The rheological properties of two kinds of oil-based drilling fluids with typically composition were studied at pressures up to 138 MPa and temperatures up to 204 ℃ using the RheoChan 7400 Rheometer.The experimental ...The rheological properties of two kinds of oil-based drilling fluids with typically composition were studied at pressures up to 138 MPa and temperatures up to 204 ℃ using the RheoChan 7400 Rheometer.The experimental results show that the apparent viscosity,plastic viscosity and yield point decrease with the increase of temperature,and increase with the increase of pressure.The effect of pressure on the apparent viscosity,plastic viscosity and yield point is considerable at ambient temperature.However,this effect gradually reduces with the increase of temperature.The major factor influencing the rheological properties of oil-based drilling fluids is temperature instead of pressure in the deep sections of oil wells.On the basis of numerous experiments,the model for predict the apparent viscosity,plastic viscosity and yield point of oil-based drilling fluids at high temperature and pressure was established using the method of regressive analysis.It is confirmed that the calculated data are in good agreement with the measured data,and the correlation coefficients are more than 0.98.The model is convenient for use and suitable for the application in drilling operations.展开更多
For waterflooding reservoir,oil trapped in pore's dead ends is hardly flushed out,and usually becomes one typical type of residual oil.The microscopic displacement characteristics of polymer solution with varied v...For waterflooding reservoir,oil trapped in pore's dead ends is hardly flushed out,and usually becomes one typical type of residual oil.The microscopic displacement characteristics of polymer solution with varied viscoelastic property were studied by numerical and experimental method.According to main pore structure characteristics and rheological property of polymer solution through porous media,displacement models for residual oil trapped in dead ends were proposed,and upper-convected Maxwell rheological model was used as polymer solution's constitutive equation.The flow and stress field was given and displacement characteristic was quantified by introducing a parameter of micro swept coefficient.The calculated and experimental results show that micro swept coefficient rises with the increase of viscoelasticity;for greater viscoelasticity of polymer solution,vortices in the dead end have greater swept volume and displacing force on oil,and consequently entraining the swept oil in time.In addition,micro swept coefficient in dead end is function of the inclination angle(θ) between pore and dead end.The smaller of θ and 180-θ,the flow field of viscoelastic fluid is developed in dead ends more deeply,resulting in more contact with oil and larger swept coefficient.展开更多
Water shutoff through injection wells is one of the most important techniques used for water injection profile control and modification in severely heterogeneous reservoirs,aiming at stabilizing oil production.It has ...Water shutoff through injection wells is one of the most important techniques used for water injection profile control and modification in severely heterogeneous reservoirs,aiming at stabilizing oil production.It has been widely reported that the effectiveness and efficiency of water shutoff using gel is mostly dependent on the gel dynamic sealing properties in the porous media.Firstly the gelation strength and gelation time of polymer gel were evaluated.Then,core flowing experiments were conducted before and after gelation in a 32 m long sand pack.In addition,water flooding core experiments were also carried out in a long core of 80 cm before and after injecting gel system to check the reliability of this evaluation method.The experimental results show that moderate-strength gel can be formed at 65 °C.According to the integrated evaluation of the plugging coefficient,plugging strength and water breakthrough time,the gel particles are capable of migrating to a distance of 7.47 m from the injection point of the 32 m long sand pack during the water injection process after gelation.Based on sands gelation status and effluent analyses,the effective migration distance of the gel particles is 4-14 m.Through the core flooding experiments using the 80 cm heterogeneous core,it is evidenced that the gel can be formed in the deep reservoir(40.63% of total length) with the plugging strength as high as 6.33 MPa/m,which leads to extra oil recovery of 10.55% of original oil in place(OOIP) by water flooding after gel treatment.展开更多
In order to present a new method for plugging channeling in oil field,the injection modes and validity period of foam system which plugged the formation water layer were studied by means of the experimental model whic...In order to present a new method for plugging channeling in oil field,the injection modes and validity period of foam system which plugged the formation water layer were studied by means of the experimental model which simulated the real conditions of oil wells existing channeling.Above all,the influence factors including reservoir pressure,permeability,oil saturation and gas-to-liquid ratio were studied through dynamic experiment.Then,in light of the technology characteristics of foam injection in oil field,the comparison between gas-liquid and liquid-gas injection modes was studied.The result shows that the gas-liquid injection mode can ensure the foam injectivity and plugging performance.The plugging validity of nitrogen foam injected into the formation water layer was evaluated in different plugging pressure gradients by the dynamic method which is more reasonable than the static evaluation method in laboratory.The research demonstrates that the plugging validity period of foam decreases with plugging pressure gradient increasing.If the plugging pressure gradient is 0.15 MPa/m,the validity period is 160 h.Finally,a empirical equation and a plate about the plugging validity and the plugging pressure gradient were obtained for forecasting the validity period of foam.展开更多
基金Project(50574061) supported by the National Natural Science Foundation of ChinaProject(IRT0411) supported by the Changjiang Scholars and Innovative Research Team,Ministry of Education
文摘The rheological properties of two kinds of oil-based drilling fluids with typically composition were studied at pressures up to 138 MPa and temperatures up to 204 ℃ using the RheoChan 7400 Rheometer.The experimental results show that the apparent viscosity,plastic viscosity and yield point decrease with the increase of temperature,and increase with the increase of pressure.The effect of pressure on the apparent viscosity,plastic viscosity and yield point is considerable at ambient temperature.However,this effect gradually reduces with the increase of temperature.The major factor influencing the rheological properties of oil-based drilling fluids is temperature instead of pressure in the deep sections of oil wells.On the basis of numerous experiments,the model for predict the apparent viscosity,plastic viscosity and yield point of oil-based drilling fluids at high temperature and pressure was established using the method of regressive analysis.It is confirmed that the calculated data are in good agreement with the measured data,and the correlation coefficients are more than 0.98.The model is convenient for use and suitable for the application in drilling operations.
