Abstract The primary function of natural gas well cementing is to provide downhole zonal isolation. However, the residual non-aqueous drilling fluid in cement and on the surface of the casing can weaken the bond of hardened cement to the casing. In this paper, the amount of remaining drilling fluid both in cement and on the casing is quantified by the fluorescent dye method, which is verified by other two methods, mass difference and laser scanning. The essential factor - surface roughness that can significantly affect the amount of residual drilling fluid - is investigated. Results show good correlations between the thickness of the remaining drilling fluid and the surface roughness. The comparison of mud removal efficiency of two commercial spacers indicates that microemulsion can remove more drilling fluid than the common spacer, as pointed out in the literature; however, microemulsion is also apt to remain on the casing and thus reduce the bonding between cement and the casing.

中文翻译：

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套管表面粗糙度对非水钻井液去除效率的影响

摘要 天然气固井的主要功能是提供井下区域隔离。然而，水泥中和套管表面残留的非水钻井液会削弱硬化水泥与套管的结合。本文采用荧光染料法对水泥中和套管上剩余钻井液量进行定量，并通过质量差法和激光扫描法两种方法进行验证。研究了可显着影响剩余钻井液量的基本因素 - 表面粗糙度。结果表明剩余钻井液的厚度与表面粗糙度之间具有良好的相关性。两种商品隔离器的除泥效率对比表明，微乳液比普通隔离器能去除更多的钻井液，正如文献中指出的那样；然而，微乳液也容易残留在套管上，从而降低水泥与套管之间的结合力。