一柴西南尕斯地区不同期次油气充注对现今油藏的贡献

摘要

The Gasi E3 1 Oilfield, Southwestern Qaidam Basin, is an important petroleum exploration region in the basin. The hydrocarbon charge history of the Gasi Oilfield in the Qaidam Basin, Western China was investigated using a suite of fluid in-clusion techniques, including fluid inclusion petrography, fluorescence spectroscopy, FT-IR spectroscopy and microthermom-etry. The study was facilitated by a detailed reservoir diagenesis investigation using optical microscopy, cathodeluminescence microscopy, SEM and XRD. The results show that the reservoir fluids evolved from alkali to acidic, and then alkalic. There were two episodes of oil charge in N1 ~ N2 2 , as reflected by three types of hydrocarbon inclusions, occurring around 28 Ma and 8 Ma, respectively. The current accumulations in the oilfield are of similar maturity and API gravity with the current oil accumulation derived from upward migration of palaeo-oil reservoirs in the depth.%尕斯库勒第三系油藏是柴达木盆地西南部(柴西南)的主力油藏。从储层成岩序列、流体包裹体等方面分析研究区油气充注期次，并通过荧光光谱和傅里叶红外光谱技术、定量荧光及原油特征等分析柴西南地区储层原油和包裹体的光谱特征及参数，探讨不同期次油气充注对现今油藏形成的贡献程度。结果表明：尕斯E31储层经历碱性—酸性—碱性—弱酸性—碱性的流体演化过程，并发育早期黄色荧光气液烃包裹体和后期蓝色荧光气液烃及伴生气烃包裹体，代表该区经历了28 Ma和8 Ma两期油气成藏阶段；尕斯E31油藏是在古油藏布局的基础上沿后期构造产生的断层输导体系向上调整而形成，是柴西地区油气早成藏，晚期调整，并较好保存的典型代表。