| At present,the sand mixing equipment used in the carbon dioxide fracturing operation is basically a ground mixing truck,it needs to be carried out under high pressure and low temperature during operation,which requires higher requirements for ground mixing equipment.,and it takes a certain time before and after the sand concentration adjustment.In order to solve the above problems,this paper designs a concentric tubular downhole supercritical carbon dioxide jet mixing equipment based on the jet principle.,it could mixes sand in the well and can adjust the sand concentration in real time.The designed sand mixing equipment is optimized by numerical calculation and software simulation to improve the performance of the sand mixing equipment.The main research contents are as follows:1.According to the basic physical properties of carbon dioxide,the influence of temperature and pressure on its density,viscosity and diffusion coefficient was studied.The wellbore temperature and pressure model was established to analyze the distribution of carbon dioxide in the wellbore.2.Proposing the structural design scheme of the concentric tubular downhole supercritical carbon dioxide jet mixing equipment,and giving the working principle and connection mode of the equipment.3.For the mixing of supercritical carbon dioxide and proppant in this paper,after studying the basic theory of two-phase flow,the model needed for subsequent simulation is selected,and the feasibility of sand mixing in the equipment is determined by two-dimensional simulation.4.The software is used to simulate the flow field of the equipment in three dimensions,and the sand volume distribution at the exit surface of the sand mixing equipment is taken as the main evaluation standard to obtain the optimal structural size parameters and optimal inlet condition parameters,which provides a theoretical basis for the structural design and parameter selection of the sand mixing equipment. |
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