Development and Application of Recyclable Fracturing Fluid in Changqing Oilfield

“Low permeability, low pressure and low abundance” is the typical characteristic of Changqing sandstone Oilfield. To develop this block economically, large-scale stimulation was often required, which would bound to be encountered with a lot of fracturing fluid flowback waste, resulting in much more emissions of wastewater and the disaster problems of environmental pollution. Studies have carried out with characteristics of fracturing fluid, mechanism of crosslinking, mechanism of gel breaking, and the analysis of the reusability conditions which impacted fracturing fluid. Two kinds of recyclable fracturing fluid system called low molecular environmental fracturing fluid and bio-clean fracturing fluid are being researched independently, thus the problems of reversible crosslinking and reusing about fracturing fluid were resolved successfully. The emission of wastewater was reduced, even water resources and raw materials were saved; as a result, the reuse of fracturing fluid was achieved. More than 520 times field tests were carried out in different regions of Changqing Oilfield by using low molecular environmental fracturing fluid and bio-clean fracturing fluid, and the volume of recycling liquid was almost over 47,600 m3. Data showed that the average utilization rate of fracturing fluid recycling solution was higher than 98% and fracturing fluid recycling solution could be reused ten times at best conditions. Both the work time was shortened to 680 days and 38,000,000 RMB of costs was saved. Site result positively shows that conducting the brand-new recyclable fracturing fluid large scale can effectively enable to reduce energy consumption and the environmental impact, at the same time achieve the reuse of water resources and raw materials and shorten the construction time, with the good efficiency socially and economically.