Pub Date : 2021-10-26DOI: 10.46690/capi.2021.04.03
Jindi Sun, Ziqiang Li, F. Furtado, Saman A. Aryana
{"title":"A microfluidic study of transient flow states in permeable media using fluorescent particle image velocimetry","authors":"Jindi Sun, Ziqiang Li, F. Furtado, Saman A. Aryana","doi":"10.46690/capi.2021.04.03","DOIUrl":"https://doi.org/10.46690/capi.2021.04.03","url":null,"abstract":"","PeriodicalId":34047,"journal":{"name":"Capillarity","volume":"75 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86018322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-23DOI: 10.46690/capi.2021.04.01
Junqian Li
There have been many theories to describe adsorbed or free gas. However, quantitative description of the occurrence characteristics of liquids in porous media has always been a great challenge due to a lack of basic theory. Through years of research, two theoretical equations, i.e., adsorption ratio equation and state equation of liquid, have been proposed to describe the characteristics of liquids in porous media, and revealed the mechanism of liquid occurrence. Further, a quantitative evaluation technology for the microscopic distribution of liquids was established by combining nuclear magnetic resonance theory. This research will be of great significance for studying the microscopic distribution of liquids in tight reservoirs, such as shale, coal, and tight sandstone. Cited as: Li, J. Development of adsorption ratio equation and state equation of liquid and their geological significance. Capillarity, 2021, 4(4): 63-65, doi: 10.46690/capi.2021.04.01
{"title":"Development of adsorption ratio equation and state equation of liquid and their geological significance","authors":"Junqian Li","doi":"10.46690/capi.2021.04.01","DOIUrl":"https://doi.org/10.46690/capi.2021.04.01","url":null,"abstract":"There have been many theories to describe adsorbed or free gas. However, quantitative description of the occurrence characteristics of liquids in porous media has always been a great challenge due to a lack of basic theory. Through years of research, two theoretical equations, i.e., adsorption ratio equation and state equation of liquid, have been proposed to describe the characteristics of liquids in porous media, and revealed the mechanism of liquid occurrence. Further, a quantitative evaluation technology for the microscopic distribution of liquids was established by combining nuclear magnetic resonance theory. This research will be of great significance for studying the microscopic distribution of liquids in tight reservoirs, such as shale, coal, and tight sandstone. Cited as: Li, J. Development of adsorption ratio equation and state equation of liquid and their geological significance. Capillarity, 2021, 4(4): 63-65, doi: 10.46690/capi.2021.04.01","PeriodicalId":34047,"journal":{"name":"Capillarity","volume":"93 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75003311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-08-17DOI: 10.46690/capi.2021.04.02
Yishen Liang, F. Lai, Yuting Dai, H. Shi, Gongshuai Shi
Cited as: Liang, Y., Lai, F., Dai, Y., Shi, H., Shi, G. An experimental study of imbibition process and fluid distribution in tight oil reservoir under different pressures and temperatures. Capillarity, 2021, 4(4): 66-75, doi: 10.46690/capi.2021.04.02 Abstract: Tight reservoirs are a major focus of unconventional reservoir development. As a means to improve hydrocarbon recovery from tight reservoirs, imbibition has been received increasing attentions in recent years. This study evaluates how the changes in temperature and pressure affect imbibition through conducting experimental tests under various conditions on samples from the Yan Chang formation, a tight reservoir in Ordos Basin. The fluid distribution is compared before and after imbibition in core samples by nuclear magnetic resonance method. The results show that the imbibition recovery is significantly improved through increasing temperature and pressure. A high temperature facilitates molecular thermal movements, increasing oil-water exchange rate. The core samples are characterized with nano-mesopores, which is followed by nano-macropores, micropores, mesopores, and nano-micropores. Comparative analysis of nuclear magnetic resonance shows that the irreducible water saturation increases after imbibition and is mainly distributed in nanopores. Increasing pressure increases the amount of residual water in nano pores, with the relatively more significant increase in the amount of residual water in nanomacro-pores compared with other types of pores.
