贝壳粉基自适应性封堵剂

以丙烯酸（AA）、丙烯酰胺（AM）、2-丙烯酰胺-2-甲基丙磺酸（AMPS）、N-乙烯基吡咯烷酮（NVP）为聚合单体，以N,N-亚甲基双丙烯酰胺（MBA）为交联剂、甲基丙烯酸十二烷酯（DM）为功能单体、过硫酸铵（APS）-亚硫酸氢钠为氧化还原引发剂，形成的凝胶聚合物将贝壳粉包裹形成多核无定形微囊。通过研究封堵剂吸水性能和形貌确定了AA∶AM质量比为1∶3时效果最佳。该封堵剂有良好的自适应性，封堵性能优异，对钻井液流变性影响较小，抗温抗盐性能良好，单剂180 ℃老化16 h后，结构保持完整，加入1%封堵剂的4%膨润土浆在150 ℃老化16 h后的API滤失量为11.4 mL，环保体系加入1%该封堵剂在150 ℃老化16 h后，中压砂床测试侵入程度为28.74%；1%30～50目封堵剂可封堵宽0.5 mm、深5 mm的模拟裂缝，且承压至4 MPa。 

A Self-Adaptive Shell Powder Plugging Agent

Multinucleated amorphous microcapsule can be made by wrapping shell powders with a gel polymer. This gel polymer was developed through polymerization, with acrylic acid (AA), acrylamide (AM), 2-acrylamide-2-methyl propanesulfonic acid (AMPS), N-vinylpyrrolidone (NVP) as the polymeric monomers, N,N-methylene-bisacrylamide (MBA) as the crosslinking agent, dodecyl methacrylate (DM) as the functional monomer, and ammonium persulfate-sodium bisulfite as the redox initiator. Laboratory studies showed that the gel polymer has the optimum performance at a mass ratio of AA∶AM = 1∶3. The multinucleated amorphous microcapsule plugging agent has good self-adaptive performance and excellent plugging capacity. It has minor effect on the rheology of the drilling fluid, and is resistant to high temperatures and salt contamination. After aging at 180 ℃ for 16 hours, the structure of the plugging agent still remains intact, and the API filter loss is 11.4 mL. Test of the plugging agent in an environmentally friendly mud system after aging at 150 ℃ for 16 hours showed that the invasion depth of filtrate into the medium pressure sand-bed was 28.74% of the whole thickness. The plugging agent with particle sizes distributed between 30 mesh and 50 mesh can be used to plug simulated fractures of 0.5 mm (width) × 5 mm (depth), and can withstand pressures up to 4 MPa.