油气固井纤维的筛选研究

Study on Fiber Selection in Oil & Gas Well Cement

针对薄水泥环条件下射孔、酸化压裂极易引起水泥石的脆性断裂,造成“二次窜流”的现象,借助建筑、桥梁行业用纤维加强混凝土的方法,通过对几种常用增强纤维性能的调研、理论分析和试验研究,对油气固井用纤维进行了筛选研究。研究表明:碳纤维、聚丙烯纤维和聚酯纤维的物理机械性质均适合于改善固井工程中水泥石强度;碳纤维、聚丙烯纤维在分散剂水溶液中的分散特性较好;纤维表面的物理及化学性质显示,碳纤维表面无缺陷和裂痕,且具有“绒毛”特征,有利于与水泥石之间的粘接,而且表面官能团有利于改善水泥石塑性;水泥浆中加入碳纤维既不影响固井施工又有利于改善水泥浆的直角稠化特性,以防止气窜的发生。

In terms of the fact that the perforation under thin cement mantle conditions and the acid fracture technology can easily result in brittle fracturing and subsequent 'Second Channeling' phenomenon, the paper investigates, analyzes and tests several common cementing fibers, and accordingly presents fiber-selection study on oil & gas well cementation by reference to the approach to use fiber to enhance concrete strength in building and bridging industry. Results imply that the physical and mechanical features of carbon fiber, polypropylene fiber and polyester fiber are all appropriate to improve cement strength; the dispersivity in dispersant aqueous solution of carbon fiber and polypropylene fiber is better; carbon-fiber's surface physical and chemical features show its non-flaw or non-fracture and 'fluff' property which can benefit the cementation with hardened cement, moreover, its surface functional group can help to improve cement plasticity; the addition of fiber can not only cause no effect on cementing operations, but can improve perpendicular-angle thickening performance of cement slurry and prevent gas channeling.