Hydraulic fracturing is the primary method used for oilfield stimulation,and the migration and settlement pattern of proppant plays a crucial role in the formation of high conductivity propping fractures in the reserv...Hydraulic fracturing is the primary method used for oilfield stimulation,and the migration and settlement pattern of proppant plays a crucial role in the formation of high conductivity propping fractures in the reservoir.This study summarizes two growth modes of sand dune:the‘overall longitudinal growth’mode and the‘push growth along fracture length direction’mode.To investigate these modes,a twophase velocity test is conducted using PIV,and the exposure difference is utilized to separate the tracer and track the single-phase velocity.By analyzing the slickwater flow field and proppant velocity field,the micro-motion mechanism behind the two dune growth modes is quantitatively examined.The results indicate that mode 1 growth of the sand dune occurs when a pump with a large mesh number,high polymer viscosity,and large displacement is used.On the other hand,mode 2 growth is observed when a pump with a small mesh number,low polymer viscosity,and small displacement is employed.It is important to note that there is no clear boundary for the migration and sedimentation mode of proppant,as they can transition into each other under certain conditions.These modes only exist during specific stages of sand dune growth.In the case of the‘backflow’pattern,the settlement of proppant is primarily influenced by the vortex structure of slickwater.Conversely,in the‘direct’pattern,the proppant is propelled forward by the drag of the fluid and settles due to its own gravity.Once the proppant placement reaches equilibrium,the direction of proppant velocity follows a normal distribution within 0°.This approach establishes a connection between the overall placement of the sand dune and the microscopic movement of the proppant and slickwater.Optimizing construction parameters during fracturing construction can enhance the effectiveness of distal proppant placement in fractures.展开更多
A new algorithm using polar coordinate system similarity （PCSS） for tracking particle in particle tracking velocimetry （PTV） is proposed. The essence of the algorithm is to consider simultaneously the changes of t...A new algorithm using polar coordinate system similarity （PCSS） for tracking particle in particle tracking velocimetry （PTV） is proposed. The essence of the algorithm is to consider simultaneously the changes of the distance and angle of surrounding particles relative to the object particle. Monte Carlo simulations of a solid body rotational flow and a parallel shearing flow are used to investigate flows measurable by PCSS and the influences of experimental parameters on the implementation of the new algorithm. The results indicate that the PCSS algorithm can be applied to flows subjected to strong rotation and is not sensitive to experimental parameters in comparison with the conventional binary image cross-correlation （BICC） algorithm. Finally, PCSS is applied to images of a real experiment.展开更多
基金prepared under the auspices of the State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation at Southwest Petroleum UniversityAnd supported by National Nat-ural Science Foundation of China(U21A20105,51874250).
文摘Hydraulic fracturing is the primary method used for oilfield stimulation,and the migration and settlement pattern of proppant plays a crucial role in the formation of high conductivity propping fractures in the reservoir.This study summarizes two growth modes of sand dune:the‘overall longitudinal growth’mode and the‘push growth along fracture length direction’mode.To investigate these modes,a twophase velocity test is conducted using PIV,and the exposure difference is utilized to separate the tracer and track the single-phase velocity.By analyzing the slickwater flow field and proppant velocity field,the micro-motion mechanism behind the two dune growth modes is quantitatively examined.The results indicate that mode 1 growth of the sand dune occurs when a pump with a large mesh number,high polymer viscosity,and large displacement is used.On the other hand,mode 2 growth is observed when a pump with a small mesh number,low polymer viscosity,and small displacement is employed.It is important to note that there is no clear boundary for the migration and sedimentation mode of proppant,as they can transition into each other under certain conditions.These modes only exist during specific stages of sand dune growth.In the case of the‘backflow’pattern,the settlement of proppant is primarily influenced by the vortex structure of slickwater.Conversely,in the‘direct’pattern,the proppant is propelled forward by the drag of the fluid and settles due to its own gravity.Once the proppant placement reaches equilibrium,the direction of proppant velocity follows a normal distribution within 0°.This approach establishes a connection between the overall placement of the sand dune and the microscopic movement of the proppant and slickwater.Optimizing construction parameters during fracturing construction can enhance the effectiveness of distal proppant placement in fractures.
基金supported by the National Natural Science Foundation of China(50206019)
文摘A new algorithm using polar coordinate system similarity （PCSS） for tracking particle in particle tracking velocimetry （PTV） is proposed. The essence of the algorithm is to consider simultaneously the changes of the distance and angle of surrounding particles relative to the object particle. Monte Carlo simulations of a solid body rotational flow and a parallel shearing flow are used to investigate flows measurable by PCSS and the influences of experimental parameters on the implementation of the new algorithm. The results indicate that the PCSS algorithm can be applied to flows subjected to strong rotation and is not sensitive to experimental parameters in comparison with the conventional binary image cross-correlation （BICC） algorithm. Finally, PCSS is applied to images of a real experiment.
