Preparation Of Novel Organomontmorillonite And Its Application Research In Oil-based Drilling Fluids

Various kinds of organomontmorillonite(OMts)were prepared from Li-montmorillonite(Li-Mt)Na-montmorillonite(Na-Mt)and Ca-montmorillonite(Ca-Mt),by solution intercalation method and extrusion method.Cationic and anionic surfactants with different species were used throughout the modification process.The prepared cationic-anionic organomontmorillonite(CA-OMts)were used in oil-based drilling fluids(OBM)to study the effect of surfactants species and modification processes on the applied performance of OBM.Furthermore,the dispersion of OMts in Pickering emulsion and the stability of Pickering emulsion were characterized to study the factors affecting the stability of Pickering emulsion.The structure,thermal stability and surface polarity of prepared OMts were characterized by XRD,TG-DTA and contact angle.The performances of OMts in OBM were characterized by six-speed rotational viscometer.The stability of OMts stabilized Pickering emulsion was characterized by using an optical microscope.The study shows that CA-OMts have greater d₀₀₁ value(44.6?),more regular crystalline,moderate contact angle(34°)and better thermal stability compared with cationic OMts.Furthermore,the performances of CA-OMts on OBM are also superior to that of cationic OMts,including greater apparent viscosity and yield point,less filtration loss and appropriate thixotropy.OMts prepared from Mt with different interlayer exchangeable cations showed that the Mt containing monovalent Na⁺,Li⁺in the interlayer have a better modification effect after being modified by surfactants,including greater d₀₀₁ value,suitable contact angle and better thermal stability compared with Ca-Mt.It is found that different species of OMts have different suitable application conditions after it being used in OBM.Ca-CTAB+SDS has optimal application in OBM under 150°C,while Li-CTAB+SDS and Na-CTAB+SDS can be applied in OBM at higher temperature than 150^oC.Under the same amount of surfactants,being modified by surfactants with a long chain or complex chain,OMts have better thermal stability and low surface polarity,which can improve application performance under high temperature conditions in OBM.Characterization of OMts stabilized oil-in-water Pickering emulsion illustrates that OMts can effectively improve the stability of Pickering emulsion after being modified by three steps and coated by cationic surfactants on the surface of it.