{"title":"An experimental study of imbibition process and fluid distribution in tight oil reservoir under different pressures and temperatures","authors":"Yishen Liang, F. Lai, Yuting Dai, H. Shi, Gongshuai Shi","doi":"10.46690/capi.2021.04.02","DOIUrl":"https://doi.org/10.46690/capi.2021.04.02","url":null,"abstract":"Cited as: Liang, Y., Lai, F., Dai, Y., Shi, H., Shi, G. An experimental study of imbibition process and fluid distribution in tight oil reservoir under different pressures and temperatures. Capillarity, 2021, 4(4): 66-75, doi: 10.46690/capi.2021.04.02 Abstract: Tight reservoirs are a major focus of unconventional reservoir development. As a means to improve hydrocarbon recovery from tight reservoirs, imbibition has been received increasing attentions in recent years. This study evaluates how the changes in temperature and pressure affect imbibition through conducting experimental tests under various conditions on samples from the Yan Chang formation, a tight reservoir in Ordos Basin. The fluid distribution is compared before and after imbibition in core samples by nuclear magnetic resonance method. The results show that the imbibition recovery is significantly improved through increasing temperature and pressure. A high temperature facilitates molecular thermal movements, increasing oil-water exchange rate. The core samples are characterized with nano-mesopores, which is followed by nano-macropores, micropores, mesopores, and nano-micropores. Comparative analysis of nuclear magnetic resonance shows that the irreducible water saturation increases after imbibition and is mainly distributed in nanopores. Increasing pressure increases the amount of residual water in nano pores, with the relatively more significant increase in the amount of residual water in nanomacro-pores compared with other types of pores.","PeriodicalId":34047,"journal":{"name":"Capillarity","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85941951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Spontaneous imbibition in porous media plays an important role in numerous industrial processes, but its underlying mechanisms are still poorly understood due to the complicated structure and multiple surface properties of natural porous media. In order to fill this gap, a quasi-three-dimensional color-gradient lattice Boltzmann model is applied to simulate the spontaneous imbibition in heterogeneous porous media micromodels, where the influence of viscosity ratio, tortuosity and mixed wettability is systematically investigated. Results show that the tortuosity has less influence on imbibition than the viscosity ratio, which leads to unstable displacement for viscosity ratios smaller than unity and to stable displacement for viscosity ratios greater than unity. By establishing the power-law relationship between wetting fluid saturation and time, it is found that the scaling exponent is not only affected by tortuosity, but also related to pore throat structure of the micromodel. In addition, the mixed wettability is found to significantly influence the stability of displacement, especially when the contact angle difference of two constituents is large. Specifically, the greater the mixing degree of two wettabilities, the more unstable the displacement will become, which results in an enhanced interface roughening. Accordingly, the scaling exponent deviates more from the prediction from the Lucas-Washburn equation. Due to the reduced connectivity of flow paths, the wetting fluid imbibition rate in mixed wettability condition is lower than that in uniform wettability condition, no matter whether the latter theoretically corresponds to a slow displacement or not. Cited as: Diao, Z., Li, S., Liu, W., Liu, H., Xia, Q. Numerical study of the effect of tortuosity and mixed wettability on spontaneous imbibition in heterogeneous porous media. Capillarity, 2021, 4(3): 50-62, doi: 10.46690/capi.2021.03.02
{"title":"Numerical study of the effect of tortuosity and mixed wettability on spontaneous imbibition in heterogeneous porous media","authors":"Zhenhan Diao, Sheng Li, Wei Liu, Haihu Liu, Q. Xia","doi":"10.46690/capi.2021.03.02","DOIUrl":"https://doi.org/10.46690/capi.2021.03.02","url":null,"abstract":"Spontaneous imbibition in porous media plays an important role in numerous industrial processes, but its underlying mechanisms are still poorly understood due to the complicated structure and multiple surface properties of natural porous media. In order to fill this gap, a quasi-three-dimensional color-gradient lattice Boltzmann model is applied to simulate the spontaneous imbibition in heterogeneous porous media micromodels, where the influence of viscosity ratio, tortuosity and mixed wettability is systematically investigated. Results show that the tortuosity has less influence on imbibition than the viscosity ratio, which leads to unstable displacement for viscosity ratios smaller than unity and to stable displacement for viscosity ratios greater than unity. By establishing the power-law