Transportation of heavy oil by the so-called water-ring technique is a very promising method by which pressure drop and pollution can be significantly reduced.Dedicated experiments have been carried out by changing th...Transportation of heavy oil by the so-called water-ring technique is a very promising method by which pressure drop and pollution can be significantly reduced.Dedicated experiments have been carried out by changing the phase’s density,viscosity,velocity and interfacial tension to systematically analyze the characteristics of the water ring.On the basis of such experimental data,a mathematical model for pressure drop prediction has been introduced.This research shows that as long as the density of oil and water remains the same,a concentric water ring can effectively be formed.In such conditions,the oil-water viscosity difference has little effect on the shape of water ring,and it only affects the pressure drop.The greater the viscosity of heavy oil,the smaller the pressure drop of the oil-water ring transportation system.The influence of phases’interfacial tension on the characteristics and pressure drop of the heavy oil-water ring can be considered negligible.The pressure drop prediction model introduced on the basis of the Buckingham’s principle provides values in good agreement(95%)with the experimental data.展开更多
By PVT fractionation experiments to model phase\|controlled and gas\|washing fractionations during the formation of petroleum reservoirs, the authors measured the physical and chemical properties of products formed in...By PVT fractionation experiments to model phase\|controlled and gas\|washing fractionations during the formation of petroleum reservoirs, the authors measured the physical and chemical properties of products formed in different fractionation stages and made a correlative analysis of the influence of depressurization and gas washing on oil/gas molecular composition and the rule of fractionation. The analytical results showed that gas washing is an important factor affecting the physical properties of crude oils, and also can be regarded as a good genetic interpretation of marine wax\|high oils in the Tarim region, Xinjiang, China. Phase\|controlled and gas\|washing fractionations can lead to the formation of condensates and their differences in chemical composition from crude oils are a direct reflection of evaporating fractionation. Phase\|controlled and gas\|washing fractionations have a great influence on the composition of molecular compounds and relevant parameters. So phase\|controlled and gas\|washing fractionations during the formation of petroleum reservoirs are not only favorable to identifying different processes of formation of petroleum reservoirs, but also to the scientific application of routine geochemical parameters.展开更多
The rock mechanical properties and elastic anisotropy of terrestrial shale oil reservoirs are affected by various factors,such as lithology,structure,pores,fractures,and fluids.The experimental study of dynamic and st...The rock mechanical properties and elastic anisotropy of terrestrial shale oil reservoirs are affected by various factors,such as lithology,structure,pores,fractures,and fluids.The experimental study of dynamic and static elastic properties can provide important mechanism analysis for the prediction of geological and engineering “sweet spots” in shale reservoirs.There are a large number of studies on the measurement of static mechanical properties of shale,but the experiments on dynamic crossband elastic anisotropy of terrestrial shale have not yet been conducted thoroughly.Therefore,we report the anisotropic dispersion mechanism of favorable lithofacies(lamellar dolomitic shale,with vertical and horizontal bedding) in the inter-salt shale oil reservoir of the Qianjiang Formation for different confining pressures and fluid saturation conditions.The experiments were conducted by the cross-band rock physics measurement technology that comprised low-frequency stress-strain measurements and a high-frequency ultrasonic test.The experimental results indicated that:(1) The elastic property dispersion of the terrestrial shale was stronger than that of marine shale due to the high viscosity of the medium oil in the terrestrial shale.The lamellar structures and interbedded fractures were the main factors that determined the strong anisotropy of the terrestrial shale.(2) The dispersion of elastic properties from low to high frequencies in a partial oil saturation state ranged from strong to weak;the wave-induced fluid flow or intrinsic dissipation of viscoelastic inclusions may be the dominant mechanisms that caused the seismic dispersion.(3) The elastic parameters measured in the direction vertical to the bedding plane had stronger dispersion and pressure sensitivity than those measured in the direction parallel to the bedding plane,and the anisotropy and pressure sensitivity at seismic frequencies were higher than those at the ultrasonic frequencies.(4) Fluid filling reduced the pressure sensitivity of the elastic parameters along the direction vertical to the bedding plane,whereas the opposite trend was observed along the direction parallel to the bedding plane.(5) The anisotropic Gassmann theory could explain the P-wave velocity well at an extremely low frequency,but the prediction of S-and P-wave velocities at a relatively high frequency remained insufficient.Overall,our study can serve as a reliable mechanism reference for the study of frequency-dependent properties of azimuthal anisotropy,and provide important guidance for the seismic prediction of “sweet spots” in shale oil reservoirs.展开更多
基金Foundation Projects:Major National R&D Project(2016ZX05025-004-005).
