Fractal characteristics of bulkmudrock, washed, and kerogen samples of Chang 7 member mudrocks from the Ordos Basin, China
Fractal characteristics of bulkmudrock, washed, and kerogen samples of Chang 7 member mudrocks from the Ordos Basin, China
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鄂尔多斯盆地长7段泥岩大块泥岩、水洗样品和干酪根样品的分形特征
DOI：
10.1016/j.petrol.2018.07.004
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Liu Yan
中科院分区：
文献类型：
--
作者：
Han Hui;Liu Yan
通过低压氮气物理吸附实验，研究了鄂尔多斯盆地长7泥岩的大块泥岩、水洗泥岩和干酪根样品的分形特征。采用Frenkel-Halsey-Hill （FHH）法对吸附数据进行了分形维数D的计算。大块泥岩样品的D值略低于水洗样品，而干酪根样品的D值最低。结果表明，洗后样品表面较粗，干酪根样品表面较光滑。对于大块泥岩和水洗样品，D随总有机碳含量的增加而减小，说明有机质的分形维数低于泥岩中其他组分。D随游离油的增加而减小，表明分形维数可以近似表征湖相泥岩剩余油含量。对于大块泥岩和水洗样，分形维数与比表面积和孔隙体积呈正相关。然而，在干酪根样品中没有发现类似的趋势，说明低压氮气吸附实验得到的分形维数不能很好地描述干酪根样品的分形特征。分形维数随平均孔径的增大而减小，这是由于分形维数越高的试样孔隙越小，比表面积越大。
We performed low-pressure N2 physisorption experiments to investigate and compare the fractal characteristics of bulk-mudrock, washed, and kerogen samples of Chang 7 mudrocks from the Ordos Basin, China. Their fractal dimensions D were obtained from adsorption data using the Frenkel–Halsey–Hill (FHH) method. The D values for the bulk-mudrock samples were slightly lower than those of the washed samples, while the kerogen samples showed lowest values. The results suggest that the surfaces of the washed samples were rougher than the bulk-mudrock samples and that the kerogen samples had the smoothest surfaces. For the bulk-mudrock and washed samples, D decreased with increasing total organic carbon content, suggesting that organic matter has lower fractal dimension than other fractions in mudrocks. D decreased with increasing free oil, indicating that the fractal dimension can be used to characterize the residual oil content in lacustrine mudrocks approximately. For the bulk-mudrock and washed samples, there are positive trends between fractal dimension and surface area and pore volume. However, similar trends cannot been found in kerogen samples, indicating that the fractal dimensions obtained from low-pressure N2 adsorption experiments cannot describe the fractal characteristics of the kerogen samples well. The fractal dimension decreased with the increasing average pore diameter, which can be attributed to that the samples with higher fractal dimensions contained more small pores and had higher surface area.