Foam is widely used in the petroleum industry thanks to its unique properties and performance. Its application to water control in oil wells has received more and more attention. The stability of nitrogen foam was inv...Foam is widely used in the petroleum industry thanks to its unique properties and performance. Its application to water control in oil wells has received more and more attention. The stability of nitrogen foam was investigated in pressurized equipment and sand pack. The result indicated that with increasing pressure （0-2 MPa） the stability of foam in the pressurized equipment increased linearly. Increased nitrogen injection pressure caused better dispersion of nitrogen-foaming solution in porous media. The initial residual resistance factor to gas was an exponential function of injection pressure, but the residual resistance factor （to gas and liquid） decreased exponentially with time. The halflife of foam in porous media （expressed in residual resistance factor） was much longer than that in bulk phase （expressed in foam height）. Pore model analysis indicated that good dispersion in porous media and the presence of thick liquid film during dispersion were the main reasons for high stability. Field test indicated that effective residence of foam in the formation not only resulted in much better heat insulation, but also improved steam stimulation by enhancing steam heating.展开更多
Carbon dioxide flooding is an effective means of enhanced oil recovery for low permeability reservoirs. If fractures are present in the reservoir, CO2 may flow along the fractures, resulting in low gas displacement ef...Carbon dioxide flooding is an effective means of enhanced oil recovery for low permeability reservoirs. If fractures are present in the reservoir, CO2 may flow along the fractures, resulting in low gas displacement efficiency. Reservoir pore pressure will fluctuate to some extent during a CO2 flood, causing a change in effective confining pressure. The result is rock deformation and a reduction in permeability with the reduction in fracture permeability, causing increased flow resistance in the fracture space. Simultaneously, gas cross flowing along the fractures is partially restrained. In this work, the effect of stress changes on permeability was studied through a series of flow experiments. The change in the flowrate distribution in a matrix block and contained fracture with an increase in effective pressure were analyzed. The results lead to an implicit comparison which shows that permeability of fractured core decreases sharply with an increase in effective confining pressure. The fracture flowrate ratio declines and the matrix flowrate ratio increases. Fracture flow will partially divert to the matrix block with the increase in effective confining pressure, improving gas displacement efficiency.展开更多
The flow characteristics of deionized water in hydrophilic and hydrophobic microtubes with diameters of 14.9,5.03 and 2.05 μm are investigated experimentally.The results indicate that the flow characteristics of deio...The flow characteristics of deionized water in hydrophilic and hydrophobic microtubes with diameters of 14.9,5.03 and 2.05 μm are investigated experimentally.The results indicate that the flow characteristics of deionized water in microtubes with diameter of 14.9 μm are in agreement with the classical Hagen-Poiseuille(H-P) equation,but for hydrophilic and hydrophobic microtubes with smaller diameters,the results show significant departure from the prediction of conventional theory,and the discrepancies are influenced by wettability of the microtubes and increase as the Reynolds numbers decrease.Besides,flows of fluid in cores are the macroscopic reflection of flows in countless micron-sized pore throats,the influence of wettability on microscale flow in pore throats will cause the change of seepage characteristic in cores.Therefore,flow experiments of brine through cores with different wettabilities are conducted.The results demonstrate that wettability exerts similar influence on water flows in cores and microtubes.展开更多
文摘Foam is widely used in the petroleum industry thanks to its unique properties and performance. Its application to water control in oil wells has received more and more attention. The stability of nitrogen foam was investigated in pressurized equipment and sand pack. The result indicated that with increasing pressure （0-2 MPa） the stability of foam in the pressurized equipment increased linearly. Increased nitrogen injection pressure caused better dispersion of nitrogen-foaming solution in porous media. The initial residual resistance factor to gas was an exponential function of injection pressure, but the residual resistance factor （to gas and liquid） decreased exponentially with time. The halflife of foam in porous media （expressed in residual resistance factor） was much longer than that in bulk phase （expressed in foam height）. Pore model analysis indicated that good dispersion in porous media and the presence of thick liquid film during dispersion were the main reasons for high stability. Field test indicated that effective residence of foam in the formation not only resulted in much better heat insulation, but also improved steam stimulation by enhancing steam heating.
基金supported by China National Key BasicResearch Development Program under grant 2006CB705805 entitled"Commercial Utilization of Greenhouse GasEnhanced Oil Recovery and Geological Storage:Study of Nonlinear Percolation Mechanisms of Multi-phase and Multi-component Mixtures of CO2 Flooding"National Key Sci-Tech Major Special Item under grant 2008ZX05009-004 entitled"The Development of Large-scale Oil and GasFields and Coal-bed Methane:New Technology on EnhancedOil Recovery in the Later Period of Oil Field Development".
文摘Carbon dioxide flooding is an effective means of enhanced oil recovery for low permeability reservoirs. If fractures are present in the reservoir, CO2 may flow along the fractures, resulting in low gas displacement efficiency. Reservoir pore pressure will fluctuate to some extent during a CO2 flood, causing a change in effective confining pressure. The result is rock deformation and a reduction in permeability with the reduction in fracture permeability, causing increased flow resistance in the fracture space. Simultaneously, gas cross flowing along the fractures is partially restrained. In this work, the effect of stress changes on permeability was studied through a series of flow experiments. The change in the flowrate distribution in a matrix block and contained fracture with an increase in effective pressure were analyzed. The results lead to an implicit comparison which shows that permeability of fractured core decreases sharply with an increase in effective confining pressure. The fracture flowrate ratio declines and the matrix flowrate ratio increases. Fracture flow will partially divert to the matrix block with the increase in effective confining pressure, improving gas displacement efficiency.
基金Supported by the National Natural Science Foundation of China (Grant No.50574060)National Basic Research Program of China (973Program) (Grant No.2005CB221303)
文摘The flow characteristics of deionized water in hydrophilic and hydrophobic microtubes with diameters of 14.9,5.03 and 2.05 μm are investigated experimentally.The results indicate that the flow characteristics of deionized water in microtubes with diameter of 14.9 μm are in agreement with the classical Hagen-Poiseuille(H-P) equation,but for hydrophilic and hydrophobic microtubes with smaller diameters,the results show significant departure from the prediction of conventional theory,and the discrepancies are influenced by wettability of the microtubes and increase as the Reynolds numbers decrease.Besides,flows of fluid in cores are the macroscopic reflection of flows in countless micron-sized pore throats,the influence of wettability on microscale flow in pore throats will cause the change of seepage characteristic in cores.Therefore,flow experiments of brine through cores with different wettabilities are conducted.The results demonstrate that wettability exerts similar influence on water flows in cores and microtubes.
