Study and application of a new retarded acidizing fluid system for sandstond matrix

In consideration of the shortcomings of aciding high reaction speed,small treatment radius,more dissolved clay,less dissolved quartz and poor matrix recontruction effect in a conventional acid fluid used for water injector acidizing of almost oilfields at present,a new type retarded acid system(OPSA) has been developed which can be used for in-depth acidization of sandstone formation,it composed mainly of organic phosphonic sulphonic acid and fluore salt and series additive.At the same time,the subsidiary acidizing technology also developed.The technique is practical applicatied in 42 wells in the HeNan oilfield with technological success ratio of 100%,valid acidizing ratio of 92.9%.