Noble gas constraints on hydrocarbon accumulation and groundwater flow in the central area of Western Sichuan Basin

The noble gas concentrations and isotope ratios of seven natural gas samples from the central area of the Western Sichuan Basin were measured. The samples all have⁴⁰Ar/³⁶Ar ratios greater than the atmospheric values, and the³He/⁴He ratios (RIR _a ) are entirely consistent with the crustal radiogenic He values. The vertical variation of the calculated Ch₄/³⁶Ar ratios with depth clearly indicates that the CH₄ and³⁶Ar are intimately associated, indicating a common reservoir intermediate to the sampled reservoirs, where they are well mixed and stored together prior to entrapment into gas reservoirs. Meanwhile, the calculated CH₄/³⁶Ar ratios range between 8×10⁶ and 64×10⁶ very much greater than the CH₄/³⁶Ar values for pure water and 5 mol/L NaCl brine at low temperature and hydrostatic conditions, reflecting the presence of “excess” thermogenic CH₄ over that supplied by a CH₄-saturated groundwater at low temperature, and the excess CH₄ saturation and dissolution to be at depth greater than the sampled reservoirs. This conclusion is consistent with the δ¹³C(CH₄) and δ¹³C(C₂H₆) values. In addition, the⁴He/³⁶Ar ratio is correlated with depth, showing that the crustal radiogenic⁴He are well mixed with the atomosphere-derived³⁶Ar before introducing into gas reservoirs. The⁴He/³⁶Ar ratio vertical variation with depth can be attributed to the preferential transport of⁴He relative to³⁶Ar in fluxes from lower aquifers through water-filled pores into the upper one. The increasing⁴He/⁴⁰Ar ratios with decreasing depth, from 1.3 times to 29 times greater than the crustal production ratio, are also assumed to be the results of preferential transport⁴He relative to⁴⁰Ar from the production site into groundwater.

     

新型高吸湿性改性粘胶纤维基本性能研究

探讨一种新型高吸湿性粘胶纤维(布拉门特纤维)的基本性能。对该纤维的外观形态、拉伸性以及吸放湿性等基本性能进行了初步研究,并与普通粘胶纤维进行了对比。结果表明:布拉门特纤维为片段式中空粘胶纤维;与普通粘胶纤维相比,该纤维断裂强度小,断裂伸长大,初始模量较小,回潮率大,具有更好的保水性。认为布拉门特纤维具有良好的吸湿保水性能,与其他纤维混纺可以改善织物的吸湿性,可用于高吸湿保水卫生产品的生产。