Feasibility Study Of Fluid Cavitation For Oil And Gas Well Production Increase

Cavitation of fluid is a very harmful phenomenon in hydraulic machinery equipment,but with the in-depth study of it,fluid cavitation has been rationally utilized in all aspects,changing harmful effect into beneficial effect.At present,at home and abroad,fluid cavitation has a lot of research in cleaning,cutting,biochemical environmental protection engineering and so on.The application of fluid cavitation in petroleum industry is mainly focused on assistant bit rock breaking,while the application of fluid cavitation in stimulation of oil and gas wells is rare.In order to study whether fluid cavitation can be applied to stimulation of oil and gas wells,this paper mainly studies three aspects.The cavitation phenomena and the initiation,development and collapse process of cavitation bubbles are studied.The kinetic equations of the expansion,compression and collapse process of a single bubble are studied from a microscopic point of view.The physical and chemical effects of fluid cavitation are also studied.The mechanism of increasing production of fluid cavitation is analyzed.Fluid cavitation produces strong vibration wave and cavitation noise,resulting in near-by-by.Well reservoir rock produces micro-fracture,blockage particle shedding,improve reservoir rock permeability and porosity,reduce the relative molecular weight of crude oil,reduce crude oil viscosity,and produce emulsification.These two aspects are helpful to improve the fluid flow ability of reservoirs,so as to increase production and enhance recovery.Cavitation nozzle is the main device of fluid cavitation,and its type and geometric parameters have an important impact on the effect of cavitation.Three different types of cavitation nozzles were simulated by computational fluid dynamics(CFD).The velocity nephogram and gas phase distribution nephogram were compared and analyzed.It was concluded that the organ pipe cavitation nozzle could produce better cavitation effect.The optimized structure parameters of the organ pipe are: the contraction ratio of the section at the inlet end of the resonant cavity Ds/D = 2,the contraction ratio at the outlet end of the resonant cavity D/d = 5,the ratio of the length of the resonant cavity to the diameter of the nozzle L/d =6,the ratio of the length of the straight column to the diameter of the nozzle s/d = 2,the ratio of the length of the diffusion section s1/d = 6,and the angle of the diffusion sectionθ = 30°.The nozzle can satisfy the requirements of the verification test of fluid cavitation.Finally,through laboratory experiments,we innovatively designed a set of experimental device to simulate fluid cavitation in underground production increase operation,to study the effect of fluid cavitation action distance,action time and pressure on reservoir rock permeability,and the effect of fluid cavitation on reservoir fluid percolation ability,and to study the feasibility of fluid cavitation on oil and gas well production increase from the experimental point of view.The experimental results show that fluid cavitation can effectively improve the permeability of reservoir rocks in a long working distance,and the increase of permeability will increase with the increase of cavitation time and pressure.Fluid cavitation can effectively reduce the viscosity of crude oil,and the viscosity reduction effect of heavy oil is as high as 73%.According to the experimental results,fluid cavitation can effectively reduce the permeability of reservoir rocks and improve the seepage ability of bottom-hole reservoirs,so it can be concluded that fluid cavitation is feasible in stimulating oil and gas wells.