Tong's B-type water drive method was proposed as early as the 1970s and has been widely applied in the dynamic prediction and effective evaluation of oilfield development.Through extensive applications and studies...Tong's B-type water drive method was proposed as early as the 1970s and has been widely applied in the dynamic prediction and effective evaluation of oilfield development.Through extensive applications and studies,many researchers found that the statistical constants in the formula of the Tong's B-type water drive method(also referred to as the Tong's B-type formula)are not applicable to multiple types of reservoirs,especially low-permeability ones,due to the limited range of reservoir types when the formula was conceived.Moreover,they put forward suggestions to improve the Tong's B-type formula,most of which focused on the research and calculation of the first constant in the formula.For oilfields in the development stages of high or ultra-high water cuts,it is widely accepted that different types of reservoirs have different limit water cuts.This understanding naturally makes it necessary to further modify the Tong's B-type formula.It is practically significant to establish the water drive formula and cross plot considering that the two constants in the formula vary with reservoir type.By analyzing the derivation process and conditions of the Tong's B-type formula,this study points out two key problems,i.e.,the two constants 7.5 and 1.69 in the formula are not applicable to all types of reservoir.Given this,this study establishes a function between key reservoir parameters and the first constant and another function between key reservoir parameters and recovery efficiency.Based on the established two functions and considering that different types of oil reservoir have different limit water cuts,this study develops an improved Tong's B-type formula and prepares the corresponding improved cross plot.The results of this study will improve the applicability and accuracy of Tong's B-type water drive method in predicting the trend of water cut increasing for different types of oil reservoirs.展开更多
With the production of strong bottom water reservoir, it will soon enter the ultra-high water cut stage. After entering the ultra-high water cut period, the main means of stable production is liquid extraction. Large ...With the production of strong bottom water reservoir, it will soon enter the ultra-high water cut stage. After entering the ultra-high water cut period, the main means of stable production is liquid extraction. Large liquid volume has a certain impact on the physical property distribution and fluid seepage law of the oilfield. The relative permeability curve measured according to the industry standard is not used for the prediction of development indicators and the understanding of the dynamic law of the oilfield. In order to understand the characteristics of water drive law in high water cut stage of water drive oilfield, starting from the water drive characteristic curve in high water cut stage, the method for calculating the relative permeability curve is deduced. Through numerical simulation verification and fitting the actual production data, it is confirmed that the obtained relative permeability curve is in line with the reality of the oilfield, It can provide some guiding significance for understanding the production law and water drive law of strong bottom water reservoir in ultra-high water cut stage.展开更多
With complex fractured-vuggy heterogeneous structures, water has to be injected to facilitate oil pro- duction. However, the effect of different water injection modes on oil recovery varies. The limitation of existing...With complex fractured-vuggy heterogeneous structures, water has to be injected to facilitate oil pro- duction. However, the effect of different water injection modes on oil recovery varies. The limitation of existing numerical simulation methods in representing fractured- vuggy carbonate reservoirs makes numerical simulation difficult to characterize the fluid flow in these reservoirs. In this paper, based on a geological example unit in the Tahe Oilfield, a three-dimensional physical model was designed and constructed to simulate fluid flow in a fractured-vuggy reservoir according to similarity criteria. The model was validated by simulating a bottom water drive reservoir, and then subsequent water injection modes were optimized. These were continuous （constant rate）, intermittent, and pulsed injection of water. Experimental results reveal that due to the unbalanced formation pressure caused by pulsed water injection, the swept volume was expanded and consequently the highest oil recovery increment was achieved. Similar to continuous water injection, intermit- tent injection was influenced by factors including the connectivity of the fractured-vuggy reservoir, well depth, and the injection-production relationship, which led to a relative low oil recovery. This study may provide a constructive guide to field production and for the devel- opment of the commercial numerical models specialized for fractured-vuggy carbonate reservoirs.展开更多
The relationship between fluid density and saturation and sonic wave velocity of rock samples taken from the WXS Depression in the South China Sea was studied by an oil-water replacement experiment under simulated in-...The relationship between fluid density and saturation and sonic wave velocity of rock samples taken from the WXS Depression in the South China Sea was studied by an oil-water replacement experiment under simulated in-situ temperature and pressure conditions.Two kinds of low-density oils（0.691 and 0.749 g/cm^3） and two kinds of high-density oils（0.834 and 0.873 g/cm^3） were used to saturate the rock samples at different oil-saturation states,and the saturated P- and S-wave velocities were measured.Through Gassmann＇s equation,the theoretical P- and S-wave velocities were also calculated by the fluid replacement method.With the comparison of the measured values and the theoretical values, this study comes to the following conclusions.（1） With the increase of oil saturation and the decrease of water saturation,the P-wave velocity of rock samples saturated by low-density oil increases and the changing rule is in accord with the effective fluid theory;the P-wave velocity of rock samples saturated by high-density oil decreases and the changing rule goes against the theory.（2） With the increase of oil density（namely 0.691→0.749→0.834→0.873 g/cm^3） when oil saturation is unchanged,P-wave velocity increases gradually.（3） The S-wave velocity is always stable and is not affected by the change of oil density and saturation.The results can be used to constrain pre-stack seismic inversion,and the variation rule of sonic wave velocity is valuable for hydrocarbon identification in the study area.展开更多
