Research on composite acid huff and puff technology for improving oil recovery in horizontal wells of low-permeability oil reservoirs in Yanchang Oilfield
In order to effectively remove blockages in horizontal wells in low-permeability blocks of the Yanchang oilfield and improve the recovery rate of horizontal wells,a composite acid unblocking system for acid flooding construction was developed through a large number of experiments.The comprehensive performance of the composite acid system was evaluated indoors.The results show that the surface activity of the composite acid solution system is strong,and it can still maintain a low surface tension after high-temperature aging,which is conducive to the reflux of acid solution after swallowing;The dissolution performance of the composite acid system is better,and it can effectively dissolve calcium carbonate,asphaltene,and on-site blockages;The composite acid system has a lower corrosion rate on N80 steel,which can ensure the safety of acid throughput construction;The compatibility between the composite acid system and the formation water of the target reservoir is good,and there will be no turbidity or sedimentation blockage;The composite acid system has a good comprehensive plugging removal effect on both artificial and natural cores.When the PV number is injected to 0.5,a higher permeability recovery value can be achieved,and the effect of improving oil recovery is good.
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