文摘Transportation of heavy oil by the so-called water-ring technique is a very promising method by which pressure drop and pollution can be significantly reduced.Dedicated experiments have been carried out by changing the phase’s density,viscosity,velocity and interfacial tension to systematically analyze the characteristics of the water ring.On the basis of such experimental data,a mathematical model for pressure drop prediction has been introduced.This research shows that as long as the density of oil and water remains the same,a concentric water ring can effectively be formed.In such conditions,the oil-water viscosity difference has little effect on the shape of water ring,and it only affects the pressure drop.The greater the viscosity of heavy oil,the smaller the pressure drop of the oil-water ring transportation system.The influence of phases’interfacial tension on the characteristics and pressure drop of the heavy oil-water ring can be considered negligible.The pressure drop prediction model introduced on the basis of the Buckingham’s principle provides values in good agreement(95%)with the experimental data.
文摘By PVT fractionation experiments to model phase\|controlled and gas\|washing fractionations during the formation of petroleum reservoirs, the authors measured the physical and chemical properties of products formed in different fractionation stages and made a correlative analysis of the influence of depressurization and gas washing on oil/gas molecular composition and the rule of fractionation. The analytical results showed that gas washing is an important factor affecting the physical properties of crude oils, and also can be regarded as a good genetic interpretation of marine wax\|high oils in the Tarim region, Xinjiang, China. Phase\|controlled and gas\|washing fractionations can lead to the formation of condensates and their differences in chemical composition from crude oils are a direct reflection of evaporating fractionation. Phase\|controlled and gas\|washing fractionations have a great influence on the composition of molecular compounds and relevant parameters. So phase\|controlled and gas\|washing fractionations during the formation of petroleum reservoirs are not only favorable to identifying different processes of formation of petroleum reservoirs, but also to the scientific application of routine geochemical parameters.
基金supported by the National Natural Science Foundation of China (Grant Nos.U20B2015,41574103,41974120,41804104,and U19B600304)。
文摘The rock mechanical properties and elastic anisotropy of terrestrial shale oil reservoirs are affected by various factors,such as lithology,structure,pores,fractures,and fluids.The experimental study of dynamic and static elastic properties can provide important mechanism analysis for the prediction of geological and engineering “sweet spots” in shale reservoirs.There are a large number of studies on the measurement of static mechanical properties of shale,but the experiments on dynamic crossband elastic anisotropy of terrestrial shale have not yet been conducted thoroughly.Therefore,we report the anisotropic dispersion mechanism of favorable lithofacies(lamellar dolomitic shale,with vertical and horizontal bedding) in the inter-salt shale oil reservoir of the Qianjiang Formation for different confining pressures and fluid saturation conditions.The experiments were conducted by the cross-band rock physics measurement technology that comprised low-frequency stress-strain measurements and a high-frequency ultrasonic test.The experimental results indicated that:(1) The elastic property dispersion of the terrestrial shale was stronger than that of marine shale due to the high viscosity of the medium oil in the terrestrial shale.The lamellar structures and interbedded fractures were the main factors that determined the strong anisotropy of the terrestrial shale.(2) The dispersion of elastic properties from low to high frequencies in a partial oil saturation state ranged from strong to weak;the wave-induced fluid flow or intrinsic dissipation of viscoelastic inclusions may be the dominant mechanisms that caused the seismic dispersion.(3) The elastic parameters measured in the direction vertical to the bedding plane had stronger dispersion and pressure sensitivity than those measured in the direction parallel to the bedding plane,and the anisotropy and pressure sensitivity at seismic frequencies were higher than those at the ultrasonic frequencies.(4) Fluid filling reduced the pressure sensitivity of the elastic parameters along the direction vertical to the bedding plane,whereas the opposite trend was observed along the direction parallel to the bedding plane.(5) The anisotropic Gassmann theory could explain the P-wave velocity well at an extremely low frequency,but the prediction of S-and P-wave velocities at a relatively high frequency remained insufficient.Overall,our study can serve as a reliable mechanism reference for the study of frequency-dependent properties of azimuthal anisotropy,and provide important guidance for the seismic prediction of “sweet spots” in shale oil reservoirs.
