Based on the oil,gas and water distribution characteristics of Khasib reservoir in Halfaya oilfield,Iraq,a core displacement experiment is designed to evaluate the influence of different displacement methods and displ...Based on the oil,gas and water distribution characteristics of Khasib reservoir in Halfaya oilfield,Iraq,a core displacement experiment is designed to evaluate the influence of different displacement methods and displacement parameters on oil displacement efficiency.The research shows that,in the displacement method with water injected from the edge of the reservoir,early depletion production is conducive to the elastic expansion of the gas cap,forming the three-dimensional displacement of"upper pressure and lower pushing",and the oil displacement effect is good.When gas injection at the top and water injection at the edge are used for synergistic displacement,the injection timing has different influences on the oil displacement effects of high and low parts.Considering the overall oil displacement efficiency,the injection pressure should be greater than the bubble point pressure of crude oil.Two displacement methods are recommended with the reasonable injection time at 20–25 MPa.The injection speed has the same influence on different injection media.Appropriately reducing the injection speed is conducive to the stability of the displacement front,delaying the breakthrough of injection media and improving the oil displacement effect.The reasonable injection rate of water flooding is 0.075 mL/min,the reasonable injection rates of water and gas are 0.15 mL/min and 0.10 mL/min,respectively in gas-water synergistic displacement.Gas-water synergistic displacement is conducive to the production of crude oil at high position,and has crude oil recovery 5.0%–14.8%higher than water flooding from the edge,so it is recommended as the development mode of Khasib reservoir at the middle and late stages.展开更多
The pore-scale mechanism of the waterflooding contributes to enhancing oil recovery,which has been widely emphasized in the petroleum industry.In this paper,the performances and accuracy of three tracking interface al...The pore-scale mechanism of the waterflooding contributes to enhancing oil recovery,which has been widely emphasized in the petroleum industry.In this paper,the performances and accuracy of three tracking interface algorithms,including VOF,LS,and VOSET,are compared and analyzed through twophase flow in the conceptual model of pore-throat.The results show that the VOSET method combines the advantages of the other two methods,which not only satisfies the mass conservation but also improves the continuity of the physical quantities near the interface.Then,based on the binary image of the pore,the two-dimensional micro pore model is reconstructed by extracting image contour.The grid independence of the reconstructed pore model is verified by the single-phase flow simulation.The waterflooding process in the reconstructed pore model is simulated using the VOSET method,and the effects of displacement speed and wettability on the oil recovery are analyzed.The morphologies of residual oil under different conditions of wettability are investigated and analyzed.The study provides a basic theory for modeling the pore-scale oil-water flow and optimizing the scheme of the water injection.展开更多
Waterflooding experiments were conducted in micro-models(microscopic scale)and on plunger cores from low permeability,extra-low permeability and ultra-low permeability reservoirs in the Ordos Basin under different dis...Waterflooding experiments were conducted in micro-models(microscopic scale)and on plunger cores from low permeability,extra-low permeability and ultra-low permeability reservoirs in the Ordos Basin under different displacement pressures using the NMR techniques to find out pore-scale oil occurrence state,oil production characteristics and residual oil distribution during the process of waterflooding and analyze the effect of pore structure and displacement pressure on waterflooding efficiency.Under bound water condition,crude oil mainly occurs in medium and large pores in the low-permeability sample,while small pores and medium pores are the main distribution space of crude oil in extra-low permeability and ultra-low permeability samples.During the waterflooding,crude oil in the medium and large pores of the three types of samples are preferentially produced.With the decrease of permeability of the samples,the waterflooding front sequentially shows uniform displacement,network displacement and finger displacement,and correspondingly the oil recovery factors decrease successively.After waterflooding,the residual oil in low-permeability samples is mainly distributed in medium pores,and appears in membranous and angular dispersed phase;but that in the extra-low and ultra-low permeability samples is mainly distributed in small pores,and appears in continuous phase formed by a bypass flow and dispersed phase.The low-permeability samples have higher and stable oil displacement efficiency,while the oil displacement efficiency of the extra-low permeability and ultra-low permeability samples is lower,but increases to a certain extent with the increase of displacement pressure.展开更多
