Polymer flooding has been proven to effectively improve oil recovery in the Bohai Oil Field. However, due to high oil viscosity and significant formation heterogeneity, it is necessary to further improve the displacem...Polymer flooding has been proven to effectively improve oil recovery in the Bohai Oil Field. However, due to high oil viscosity and significant formation heterogeneity, it is necessary to further improve the displacement effectiveness of polymer flooding in heavy oil reservoirs in the service life of offshore platforms. In this paper, the effects of the water/oil mobility ratio in heavy oil reservoirs and the dimensionless oil productivity index on polymer flooding effectiveness were studied utilizing rel- ative permeability curves. The results showed that when the water saturation was less than the value, where the water/oil mobility ratio was equal to 1, polymer flooding could effectively control the increase of fractional water flow, which meant that the upper limit of water/oil ratio suitable for polymer flooding should be the value when the water/oil mobility ratio was equal to 1. Mean while, by injecting a certain volume of water to create water channels in the reservoir, the polymer flooding would be the most effective in improving sweep efficiency, and lower the fractional flow of water to the value corresponding to △Jmax. Considering the service life of the platform and the polymer mobility control capacity, the best polymer injection timing for heavy oil reservoirs was optimized. It has been tested for reservoirs with crude oil viscosity of 123 and 70 mPa s, the optimum polymer flooding effec- tiveness could be obtained when the polymer floods were initiated at the time when the fractional flow of water were 10 % and 25 %, respectively. The injection timing range for polymer flooding was also theoretically analyzed for the Bohai Oil Field utilizing which provided methods for effectiveness. relative permeability curves, improving polymer flooding展开更多
In order to improve the effect of water control and oil stabilization during high water cut period, a mathematical model of five point method well group was established with the high water cut well group of an Oilfiel...In order to improve the effect of water control and oil stabilization during high water cut period, a mathematical model of five point method well group was established with the high water cut well group of an Oilfield as the target area, the variation law of water cut and recovery factor of different injection parameters was analyzed, and the optimization research of injection parameters of polymer enhanced foam flooding was carried out. The results show that the higher the injection rate, the lower the water content curve, and the higher the oil recovery rate. As the foam defoamed when encountering oil, when the injection time was earlier than 80% of water cut, the later the injection time was, the better the oil displacement effect would be. When the injection time was later than 80% of water cut, the later the injection time was, the worse the oil displacement effect would be. The larger the injection volume, the lower the water content curve and the higher the recovery rate. After the injection volume exceeded 0.2 PV, the amplitude of changes in water content and recovery rate slowed down. The optimal injection parameters of profile control agent for high water content well group in Oilfield A were: injection rate of 15 m<sup>3</sup>/d, injection timing of 80% water content, and injection volume of 0.2 PV.展开更多
The experimental tests were carried out on a single cylinder hydrogen fueled spark ignition(SI)generator set with different spark timings(4-20℃A bTDC),exhaust gas recirculation(EGR)up to 28% by volume and water injec...The experimental tests were carried out on a single cylinder hydrogen fueled spark ignition(SI)generator set with different spark timings(4-20℃A bTDC),exhaust gas recirculation(EGR)up to 28% by volume and water injection up to 1.95 kg/h(maximum water to fuel mass ratio of 8:1).The engine speed was kept constant of 3000 r/min.The NOx emission and thermal efficiency of engine with gasoline and hydrogen fuel operation at 1.4 kW power output are 5 g/kWh and 12.1 g/kWh,and 15% and 20.9% respectively.In order to reduce the NOx emission at source level,retarding spark timing,exhaust gas recirculation(EGR),and water injection techniques were studied.Nox emission decreased with spark timing retardation,EGR,and water injection.NOx emission with hydrogen at 1.4 kW power output decreased from 12.1 g/kWh with maximum brake torque(MBT)spark timing(10℃A bTDC)to 8.1 g/kWh with retarded spark timing(4℃A bTDC)due to decrease in the in-cylinder peak pressure and temperature.The Nox emission decreased to 6.1 g/kWh with 20% EGR due to thermal and chemical dilution effect.However,thermal efficiency decreased about 33% and 17% with spark timing retardation and 20EGR respectively as compared to that of MBT spark timing.But,in the case of water injection,the NOx emission decreased significantly without affecting the thermal efficiency of the engine and it is 5.6 g/kWh with water-hydrogen ratio of 4:1(water flow rate of 0.92 kg/h).Water injection is the best suitable method to reduce the NOx emission in a hydrogen fueled engine compared with the spark timing retardation and EGR technique.展开更多