In recent years,urbanization has accelerated and the gap between urban water supply and demand has become more significant.This phenomenon has led to greater demands on urban water resource management. Thus,analyses o...In recent years,urbanization has accelerated and the gap between urban water supply and demand has become more significant.This phenomenon has led to greater demands on urban water resource management. Thus,analyses of the forces that drive urban water demand growth can help efficient management of urban water resources. "Jing-Jin-Ji" refers to the district composed of Beijing and Tianjin,municipality as well as Hebei Province,which is among the political and economic centers of China. The traditional analysis of driving force for water resources often consider cities as independent individuals and ignores the interaction between them. Such method cannot describe the spatial distribution of regional water demand. In this study,the water demand field theory is used to construct water demand and social development fields for the Jing-Jin-Ji district with relevant indicators. The distribution trends of the two fields,and the correlation of their intensities,are then analyzed. Principal component analysis is used to specifically determine the forces that drive water demand at different stages of development.Results indicate that the water demand field theory can accurately describe spatial variations in water demand intensity in the study area. The main driving force for water demand in the Jing-Jin-Ji district from 2000 to 2014 is the growth of urban population. However,in 2015 and 2016,"GDP of the tertiary industry" overtook it. The results of this study can serve as a basis for regional water demand forecasting,with large potential to be applied to urban water resource management.展开更多
Pore volume of Cumulative water injection is one of the factors for evaluating water flood effect in a water flood oil field.In previous study,there were limited lab studies for evaluating oil displacement efficiency....Pore volume of Cumulative water injection is one of the factors for evaluating water flood effect in a water flood oil field.In previous study,there were limited lab studies for evaluating oil displacement efficiency.A method to characterize the distribution of pore volume of cumulative water injection is proposed in this paper,and it is verified by a five-spot water flooding streamline simulation model.The logarithmic relation between pore volume of cumulative water injection and water saturation is established by regression.An inflection point and limit point of cumulative water injection pore volume are identified.Current simulation model indicates inflection point appears after 2e5 pore volume(PV)injection,and limit point appears after 15e25 PV injection.Both inflection and limit point vary in different regions of reservoir.展开更多
文摘Tong's B-type water drive method was proposed as early as the 1970s and has been widely applied in the dynamic prediction and effective evaluation of oilfield development.Through extensive applications and studies,many researchers found that the statistical constants in the formula of the Tong's B-type water drive method(also referred to as the Tong's B-type formula)are not applicable to multiple types of reservoirs,especially low-permeability ones,due to the limited range of reservoir types when the formula was conceived.Moreover,they put forward suggestions to improve the Tong's B-type formula,most of which focused on the research and calculation of the first constant in the formula.For oilfields in the development stages of high or ultra-high water cuts,it is widely accepted that different types of reservoirs have different limit water cuts.This understanding naturally makes it necessary to further modify the Tong's B-type formula.It is practically significant to establish the water drive formula and cross plot considering that the two constants in the formula vary with reservoir type.By analyzing the derivation process and conditions of the Tong's B-type formula,this study points out two key problems,i.e.,the two constants 7.5 and 1.69 in the formula are not applicable to all types of reservoir.Given this,this study establishes a function between key reservoir parameters and the first constant and another function between key reservoir parameters and recovery efficiency.Based on the established two functions and considering that different types of oil reservoir have different limit water cuts,this study develops an improved Tong's B-type formula and prepares the corresponding improved cross plot.The results of this study will improve the applicability and accuracy of Tong's B-type water drive method in predicting the trend of water cut increasing for different types of oil reservoirs.
文摘With the production of strong bottom water reservoir, it will soon enter the ultra-high water cut stage. After entering the ultra-high water cut period, the main means of stable production is liquid extraction. Large liquid volume has a certain impact on the physical property distribution and fluid seepage law of the oilfield. The relative permeability curve measured according to the industry standard is not used for the prediction of development indicators and the understanding of the dynamic law of the oilfield. In order to understand the characteristics of water drive law in high water cut stage of water drive oilfield, starting from the water drive characteristic curve in high water cut stage, the method for calculating the relative permeability curve is deduced. Through numerical simulation verification and fitting the actual production data, it is confirmed that the obtained relative permeability curve is in line with the reality of the oilfield, It can provide some guiding significance for understanding the production law and water drive law of strong bottom water reservoir in ultra-high water cut stage.
