Numerical Simulation And Experimental Study Of Pulse Gravel Packing In The Horizontal Well

Gravel pack completion technology is one of the key technologies in horizontal well completion.There are many complicated conditions such as high sand bed,slow migration of gravel and short migration distance during gravel packing engineering operations,which can easily lead to string blockage,reduce the filling efficiency and greatly affect the stimulation effect of oil-gas wells.Therefore,it is of great significance to carry out the research on efficient gravel packing in horizontal wells.In this thesis,the hydraulic pulse is applied to gravel packing in horizontal wells.The working mechanism of pulse gravel packing in horizontal well is analyzed.Based on hydraulic pulse theory,solid-liquid two-phase flow model and computational fluid dynamics theory,the numerical simulation of sinusoidal,triangular and rectangular waveform optimization for pulse gravel packing in horizontal wells is carried out.At the same time,the numerical simulation of influencing factors of horizontal well pulse and conventional gravel packing is carried out,including carrying fluid displacement,carrying fluid viscosity,sand carrying ratio,gravel size and string eccentricity,which analyzing the distribution law of gravel migration velocity and volume fraction.The feasibility experiment,waveform optimization experiment and influencing factor experiment are carried out by establishing the laboratory experiment platform of horizontal well pulse gravel packing,which obtaining the distribution of gravel bed and the law of migration velocity.The research results show that: Comparing the pulse gravel pack with the conventional gravel pack,under the action of fluctuating sandcarrying fluid drag force,the force on gravel particles changes significantly,which makes gravel particles have stronger migration ability.It has certain advantages to improve gravel packing efficiency.The sinusoidal pulse of the three pulse waveforms can reduce the height of gravel-packed sand bed to the greatest extent.The frequency and amplitude of the best waveform parameters are 5 Hz and 1.65 m/s.Under the optimal waveform and parameters,the fixed bed volume fraction decreases by 42.1%,the suspended bed volume fraction increases by 14.5%,the gravel bed height decreases by 67%,and the migration velocity increases by 50%.The experiment also proves that the turbulent kinetic energy of hydraulic pulse can make the gravel particles on the surface of gravel bed obtain kinetic energy for several times,so that the gravel particles continue to extend forward,which not only reduces the gravel bed to the appropriate height,improves the gravel bed migration speed,but also improves the gravel packing efficiency.In this thesis,theoretical research,numerical simulation and laboratory experiment on horizontal well pulse gravel packing are carried out.The research results can lay a theoretical foundation for the development of this technology,and the research method can provide reference for efficient gravel packing in horizontal wells.