The Technology Research Of Foam Expanding Swept Volume In The Process Of CO₂ Displacement In The Low-Permeability Field

The researched field,which is Jilin DaAn field,is a fissured low-permeability reservoir which has problems of high water injection pressure and gas breakthrough.Therefore,the paper proposed that through drop injection,a small quantity of foaming agent is injected in the process of injecting gas and injected gas and foam agent formed foam with water,which could prevent gas breakthrough,expand swept volume of injected gas and increase oil production.First of all,the paper studied foaming agent select for hydrotrope foam while temperature and salinity is researched how to affect foam system.At the same time,the adsorbability of foam agent in natural core and select and stability theory of foam stabilizer is studied.Secondly,this paper also researched the seepage ability of foam agent,and through experiments of two-tube parallel cores,the foam ability of expanding swept volume is investigated.Finally,it researched the formation water saturation how to impact the foaming ability studies and CO₂ displacement effect in low permeability fissure reservoir.The results show that:among the three kinds of selected foaming agents,one of HY-3 has the stronger foaming ability and the better foam stability.With the increase in salinity and temperature,the composite index of HY-3,13#,HABS foaming agents declined.At simulated oilfield reservoir conditions in the Jilin Daan field,a certain intensity foam can be formed.According to the dynamic and static measurement results of Absorption in the natural rock,absorption loss of three kinds of foaming agent is little and could meet field requirements.Experimental results of foam stability showed that the foaming agent added to the foam stability WP-1 can play a role in stabilizing foam,foam composite index increased and foam performance enhanced.Foam system seepage capacity experimental results show that when the gas injection rate is fixed,along with the gas-liquid ratio increasing(that is,reduce the volume of injected fluid),foam stabile seepage pressure is reduced;with the surfactant concentration increased, the pressure increased When the foam drive achieve a stable flow.At parallel two-tube cores, through injecting a certain amount of foaming agent with drop injection method,HY-3,13#, HABS formed foam systems have effect of adjusting gas entry profiling and expanding swept volume.At bound water saturation the foam could be formed,and as the water saturation increased,the foam stable seepage flow pressure increased so that the quantity of foaming agent reduced when the steady seepage pressure is reached.Homogeneous core experimental results show that when different foam systems which have different foaming capacity are injected at the end of gas drive,foam flow pressure and oil production increased.Therefore it has a certain ability to improve oil recovery.