An Analysis of Continuously-Mixed Hydraulic Fracturing Treatments

As hydraulic fracturing treatments continue to increase in fluid volume and in expense, emphasis is now being placed on more efficient treatment techniques. The traditional method of batch mixing a fracturing fluid has several disadvantages. Once the chemicals are added to the mixing water, they must be pumped within a specific length of time in order to retain their effectiveness. A delay due to well, weather or equipment problems can cause the premixed chemicals to degrade. Chemicals used to mix fracturing fluids constitute a substantial part of the treatment cost. Finally, any fluid left from the treatment usually cannot be reused unless it is transported to another location within a certain time limit. A continuous-mixing technique has been recently developed to more efficiently mix fracturing fluids. The technique eliminates pretreatment mixing of the fracturing fluid by proportionally combining the fracturing fluid chemicals with the mixing water in the blender tub at the time of the job. Sand is then added to the fluid, and the resulting fracturing slurry is pumped to the high pressure pumps for injection into the wellbore. In this paper, field and laboratory studies are cited in the attempt to describe the continuous-mix methodology. A cost comparison of continuous mixing and of traditional batch mixing based on job analysis is also presented.