Quantitative Fluorescence Techniques for Investigating Hydrocarbon Charge History in Carbonate Reservoirs

Abstract

The quantitative grain fluorescence (QGF) and quantitative grain fluorescence on extract (QGF-E) have been becoming effective approaches in the analysis of hydrocarbon evolution in clastic reservoirs recently. The cut-off threshold for differentiating current/paleo-oil and water zones is crucial to reconstruct accurately hydrocarbon accumulation history. However, the absence of theoretical study on the cut-off threshold in the carbonate reservoir has precluded their application and development. In this study, we attempted to investigate the cut-off threshold by analyzing the QGF and QGF-E parameters and spectra of the cores and natural carbonate outcrop samples in known current/paleo-oil and water zones revealed by the frequency of oil inclusions (FOI), formation test and logging analysis. Based on this, the hydrocarbon charging history of the Suqiao Buried-hill Zone, Bohai Bay Basin, eastern China was reconstructed using the gotten threshold. Results show that the carbonate minerals fluorescing will lead to a higher cut-off threshold of QGF Index value in the carbonate reservoir, while the threshold of QGF-E Intensity value is coincident with the corresponding value in the clastic reservoir. The QGF and QGF-E data have unraveled a complicated reservoir accumulation history in Suqiao Buried-hill Zone including oil charging before gas and paleo-oil loss due to the tectonism. The ascertained cut-off threshold in this study is of great significance for reconstructing accurately and effectively the complicated hydrocarbon charging history in the carbonate reservoir, which provides significant models for future petroleum exploration.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018