Preparation of a novel superior strength plugging agent resistant to heat and salt

Key words:  KYPAM/polyethyleneimine gel system  plugging agent  high temperature high salty reservoir  aqueous gels  superior strength gels  preparation

Abstract:

A novel plugging agent resistant to heat and salt was prepared by the crosslinking reaction of amide groups of polyacrylamide(KYPAM) with NH of crosslinker polyethyleneimide and formed strength covalent bond. The effect of several factors on gelling properties was studied experimentally. The results show that with the increase of KYPAM relative molecular weight, crosslinker concentration and KYPAM concentration, gelation time shortens and gel strength goes up, but if KYPAM relative molecular weight or crosslinker concentration is too high, plugging agent will dehydrate. With the increase of pH, change tendency of gelation time first shortens, then lengthens and last shortens. With the increase of temperature, gelation time shortens and gel strength increases, but if temperature is too high, plugging agent will be of small elasticity, become brittle and be destroyed easily. With the increase of salinity, gelation time lengthens and gel strength reduces. The formulation of suitable plugging agent are as follows:KYPAM relative molecular weight of 8×10⁶, KYPAM concentration of 12 g/L,crosslinker concentration of 9 g/L,pH=5-7, reservoir temperature of 80-110 ℃, salinity ≤80 g/L NaCl+1.2 g/L CaCl₂. PEI/KYPAM shutoff agent has higher breakthrough pressure and strength and stronger washing resistance than phenolic resin/KYPAM shutoff agent.