一种新型外柔内刚型封堵剂的研制

Research and Development of a Novel Internal Rigid External Soft Plugging Agent

刚性封堵剂强度大,难以有效适应地层孔隙的尺寸及形状;柔性封堵剂自适应能力强,但承压强度低,两者均都难以形成有效封堵。结合刚性封堵剂强度大和柔性封堵剂自适应能力强的优点,采用碳酸钙作为刚性内核,以丙烯酰胺和2-丙烯酰胺基-2-甲基丙磺酸为主要聚合单体,以N,N-亚甲基双丙烯酰胺为交联剂,以过硫酸铵-亚硫酸氢钠氧化还原体系为引发剂,采用溶液聚合法制备了一种外柔内刚型封堵剂。该封堵剂吸水膨胀倍数较小,抗压强度高,抗温性好,对钻井液流变性影响小,并具有较柔性封堵剂更好的降滤失和砂床封堵性能。

Rigid plugging agents have high strength and are difficult to adapt themselves to the sizes and shapes of the formation pores;Soft plugging agents,on the other hand,have strong self-adaptive capacity,but their compressive strength is low.Effective and efficient plugging cannot be obtained by the rigid or the soft plugging agent only.By combining the advantages of the soft and the rigid plugging agents,a new“soft outside rigid inside”plugging agent was developed through solution polymerization.This new plugging agent was made with calcium carbonate as the rigid core material,acrylamide and 2-acrylamido-2-methylpropane sulfonic acid as the main polymerization monomers,N,N-Methylene-bisacrylamide as the crosslinking agent,and ammonium persulfate-sodium bisulfite redox system as the initiator.The new plugging agent has small expansion ratio when water is absorbed,high compressive strength,good thermal stability and little impact on the rheology of the drilling fluid.Compared with soft plugging agents,this new plugging agent has better filtration control capacity and plugging performance in sand-bed test.