高密度钻井液除气系统设计与模拟试验

Design and simulation experiment of the degassing system for the high-density drilling fluid

针对高压气井使用的高密度钻井液受气侵后除气难度大的问题,设计了室内模拟2级除气试验台架,并给出了具体的试验方案。应用计算流体力学软件模拟分离器内流场分布情况,优化和完善了分离器结构和操作参数。结合室内实测数据分析认为,高密度钻井液由于受高粘度的影响,使得气泡滑脱逃逸能力降低,气泡浮于液相中的时间增加;重力式除气可以清除大气泡,离心式除气可以清除毫米级的小气泡,二者结合使用可以很好地解决高密度、高粘度钻井液除气困难的问题。

In light of the great difficulty in the degassing of the high-density drilling fluid used by high-pressure gas wells,the laboratory simulated two-stage degassing test bench was designed and the specific testing scheme was offered.The applied computational fluid dynamics software was employed to simulate the distribution of the flow field of the separator,optimizing and perfecting the structural and operating parameters of the separator.Referring to the measured data analysis,it is thought that,due to the effect of high viscosity,the high-density drilling fluid leads to the reduction in the slippage-escape capacity of air bubble and the time delay for air bubble floating in liquid phase.The gravitational degassing can remove big bubbles while centrifugal degassing can remove millimeter-sized bubbles.The combination of both kinds of degassing can well deal with the difficulty in degassing of high-density and high-viscosity drilling fluid.