基金supported by China National Science and Technology Major Project(2011ZX05009-004,2011ZX05014-003)National Key Basic Research and Development Program(973 Program),China(2011CB201006)Science Foundation of China University of Petroleum,Beijing(2462014YJRC053)
文摘With complex fractured-vuggy heterogeneous structures, water has to be injected to facilitate oil pro- duction. However, the effect of different water injection modes on oil recovery varies. The limitation of existing numerical simulation methods in representing fractured- vuggy carbonate reservoirs makes numerical simulation difficult to characterize the fluid flow in these reservoirs. In this paper, based on a geological example unit in the Tahe Oilfield, a three-dimensional physical model was designed and constructed to simulate fluid flow in a fractured-vuggy reservoir according to similarity criteria. The model was validated by simulating a bottom water drive reservoir, and then subsequent water injection modes were optimized. These were continuous （constant rate）, intermittent, and pulsed injection of water. Experimental results reveal that due to the unbalanced formation pressure caused by pulsed water injection, the swept volume was expanded and consequently the highest oil recovery increment was achieved. Similar to continuous water injection, intermit- tent injection was influenced by factors including the connectivity of the fractured-vuggy reservoir, well depth, and the injection-production relationship, which led to a relative low oil recovery. This study may provide a constructive guide to field production and for the devel- opment of the commercial numerical models specialized for fractured-vuggy carbonate reservoirs.
基金supported by the Science and Technology Research Key Project of Ministry of Education (Grant No.109035)the National Natural Science Foundation Key Project(Grant No.40830423)the Key Project of Students Extra-curricular Science and Technology Research Program of Schlumberger(Grant No.SLBX0908)
文摘The relationship between fluid density and saturation and sonic wave velocity of rock samples taken from the WXS Depression in the South China Sea was studied by an oil-water replacement experiment under simulated in-situ temperature and pressure conditions.Two kinds of low-density oils（0.691 and 0.749 g/cm^3） and two kinds of high-density oils（0.834 and 0.873 g/cm^3） were used to saturate the rock samples at different oil-saturation states,and the saturated P- and S-wave velocities were measured.Through Gassmann＇s equation,the theoretical P- and S-wave velocities were also calculated by the fluid replacement method.With the comparison of the measured values and the theoretical values, this study comes to the following conclusions.（1） With the increase of oil saturation and the decrease of water saturation,the P-wave velocity of rock samples saturated by low-density oil increases and the changing rule is in accord with the effective fluid theory;the P-wave velocity of rock samples saturated by high-density oil decreases and the changing rule goes against the theory.（2） With the increase of oil density（namely 0.691→0.749→0.834→0.873 g/cm^3） when oil saturation is unchanged,P-wave velocity increases gradually.（3） The S-wave velocity is always stable and is not affected by the change of oil density and saturation.The results can be used to constrain pre-stack seismic inversion,and the variation rule of sonic wave velocity is valuable for hydrocarbon identification in the study area.
基金This work was supported by the National Key Research and Development Program of China(Grant No.2016YFC0401401)the National Natural Science Foundation of China(Grant Nos.51739011&51879274)the Research Fund of the State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin(Grant No.2017ZY02)。
文摘In recent years,urbanization has accelerated and the gap between urban water supply and demand has become more significant.This phenomenon has led to greater demands on urban water resource management. Thus,analyses of the forces that drive urban water demand growth can help efficient management of urban water resources. "Jing-Jin-Ji" refers to the district composed of Beijing and Tianjin,municipality as well as Hebei Province,which is among the political and economic centers of China. The traditional analysis of driving force for water resources often consider cities as independent individuals and ignores the interaction between them. Such method cannot describe the spatial distribution of regional water demand. In this study,the water demand field theory is used to construct water demand and social development fields for the Jing-Jin-Ji district with relevant indicators. The distribution trends of the two fields,and the correlation of their intensities,are then analyzed. Principal component analysis is used to specifically determine the forces that drive water demand at different stages of development.Results indicate that the water demand field theory can accurately describe spatial variations in water demand intensity in the study area. The main driving force for water demand in the Jing-Jin-Ji district from 2000 to 2014 is the growth of urban population. However,in 2015 and 2016,"GDP of the tertiary industry" overtook it. The results of this study can serve as a basis for regional water demand forecasting,with large potential to be applied to urban water resource management.
基金This work was financially supported by the National Basic Research Program of China(973)Program,‘study on water injection in fracture-cave carbonate reservoir’(2011CB201000).
文摘Pore volume of Cumulative water injection is one of the factors for evaluating water flood effect in a water flood oil field.In previous study,there were limited lab studies for evaluating oil displacement efficiency.A method to characterize the distribution of pore volume of cumulative water injection is proposed in this paper,and it is verified by a five-spot water flooding streamline simulation model.The logarithmic relation between pore volume of cumulative water injection and water saturation is established by regression.An inflection point and limit point of cumulative water injection pore volume are identified.Current simulation model indicates inflection point appears after 2e5 pore volume(PV)injection,and limit point appears after 15e25 PV injection.Both inflection and limit point vary in different regions of reservoir.
