Reuse treatment technology of fracturing backflow fluid and its application in Wuqi Oilfield

Abstract

The fracturing backflow fluid in Wuqi(WQ) Oilfield has problems such as large quantity, high viscosity, and difficult treatment, and the environmental situation is extremely severe. Combined with the actual oilfield development, the main components of fracturing backflow fluid were analyzed, and the factors affecting the reuse of fracturing fluid and the treatment methods to deal with the impact were studied systematically. The results showed that the concentrations of Na+, K+ and SO42- had a little influence on the viscosity of base fluid, while Ca2+, Mg2+ and total iron concentrations had greater influence. The order of ion influencing factors was as follows: Total iron>Ca2+>Mg2+>K+>Na+>SO42-. Residual cross-linking agent concentration, gel breaker concentration, bacterial content and pH also had great influence on the viscosity of base liquid. Based on the results of influencing factors analysis, the backflow was treated by chemical reaction, nano-activated carbon absorption, UV lamp or sunlight, and sodium hydroxide addition. On this basis, a set of in-situ treatment process of “oil removal by air flotation-oxidation gel breaking and cation removal-coagulation destabilization-plate frame pressure filtration-water purification” was formed. The fracturing flowback fluid treated by this process was used to prepare new fracturing fluid, which could meet the needs of the field, and the application effect was good. The recycling of the backflow liquid was realized, and the purpose of cleaner production and cost saving was achieved.

Keywords

• fracturing flowback fluid
• fracturing fluid performance
• recycling
• cleaner production