Study on a Hydrophobically Associating Polymer Viscosifier for Fracturing Fluids

A new hydrophobically associating polymer, LP-3A was synthesized through inverse emulsion polymerization, using AM, AMPS and monomers with hydrophobic chains and polyoxyalkylene groups as raw material, and benzoperoxide (BPO) as initiator. The polymerization conditions such as the optimum ratios of monomers, reaction time, temperature and initiator concentration etc. were determined through one-factor-at-a-time method. The molecular structure of LP-3A, a viscosifier used in fracturing fluids, was characterized, and the properties of LP-3A, such as temperature stability, shearing stability, recovery performance after shearing, viscoelasticity and thixotropy were studied. The study demonstrated that LP-3A had good high temperature stability and shearing performance. After being sheared under 150℃ and 170 s^-1 for 2 h, LP-3A still had residue viscosity of 200 mPa·s. After being sheared for 20 min at 500 s^-1 and 1,000 s^-1, respectively, shearing was stopped, and 90% of the viscosity of the LP-3A solution can be recovered. Compared with guar gum, energy needed to destroy the network structure of LP-3A was higher, and time needed for the recovery of the structure was longer. In the LP-3A fracturing fluids, elasticity prevails, and the viscoelasticity of LP-3A fracturing fluids is superior to guar gum fracturing fluids.