合成基钻井液流型调节剂的研制及其作用机理

Development and Working Mechanism of Flow Pattern Enhancer for Synthetic Base Drilling Fluids

合成了一种可解决低温条件下合成基钻井液流变性问题的流型调节剂,测定流型调节剂对油包水乳状液流变性的影响,对比分析流型调节剂、有机土样品的红外特征和XRD特征,使用冷冻扫描电镜和透射电镜观察流型调节剂对乳液微观结构的影响,分析流型调节剂的作用机制,进行在高密度合成基钻井液中适用性评价。结果表明:流型调节剂能够显著改善合成基钻井液的低温流变性,有利于乳液稳定;流型调节剂吸附在油水界面,降低乳滴与有机土之间结构力,改善有机土颗粒与乳状液滴之间的相互作用,从而稳定油包水乳液的切力。与传统合成基钻井液相比,恒定流变的合成基钻井液具有更加稳定的低温流变性,保证井下安全。

A flow pattern enhancer has been developed to deal with the rheology problem of synthetic base drilling fluids at low temperatures.In laboratory experiment,the effects of the flow pattern enhancer on the rheology of water-in-oil emulsion were measured,the IR and XRD characteristics of the flow pattern enhancer and organophilic clays were compared and analyzed.Using Cryo-SEM and TEM,the effects of the flow pattern enhancer on the micro-structure of the emulsion were observed and the working mechanisms of the flow pattern enhancer analyzed.The laboratory experimental results were then used to evaluate the applicability of the flow pattern enhancer in high density synthetic base drilling fluids.It was found that the flow pattern enhancer was able to remarkably improve the low-temperature rheology of synthetic base drilling fluids and was beneficial to the stability of emulsion.The molecules of the flow pattern enhancer are adsorbed on the interface of oil and water in the emulsion,thereby reducing the structural force between the drops of the emulsion and the particles of the organophilic clay,and improving the interaction between the clay particles and emulsion drops.All these are helpful to the stability of the gel strength of the water-in-oil emulsion.Compared with conventional synthetic base drilling fluids,the constant-rheology synthetic base drilling fluids have more stable low-temperature rheology which is critical to the safety of downhole operation.