摘要
以普光气藏普光2、6井为研究对象,取其长兴—飞仙关组116个白云岩样品,分析C、O同位素及微量元素特征,判断古海水盐度,并与沉积特征相结合,研究其沉积环境。分析得δ13C与盐度Z呈正相关关系。普光2井飞仙关组一段、二段—飞仙关组三段,盐度及δ13C、Sr、P、Ti、Mn值呈逐渐增大的趋势,沉积相经边缘浅滩—潮坪的演化进程。飞仙关组一段、二段时期,其δ13C及Sr、P、Ti、Mn值较低、δ13C波动小,反映海平面变化不大,且遭到淡水的冲淋,导致盐度降低;飞仙关组三段时期,处于潮坪环境,气候干燥炎热,淡水不断地被大量蒸发,其结果导致盐度增大,δ13C及Sr、P、Ti、Mn值增高,在此期间海平面变化较明显,造成δ13C波动较大。碳同位素值在长兴组末期发生突降,其原因可能是在二叠纪末,大量狭盐生物死亡而造成的。
With Wells Puguang 2 and 6 in the Puguang gas field as the research object, the authors used 116 dolomite samples from Changxing-Feixianguan Formation to analyze characteristics of carbonate and oxygen isotopes, judge the ancient seawater salinity and, combined with sedimentary characteristics, study the sedimentary environment. The result shows that δ13C and salt Z is positively correlated with each other. From Member 1 and 2 through Member 3 to Member 4 of Feixiangaun Formation in Well Puguang 2, sedimentary facies experienced the evolutionary process of platform edge shallow facies-restricted platform-evaporate fiat, and the salinity, δ13C, Sr, P, Ti and Mn values gradually decreased. During the period of Member 1 and 2 of Feixiangaun Formation,δ13C, St, P, Ti and Mn values were low and the fluctuation was not obvious, suggesting that the variation of the sea level was insignificant. In addition, the elution of fresh water caused the devrease of the salinity. The period of Member 3 of Deixiangaun Formation was in a tidal flat environment with dry and hot climate, during which the fresh water was considerably evaporated, the salinity increased, the δ13C, Sr, P, Ti and Mn values increased, the sea level change was obvious and, as a result, the δ13C fluctuation was remarkable.The carbon isotope values decreased abruptly at the last stage of the Changxing Formation, which is probably attributed to the death of large quantities of stenohaline organisms at the end of Permian.
出处
《地球学报》
EI
CAS
CSCD
北大核心
2009年第1期103-110,共8页
Acta Geoscientica Sinica
基金
中国石油化工股份有限公司项目(编号:G0800-06-ZS-138)资助。
关键词
普光气藏
长兴-飞仙关组
碳酸盐岩
碳同位素
氧同位素
微量元素
古环境
Puguang gas field
Changxing-Feixianguan Formation
carbonate rocks： carbon isotopic
oxygen iso- topic
trace elemet
paleo-envionmen
