with high temperature and deep depth and the reservoir with high clay content.