STUDY OF EOR BY GAS INJECTION IN BURIED HILL RESERVOIRS CONSISTING OF FRACTURED METAMORPHIC ROCKS

There is a fractured metamorphic rock and buried hill reservoir,complex in lithology,high oil rate,highly heterogeneous and affected by the fracture,so has little experience.In order to maintain high and stable yield,a reasonable artificial-energy supplementary way is to be used.There is an urgent need to study the feasibility of EOR by gas injection.Under the condition of formation temperature 108.5 ℃ and pressure 34.47MPa,the seam core manufacturing technology to build a natural seam is used to develop long core test,which include top longitudinal gas drive,vertical bottom of water flooding and horizontal depletion.According to laboratory findings,gas drive has the highest displacement efficiency 73.88%,followed by depletion,its efficiency is 56.01%,and the third one is water flooding,its efficiency is just 54.65%.It is obvious that this reservoir is more suitable for the top of associated gas drive or dry-gas drive.