SOME INSIGHTS ON HYDROCARBON-BEARING FLUID INCLUSIONS IN CARBONATE RESERVOIRS: EVIDENCE FROM SYNTHETIC FLUID INCLUSIONS
All the synthetic hydrocarbon-bearing fluid inclusions were checked and analyzed by microscopy, micro-fluorescence and Fourier transform infrared spectroscopy. The results show that synthesized hydrocarbon-bearing fluid inclusions are very similar to natural ones in carbonate reservoirs. Experimental results give us some important insights as follows.
(1) Usually, homogenization temperatures of hydrocarbon-bearing fluid inclusions are lower than those of aqueous inclusions. Immiscibility of oil and water is the main reason for hydrocarbon-bearing inclusions and aqueous inclusions being distributed in different cracks.
(2) Rapid accumulation of oil and gas can be recorded by fluid inclusions as hydrocarbon-bearing inclusion can be formed in 15 days at temperatures and pressures similar to natural reservoirs.
(3) The growth of calcite was affected by oil, but was not terminated at any volume ratio of oil to water. That means the fluid inclusions can record whole history of oil accumulation. The proportion of hydrocarbon-bearing inclusions increases with volume ratio of oil to water, but decreases after the volume ratio of oil to water reaches 7:3.
This work was supported by the National Natural Science Foundation of China (No. 40902040, 41172111), the Excellent Young Scientist Foundation of Shandong Province, China (No. BS2012NJ014), the Basic Research Foundation of Central University (No. 10CX05004A), and by a Project of PetroChina Exploration and Development Institute, China (No. 2011Y-003).