采出水中核壳型荧光微球浓度的检测方法

Concentration Detection Method of Core-shell Type Fluorescent Microspheres in Extracted Water

聚合物微球调驱是改善水驱效果的主要技术之一。微球在地层中的运移以及能否在采出水中有效检出会直接影响调驱效果。因此,将荧光碳点引入微球调驱剂中,起到示踪的作用。荧光核壳微球调驱剂由含荧光碳点的核心微球溶液和壳层水溶液混合吸附而成。为了降低油水分离后采出水中的杂质对核壳荧光微球有效检出的干扰,首先对荧光微球的浓度与荧光强度进行线性拟合,验证该方法的可行性;然后用硅胶对地层采出水进行吸附,通过对比采出水吸附前后的荧光发射光谱,验证硅胶吸附的实用性;最后用硅胶对采出水配制的荧光微球进行吸附,绘制荧光强度和微球浓度的标准曲线。结果表明,在激发波长为347 nm的条件下,荧光微球的质量浓度与445 nm发射波长处的荧光强度具有良好的线性关系,相关判定系数(R^(2))为0.9870。经硅胶处理后,水驱采出水的荧光发射强度显著降低,硅胶吸附能有效去除采出水中的杂质。在激发波长为347 nm、荧光光谱仪狭缝为10~20 nm、微球质量浓度为1~1200 mg/L时,荧光核壳微球水分散液的质量浓度(x)与462 nm处的荧光发射峰值(y)呈正比线性关系,拟合方程为y=2497.1042+3.1847x,R^(2)为0.9972,置信度较高。荧光强度与核壳微球浓度的线性阶段可满足现场检测要求。该方法可为类似油藏荧光微球含量的定量检测提供借鉴。

Polymer microspheres drive conditioning are one of the main techniques to improve water drive effectiveness.The transportation in formation and effectively detection in extracted water of microspheres will directly affect the modulation drive.So the fluorescent carbon dots were introduced into the microsphere drive conditioner to play the role of tracer.The fluorescent core-shell microspheres drive conditioner formed from a mixture of core microsphere solution containing fluorescent carbon dots and shell layer aqueous solution.In order to reduce the interference of impurities in the extracted water after oil-water separation on the effective detection of core-shell fluorescent microspheres,the feasibility of the method was verified by firstly performing a linear fitting between the concentration of fluorescent microspheres and fluorescence intensity.Then the extracted water was adsorbed by silica gel.The practicability of silica gel adsorption was verified by comparing the fluorescence emission spectra of the extracted water before and after adsorption.Finally,the fluorescent microspheres prepared from the extracted water were adsorbed with silica gel,and then the standard curve of fluorescence intensity and microsphere concentration was plotted.The results showed that at the excitation wavelength of 347 nm,there was a good linear relationship between the mass concentration of fluorescent microspheres and the fluorescence intensity at the emission wavelength of 445 nm,with the correlation coefficient of determination(R^(2))of 0.9870.The fluorescence intensity of the water-driven extracted water was significantly reduced after silica gel treatment.The silica gel adsorption could effectively remove the impurities in extracted water.At the excitation wavelength of 347 nm,the fluorescence spectrometer slit of 10—20 nm,and the mass concentration of microspheres from 1 to 1200 mg/L,the mass concentration of fluorescent core-shell microspheres in aqueous dispersion(x)was positively and linearly related to the fluorescence emission peak at 462 nm(y).The fitted equation was y=2497.1042+3.1847x,with R^(2) of 0.9972,which had a high confidence level.The linear phase between the fluorescence intensity and the concentration of core-shell microspheres could meet the requirements of field detection.The method could provide a reference for the quantitative detection of fluorescent microsphere content in similar reservoirs.