压裂返排液取水应用技术

为了解决非常规储层压裂改造过程中水资源的大量消耗以及日益增多的废液污染问题,研究了压裂返排液经过化学处理后用于重新配制压裂液的新方法。以长庆油田压裂返排液为例,分析了主要矿物离子Ca2+、Mg2+及残存破胶剂(过氧化物)和硼离子交联剂对重新配制的压裂液主要性能的影响,开发了通过络合反应降低压裂返排液中矿物离子的处理剂TR-1、通过氧化-还原反应处理残余破胶剂的处理剂TR-2及通过屏蔽残余硼离子交联剂从而阻止硼离子与植物胶多糖上的羟基交联的处理剂TR-3。应用该方法,2013年在长庆油田处理了15口水平井、125个水平段,回收处理液量14 000 m3,占施工液量的23%,达到了压裂返排液的重复利用效果并减少了对环境的污染。

Application of recycling technology for fracturing flowback fluid

To solve the problems such as considerable water consumption and increasing waste fluid pollution during unconventional reservoir fracturing transformation process, a new method was studied on the use of fracturing flowback fluid for re-preparing fracturing fluid after chemical treatment. Taking the fracturing flowback fluid in Changqing Oilfield as an example, the effects of the main mineral ions Ca²⁺ and Mg²⁺, residual gel breaking agent (peroxide) and boron crosslinking agent on re-prepared fracturing fluid were analyzed. Meanwhile, three different treatment agents TR-1, TR-2 and TR-3 were formulated, and used to reduce the mineral ions in fracturing backflow fluid through complexation, remove the residual gel breaking agent by oxidation-reduction reaction, and prevent the boron-plant galactomannan gum hydroxyl crosslinking by shielding residual boron crosslinking agent, respectively. This method was applied to 15 horizontal wells and 125 horizontal members of Changqing Oilfield in 2013. Moreover, 14 000 m³ treatment fluid was recovered, which accounted for 23% of the total fracturing fluid volume, thus achieving the reutilization effect of fracturing flowback fluid and reducing environmental pollutions.