Study On Micro-foam Steering Acid Technology

Foam acidification technology can effectively solve the reaction rate of acid rock too fast,acidification effect not uniform and the water content increased after the acidification in conventional acidizing process;Foaming acidification can make acid liquor into low permeability stratum and oil stratum,controlling the rise of water content after acidification,so that the acid liquor achieved the purpose of diversion.But the usual foam acidification technology requires gas and gas injection equipment,increasing the cost of acidizing treatment.This paper focuses on foam acidification technology,using the acid liquor react with carbonate and the release of CO₂ as the gas source in the reservoir formation of foam acid.Using the airflow method and core displacement equipment at the same time,doing research on formulation and corrosion inhibition performance of foam acid,and drawn the following conclusions:?1?Use the CO₂ as the source gas;By add different acid additives to form the system of gelled acid,complex acid,conventional acid;And evaluating in three acid systems by adding different foaming agents.The results showed that the foaming comprehensive index of OP-10 was the highest among the three acid systems;The additive amount of conventional acid and gelled acid is 0.6%,when the amount of complex acid is 0.45%,there is a strong foaming performance,stable foam performance,with resistance to mineralization and temperature performance.The foam comprehensive index of the same concentration of foaming agent in the gelled acid and the complex acid is better than that of the conventional acid.?2?It can be seen by the dissolution experiments of foamed acid and carbonate debris,the dissolution rate of the foam acid in the same time is about 4%-10% lower than that of the acid liquid base solution,but the temperature is higher,the dissolution rate is faster;This shows that the bubble acid has a certain role in corrosion inhibition,it can effectively prevent the zone near the borehole happened excessive collapse due to the acid rock reaction,and the depth of the formation can be acidified.Through the reaction of foam acid with 20#steel corrosion coupons can be seen that the corrosion rate of the foam acid is lower than that of the acid liquid,and there will be no pitting phenomenon.The corrosion rate of the gelled acid and the complex acid in the three acid systems was lower than 0.4g/m2 h.?3?Through single core temporary plugging and dual core shunt experiment shows that,The experimental solution of the foam acid solution can rely on acid rock reaction to generate CO₂ gas to form a white emulsion state of the bubble.The resulting foam acid can effectively block the aqueous core,the ability to block the oil core is very weak.Displacing parallel cores with a penetration rate of around 8,foam acid will preferentially block high permeability cores,so that acid liquor into the low permeability of the core,it is more suitable for non-homogeneous stratigraphy.Among them,the viscous acid that has high viscosity is better for the temporary plugging and shunting effect of the core,but the pressure requirement is higher when adding acid,in the practical application of foam acid,should choose the appropriate acid fluid viscosity.