Experimental Study Of Particle Settling In Supercritical Carbon Dioxide

The needs of petroleum reserves become increasingly severe,which makes the development of unconventional reservoirs of high importance.The superctitical carbon dioxide drilling and fracturing technology is one of the most important means to develop unconventional oil and gas reservoirs.In the process of drilling and fracturing,it is an important research direction to study the two-phase flow between cuttings,proppant and supercritical carbon dioxide.The settling law of particles in supercritical carbon dioxide is the basis for the study of the two-phase flow between them.Therefore,correctly understanding the rule of particle settling in supercritical carbon dioxide and establishing effective settlement model is of great significance to the development of supercritical carbon dioxide drilling and fracturing technology.Firstly,establish differential equation of the process of particle settlement on the basis of the stress state when the particle settling in supercritical carbon dioxide.Select the relational expression between the Reynolds number and the Drag coefficient as well as the calculation method of the density of supercritical carbon dioxide effectively.Then analyze the effect of Basset force and Virtual mass force comprehensively to improve computational accuracy.The fourth order Runge-Kutta method was used to solve the differential equation and establish an effective settlement model of partical settling in supercritical carbon dioxide.Secondly,design and manufacture a multifunctional experimental apparatus of supercritical carbon dioxide and perform an experiment on the process of different partical settling in supercritical carbon dioxide on different temperature and pressure condition.Use a high-speed photography device to measure the terminal settling velocity.The experimental results are in good agreement with the theoretical model.Finally,based on the experiment,use the numerical simulation method to study the rule of particle settling in supercritical carbon dioxide.The results show that terminal settling velocity increase with the increase of temperature and decrease with the increase of the pressure and partical diameter.The simulation results further confirm the correctness of experimental results and settlement model.This paper combine the theoretical analysis,experimental research and numerical simulation to preliminary establish a settlement model that partical settling in supercritical carbon dioxide.Then design and manufacture a multifunctional experimental device of supercritical carbon dioxide.These work laid a solid theoretic foundation for the future study of two-phase flow between supercritical carbon dioxide and particle and the development of supercritical carbon dioxide drilling technology.