relationship between wetting fluid saturation and time, it is found that the scaling exponent is not only affected by tortuosity, but also related to pore throat structure of the micromodel. In addition, the mixed wettability is found to significantly influence the stability of displacement, especially when the contact angle difference of two constituents is large. Specifically, the greater the mixing degree of two wettabilities, the more unstable the displacement will become, which results in an enhanced interface roughening. Accordingly, the scaling exponent deviates more from the prediction from the Lucas-Washburn equation. Due to the reduced connectivity of flow paths, the wetting fluid imbibition rate in mixed wettability condition is lower than that in uniform wettability condition, no matter whether the latter theoretically corresponds to a slow displacement or not. Cited as: Diao, Z., Li, S., Liu, W., Liu, H., Xia, Q. Numerical study of the effect of tortuosity and mixed wettability on spontaneous imbibition in heterogeneous porous media. Capillarity, 2021, 4(3): 50-62, doi: 10.46690/capi.2021.03.02","PeriodicalId":34047,"journal":{"name":"Capillarity","volume":"219 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75855941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-02DOI: 10.46690/capi.2021.03.01
T. Si
Experimental study on the liquid dripping in a capillary flow focusing process is performed. Due to the high-speed gas stream that drives the inner liquid co-flowing through an orifice, complex phenomena for the droplet formation in dripping regime can be found as the gas pressure drop and the liquid flow rate change. Periodic dripping mode can produce uniform droplets, and non-periodic ones can result in satellites and droplets of different diameters. The droplet-droplet coalescence in the core of co-flowing gas stream is also obtained. The size of resultant droplets is measured under different values of gas pressure drop and liquid flow rate. It can be seen that the droplet size tends to decrease as the gas pressure drop increases and keeps nearly the same as the liquid flow rate increases. The results also indicate that the dynamic behavior of droplet formation in dripping mode of capillary flow focusing is mainly dominated by the gas pressure drop, and the capillary flow focusing technique can produce droplets with high throughput even in the dripping regime. Cited as: Si, T. Dynamic behavior of droplet formation in dripping mode of capillary flow focusing. Capillarity, 2021, 4(3): 45-49, doi: 10.46690/capi.2021.03.01
{"title":"Dynamic behavior of droplet formation in dripping mode of capillary flow focusing","authors":"T. Si","doi":"10.46690/capi.2021.03.01","DOIUrl":"https://doi.org/10.46690/capi.2021.03.01","url":null,"abstract":"Experimental study on the liquid dripping in a capillary flow focusing process is performed. Due to the high-speed gas stream that drives the inner liquid co-flowing through an orifice, complex phenomena for the droplet formation in dripping regime can be found as the gas pressure drop and the liquid flow rate change. Periodic dripping mode can produce uniform droplets, and non-periodic ones can result in satellites and droplets of different diameters. The droplet-droplet coalescence in the core of co-flowing gas stream is also obtained. The size of resultant droplets is measured under different values of gas pressure drop and liquid flow rate. It can be seen that the droplet size tends to decrease as the gas pressure drop increases and keeps nearly the same as the liquid flow rate increases. The results also indicate that the dynamic behavior of droplet formation in dripping mode of capillary flow focusing is mainly dominated by the gas pressure drop, and the capillary flow focusing technique can produce droplets with high throughput even in the dripping regime. Cited as: Si, T. Dynamic behavior of droplet formation in dripping mode of capillary flow focusing. Capillarity, 2021, 4(3): 45-49, doi: 10.46690/capi.2021.03.01","PeriodicalId":34047,"journal":{"name":"Capillarity","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86588223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-03DOI: 10.46690/capi.2021.02.02
A. Salama, Jianchao Cai, Jisheng Kou, Shuyu Sun, M. El-Amin, Yi Wang