基金Project(50574060) supported by the National Natural Science Foundation of ChinaProject(2005CB221300) supported by the National Basic Research Program of China
文摘For waterflooding reservoir,oil trapped in pore's dead ends is hardly flushed out,and usually becomes one typical type of residual oil.The microscopic displacement characteristics of polymer solution with varied viscoelastic property were studied by numerical and experimental method.According to main pore structure characteristics and rheological property of polymer solution through porous media,displacement models for residual oil trapped in dead ends were proposed,and upper-convected Maxwell rheological model was used as polymer solution's constitutive equation.The flow and stress field was given and displacement characteristic was quantified by introducing a parameter of micro swept coefficient.The calculated and experimental results show that micro swept coefficient rises with the increase of viscoelasticity;for greater viscoelasticity of polymer solution,vortices in the dead end have greater swept volume and displacing force on oil,and consequently entraining the swept oil in time.In addition,micro swept coefficient in dead end is function of the inclination angle(θ) between pore and dead end.The smaller of θ and 180-θ,the flow field of viscoelastic fluid is developed in dead ends more deeply,resulting in more contact with oil and larger swept coefficient.
基金Project(2011ZX05009-004)supported by the National Significant Science and Technology Program of China
文摘Water shutoff through injection wells is one of the most important techniques used for water injection profile control and modification in severely heterogeneous reservoirs,aiming at stabilizing oil production.It has been widely reported that the effectiveness and efficiency of water shutoff using gel is mostly dependent on the gel dynamic sealing properties in the porous media.Firstly the gelation strength and gelation time of polymer gel were evaluated.Then,core flowing experiments were conducted before and after gelation in a 32 m long sand pack.In addition,water flooding core experiments were also carried out in a long core of 80 cm before and after injecting gel system to check the reliability of this evaluation method.The experimental results show that moderate-strength gel can be formed at 65 °C.According to the integrated evaluation of the plugging coefficient,plugging strength and water breakthrough time,the gel particles are capable of migrating to a distance of 7.47 m from the injection point of the 32 m long sand pack during the water injection process after gelation.Based on sands gelation status and effluent analyses,the effective migration distance of the gel particles is 4-14 m.Through the core flooding experiments using the 80 cm heterogeneous core,it is evidenced that the gel can be formed in the deep reservoir(40.63% of total length) with the plugging strength as high as 6.33 MPa/m,which leads to extra oil recovery of 10.55% of original oil in place(OOIP) by water flooding after gel treatment.
基金Project(2006CB705800)supported by the National Basic Research Program of China
文摘In order to present a new method for plugging channeling in oil field,the injection modes and validity period of foam system which plugged the formation water layer were studied by means of the experimental model which simulated the real conditions of oil wells existing channeling.Above all,the influence factors including reservoir pressure,permeability,oil saturation and gas-to-liquid ratio were studied through dynamic experiment.Then,in light of the technology characteristics of foam injection in oil field,the comparison between gas-liquid and liquid-gas injection modes was studied.The result shows that the gas-liquid injection mode can ensure the foam injectivity and plugging performance.The plugging validity of nitrogen foam injected into the formation water layer was evaluated in different plugging pressure gradients by the dynamic method which is more reasonable than the static evaluation method in laboratory.The research demonstrates that the plugging validity period of foam decreases with plugging pressure gradient increasing.If the plugging pressure gradient is 0.15 MPa/m,the validity period is 160 h.Finally,a empirical equation and a plate about the plugging validity and the plugging pressure gradient were obtained for forecasting the validity period of foam.
