Damage mechanism and removal technology of hydrophobic associative blockages in Bohai Oilfield

The polymer injection wells in Bohai S Oilfield cannot meet the injection allocation demand of the oil reservoirs even though blockage removal is carried out many times. In order to solve this production difficulty, this paper researched the characteristics and damage mechanisms of the blockages. The hydrophobic associative blockages formed in the process of polymer injection in this oilfield were compared with the common polyacrylamide blockages by means of scanning electron microscope (SEM), infrared spectrum, atomic force microscope (AFM) and other experimental instruments. It is shown that compared with conventional blockages, hydrophobic associative blockages are structurally more complicated and have stronger oil fouling enveloping ability. Then, based on their damage characteristics, a new type of SOA blockage removal agent was developed. It is indicated from the laboratory experiments that this new SOA blockage removal agent has the degradation rate of hydrophobic associative blockage over 90% and when it is combined with acid, the degradation rate is as high as 99%. Based on this, a new set of alternating SOA blockage removal agent and acid injection process is formed. The research result has been applied on site four well times in Bohai S Oilfield and its efficiency is 100%. It provides powerful guidance for the efficient blockage removal in polymer injection wells of offshore oilfields and its application and promotion prospect is promising.