In this work the problem of displacing a ganglion of a fluid by another immiscible one in capillaries is investigated. A modeling approach is developed to predict the location of the ganglion with time. The model describes two patterns; namely, when the ganglion totally exists inside the tube, and when the advancing interface of the ganglion has broken through the exit of the tube. The model is valid for the case in which the ganglion is wetting as well as when it is nonwetting to the wall of the tube. It also considers the situation in which both the advancing and the receding interfaces assume, generally, different contact angles. For the special case when the displacement process is quasistatic, both the receding and the advancing contact angles may be considered the same. Under these conditions, interfacial tension force plays no role and the ganglion moves as a plug inside the tube with a constant velocity. When the viscosity ratio between the invading fluid and the ganglion is one (i.e., both phases are having the same viscosity) the motion reduces to the Hagen-Poiseuille flow in pipes. Once the advancing interface breaks through the exit of the tube, interfacial tension starts to take part in the displacement process and the ganglion starts to accelerate or decelerate according to the viscosity ratio. When the ganglion is nonwetting, interfacial tension becomes in the direction of the flow and is opposite to the flow otherwise. The model accounts for external forces such as pressure and gravity in addition to capillarity. A computational fluid dynamics analysis of this system is conducted for both types of wettability scenarios and shows very good match with the results of the developed model during both the two modes of flow patterns. This builds confidence in the developed modeling approach. Other cases have also been explored to highlight the effects of other scenarios. Cited as: Salama, A., Cai, J., Kou, J., Sun, S., EI-Amin, M. F., Wang, Y. Investigation of the dynamics of immiscible displacement of a ganglion in capillaries. Capillarity, 2021, 4(2): 31-44, doi: 10.46690/capi.2021.02.02
{"title":"Investigation of the dynamics of immiscible displacement of a ganglion in capillaries","authors":"A. Salama, Jianchao Cai, Jisheng Kou, Shuyu Sun, M. El-Amin, Yi Wang","doi":"10.46690/capi.2021.02.02","DOIUrl":"https://doi.org/10.46690/capi.2021.02.02","url":null,"abstract":"In this work the problem of displacing a ganglion of a fluid by another immiscible one in capillaries is investigated. A modeling approach is developed to predict the location of the ganglion with time. The model describes two patterns; namely, when the ganglion totally exists inside the tube, and when the advancing interface of the ganglion has broken through the exit of the tube. The model is valid for the case in which the ganglion is wetting as well as when it is nonwetting to the wall of the tube. It also considers the situation in which both the advancing and the receding interfaces assume, generally, different contact angles. For the special case when the displacement process is quasistatic, both the receding and the advancing contact angles may be considered the same. Under these conditions, interfacial tension force plays no role and the ganglion moves as a plug inside the tube with a constant velocity. When the viscosity ratio between the invading fluid and the ganglion is one (i.e., both phases are having the same viscosity) the motion reduces to the Hagen-Poiseuille flow in pipes. Once the advancing interface breaks through the exit of the tube, interfacial tension starts to take part in the displacement process and the ganglion starts to accelerate or decelerate according to the viscosity ratio. When the ganglion is nonwetting, interfacial tension becomes in the direction of the flow and is opposite to the flow otherwise. The model accounts for external forces such as pressure and gravity in addition to capillarity. A computational fluid dynamics analysis of this system is conducted for both types of wettability scenarios and shows very good match with the results of the developed model during both the two modes of flow patterns. This builds confidence in the developed modeling approach. Other cases have also been explored to highlight the effects of other scenarios. Cited as: Salama, A., Cai, J., Kou, J., Sun, S., EI-Amin, M. F., Wang, Y. Investigation of the dynamics of immiscible displacement of a ganglion in capillaries. Capillarity, 2021, 4(2): 31-44, doi: 10.46690/capi.2021.02.02","PeriodicalId":34047,"journal":{"name":"Capillarity","volume":"129 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79584576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-22DOI: 10.46690/CAPI.2021.02.01
L. M. Siqveland, S. Skjaeveland
The classical Young-Laplace equation relates capillary pressure to surface tension and the principal radii of curvature of the interface between two immiscible fluids. In this paper the required properties of space curves and smooth surfaces are described by differential geometry and linear algebra. The equilibrium condition is formulated by a force balance and minimization of surface energy. Cited as: Siqveland, L. M., Skjaeveland, S. M. Derivations of the Young-Laplace equation. Capillarity, 2021, 4(2): 23-30, doi: 10.46690/capi.2021.02.01
经典的Young-Laplace方程将毛细管压力与表面张力和两种不混相流体界面的主曲率半径联系起来。本文用微分几何和线性代数描述了空间曲线和光滑曲面的必要性质。平衡条件由力平衡和表面能最小化表述。引自:Siqveland, L. M.， Skjaeveland, S. M. Young-Laplace方程的推导。毛细管学，2021,4(2):23-30,doi: 10.46690/capi.2021.02.01
