Research and Application of Anti-Sloughing Drilling Fluid of Poly Aluminum-Amine Salt

To solve the problem of soft mudstone and hard brittle shale formation collapse in Yitong,Da’an blocks,Jilin Oilfield,polyamine salt and poly aluminum salt were compounded to give full play to their synergy effect in enhancing the inhibition anti-collapse performance of drilling fluid.According to the practice of soft rock and hard brittle shale formations drilling in Jilin Oilfield,the other additives and their dosage were optimized through experiments,ultimately the poly aluminum amine salt drilling fluid formula with strong inhibition was obtained:2.0% sodium base bentonite+2.0% blocking agent poly aluminum salt PAC-1+3.0% HPA inhibitors poly amine salt+1.0% fluid loss agent SMP-1+1.5% fluid loss agent APC-026+2.0% inhibitors sulfonated asphalt+the pH regulator NaOH.Performance evaluation showed that:strong water-sensitive shale recovery was 75%,and swelling rate was 17.4% in poly aluminum amine salt anti-collapse drilling fluid;and the drilling fluid could tolerate 15% NaCl and 1% CaCl2,temperature up to 150 ℃.Field application results showed that:the poly aluminum amine salts drilling fluid had strong inhibition and blocking ability and could effectively prevent the wellbore collapse when drilling through shale formation,which solve sloughing,drill string sticking,and slacking due to wellbore collapse in shale formation drilling in the region.