基金supported by Open Fund (CRI2012RCPS0152CN) of State Key Laboratory of Offshore Oil Exploitationthe National Science and Technology Major Project (2011ZX05024-004-01)
文摘Polymer flooding has been proven to effectively improve oil recovery in the Bohai Oil Field. However, due to high oil viscosity and significant formation heterogeneity, it is necessary to further improve the displacement effectiveness of polymer flooding in heavy oil reservoirs in the service life of offshore platforms. In this paper, the effects of the water/oil mobility ratio in heavy oil reservoirs and the dimensionless oil productivity index on polymer flooding effectiveness were studied utilizing rel- ative permeability curves. The results showed that when the water saturation was less than the value, where the water/oil mobility ratio was equal to 1, polymer flooding could effectively control the increase of fractional water flow, which meant that the upper limit of water/oil ratio suitable for polymer flooding should be the value when the water/oil mobility ratio was equal to 1. Mean while, by injecting a certain volume of water to create water channels in the reservoir, the polymer flooding would be the most effective in improving sweep efficiency, and lower the fractional flow of water to the value corresponding to △Jmax. Considering the service life of the platform and the polymer mobility control capacity, the best polymer injection timing for heavy oil reservoirs was optimized. It has been tested for reservoirs with crude oil viscosity of 123 and 70 mPa s, the optimum polymer flooding effec- tiveness could be obtained when the polymer floods were initiated at the time when the fractional flow of water were 10 % and 25 %, respectively. The injection timing range for polymer flooding was also theoretically analyzed for the Bohai Oil Field utilizing which provided methods for effectiveness. relative permeability curves, improving polymer flooding
文摘In order to improve the effect of water control and oil stabilization during high water cut period, a mathematical model of five point method well group was established with the high water cut well group of an Oilfield as the target area, the variation law of water cut and recovery factor of different injection parameters was analyzed, and the optimization research of injection parameters of polymer enhanced foam flooding was carried out. The results show that the higher the injection rate, the lower the water content curve, and the higher the oil recovery rate. As the foam defoamed when encountering oil, when the injection time was earlier than 80% of water cut, the later the injection time was, the better the oil displacement effect would be. When the injection time was later than 80% of water cut, the later the injection time was, the worse the oil displacement effect would be. The larger the injection volume, the lower the water content curve and the higher the recovery rate. After the injection volume exceeded 0.2 PV, the amplitude of changes in water content and recovery rate slowed down. The optimal injection parameters of profile control agent for high water content well group in Oilfield A were: injection rate of 15 m<sup>3</sup>/d, injection timing of 80% water content, and injection volume of 0.2 PV.
文摘The experimental tests were carried out on a single cylinder hydrogen fueled spark ignition(SI)generator set with different spark timings(4-20℃A bTDC),exhaust gas recirculation(EGR)up to 28% by volume and water injection up to 1.95 kg/h(maximum water to fuel mass ratio of 8:1).The engine speed was kept constant of 3000 r/min.The NOx emission and thermal efficiency of engine with gasoline and hydrogen fuel operation at 1.4 kW power output are 5 g/kWh and 12.1 g/kWh,and 15% and 20.9% respectively.In order to reduce the NOx emission at source level,retarding spark timing,exhaust gas recirculation(EGR),and water injection techniques were studied.Nox emission decreased with spark timing retardation,EGR,and water injection.NOx emission with hydrogen at 1.4 kW power output decreased from 12.1 g/kWh with maximum brake torque(MBT)spark timing(10℃A bTDC)to 8.1 g/kWh with retarded spark timing(4℃A bTDC)due to decrease in the in-cylinder peak pressure and temperature.The Nox emission decreased to 6.1 g/kWh with 20% EGR due to thermal and chemical dilution effect.However,thermal efficiency decreased about 33% and 17% with spark timing retardation and 20EGR respectively as compared to that of MBT spark timing.But,in the case of water injection,the NOx emission decreased significantly without affecting the thermal efficiency of the engine and it is 5.6 g/kWh with water-hydrogen ratio of 4:1(water flow rate of 0.92 kg/h).Water injection is the best suitable method to reduce the NOx emission in a hydrogen fueled engine compared with the spark timing retardation and EGR technique.
