One of the most crucial decisions in drilling operations is the choice between water-based mud (WBM) and oil-based mud (OBM). Although WBM is often preferred, mainly due to its low cost, OBM usage is on the rise in light of drilling deeper and increasingly more complex wells. A key disadvantage of using OBM is the effect of mud-filtrate invasion on formation properties in the near-wellbore region, which can complicate interpretation of petrophysical measurements. Rock surfaces for this study were prepared by grinding with silicon carbide powder and polishing with diamond paste. Surface roughness was quantified and OBM surfactant adsorption was visualized, both by atomic force microscopy. Wettability changes on the rock surfaces upon conditioning with surfactant, contained in OBM filtrate, were characterized by contact angle measurements. It was found that, regardless of surface roughness and lithology, conditioning of rock surfaces with low concentrations of surfactant, contained in OBM, resulted in surface alteration to more oil-wet, as shown in the current study for calcite, dolomite, quartz, and mica surfaces. When applied to porous media, this suggests that part of the capillary bound water in the invaded zone becomes more likely to be displaced by the hydrocarbon phase, a factor that needs to be considered when interpreting shallow reading petrophysical measurements.

中文翻译：

---

油基泥浆滤液对不同矿物学和拓扑结构岩石表面润湿性的影响

钻井作业中最关键的决定之一是在水基泥浆（WBM）和油基泥浆（OBM）之间进行选择。尽管通常首选WBM，主要是因为其成本低廉，但随着钻探更深，越来越复杂的井，OBM的使用正在增加。使用OBM的主要缺点是泥浆渗透对近井眼区域地层性质的影响，这会使岩石物理测量的解释变得复杂。本研究的岩石表面是通过用碳化硅粉末研磨并用金刚石膏抛光而制备的。通过原子力显微镜对表面粗糙度进行定量并且使OBM表面活性剂吸附可视化。通过接触角测量来表征OBM滤液中所含的表面活性剂处理后岩石表面的润湿性变化。已发现，不管表面粗糙度和岩性如何，OBM所含的低浓度表面活性剂对岩石表面的处理都会导致表面改变为更多的油湿性，如对方解石，白云石，石英和云母表面。当将其应用于多孔介质时，这表明侵入区中的部分毛细管束缚水变得更有可能被烃相驱替，这是解释浅层岩石物理测量时需要考虑的因素。