{"title":"Derivations of the Young-Laplace equation","authors":"L. M. Siqveland, S. Skjaeveland","doi":"10.46690/CAPI.2021.02.01","DOIUrl":"https://doi.org/10.46690/CAPI.2021.02.01","url":null,"abstract":"The classical Young-Laplace equation relates capillary pressure to surface tension and the principal radii of curvature of the interface between two immiscible fluids. In this paper the required properties of space curves and smooth surfaces are described by differential geometry and linear algebra. The equilibrium condition is formulated by a force balance and minimization of surface energy. Cited as: Siqveland, L. M., Skjaeveland, S. M. Derivations of the Young-Laplace equation. Capillarity, 2021, 4(2): 23-30, doi: 10.46690/capi.2021.02.01","PeriodicalId":34047,"journal":{"name":"Capillarity","volume":"66 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89011880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-25DOI: 10.46690/CAPI.2021.01.02
Yinglin Li, Di Yu, B. Niu
Spontaneous imbibition plays a significant role in different technical applications, and several analytical models have been proposed for predicting the fluid imbibition mass into porous media based on the fractal theory. Herein, these previous models are reconsidered in view of the obvious difference between the effective porosity and the areal porosity of porous media. Firstly, an implicit equation for fractal tortuosity is proposed and a modified correlation for the areal porosity is presented; then, a semi-analytical prediction model for fluid imbibition mass with gravity pressure is derived; finally, comparisons of predictions among several previous models with the present model are carried out. The modeling results show consistency with the experimental data published in the literature. Cited as: Li, Y., Yu, D., Niu, B. Prediction of spontaneous imbibition in fractal porous media based on modified porosity correlation. Capillarity, 2021, 4(1): 13-22, doi: 10.46690/capi.2021.01.02
{"title":"Prediction of spontaneous imbibition in fractal porous media based on modified porosity correlation","authors":"Yinglin Li, Di Yu, B. Niu","doi":"10.46690/CAPI.2021.01.02","DOIUrl":"https://doi.org/10.46690/CAPI.2021.01.02","url":null,"abstract":"Spontaneous imbibition plays a significant role in different technical applications, and several analytical models have been proposed for predicting the fluid imbibition mass into porous media based on the fractal theory. Herein, these previous models are reconsidered in view of the obvious difference between the effective porosity and the areal porosity of porous media. Firstly, an implicit equation for fractal tortuosity is proposed and a modified correlation for the areal porosity is presented; then, a semi-analytical prediction model for fluid imbibition mass with gravity pressure is derived; finally, comparisons of predictions among several previous models with the present model are carried out. The modeling results show consistency with the experimental data published in the literature. Cited as: Li, Y., Yu, D., Niu, B. Prediction of spontaneous imbibition in fractal porous media based on modified porosity correlation. Capillarity, 2021, 4(1): 13-22, doi: 10.46690/capi.2021.01.02","PeriodicalId":34047,"journal":{"name":"Capillarity","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91340962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-14DOI: 10.46690/capi.2020.02.02
Yixin Cao, Mingming Tang, Qian Zhang, Jiafan Tang, Shuangfang Lu
In recent studies, dynamic capillary pressure has shown significant impacts on the flow behaviors in porous media under transient flow condition. However, the effect of dynamic capillary pressure effect on tight sandstone is still not very clear. Since lattice Boltzmann method (LBM) is a very promising and widely used method in analyzing flow behaviors, therefore, a two-phase D3Q27 LBM model is adopted in this paper to simulate the flow behaviors and analyze the dynamic capillary pressure effect in tight sandstone. Moreover, a new pore segmentation method for tight sandstone base on U-net deep learning model is implemented in this study to improve the pore boundary qualities of pore space, which is crucial for two-phase LBM simulation of tight sandstone. A total of 3800 3D sub-volume data sets extracted from computed tomography data of 19 tight sandstone samples are selected as ground truth data to train the network and segment the pore space afterward. The simulation results based on the segmented digital rock model, show that nonwetting phase fluid prefer the path with lower dynamic capillary pressure in the seepage process before breaking through the porous model. Furthermore, the increase of injection rate causes the saturation changes more quickly, injection rate also shows apparent positive correlation relationship with capillary pressure, which implies that dynamic capillary pressure effect also exists in tight sandstone, and LBM based two-phase flow simulation could be used to quantitatively analyze such effect in tight sandstone. Cited as : Cao, Y., Tang, M., Zhang, Q., Tang, J., Lu, S. Dynamic capillary pressure analysis of tight sandstone based on digital rock model. Capillarity, 2020, 3(2): 28-35, doi: 10.46690/capi.2020.02.02.
