聚合物降解产物伤害与糖甙键特异酶破胶技术

综述了钻井，完井，尤其是水力压裂作业中产生的多糖类聚合物伤害和应用糖甙键特异酶破胶，解除多糖类聚合物伤害的技术。第一节报道了聚合物降解产物造成的伤害，指出冻胶破胶液粘度低并不代表压裂液已从充填裂缝中充分返排，氧化破胶剂和普通酶破胶剂不能使多糖类聚合物充分降解，产生的大分子量，水不溶的降解产物可对地层造成伤害，消除伤害的办法是采用对糖甙键有特异性的各种水解酶作压裂液破胶剂或伤害地层处理剂。第二节报道了各种聚合物（纤维素，瓜尔胶，淀粉）糖甙键特异酶降解聚合物的机理。第三节报道了糖甙键特异酶（主要针对瓜尔胶）的应用性能测试及结果，包括岩心流动实验，含糖量和分子量测定，传导性测试。第四节介绍了糖甙键特异酶消除聚合物伤害和用作压裂液破胶剂的现场应用，包括选井原则，实施工艺要点及3个典型井例。

Polymeric Fragment Damage and Polymeric Linkage-Specific Enzyme Breaker Technology

The formation damage caused by polysaccharides in well drilling and completion and in hydrofracturing operations, in particular, and the methods of gel breakdown and polymer damage removal by using polymeric linkage-specific enzymes (LSEs) are reviewed. The 1st part of the article introduces the polymeric fragment damage and shows that low viscosity of brocken-down fluids does not indicate the fullness of backflow of the fluids from fracture packs, oxidizing and common enzyme breakers do not degrade the polysaccharide sufficiently and high molar mass, water-insoluble degradation products create damages; for removing such damages, various glycosyl hydrolases can be used as gel breaker or damage removal agent. The 2nd part presents the mechanisms of degrading polysaccharides (celluloses, starches and guar). The 3rd part describes the methods and results of evaluating LSEs, mainly for guar and its derivatives: core flow tests, total carbohydrate content and molar mass determinations, and fracture conductivity test. The 4th part presents the field uses of LSEs for damage removal and as gel breaker: well selection; technologic aspects; and three well cases.