Preparation and Application of an Emulsion Supramolecular Fracturing Fluid for Shale Gas Development

To satisfy the needs of producing shale gas efficiently and cleanly, anemulsion-like hydrophobic association polymer ASNP was developed through inverse emulsion polymerization. The ASNP was then compounded with an extender SD-Z to produce an emulsion supramolecular fracturing fluid SMF-1, which can be prepared at the moment of using, without the needing of extra additives. Changing the concentration of ASNP, the fracturing fluid can be turned into slick water, linear gel or colloidal solution. SMF-1 slick water has excellent drag reducing ability, fresh water and fracturing fluid flowed back containing 0.08% SMF-1 have their drag reduced by about 70%, and their salt resistance can be 10000 mg/L. SMF-1 colloidal solution has excellent high temperature and shearing performance, 0.6% SMF-1 solution sheared at 110 ℃ and 170 sup>-1 for 120 min has viscosity that is at least 120 mPa·s throughout the test process. SMF-1 fracturing fluid is a fluid with low viscosity, high elasticity and good sand carrying capacity. SMF-1 fluid after gel breaking has viscosity that is less than 1.5 mPa·s, and the residue content of the gel breaking fluid is only 12.8 mg/L. In core test with the SMF-1 fracturing fluid, permeability impaired by the SMF-1 fluid is as low as 11.8%. In field application, SMF-1 can be switched to different fluids with stable properties, and the sand content is also higher than the fracturing fluid used in the offset section of the same well and in offset wells.