The Properties of Non-Aqueous Fracturing Fluid with Low-Molecular Alkane Suitable for Shales

During the fracturing stimulation of unconventional oil and gas reservoirs (e.g. shale gas), various challenges are encountered, including the large amount of water consumption, difficult disposal of flow-back waste fluid and formation/reservoir damage. It is meaningful to explore a new non-aqueous fracturing technology to replace the traditional hydraulic fracturing technology for development and production of unconventional oil and gas reservoirs. The dialkyl phosphate gelling agent was formed through the reaction among phosphorus pentoxide (P2O5), triethyl phosphate (TEP) and mixed alcohols, it was mixed with a modified complex iron crosslinking agent in the low-carbon alkane to produce the low-molecular alkane non-aqueous fracturing fluid. By analyzing its basic performance and rheological property,the result showed that the fracturing fluid gel was prepared by the crosslinking ratio 100.0:3.5 and gelling agent mass fraction 1.5%), which can meet the requirements of reservoir fracturing operations with good temperature resistance, shear resistance and proppant carrying capacity.The viscous elasticity and shear thinning capacity of crosslinking gel tend to vary with the mass fraction of gelling agent, with obvious regularity. The rheological curves of the low-molecular alkane fracturing fluid can be characterized by the non-linear co-rotational Jeffreys constitutive equation, which provides the theoretical basis for the new fracturing fluid.