In this paper, an elastic particle mesh （EPM） model is presented. It can be used like a cover to sketch images. EPM offers two advantages： first, when putting on a sketch image, it helps to repair disconnections on...In this paper, an elastic particle mesh （EPM） model is presented. It can be used like a cover to sketch images. EPM offers two advantages： first, when putting on a sketch image, it helps to repair disconnections on salient features. Second, it hides trivial details in the image, thus has the ability of decreasing over-segmentation when used with watershed transformation.展开更多
Knowledge of migration and retention mechanisms of elastic gel particles(EGPs)in pore-throats is essential for the effective application of EGPs as a smart sweep improvement and profile control agent for enhanced oil ...Knowledge of migration and retention mechanisms of elastic gel particles(EGPs)in pore-throats is essential for the effective application of EGPs as a smart sweep improvement and profile control agent for enhanced oil recovery(EOR).The matching coefficient(defined as the ratio of particle size to pore-throat size)is used to investigate its influence on migration,retention and profile control performance of EGPs.A 1-D continuous pore-throat visualization model(PTVM),a 2-D heterogeneous PTVM and a 3-D heterogeneous core model were constructed and used to investigate pore-scale migration,retention and controlling mechanism of migration and retention characteristics on EGPs profile control.The results of the 1-D continuous PTVM indicated that while the matching coefficient was in the optimal range(i.e.,0.20-0.32),the EGPs could not only smoothly migrate to the deeper pore-throats,but also form stable retention in the pores to resist the erosion of injected water,which was conducive to the effective indepth profile control.The results of the 2-D heterogeneous PTVM verified that the sweep efficiency in low-permeability regions could be significantly improved by in-depth migration and stable retention of EGPs in the pore-throats with an optimal matching coefficient(0.29),which was much better than that in cases with a smaller matching coefficient(0.17)or an excessive matching coefficient(0.39).Moreover,the NMR displacement experiments of 3-D heterogeneous cores were carried out to simulate the EGPs profile control in actual reservoir porous media.Saturation images and T2 spectrum curves of crude oil showed that EOR in the low-permeability layer was highest(56.1%)using EGPs profile control with an optimal matching coefficient,attributing to the in-depth migration and stable retention of EGPs.展开更多
Lost circulation control in millimeter-wide fractures has been a challenge in well drilling all the time.Low pressure-bearing capacity of a plugging zone will result in excessive consumption of lost circulation materi...Lost circulation control in millimeter-wide fractures has been a challenge in well drilling all the time.Low pressure-bearing capacity of a plugging zone will result in excessive consumption of lost circulation materials(LCMs)and extra down time.In this study,laboratory ex-periments were conducted on the plugging of millimeter-wide fractures to evaluate the plugging effects of different types of LCM including rigid granules,elastic particles andfiber.Maximum plugging pressure,total loss volume before sealing and plugging time were taken as the evaluation index of the LCM plugging effect.According to the experimental results,the synergistic plugging mechanisms of different LCM combinations were also analyzed.Experimental results showed that the total loss volume of the plugging zone formed by rigid and elastic particle combination was generally greater than 400 mL,and the maximum plugging pressure of the plugging zone formed by elastic particle andfiber combination was generally less than 6 MPa.In contrast,the plugging zone formed by the combination of the three types of LCMs has the maximum plugging pressure of up to 13 MPa and total loss volume before sealing of 75 mL.In the synergistic plugging process,rigid granules form a frame with high pressure-bearing capacity in the narrower parts of the fractures;elastic particles generate elastic force through elastic deformation to increase the friction between a fracture and a plugging zone to make the plugging zone more stable;fibersfilling in the pore space between the particles increase the tightness and integrity of the plugging zone.The experimental results can provide guidance for the optimal design of LCMs used in thefield.展开更多
基金Project supported by National Natural Science Foundation of China（ Grant No. 60272081 ）
文摘In this paper, an elastic particle mesh （EPM） model is presented. It can be used like a cover to sketch images. EPM offers two advantages： first, when putting on a sketch image, it helps to repair disconnections on salient features. Second, it hides trivial details in the image, thus has the ability of decreasing over-segmentation when used with watershed transformation.
基金supported by the National Key Research and Development Project(2019YFA0708700)the National Natural Science Foundation of China(52104061)+2 种基金the project funded by China Postdoctoral Science Foundation(2020M682264)the Shandong Provincial Natural Science Foundation(ZR2021QE075)the Fundamental Research Funds for the Central Universities(20CX06090A)。
文摘Knowledge of migration and retention mechanisms of elastic gel particles(EGPs)in pore-throats is essential for the effective application of EGPs as a smart sweep improvement and profile control agent for enhanced oil recovery(EOR).The matching coefficient(defined as the ratio of particle size to pore-throat size)is used to investigate its influence on migration,retention and profile control performance of EGPs.A 1-D continuous pore-throat visualization model(PTVM),a 2-D heterogeneous PTVM and a 3-D heterogeneous core model were constructed and used to investigate pore-scale migration,retention and controlling mechanism of migration and retention characteristics on EGPs profile control.The results of the 1-D continuous PTVM indicated that while the matching coefficient was in the optimal range(i.e.,0.20-0.32),the EGPs could not only smoothly migrate to the deeper pore-throats,but also form stable retention in the pores to resist the erosion of injected water,which was conducive to the effective indepth profile control.The results of the 2-D heterogeneous PTVM verified that the sweep efficiency in low-permeability regions could be significantly improved by in-depth migration and stable retention of EGPs in the pore-throats with an optimal matching coefficient(0.29),which was much better than that in cases with a smaller matching coefficient(0.17)or an excessive matching coefficient(0.39).Moreover,the NMR displacement experiments of 3-D heterogeneous cores were carried out to simulate the EGPs profile control in actual reservoir porous media.Saturation images and T2 spectrum curves of crude oil showed that EOR in the low-permeability layer was highest(56.1%)using EGPs profile control with an optimal matching coefficient,attributing to the in-depth migration and stable retention of EGPs.
文摘Lost circulation control in millimeter-wide fractures has been a challenge in well drilling all the time.Low pressure-bearing capacity of a plugging zone will result in excessive consumption of lost circulation materials(LCMs)and extra down time.In this study,laboratory ex-periments were conducted on the plugging of millimeter-wide fractures to evaluate the plugging effects of different types of LCM including rigid granules,elastic particles andfiber.Maximum plugging pressure,total loss volume before sealing and plugging time were taken as the evaluation index of the LCM plugging effect.According to the experimental results,the synergistic plugging mechanisms of different LCM combinations were also analyzed.Experimental results showed that the total loss volume of the plugging zone formed by rigid and elastic particle combination was generally greater than 400 mL,and the maximum plugging pressure of the plugging zone formed by elastic particle andfiber combination was generally less than 6 MPa.In contrast,the plugging zone formed by the combination of the three types of LCMs has the maximum plugging pressure of up to 13 MPa and total loss volume before sealing of 75 mL.In the synergistic plugging process,rigid granules form a frame with high pressure-bearing capacity in the narrower parts of the fractures;elastic particles generate elastic force through elastic deformation to increase the friction between a fracture and a plugging zone to make the plugging zone more stable;fibersfilling in the pore space between the particles increase the tightness and integrity of the plugging zone.The experimental results can provide guidance for the optimal design of LCMs used in thefield.
