ANALYSIS ON THE HETEROGENEITY AND GENESIS OF CRUDE OIL IN THE CLASTIC ROCK RESERVOIRS OF XINZHAN OILFILED, THE SONGLIAO BASIN

Some abroad cases showed that the analysis of fluid composition heterogeneity in reservoirs was an important tool to estimate reservoir connectivity. There is obvious heterogeneity of terrestrial clastic reservoirs in the petroleum-bearing basins of China, so that the variety of petroleum composition in reservoirs is more complication and diversification. This paper analyzed the heterogeneity and distribution features of group composition, saturated hydrocarbon components and biomarker composition in the crude oil of reservoirs in Xinzhan oilfield of the Songliao Basin. The geological and/or geochemical factors, such as petroleum sources, oil migration, reservoir rock lithology, geochemical changes of crude oil in reservoirs and reservoir connectivity, which affect heterogeneity and mixed actions of petroleum in reservoirs, had also been discussed. The results showed that the factors affecting fluid composition heterogeneity are very complex, and the reservoir connectivity can not been estimated easily only according to the fluid heterogeneity in reservoirs. It is important to divide oil populations and families and to study various factors affecting petroleum composition before to estimate reservoir connectivity.