Abstract:

Shenglihe oil shales orientating in NWW-SEE with about 30 kilometers in length are located in the transitional belt between north Qiangtang basin and central uplift belt. The oil shales deposited in Upper Jurassic-Lower Cretaceous marine carbonates and are overlain by tremendous gypsum-salt strata. There are 3 to 7 oil shale layers ranging from 0.4 to 1.2 m in thickness, of which the thinnest layer is 0.1 m and the thickest layer is 3.27 m. The results of industrial analysis show that Shenglihe oil shales are a kind of low content of ash, medium to low oil yield and low calorific value. Organic carbon content of oil shales ranges from 4.31% to 21.37% with an average of 9.76%, indicating a relatively high abundance. Hydrocarbon generating capability ranges from 5.66 mg/g to 111.1mg/g with an average of 40.17 mg/g and they show a good potentiality. Microscopic observations indicate that organic matter of oil shales is a kind of mixed-type kerogen. Vitrinite reflectance of kerogen range from 0.37% to 0.9% with an average of 0.58%, indicating that organic matter of oil shales was underwent a stage of immature to low maturation. Under the condition of stable tectonics and humid-hot climate the oil shales were deposited in a saline lagoon of restricted carbonate platform with reducing condition. After that stage the climate evolved into hot-dry conditions.

Key words: oil shale, Upper Jurassic-Lower Cretaceous, oil yield, Lagoon, restricted platform, Qiangtang basin, petroleum geology