High Temperature Salt Resistant Filter Loss Reducers for Water Base Drilling Fluids: Synthesis with Explosive Polymerization Method and Performance Evaluation

Sodium styrene sulfonate and AMPS were used to react with acrylamide and dimethyl diallyl ammonium chloride respectively in explosive polymerization to produce two high temperature salt resistant filter loss reducers WS-1 and WS-2. Explosive polymerization was used in the synthesis reaction because in aqueous phase polymerization, the yield of the product is low, the molecular weight of the product is easy to increase during drying, and the energy required for the reaction is high. The molecular structure and thermal; stability of WS-1 and WS-2 were characterized using FT-IR spectroscopy and TGA. The effects of WS-1 and WS-2 on the rheology and HTHP filtration rate of high salinity water base drilling fluids at elevated temperatures were evaluated in laboratory experiment. The experimental results showed that WS-2, having rigid sodium styrene sulfonate molecular chains in its molecules, had good high temperature stability, the thermal decomposition temperature of WS-2 was tested to be 310℃. HTHP filter loss at 220℃ of a saturated saltwater base drilling fluid treated with WS-2 was 7.6 mL. WS-1, having large molecular chain of AMPS in its molecules, had thermal decomposition temperature of 270℃. HTHP filter loss at 200℃ of a saturated saltwater base drilling fluid treated with WS-1 was 1.6 mL. These experimental results showed that WS-1 and WS-2 both have good high temperature and salt resistant performance.