Abstract:

By the comprehensive analysis of the cases of polymer flooding and profile control in the Block B19 in Shengli Oilfield, it is suggested that the main factor causing plugging in B19 was the injecting water that did not meet the standards of water flooding, which caused the excessive crosslinks of the injecting polymer and the formation of strong gelatinous material. The chemical analysis, the energy spectroscopy and the IR spectroscopy were used to investigate the mineral morphology and main compositions of gel scales. It was shown that the gel scales are composed of crosslinked polyacrylamide (PAM)，in which a mass of water have been absorbed. The chloride mineral crystals as the inorganic scale material were gradually enriched and formed the inorganic scale structures in vivo environment of crosslinked polymeric inclusions. Moreover, some clay minerals from the formation were wrapped into the polymeric inclusions, eventually leading to the formation of the strong gelatinous materials with the complex polymermineral structural characteristics, which seriously affected and even obstructed the flow path of the polymer solution in polymer profile control and polymer flooding.

Key words:  plugging material, mineral morphology, composition, polymer flooding, Shengli Oilfield