Trace elements, δ13C, δl8O and 87Sr/86Sr of cave-filling giant crystalline calcites and fluid inclusion homogenization temperatures (HTs) were analyzed from each formation in the Eopalaeozoic carbonate reservoirs. Result shows that the giant crystalline calcite samples in different wells may have various fluid origins. The shared characters of giant crystalline calcites in well T417 (Yingshan Formation) , S76 (Yingshan Formation), T904 (Yijianfang Formation) and TS1 (Qiulitage Formation) are: U-rich, high V/Cr ratios and at least 20 °C higher than the ambient rocks. It reflects that there is a hot fluid in these wells and these fluids show high 87Sr/86Sr ratios and low δ18O values. The giant crystalline calcite samples in well T904 (Lianglitage Formation) are charactized by U-deplete, low V/Cr ratios and temperature(75 81 °C), which indicates a low temperature fluid. The characters of 87Sr/86Sr-rich and low δ18O values suggest that this low temperature fluid should be derived from meteoric water. The migration of the hot fluid and meteoric water is likely controlled by various elements : faults, cracks, and unconformity ,etc. So the giant crystalline calcites in different formations and wells may origin from various fluids.
|Number of pages||11|
|Journal||Scientia Geologica Sinica|
|Publication status||Published - Apr 2010|
- Fluid inclusion
- Giant crystalline calcites
- Tahe oilfield
- Trace elements