Geotemperature evolution of the Ordovician strata in the Tarim Basin and its petroleum geology significance

摘要

The Tarim basin is an important petroleum basin in China, which produces a large amount of oil and gas resources. This paper calculates the geotemperature of the middle-upper Ordovician basal boundary during the main geological periods using the one-dimensional steady-state heat conduction equation. The simulation result reveals that from the late Ordovician to the present, the Manjiaer sag in the Tabei depression retains the highest temperature in the Tarim basin, and its highest temperature reaches 400°C in the present, while other areas in the Tarim basin have undergone relatively low temperature. Only in the Manjiaer sag of the Tabei depression and the Yecheng and Tanggubasi sags in the Southwest depression, the temperature exceeds 250°C, reaching the condition of liquid oil cracking into gas. Geo temperature of the middle-upper Ordovician basal boundary in the Tahe oilfield of the Central uplift is lower than 250°C. It is thus inferred that there are abundant oil resources in the Ordovician strata of the Tahe oilfield. This study may provide effective geo temperature data for the next petroleum exploration in the Tarim basin.