Research On Agent Channeling Prevention Technology Of Reduced Oxygen Air Displacement In A Test Area

The oxygen-reduced air flooding test of Changqing Oilfield started from single well test injection,and has gone through pilot test and expanded test stages,and the application effect is remarkable.Due to the strong reservoir heterogeneity,the development of micro-fractures,the fracturing of oil wells,the existence of artificial fractures,and the dominant water drive channel formed by long-term water injection,the oxygen-injected air has a greater risk of gas channeling.In order to make this To expand the implementation of oxygen-reduced air flooding in the test area,it is necessary to have a certain understanding of the law of gas channeling by oxygen-reduced air flooding in the test area,and it is also necessary to conduct research on gas channeling prevention technology for different well conditions in the test area.This paper firstly uses well test identification method and fuzzy mathematics identification method to identify the dominant channels in test area A,and analyzes the gas channeling laws and influencing factors of oxygen-reduced air flooding in test area A using digital simulation.On this basis,the performance evaluation of the plugging agent used in the A test area was carried out,and the evaluation of the single plugging agent and the foam auxiliary plugging agent for the blockage and channeling prevention of the A test area by the reduced oxygen air flooding was studied.Due to the micro-cracks in the A test area and the poor stability of the gel plugging agent,the gel system suitable for fractured reservoirs was improved and performance evaluation was carried out.The main research results obtained in this paper are as follows:（1）Through the well test identification method and fuzzy mathematical identification method,the dominant channel was identified,and the gas channeling evaluation standard was determined.Data analysis of the given 20 production wells and 13 injection wells has drawn the dominant channel plan.The results show that the dominant gas drive channels are mainly developed along NE60°-70°.（2）Modeling 44 wells in the test area was established using digital simulation software.The classification standard for gas channeling law in the test area is that the mole fraction of produced gas N₂ is greater than 60%,and the gas-oil ratio is greater than 400 m³·t^-1;It is clear that the dominant channel is the main factor of gas channeling.（3）Through the performance evaluation of the plugging agent currently used in the A test area,it is concluded that the particle size of the microsphere plugging agent is small and hydrolyzes quickly;the PEG plugging agent has good stability;the preferred weak fluidity gel system is:0.1%HPAM+0.1%Organic chromium crosslinking agent.（4）The anti-gas channeling performance of a single plugging agent and a foam-assisted plugging agent was studied through the gas drive double-tube sand-packing experiment.The results show that the anti-gas channeling effect of a single plugging agent is weaker than that of the foam-assisted plugging agent.Microsphere-enhanced foam is used for plugging of developed reservoirs;PEG-enhanced foam is used to seal the well-developed reservoirs with grades 3-12;movable jelly foam is suitable for the plugging of well-developed reservoirs with dominant channels.（5）An improved plugging agent:0.1%HPAM+0.1%organic chromium+0.05-0.1%nano Si O₂ was developed,and performance evaluation was carried out.The results showed that the improved gel system had strong stability.The split core was used to simulate the reservoir model,which made ordinary The enhanced oil recovery performance of the jelly foam system and the enhanced jelly foam system were studied after 15 days of aging.The results showed that the enhanced jelly foam had a higher recovery rate than the ordinary jelly foam.