In the context of both production and well abandonment, effective cementing of the surface casing is key in preventing leakage of formation fluids. Although there are general guidelines for the effective cementing of vertical casings, there is little known about the effects of wellbore irregularity, e.g. from formations that are badly eroded during drilling - washouts. Here we present a systematic study of the cementing of a vertical surface casing with a washout section. We study the effects of washout length, pump rate, positive density difference and viscosity ratio, all in the displacement flow of the drilling mud by a spacer. Of these parameters, flow rate increases can lead to both improved displacements and to mixing and potential contamination. A positive density difference improves the mud displacement and viscosity differences have minimal effect, at least over the ranges studied. We then propose a pumping strategy that may improve the displacement process in a targeted washout, potentially valuable as we move into the era of real-time (and while drilling) well calipers and are progressively able to include irregular borehole geometries into cementing designs.

在生产和废弃井的情况下，有效地固结表层套管是防止地层流体泄漏的关键。尽管有有效固井垂直套管的通用指南，但对井眼不规则性的影响知之甚少，例如井眼不规则性的影响，例如钻井过程中冲蚀严重的地层。在这里，我们对带有冲洗段的垂直地面套管的固井进行了系统的研究。我们研究了冲洗长度，泵送速度，正密度差和粘度比的影响，这些影响都在由隔离层驱替的钻井泥浆流中。在这些参数中，流速的增加既可以改善位移，又可以导致混合和潜在的污染。正密度差改善了泥浆驱替，而粘度差至少在所研究的范围内影响最小。然后，我们提出一种泵送策略，该策略可以改善目标井喷过程中的驱替过程，这在我们进入实时（和随钻）井卡尺时代并逐步能够将不规则井眼几何形状纳入固井设计中时具有潜在的价值。