化学破胶剂SD02用于压裂后地层处理

Chemical Gel Breaker SD02 for Post-Treatment of Reservoir Formations after Hydrofracturing

考察了低碳羧酸、过氧化氢、有机氢过氧化物、过酸盐及一种有机过氧化物与一种低碳羧酸的复配物(代号SD02)对4种压裂液冻胶(含0.5%聚合物的HPG/有机硼、香豆胶/有机硼、羟丙基田菁胶/有机硼及改性PAM/硫酸铝钾压裂液)的破胶性能。等体积压裂液与5%破胶剂溶液混合,分别在25℃和85℃反应0.5h后,混合液粘度比压裂液粘度分别降低78.9%～97.2%和69.6%～98.2%,其中SD02的降粘率最高,分别为94.8%～97.2%和96.5%～98.2%,对于HPG/有机硼压裂液分别为94.8%和96.5%。取以上4种压裂液及黄胞胶/有机硼压裂液制备残渣,将残渣分散于水中,与等量SD02溶液混合,在25℃反应0.5h,残渣溶解率在79.3%～91.4%,对于HPG/有机硼压裂液残渣,溶解率为91.4%。85℃下5%SD02溶液对石英砂及不同产地陶粒的4h溶蚀率≤0.3%。用5%SD02溶液作二次破胶剂,用于处理压裂后破胶效果不好的14口井,与3口未处理井相比,返排率由8.2%～11.4%上升到19.8%～33.1%,破胶液粘度由157～172mPa·s下降到1.5～5.1mPa·s,增产原油效果良好。表4。

The breakdown of 4 hydrofracturing gelled fluids (0.5% Fenumgreek gum, hydroxypropyl Guar gum and Sesbania cannabina gum fluids gelled by a bororganic crosslinker and 0.5% modified PAM/alumopotassium sulfate fluid) by low carbon number carboxylic acids (LCCAs), H_2O_2, organic hydroperoxides (HPOs), peracid salts and an HPO/LCCA mixture denoted as SD02 is experimentally studied. For these gelled fluids treated by equal volume of 5% aqueous solution of the chemicals in 30 min at 25℃ and 85℃, the viscosity is reduced by 78.9—97.2% and 69.6—98.2%, for these fluids treated by SD02 solution—by 94.8—97.2% and 96.5—98.2% and for HPG/B fluid by SD02—by 94.8% and 96.5%, respectively. The solubility of the brokendown gelled fluid residue in 5% SD02 solution measured at 25℃ in 30 min is in range 79.3—91.4% for the above mentioned fluids and a xanthan/B fluid and is of 91.4% for HPG/B fluid. The substances dissolving out of quartz and haudite of different origin by 5% SD02 solition are tiny, being of ≤0.3% only. Using 5% SD02 solution as secondary breaker to treat 14 wells of the 17 wells having been hydrofractured with bad breaking results, the percent backflow is increased from 8.2—11.4% to 19.8—33.1%, the viscosity of the flown fluid is decreased from 157—172 mPa·s to 1.5—5.1 mPa·s and the productivity of these wells is notably raised.