高孔高渗油藏无机堵水剂适应性及注入参数研究

Study of adaptability and injection parameters of inorganic plugging agent in high porosity and permeability reservoirs

关键词:  延迟成胶  高孔高渗油藏  堵水  适应性评价  注入参数

Key words:  delayed gelation  high porosity and permeability reservoir  water plugging  adaptability evaluation  injection parameters

摘要:

目的 针对海上高孔高渗油藏油水关系矛盾突出的问题，展开了延迟成胶弹性硅酸凝胶堵水剂（6%（w）水玻璃+0.85%（w）三元弱酸一铵GL-1+0.1%（w）正电胶）的适应性及注入参数研究。方法 采用目测法考查了堵水剂的成胶性能和长期稳定性能；采用填砂管实验对堵水剂的注入性、封堵性、耐冲刷性和渗透率选择性进行评价，并对注入量、作用位置和注入速度进行优化。结果 适应性评价结果表明：堵水剂从A级强度到E级强度的成胶时间为72 h，最终凝胶强度可达I级，满足现场施工要求；堵水剂具有良好的注入性，最高注入压力仅为0.72 MPa；堵水剂具有良好的渗透率选择性、封堵性和耐冲刷性，能够优先进入高渗窜流通道，成胶后对高渗窜流通道的封堵率均高于96%，突破压力梯度均高于4.46 MPa/m，在50 PV回注水的高强度冲刷下，封堵率仅下降2.31%；堵水剂具有良好的长期稳定性能，在65 ℃下老化180天，脱水率仅为2.61%。注入参数研究结果表明：堵水剂最佳注入量为0.8 PV，最佳注入流量为3 mL/min，最佳作用位置为填砂管中部；在最佳注入参数下，封堵率可达98.03%。结论 延迟成胶弹性硅酸凝胶堵水剂可用于高孔高渗油藏堵水。

Abstract:

Objective The contradiction of the oil-water relationship is prominent in offshore high porosity and permeability reservoirs. To address this issue, the adaptability evaluation of delayed gelation elastic silicic acid gel water plugging agent (6 wt% sodium silicate, 0.85 wt% activator ternary weak acid monoammonium GL-1 and 0.1 wt% mixed meter hydroxide) and the study of injection parameters were carried out. Methods The gelation properties and long-term stability of the water plugging agent were investigated using a visual method. The injectability, plugging ability, water erosion resistance, and selectivity of the water plugging agent were evaluated using sand-filled tube experiments, and the injection volume, acting position and injection rate of the water plugging agent were optimized. Results The adaptability evaluation showed that the gelation time of the water plugging agent from strength A to strength E was 72 h, and the final gel strength could reach strength I, which could meet the requirements of on-site implementation. The highest injection pressure was only 0.72 MPa, and the water plugging agent had good injectability. The water plugging agent had good selectivity, plugging and water erosion resistance properties. It could preferentially enter the high permeability channeling path. The plugging rate of the high permeability channeling path after gelation was more than 96%, and the breakup pressure gradient was higher than 4.46 MPa/m. The plugging rate was reduced by 2.31% after 50 PV continuously high-intensity water injection. After aging at 65 ℃ for 180 days, the dehydration rate was only 2.61%, indicating that the water plugging agent had good long-term properties after gelation. The experimental study of injection parameters showed that the optimal injection parameters of the water plugging agent were 0.8 PV of injection volume, 3 mL/min of injection rate, and the best acting position in the middle of the sand-filled tube. The plugging rate was 98.03% under the optimal injection conditions. Conclusion The delayed gelation elastic silicic acid gel water plugging agent was available for water plugging the high porosity and permeability reservoirs.