Source, oil charging history and filling pathways of the Ordovician carbonate reservoir in the Halahatang Oilfield, Tarim Basin, NW China

摘要

The Ordovician reservoir in the Halahatang Depression is one of the most commercially prolific oil reservoirs in the Tabei Uplift of the Tarim Basin, NW China. For this study, a total of 94 oil samples were collected from 88 exploration/production wells in this oilfield. All of the oils possess similar organic molecular compositions and belong to the same oil population. Oil-to-source correlation results indicate that oil accumulations discovered in Halahatang Oilfield were derived from the Upper Ordovician source rocks. The homogenization temperatures of fluid inclusion in the Ordovician reservoir in the Halahatang Oilfield range from 90 degrees C to 100 degrees C and from 140 degrees C to 160 degrees C. The bimodal distribution pattern shown in a histogram of the homogenization temperatures indicates that the Ordovician oil reservoir in the Halahatang Oilfield has been charged twice. Coupling this information with the reconstructed burial and geothermal histories by 1-D basin modeling, the homogenization temperatures can be related to the relative geological ages of 419 Ma to 410 Ma and 16 Ma to 8 Ma, namely, the Middle to Late Silurian and the Middle Miocene respectively, representing the two phases of oil charging and entrapment.