川西地区体积压裂气井井底复合堵塞净化剂体系优化研究

Optimization of Cleaning Agent Formulation for Bottom-Hole Composite Plugging in Volumetrically Fractured Gas Wells in Western Sichuan

摘要: 针对川西体积压裂气井投产后井底复合堵塞导致产能下降的问题，以研究区3口体积压裂气井为例，明确了堵塞物组成并优化了解堵体系。堵塞物主要由压裂砂、黏土矿物、碳酸盐矿物及铁氧化物构成，呈多矿物共存复合污染特征。基于组成特征优选土酸体系，溶蚀与岩心渗透率恢复实验表明，12% HCl + 3% HF土酸溶蚀率达57.62%，明显优于单一15% HCl或3% HF体系，处理后岩心渗透率可提高1.63~1.76倍。通过渗透剂、螯合剂、缓蚀剂和助排剂优选，形成最终配方：12% HCl + 3% HF + 0.6% OPE-3 + 5% DTPA + 5% SA1-3C + 1.0%~1.5% SA1-8。综合性能评价显示，该体系配伍性良好，表面张力和缓蚀性能满足施工要求，具备良好的现场应用前景。

Abstract: To address the problem of productivity decline caused by composite plugging in the bottomhole after production in volume-fractured gas wells in western Sichuan, three volume-fractured gas wells in the study area were taken as examples. The composition of the plugging materials was identified and the plug-removal system was optimized. The plugging materials consist mainly of fracturing sand, clay minerals, carbonate minerals, and iron oxides, exhibiting characteristics of multi-mineral coexisting composite contamination. Based on the compositional characteristics, a mud acid system was selected and optimized. Dissolution and core permeability recovery experiments showed that the dissolution rate of the 12% HCl + 3% HF mud acid system reached 57.62%, which was significantly higher than that of the single 15% HCl or 3% HF systems. After treatment with this system, the core permeability increased by a factor of 1.63 to 1.76. Through the optimization of penetrating agents, chelating agents, corrosion inhibitors, and cleanup additives, the final formulation was determined as: 12% HCl + 3% HF + 0.6% OPE-3 + 5% DTPA + 5% SA1-3C + 1.0%~1.5% SA1-8. Comprehensive performance evaluation demonstrated that the system has good compatibility, and its surface tension and corrosion inhibition performance meet the requirements for field operations, indicating promising prospects for field application.