低孔低渗砂岩储层强水锁伤害消减技术

Damage Reduction Technology of Strong Water Lock in Low Porosity and Low Permeability Sandstone Reservoir

低孔低渗砂岩储层具有岩石亲水性与孔吼小的特征,微纳米控制的孔吼易产生自吸现象,造成强水锁伤害。造成强水锁伤害的微观因素为毛管压力,通过分析毛管压力的控制因素,形成水锁伤害控制技术。结果表明:纳米增效剂EM-50能有效降低表面张力至23.22 mN/m、增大接触角至76.3°,降低自吸水量72.7%。岩心实验渗透率恢复率为53.04%。在苏里格区块应用后,通过压裂液添加纳米增效剂及压后强制快排工艺,单井见气时间缩短至2.9 h,一次点火成功率100%,单井返排率增加36.9%。

The low porosity and low permeability sandstone reservoir has the characteristics of rock hydrophilicity and small pore size.The pore size controlled by micro-nanometer is easy to produce self-absorption and cause strong water lock damage.The micro factor causing strong water lock injury is capillary pressure.Through analyzing the control factors of capillary pressure,the water lock injury control technology was formed.The results showed that EM-50 could effectively reduce the surface tension to 23.22 mN/m,increase the contact angle to 76.3°,and reduce the water absorption by 72.7%.The permeability recovery rate of core test was 53.04%.After the application in Sulige block,the gas breakthrough time of single well was reduced to 2.9 h,the success rate of primary ignition was 100%,and the flowback rate of single well was increased by 36.9%by adding nano synergist to the fracturing fluid and the forced rapid drainage process after fracturing.