The stability, dispersion, and rheological properties of clay suspensions are important in the process of drilling. Organic clays were obtained traditionally by cation exchange, which is thermally unstable due to weak electrostatic interaction between the cationic surfactant and clay minerals. The purpose of the present study was to yield a stable and well dispersed organic bentonite (OBent) as a rheological additive for oil-based drilling mud. The co-modified method was used to modify bentonite by a cationic surfactant (cetyltrimethoxyammonium bromide: CTAB) and a silane coupling agent (hexadecyltrimethoxysilane: HDTMS). Firstly, the basal spacing of bentonite was enlarged by intercalation of CTAB, and the thermal stability of bentonite was improved by covalent bonds of HDTMS onto the bentonite platelets. The as-prepared OBent was characterized by infrared analysis, X-ray diffraction analysis, thermogravimetric analysis, and scanning electron microscopy. The hydrophobicity, solubility, viscosity, and tribological performance of the OBent were also recorded. The test results showed that the hydrophobicity of the co-modified bentonite was improved significantly, and was greater than that of bentonite modified with single surfactant CTAB or HDTMS. The bentonite modified by the surfactant together with the silane coupling agent had stable rheology and a lower coefficient of friction than the single surfactant-modified bentonite because more HDTMS entered into the interlayer spaces and formed chemical bonds at the inner surface of platelets.

中文翻译：

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CTAB与硅烷共改性膨润土及其在油基钻井泥浆中的性能

粘土悬浮液的稳定性、分散性和流变特性在钻井过程中很重要。有机粘土传统上是通过阳离子交换获得的，由于阳离子表面活性剂和粘土矿物之间的弱静电相互作用，它是热不稳定的。本研究的目的是生产稳定且分散良好的有机膨润土 (OBent) 作为油基钻井泥浆的流变添加剂。采用共改性法通过阳离子表面活性剂（十六烷基三甲氧基溴化铵：CTAB）和硅烷偶联剂（十六烷基三甲氧基硅烷：HDTMS）对膨润土进行改性。首先，通过CTAB的插层扩大了膨润土的基间距，通过HDTMS在膨润土片晶上的共价键提高了膨润土的热稳定性。所制备的 OBent 通过红外分析、X 射线衍射分析、热重分析和扫描电子显微镜进行表征。还记录了 OBent 的疏水性、溶解性、粘度和摩擦学性能。试验结果表明，共改性膨润土的疏水性显着提高，且大于单一表面活性剂CTAB或HDTMS改性的膨润土。表面活性剂与硅烷偶联剂一起改性的膨润土具有稳定的流变性和比单一表面活性剂改性的膨润土更低的摩擦系数，因为更多的 HDTMS 进入层间空间并在片晶的内表面形成化学键。还记录了 OBent 的疏水性、溶解性、粘度和摩擦学性能。试验结果表明，共改性膨润土的疏水性显着提高，且大于单一表面活性剂CTAB或HDTMS改性的膨润土。表面活性剂与硅烷偶联剂一起改性的膨润土具有稳定的流变性和比单一表面活性剂改性的膨润土更低的摩擦系数，因为更多的 HDTMS 进入层间空间并在片晶的内表面形成化学键。还记录了 OBent 的疏水性、溶解性、粘度和摩擦学性能。试验结果表明，共改性膨润土的疏水性显着提高，且大于单一表面活性剂CTAB或HDTMS改性的膨润土。表面活性剂与硅烷偶联剂一起改性的膨润土具有稳定的流变性和比单一表面活性剂改性的膨润土更低的摩擦系数，因为更多的 HDTMS 进入层间空间并在片晶的内表面形成化学键。且大于单一表面活性剂 CTAB 或 HDTMS 改性的膨润土。表面活性剂与硅烷偶联剂一起改性的膨润土具有稳定的流变性和比单一表面活性剂改性的膨润土更低的摩擦系数，因为更多的 HDTMS 进入层间空间并在片晶的内表面形成化学键。且大于单一表面活性剂 CTAB 或 HDTMS 改性的膨润土。表面活性剂与硅烷偶联剂一起改性的膨润土具有稳定的流变性和比单一表面活性剂改性的膨润土更低的摩擦系数，因为更多的 HDTMS 进入层间空间并在片晶的内表面形成化学键。