纳米聚合物微球封堵剂的制备及特性

页岩具有极低的渗透率和极小的孔喉尺寸,传统封堵剂难以在页岩表面形成有效的泥饼,只有纳米级颗粒才能封堵页岩的孔喉,阻止液相侵入地层,维持井壁稳定,保护储层。以苯乙烯(St)、甲基丙烯酸甲酯(MMA)为单体,过硫酸钾(KPS)为引发剂,采用乳液聚合法制备了纳米聚合物微球封堵剂SD-seal。通过红外光谱、透射电镜、热重分析和激光粒度分析对产物进行了表征,通过龙马溪组岩样的压力传递实验研究了其封堵性能。结果表明,SD-seal纳米粒子分散性好,形状规则(基本为球形),粒度较均匀(20 nm左右),分解温度高达402.5℃,热稳定性好,阻缓压力传递效果显著,使龙马溪组页岩岩心渗透率降低95%。 

Preparation and Characteristics of Nano Polymer Microspheres Used as Plugging Agent in Drilling Fluid

Conventional plugging agents can hardly form mud cakes on the surface of shales because of the very low permeability and very small size of pore throat in shales. Nano particles, on the other hand, are easy to block the pore throats in shales, hence to hinder the invasion of liquid phase of drilling fluid, to maintain the stability of borehole wall, and to protect reservoir formations. A nano polymer microsphere plugging agent, SD-Seal, was developed through emulsion polymerization, using styrene and methylmethacrylate as reactive monomers and KPS as initiator. Laboratory studies show that SD-Seal particles have good dispersity and regular shapes (mostly spherical). The particle size of SD-Seal is about 20 mm, and the decomposition temperature is 402.5℃. Test of SD-Seal on rock sample taken from the Maxi Formation reducesthe permeability of the rock by 95%.