基金Supported by the Scientific Research and Technology Development Project of CNPC(2019D-4410)。
文摘Based on the oil,gas and water distribution characteristics of Khasib reservoir in Halfaya oilfield,Iraq,a core displacement experiment is designed to evaluate the influence of different displacement methods and displacement parameters on oil displacement efficiency.The research shows that,in the displacement method with water injected from the edge of the reservoir,early depletion production is conducive to the elastic expansion of the gas cap,forming the three-dimensional displacement of"upper pressure and lower pushing",and the oil displacement effect is good.When gas injection at the top and water injection at the edge are used for synergistic displacement,the injection timing has different influences on the oil displacement effects of high and low parts.Considering the overall oil displacement efficiency,the injection pressure should be greater than the bubble point pressure of crude oil.Two displacement methods are recommended with the reasonable injection time at 20–25 MPa.The injection speed has the same influence on different injection media.Appropriately reducing the injection speed is conducive to the stability of the displacement front,delaying the breakthrough of injection media and improving the oil displacement effect.The reasonable injection rate of water flooding is 0.075 mL/min,the reasonable injection rates of water and gas are 0.15 mL/min and 0.10 mL/min,respectively in gas-water synergistic displacement.Gas-water synergistic displacement is conducive to the production of crude oil at high position,and has crude oil recovery 5.0%–14.8%higher than water flooding from the edge,so it is recommended as the development mode of Khasib reservoir at the middle and late stages.
基金by the National Natural Science Foundation of China(Grant Number 51909225)National Major Science and Technology Projects of China(Grant Number 2017ZX05013001-002)Open research fund of CNPC(grant No.2018A-0908),and the Natural Science Foundation of SWUST(Grant Number 20zx7129).
文摘The pore-scale mechanism of the waterflooding contributes to enhancing oil recovery,which has been widely emphasized in the petroleum industry.In this paper,the performances and accuracy of three tracking interface algorithms,including VOF,LS,and VOSET,are compared and analyzed through twophase flow in the conceptual model of pore-throat.The results show that the VOSET method combines the advantages of the other two methods,which not only satisfies the mass conservation but also improves the continuity of the physical quantities near the interface.Then,based on the binary image of the pore,the two-dimensional micro pore model is reconstructed by extracting image contour.The grid independence of the reconstructed pore model is verified by the single-phase flow simulation.The waterflooding process in the reconstructed pore model is simulated using the VOSET method,and the effects of displacement speed and wettability on the oil recovery are analyzed.The morphologies of residual oil under different conditions of wettability are investigated and analyzed.The study provides a basic theory for modeling the pore-scale oil-water flow and optimizing the scheme of the water injection.
基金Supported by the National Natural Scienceof China(No.U19B2010)Youth Science and Technology Innovation Team of the Southwest Petroleum University(2018CXTD10)。
文摘Waterflooding experiments were conducted in micro-models(microscopic scale)and on plunger cores from low permeability,extra-low permeability and ultra-low permeability reservoirs in the Ordos Basin under different displacement pressures using the NMR techniques to find out pore-scale oil occurrence state,oil production characteristics and residual oil distribution during the process of waterflooding and analyze the effect of pore structure and displacement pressure on waterflooding efficiency.Under bound water condition,crude oil mainly occurs in medium and large pores in the low-permeability sample,while small pores and medium pores are the main distribution space of crude oil in extra-low permeability and ultra-low permeability samples.During the waterflooding,crude oil in the medium and large pores of the three types of samples are preferentially produced.With the decrease of permeability of the samples,the waterflooding front sequentially shows uniform displacement,network displacement and finger displacement,and correspondingly the oil recovery factors decrease successively.After waterflooding,the residual oil in low-permeability samples is mainly distributed in medium pores,and appears in membranous and angular dispersed phase;but that in the extra-low and ultra-low permeability samples is mainly distributed in small pores,and appears in continuous phase formed by a bypass flow and dispersed phase.The low-permeability samples have higher and stable oil displacement efficiency,while the oil displacement efficiency of the extra-low permeability and ultra-low permeability samples is lower,but increases to a certain extent with the increase of displacement pressure.
