Study On Mechanism And Main Controlling Factors For Plugging Agent Assisted CO₂ Huff-puff

In recent years,gas injection to improve the recovery rate of rapid development,and there is marked effect to improve the recovery rate for CO₂ huff-puff.CO₂ huff-puff technology mainly depends on the dissolved viscosity and solubilization expansion mechanism to improve the capacity of crude oil production.But for reservoir with serious heterogeneity,especially there are many preferential seepage channels,The gas channeling will happen for CO₂ gas channeling along preferential seepage channels which could reduce the effect of CO₂ significantly.The use of plugging agent to assist CO₂ huff-puff could seal preferential seepage channels,balanced injection profile,expand the scope of the spread and improve the huff-puff effect.This article first to carring out the plugging agent auxiliary CO₂ physical model experiment.Experiment includes directly,plugging agent auxiliary CO₂ huff-puff for the first rounds and plugging agent assisted CO₂ huff-puff for the second rounds with large real rock model.The experimental results show that,the injected water in the process of water drive will happen along fingering phenomenon along preferential seepage channels.CO₂ huff-puff directly only affected the nearby seepage flow near the remaining oil.Throughput of three rounds,the recovery rate is only 21%.First injecting plugging agent after water drive,plugging agent has good sealing effect for preferential seepage channels,which could expanded the reach of CO₂ and oil,and help late discharge of CO₂.Throughput of three rounds,the recovery rate is only 50.2%.Before the second rounds CO₂ huff-puff to injecting plugging agent,part of the the plugging agent will into the throughput residual gas area and seal preferential seepage channels,which could reduce CO₂ injection.Throughput of three rounds,the recovery rate is only 24.7%.The numerical simulation model of the mechanism of CO₂ huff-puff is established,and the results of the physical simulation are fitted,the fitting precision is more than 95%.Depth understanding mechanism of CO₂ huff-puff directly and plugging agent assisted CO₂huff-puff to improving oil recovery.The results showed that when CO₂ huff and puff directly,by CO₂ solubilization expansion effect,it could reduce the viscosity of crude oil and improve its liquidity to raising the oil saturation near wellbore area;preferential seepage channels model,the gas channeling will happen when CO₂ huff and puff directly and the remaining oil is still on both sides of preferential seepage channels;After plugging agent injection,it could seal preferential seepage channels to expanding sweep area and improving the effect of oil increased.This artcle taks the CO₂ huff and puff of G area in Jidong Oilfield as the research object,and analysis of the well production.Through the reservoir numerical simulation method,discussing the influence of the static parameters and the dynamic parameters on the effect of the plugging agent auxiliary and drawing a partition map of CO₂ huff-puff effect.And through the"sensitive index"to determine the blocking agent auxiliary CO₂ huff-puff and increase the oil content of the main factors for the preferential seepage channels differentia,plugging agent and sealing capacity,that is residual resistance factor.The sealing radius and the residual resistance coefficient were used as quantitative indexes to establish the selection and dosage of CO₂ and the huff-puff method of plugging parameters,which has been applied in the typical blocks of Jidong Oilfield,and achieved a better yield effect.Predicting the plugging agent assisted CO₂ huff-puff optimization scheme relative to the CO₂ huff-puff directly scheme,single well average oil increces 230t.