The Characteristics, Genetics and Potential Resources of Oil Shale in Dalianhe Mining Area of Yilan, Heilongjiang Province in China

摘要

In order to explore and exploit oil shale located at Dalianhe Mining Area of Yilan, Heilongjiang Province, a study was conducted to evaluate the characteristics, genetics and potential of the oil shale resource based on regional geology, geochemistry, palaeontology and geophysics works. The distribution of oil shale, its kerogen type and maturity, sedimentary environment and geochemical characteristics have been examined through sequence stratigraphy, sedimentary system analysis, biogeochemistry and geochemistry. These studies identify two oil shale layers in the Dalianhe group that are composed of sandy shale, oil shale, coal-bearing and glutenite segments. Biogeochemistry result shows good source rocks bedded in the middle and lower coal-bearing section in the premature and mature stages. The organic matter in the oil shale layers of the oil shale segment are primarily type Ⅱ1 and Ⅱ2 from a fresh to brackish deep lacustrine depositional environment, and the middle and lower parts of the oil shale among the coal bedding segment have higher organic abundance and mainly type Ⅰ and Ⅱ kerogen in dysoxic and reduced fresh lake and marsh depositional environment. The rare earth elements (REEs) have similar distribution patterns in the different layers and are relatively rich in light REEs but lean in heavy REEs and no REEs are present at a high enough concentration to reach minimum mining grade. Eu is in negative anomaly and 5Ce indistinctive anomaly with the criterion of chondrite. Oil shale in the coal-bearing segment can be utilized to extract oil, while the layers in the oil shale segment are fit for apyrous clay or kaoline material preparation. This study confirms that the global cooldown climate during the Eocene appeared in this area and we report that there was a large paleoclimate fluctuation in the depositional stage of the oil shale segment, affecting oil generating potential in those oil shales. The results show two types of oil shale accumulation in a faulted basin, builds two mineralization patterns, summarises the regularity and evaluates the resource potential comprehensively, amounting to 456 million tons of oil shale and 29 million tons of potential shale oil. A favorable place for prospecting is adjacent to the study area to the southwest in the Shahezi Area.