保护储层的碱溶性暂堵剂LZ-1

Alkaline-Soluble Temporarily Plugging Agent LZ-1 for Reservoir Formation Damage Control

新型钻井液暂堵剂LZ 1是含有羟基、羧基、羰基等官能团 ,相对分子质量 <6 .0× 10 3 、熔点 >30 0℃、密度1.4 4 g/cm3 ,性脆 ,易加工成要求粒度的碱溶性物质。在 pH≥ 9的碱液中溶解率≥ 6 0 % ,在较低 pH值下不溶于水和水基钻井液。LZ 1粉剂 (粒径 <0 .0 74mm)在碱液中的溶解率随温度升高 (2 0～ 80℃ )而增大 ,随碱 (Na2 CO3 )质量浓度 (0～ 3.0× 10 4mg/L)增加而增大 ,碱液通过加有暂堵剂的两性聚合物钻井液形成的滤饼渗滤时可将暂堵剂溶出。加量 3%的暂堵剂对该钻井液的室温性能和 80℃热滚 16h后的性能无不良影响 ,且有降粘降切作用。加量1%～ 5 %的暂堵剂不影响钻井液中固相粒度分布。与不加暂堵剂的钻井液相比 ,加入 1%～ 5 %暂堵剂的钻井液引起的岩心渗透率损害 ,经 3.0× 10 4mg/LNa2 CO3 溶液浸洗 3.5h后可降低 10 %～ 2 3%。

The newly developed temperarily plugging agent (TPA) LZ 1 for use in drilling in fluids is a brittle organic substance containing hydroxyl, carboxyl, and carbonyl functional groups, of molar mass <6.0×10 3, melting point >300℃, and density 1.44 g/cm 3 and can be easily processed to powder of required particle size distribution. Its solubility in alkaline solutions of pH≥9 is of ≥60% and increases with increasing temperature (20-80℃) and alkaline (Na 2CO 3) concentration (0-3.0×10 4 mg/L) for LZ 1 of particle size <0.074 mm. It does not dissolve in water and water base drilling fluids. The alkaline solutions dissolve out TAP when flowing through the filter cake formed by an amphoteric polymer fluid with TAP LZ 1 added. 3% TAP does not affect negatively the properties of the fluid, original and after rolling at 80℃ in 16 hrs, and causes in some extent reduction in fluid viscosity and yield stress. With 1-5% TPA LZ 1 added the solid particle size distribution of the fluid is not changed. The damage for reservoir core permeability caused by the fluid with 1-5% TAP LZ 1 added and then dimished by flowing and leaching 3.0×10 4 mg/L Na 2CO 3 solution in 3.5 hrs is by 10-23% less than that caused by the fluid without TPA LZ 1.