{"title":"Dynamic capillary pressure analysis of tight sandstone based on digital rock model","authors":"Yixin Cao, Mingming Tang, Qian Zhang, Jiafan Tang, Shuangfang Lu","doi":"10.46690/capi.2020.02.02","DOIUrl":"https://doi.org/10.46690/capi.2020.02.02","url":null,"abstract":"In recent studies, dynamic capillary pressure has shown significant impacts on the flow behaviors in porous media under transient flow condition. However, the effect of dynamic capillary pressure effect on tight sandstone is still not very clear. Since lattice Boltzmann method (LBM) is a very promising and widely used method in analyzing flow behaviors, therefore, a two-phase D3Q27 LBM model is adopted in this paper to simulate the flow behaviors and analyze the dynamic capillary pressure effect in tight sandstone. Moreover, a new pore segmentation method for tight sandstone base on U-net deep learning model is implemented in this study to improve the pore boundary qualities of pore space, which is crucial for two-phase LBM simulation of tight sandstone. A total of 3800 3D sub-volume data sets extracted from computed tomography data of 19 tight sandstone samples are selected as ground truth data to train the network and segment the pore space afterward. The simulation results based on the segmented digital rock model, show that nonwetting phase fluid prefer the path with lower dynamic capillary pressure in the seepage process before breaking through the porous model. Furthermore, the increase of injection rate causes the saturation changes more quickly, injection rate also shows apparent positive correlation relationship with capillary pressure, which implies that dynamic capillary pressure effect also exists in tight sandstone, and LBM based two-phase flow simulation could be used to quantitatively analyze such effect in tight sandstone. Cited as : Cao, Y., Tang, M., Zhang, Q., Tang, J., Lu, S. Dynamic capillary pressure analysis of tight sandstone based on digital rock model. Capillarity, 2020, 3(2): 28-35, doi: 10.46690/capi.2020.02.02.","PeriodicalId":34047,"journal":{"name":"Capillarity","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86988821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-01DOI: 10.46690/capi.2020.02.01
Liu Yang, Chenjiu Chen, Yifan Liu, Yuanhan Zheng
The recovered fracturing fluid is generally high in salinity (close to 200 kppm), which is related to the diffusion of salt ions from shale reservoir to the fracturing fluid. However, it is not clear about the diffusion capacity of salt ions in different types. In this paper, the shale, tight volcanic and sandstone are selected as comparative study and a series of tests are carried out for the porosity, permeability and mineral composition. The results show that the shale immersing in fracturing fluid will cause ions dissolution and diffusion, which will increase the salinity of the fracturing fluid. The solution salinity increases rapidly in the early stage and gradually slows down in the later stage. The salinity of the fracturing fluid has a linear relationship with the square root of time, so the slope of the curve can be used as a characteristic parameter to evaluate the ion diffusion rate. The process of dissolution and diffusion of salt ions will induce the expansion of micro-cracks, increasing the contact area between the fracturing fluid and shale and enhancing the solution salinity. The ion diffusion rate is positively related with the content of clay minerals and carbonate. The soluble ions include mainly SO 4 2− , Ca 2+ , Na + and K + . The Na + /Cl − ratio is closely related to the content of clay minerals and carbonate minerals. It has a positive correlation with content of illite and chlorite, and a negative correlation with carbonate minerals, suggesting NaCl source from illite and chlorite. This study is significant for understanding the salinity characteristics of recovered fracturing fluid and evaluating the fracture network shape. Cited as : Yang, L., Chen, C., Liu, Y., Zheng, Y. A comparative study of ion diffusion during water imbibition in shale, sandstone and volcanic rock. Capillarity, 2020, 3(2): 16-27, doi: 10.46690/capi.2020.02.01.
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