一种抗高温凝胶封堵剂

凝胶类封堵剂具有自适应强的特点，但钻井液用凝胶封堵剂普遍存在抗温性较差的问题。以聚乙烯醇（PVA）、丙烯酸（AA）、丙烯酰胺（AM）为反应单体，N，N-二甲基双丙烯酰胺（MBA）为交联剂，过硫酸铵为引发剂制备了一种新型凝胶封堵剂（PPAA），该封堵剂抗温可达180 ℃。PPAA膨胀倍数低，对钻井液流变性影响小，能降低钻井液滤失量。180 ℃老化后，含2%PPAA的钻井液对80～100目砂床的侵入深度为2.6 cm，较常规封堵剂封堵率提高60.6%，在6%NaCl条件下封堵率提高48.6%，且高温高压砂盘滤失量降低69.7%。 

A High Temperature Gel Plugging Agent

Gel plugging agents have the characteristics of strong self-adaptation, their use in drilling fluids, on the other hand, has the shortage of poor thermal stability. To overcome this shortage, a new gel plugging agent, PPAA, was developed with poly vinyl alcohol (PVA), acrylic acid (AA) and acrylamide (AM) as the reaction monomers, N, N-dimethyl bisacrylamide (MBA) as the crosslinking agent and ammonium persulphate as the initiator. PPAA functions normally at temperatures as high as 180 ℃. PPAA has low expansion factor, minor effect on the rheology of mud, and is able to control the filtration rate of the mud. A drilling fluid containing 2% PPAA, after aging at 180 ℃, can invade into a 80 – 100 mesh sand-bed by 2.6 cm, and the plugging efficiency of the mud is 60.6% higher than that of a mud treated with conventional plugging agents. Compared with conventional plugging agents, 6% NaCl solution treated with PPAA has efficiency of plugging increased by 48.6%, and the HTHP filter loss through sand plate reduced by 69.7%.