Study on Characterization of the Performance of Fracturing Fluids in Large Scale Volumetric Fracturing

In the national standard “The evaluation measurement for properties of water based fracturing fluid” (SY/T 5107-2016), the shearing history of a fracturing fluid in large scale volumetric fracturing and the high shear rate of the fracturing fluid when it passes through a perforation cannot be simulated. A study has been performed on the investigation of how to measure the performance of a fracturing fluid in the whole process of volumetric fracturing job. Based on the actual flow rates in field fracturing operation, the shear history of a fracturing fluid flowing through pipes, perforation and formation fractures was simulated. Meanwhile, the dosage of gel breaker was optimized in an effort to find the concentration of the gel breaker when the lowest damaging to the reservoir is required. Thus, the evaluation of a fracturing fluid should be able to quantify two parameters; sand carrying capacity of the fracturing fluid which satisfy the needs of fracturing job and thorough breaking of the gel some time after the fracturing job is completed. Using the transparent parallel board model, the dynamic sand carrying capacity of a fracturing fluid was investigated, and the test results will provide a design basis for the “full fracture propping” in large scale volumetric fracturing. The results of the new evaluation method show that the compound crosslinked guar gum fracturing fluid and the crosslinked polymer fracturing fluid have the highest viscosity losses when passing through perforations at high flow velocity. The emulsion association fracturing fluid is sensitive to gel breaker, if the formation damage caused by gel breaking process is low, the dynamic sand carrying performance will not be able to satisfy the needs of placing proppant particles into the distal end in a fracture. A low concentration guar gum fracturing fluid treated with optimized amount of gel breaker will have good dynamic sand carrying capacity at flow rates prevailing in field operations, and thus satisfy the technical goals of placing proppants into the distal end of a fracture.