油基钻井液劣质固相絮凝剂双十六烷基二甲基氯化铵

Research on Dihexadecyldimethyl Ammonium Chloride As A Poor Solid flocculant for Oil-based Drilling Fluid

劣质固相对油基钻井液的性能影响大,且由于其粒径小难以被固控设备清除。絮凝剂能通过絮凝作用增大劣质固相粒径,但几乎都用于水基钻井液而少有用于油基钻井液。以高岭土作为油基钻井液劣质固相,通过静置观察、浊度分析、显微镜观察等方法,研究了双十六烷基二甲基氯化铵(DCDAC)对高岭土的絮凝作用。结果表明,DCDAC能加快高岭土的沉降速度,当加量为5%时,高岭土在48 h后基本沉淀完毕;静置5 h后,高岭土悬浮液的浊度降低率接近80%;通过光学显微镜观察发现,当DCDAC加量不小于4%时,高岭土出现明显的团聚行为;通过体系实验发现,离心后油基钻井液的密度及固相含量与DCDAC加量成反比,固相清除率与DCDAC的加量成正比,塑性黏度与动切力随着DCDAC的增加呈现出先降低后增大的趋势,说明DCDAC对油基钻井液中的高岭土有良好的絮凝作用,可用于清除油基钻井液中的劣质固相。

Drilled cuttings of low quality have great influence on the properties of oil base drilling fluids and are difficult to remove because of their small particle sizes.Flocculants can be used to enlarge the particle sizes of the drilled cuttings through flocculation but are generally used in water base drilling fluid and seldomly are used in oil base drilling fluids.An oil base drilling fluid contaminated with kaolin as the poor-quality solids was studied for the flocculating performance of dihexadecyl dimethyl ammonium chloride(DCDAC)to flocculate kaolin.Observation of the contaminated and DCDAC treated oil base drilling fluid under stationary state,turbidity analysis and observation under microscope of the drilling fluid showed that DCDAC is able to accelerate the settling of kaolin particles;at 5%of DCDAC in the kaolin containing oil base drilling fluid,all the kaolin particles settled to the bottom in 48 hours.After kept stationary for 5 hours,the percent decrease of the turbidity of a kaolin suspension was nearly 80%.Observation under microscope of the drilling fluid showed that when the concentration of DCDAC in the oil base drilling fluid was greater than or equal to 4%,the kaolin particles showed obvious agglomeration behavior.It was also found in the laboratory experiment that the density and solids content of an oil base drilling fluid after centrifugation are inversely proportional to the concentration of DCDAC,while the percent removal of solids is in direct proportion to the concentration of DCDAC.With the increase of the concentration of DCDAC in the oil base drilling fluid,the plastic viscosity and yield point of the drilling fluid were first decreasing and then increasing.All these phenomena shown in laboratory experiment indicate that DCDAC has good flocculating capacity to kaolin in oil base drilling fluids,and can be used in removing low quality solids from oil base drilling fluids.