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常规钻井返出管线敞口,钻井液在返出管线中流动为非满管流动,小气侵量时,泥浆池液面变化不明显,检测装置无法测量液面变化,钻井液返出流量无法测量或者测量误差较大,无法感知小流量差的变化。本文基于气液两相流理论建立了井筒气液两相流参数与井口溢流速度的关系模型,计算表明气侵速度越大,气泡运移距井口越近,井口溢流速度越大。并以空气和钻井液(非牛顿流体)为介质,基于VOF多相流模型,模拟了钻井液返出流量变化时气液界面变化情况,分析了纯钻井液和不同含气率钻井液在返出管线流动时液面变化特征,得出纯钻井液流动时喇叭口处液面变化最明显,优化液面检测装置安装在喇叭上,更能准确及时地检测液面变化早期发现溢流,进气速度影响返出管线钻井液液面稳定性。
Conventional drilling back out of the pipeline exposure, the drilling fluid flow in the return line of non-full pipe flow, the stinky invasion, the mud pool liquid level change is not obvious, the detection device can not measure the liquid level, the drilling fluid backflow can not be measured Or measurement error is large, can not perceive changes in small flow difference. Based on the theory of gas-liquid two-phase flow, the relationship model between wellbore gas-liquid two-phase flow and wellhead overflow velocity is established. The calculation shows that the greater the gas intrusion rate, the closer the bubble is from the wellhead and the greater the wellhead overflow velocity. Based on the VOF multi-phase flow model, the air and drilling fluids (non-Newtonian fluid) are used as media to simulate the change of gas-liquid interface when the return flow of drilling fluid changes. The effects of pure drilling fluid and drilling fluid with different gas- When the flow of the pipeline is flowing, the change of the liquid level is found. The result shows that when the pure drilling fluid flows, the change of the liquid level at the bell mouth is the most obvious. The optimized liquid level detecting device is installed on the loudspeaker, which can detect the liquid level change accurately and timely, Gas velocity affects the liquid level stability of the return line drilling fluid.