密度对油基钻井液性能的影响

Effect of Density on the Performance of Oil Base Drilling Fluids

随着高密度油基钻井液被使用的越来越多,高密度时油基钻井液表现出的性能不稳定也逐渐被现场工程师发现。研究了密度对油基钻井液性能的影响,以及不同密度下温度、剪切时间、油水比、有机土、CaCl2浓度和劣质固相对油基钻井液性能的影响。研究结果表明,重晶石能增加油基钻井液的黏度和切力,提高钻井液的乳化稳定性;油基钻井液的破乳电压和重晶石的加入量呈线性关系;在高密度时,油基钻井液的表观黏度受温度、油水比、有机土和劣质固相的影响程度比低密度时大;破乳电压在高密度时受油水比、CaCl2浓度和有机土的影响比低密度时大。综上可知,密度的增加不仅单独对油基钻井液性能造成影响,还提高了油基钻井液对其它因素的敏感性。因此在使用高密度油基钻井液时,要加强对现场钻井液性能的监控和调节。

In field use of high density oil base drilling fluids, it was found that the properties of the oil base drilling fluids become unstable with increase in mud density. Laboratory study shows that addition of barite increases the viscosity and gel strength, and enhances the emulsion stability of oil base drilling fluids. There is a linear relationship between the electric stability potential and the concentration of barite. An oil base drilling fluid, when at higher densities, has an apparent viscosity that is affected by temperature, oil/ water ratio, concentrations of organophilic clay and poor quality solids to a larger extent than when it is at lower densities. Also, an oil base drilling fluid, when at higher densities, has an electric stability potential that is affected by oil/water ratio, concentrations of CaCl2 and organophilic clay to a larger extent than when it is at lower densities. Summarization of laboratory studies shows that increase in the density of an oil base drilling fluid not only affects the properties of the drilling fluid, it also increases the sensibility of the fluid to other factors. Thus, when using high density oil base drilling fluids, the monitoring and adjustment of the properties of the drilling fluids should be strengthened.