Indoor Research on Organic Polyacid System Suitable for Water Injection Wells in Low Permeability Reservoirs in Yumen Oilfield
One of the main challenges of the acidic injection process in carbonate matrices is the formation of dominant pattern wormholes,which is generally not possible using concentrated hydrochloric acid.The high activity of calcite depletes the acid around the well,thus preventing the formation of extended channels to achieve the desired breakthrough.In this paper,the effect of the reaction between the organic polyacid system surfactant nonylphenol 100 EO delayed 15%HCl and carbonate on the formation of wormholes was evaluated,little or no significant acid was consumed to achieve breakthrough.For this purpose,flow tests were carried out in porous media at different injection rates(0.5,2,5 mL·min-1)to determine the PVBt curves of HCl and HCl with 10%surfactant added.The results showed that in acidic solutions,the presence of surfactant slowed down the rate of acid rock reaction,thus reducing the PVBt values at different flow rates.
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