The Progress of Reservoir Geochemistry and its Application in Hydrocarbon Exploration: An Example From the Halahatang Oilfield of the Tarim Basin, NW China

Abstract

Reservoir geochemistry has been successfully applied to trace oil migration orientations, charging pathways and to predict the location of potential source kitchens and “satellite” reservoirs. The tracing indicators relative to carbazoles (CAs) and benzocarbazoles have been widely and successfully utilized in hydrocarbon exploration. More and more studies indicate that the sulfur and oxygen heterocyclic aromatic compounds such as dibenzothiophenes (DBTs), dibenzofurans (DBFs), benzonaphthothiophenes (BNTs) and benzonaphthofurans (BNFs) are effective geochemical molecular markers for tracing oil migration orientations and charging pathways. A series of new indicators relative to sulfur and oxygen heterocyclic aromatic compounds have been proposed and successfully applied in reservoir geochemistry. Compared to carbazoles and regular sterane and terpane biomarkers, sulfur and oxygen heterocyclic aromatic compounds are present in higher concentration and are thermodynamically stable in high mature oils and condensates. Therefore, they are applicable for high mature or even over-mature oils. The majority of hydrocarbons in the Halahatang Oilfield in the Tabei Uplift of the Tarim Basin (NW China) were discovered in the Ordovician marine carbonate reservoirs. Oils ranging from heavy oil to light oil with various physical properties occurred in this oilfield. The organic geochemistry study in the year of 2011 indicated that the discovered accumulations in the Halahatang Oilfield are mainly migrated and charged from the south to the north. It can be predicted that the oils in the Halahatang Oilfield should be sourced from the source kitchen, which was predicted to locate at the Manxi Low-uplift. The south part of the Halahatang region should be the most favorable prospecting zones, which have been proved by the hydrocarbon exploration discoveries afterwards and latest reservoir geochemistry study in the year of 2015. The filling points and preferential pathways indicated by isopleth maps of DBTs, DBFs, BNTs and BNFs parameters are in good agreement with oil reservoirs with high yields. It is concluded that the isopleth maps of geochemical parameters can be used not only to determine the oil migration orientations and predict the location of source kitchen, but also to predict the favorable charging pathways and prolific prospecting zones.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016