Study On The Policy Of Increasing Oil Recovery In CO 4 Low - Permeability Reservoir

Gas injection EOR is one of the three technologies (Polymer flooding, Thermal recovery, and CO2 flooding) of tertiary oil recovery. Gas injection enhanced oil recovery developed rapidly in western country such as United States and Canada in the past decades. United States began development and utilization of carbon dioxide to enhanced oil recovery in 70s 20th centuries. American practice shows that:most of the reservoir use CO2 enhanced oil recovery technology and improve oil recovery by a big margin and return on investment in the high oil price is higher.Injection CO2 enhanced oil recovery technology will be the future new direction, Domestic oil field such as Daqing、Jilin has successfully conducted field trials CO2 flooding and have achieved good results, The attempts of gas injection EOR will be more and more as the coming of eastern area oil field has entered in middle or late period.proved that it’s one of the most potential for secondary oil recovery enhanced oil recovery methods. It’s expected to increased oil recovery to 60% that the new generation of carbon dioxide enhanced oil recovery technology.The water absorption capacity of oil layer that has been developed is poor, injection pressure is high, the effect of water injection is poor, and recovery is low in Fuyang oil layer of low permeability oil reservoir of Daqing oil field. We develop field test of gas injection in low permeability reservoir in order to develop Daqing low permeability reservoirs effectively.In this paper, According to the study of injection CO2 program of Fang 48 fault block oil reservoir using numerical simulation methods combined with reservoir engineering. Results put it that1. Pulse gas injection could improve displacement efficiency according to adjustment gas displacement profile.2. The rule of CO2 flooding is immiscible displacement breakthrough time early, after break Gas Oil Ratio increased first and then keeps a certain value level; but for miscible flooding, GOR rose rapidly and gas oil production dropped significantly after the break.3. The greatest impact on the recovery level is the intensity ratio of water gas, followed by daily water injection rate, periodic injection of HCPV, water and gas slug ratio in the given four factors in WAG simulations.4. The program of remove crack may benefit uniform displacement of CO2, but the initial well productivity is low and build capacity difficulty and inspiration capacity of formation reduce significantly in early simulation, resulting in hard to inject in the injection well.5. Fracturing program may receive a higher productivity in initial, but we will face the problem that the challenges of gas breakthrough and control or adjust gas displacement profile in the latter. So it’s particularly important to prevent CO2 gas break.6. The main affecting factor of pulse gas injection is stopping injection time, followed by periodic injection of HCPV, the last is gas injection time.7. Pulse gas injection could slow down gas breakthrough time in no gas wells and could save more CO2 in the case of ultimate recovery in the same.8. Huff-Puff simulation results show that the longer gas injection, the more gas injection speed, the better the results. It’s appropriate time of 30 days that shut wells. The optimal scheme is F10, injection rate is 8t/d, gas injection time of 40 days. The effective time is up to one year after a cycle and will add oil 116m39. The main effect factor of oil displacement is permeability, followed by fluid properties in Fang 48 blocks reservoir.