A DISCUSSION ON WELL LOGGING INTERPRETATION METHOD: A CASE FROM PALEOGENE WENGCHANG AND ENPING FORMATIONS IN THE HUIZHOU DEPRESSION

The Paleogene dark mudstone in the Wengchang and Enping Formations is not only a source rock, but also a cover layer for oil accumulation. It usually shows complete gas logging composition of higher content comparing to adjacent reservoirs, and always brings great trouble to the fluid evaluation. Conventional interpretation methods are not effective enough to distinguish the fluid properties. In this study, a regional interpretation chart for calculating total hydrocarbon-fluid types is built upon the characteristics of the FLAIR components for different fluid types, combined with sampling and testing data. There is certain limitation to distinguish oil from oil-bearing water. According to the gas chromatogram data for geochemical rock pyrolysis analysis for 93 samples from 7 wells in the depression, the characteristics are summarized in this paper for oil layers, oil-bearing water layers, water layers and dry layers respectively. To integrate the two logging interpretation methods based on different data carriers, reservoir fluid properties of the Paleogene can be accurately evaluated. The consistency of comprehensive logging interpretation method may reach 88.5%.