Experiment And Mechanism Study Of Water Flooding Transforming To Air-Foam Flooding In Block A Of Daqing Oilfields

Air-foam flooding technology is a new technology with the dual properties of flooding and profile control,and is especially suitable for high water cut and heterogeneous reservoirs.There are many problems after years of exploitation in the Block A of Daqing Oilfield.It is necessary to conduct a study on the suitability of water flooding transforming to air foam flooding.This paper takes Block A of Daqing Oilfield as the research object,uses crude oil from Daqing Oilfield to conduct physical simulation and numerical simulation experiments,and draws the following conclusions:(1)Low-temperature oxidation experiment results showed that the viscosity and heavy component content increased slightly,because-OH,-C=O,-CO-chemical bonds are formed due to the "oxygenation" reaction.The oxidation reaction rate is positively correlated with temperature and pressure.The presence of formation water and formation sand promotes the oxidation reaction while the presence of foam inhibits the oxidation reaction.(2)The foaming agent AD300 was picked from five candidates.The effective concentration of the optimal foaming agent was 1.0‰,take the gas and liquid coinjection method,the best injection speed is 0.2mL/min,the optimal gas-liquid ratio was 1.5:1,and the recovery increased from 49.98% to 68.35%.(3)Using numerical simulation technology,we carried out the design of air-foam flooding scheme and forecasted development indicators.The results show that injecting gas to the main oil layer accurately is better than injecting to the whole area,and optimizing the original five-point well pattern as a similar anti-seven-point well pattern will achieve better production results.The recovery factor is predicted to increase from 2.89% to 12.38% after six years.Theoretical and experimental studies have shown that the air-foam flooding technology is suitable for the reservoir development of the Daqing target block.It can effectively solve the problems encountered in the development process of traditional water flooding,and increase the sweep coefficient and improve crude oil recovery.