缔合非交联压裂液储层伤害特征

高尚堡深层为低渗透油藏,以大孔细喉以主,微结构杂基含量高,易造成微粒运移损害。笔者开展了缔合非交联压裂液伤害特征分析,稠化剂粘均分子量为380×104,是具有长链疏水基团的聚丙烯酰胺类高分子化合物。破胶液粘度对基质渗透率伤害影响较大,破胶液表观粘度为2.71 mPa · s时,基质伤害率为28.75%;破胶液表观粘度为29.6 mPa · s时,对基质伤害率为51.9%。返排12 h后,基质渗透率下降15%~20%,说明该储层易造成颗粒运移伤害。核磁共振、压汞实验表明高分子聚合物主要堵塞对渗透率贡献值较大的孔喉（半径为2~9 μm）。扫描电镜实验表明残胶中的聚合物呈粒状、絮状,吸附滞留在岩石、粘土颗粒表面造成大吼喉数量减少,并且残渣及残胶相互缠结集中在岩芯入口端,远端逐渐减少,说明压裂液对储层的伤害主要集中在近井地带。综合研究认为,该体系不是完全清洁压裂液,宜在压裂液配方中关注彻底破胶性能和降低稠化剂的分子量。

The Characteristics about the Damage of Associated Non Cross-linking Fracturing Fluid to Reservoirs

The deep layer of Gaoshangbao oilfield is a low-permeability reservoir with large pores and fine throats and high content of micro-structured heterogeneous.It is easy to cause particle migration.The characteristics about the damage of associated non crosslinking fracturing fluid to reservoirs were analyzed.The viscosity average molecular weight of the chickening agent is 3.8 million. The chickening agent belongs to polyacrylamide polymer which has long-chain dewatering group. The influence of viscosity of fracturing fluid to the formation damage proportion is great. When the viscosity of breaking fluid is 2.71 mPa·s, the static formation damage proportion is over 28.75%. When the viscosity of breaking fluid is 29.6 mPa·s, the static formation damage proportion is over 51.9%. By long-time flow back(12 h), it is obvious that the permeability is declined about 15%~20%, indicating that it is easy for the reservoir to cause particle migration. By means of nuclear magnetic resonance and mercury injection test, it is indicated that high molecule polymer is mainly blocking pore throat(radius is 2~9 μm), which is mainly contributed to permeability. By means of SEM, it is proved that the grainy polymer is adsorbed on the rocks and the quantity of pore throat is decreased. The residual is interlaced and focused on the entry of the core, and is reducing at the end of core. It shows that the damage of the fracturing fluid to the reservoir is mainly concentrated near the well. According to comprehensive research,it is considered that this fracturing fluid is not completely clean fracturing fluid. It is emphasized the whole breaking and low molecular weight.