Difference Characteristics between Continental Shale Oil and Tight Oil and Exploration Practice: A Case from Huanghua Depression, Bohai Bay Basin

Both terrestrial tight oil and shale oil belong to low-porosity and low-permeability oil and gas reservoirs. They have great similarities and often have symbiotic relationships. However, their accumulation mechanism and dessert evaluation methods are quite different. In this paper, it uses systematic coring, logging and various tests and analysis data to synthesize the previous research results, and comprehensively discusses the differences between tight oil and shale oil accumulation conditions and enrichment rules, and further discusses the difference exploration directions between tight oil and shale oil. Studies indicate lithology differences. The types of tight oil and gas reservoirs are diverse, including tight sandstones, dense carbonate rocks, dense igneous rocks, etc.; shale oil and gas is mainly composed of fine-grained sediment rocks, which is reflected in the diversity of mineral components and is divided into carbonate shale, and can be divided into felsic shale, clay shale, mixed shale, etc.. In addition, property differences are also found. Both belong to tight reservoirs, which mainly develop intergranular pores, intercrystalline pores, dissolved pores, cracks, etc., mostly in micron pores. Shale oil reservoir is dominated by the original tight reservoir which is characterized by the development of organic pores, intergranular pores, interlayer cracks, etc., mostly based on nano-scale pores. Furthermore, accumulation condition differences are disclosed in the study. Both oil and gas sources are closely related to high-quality source rock, tight oil and gas reservoirs themselves do not produce hydrocarbons, the crude oil relies on the source-storage pressure difference caused by the kerogenization of organic-rich mud shale, and undergoes short-distance migration, compared with charging, the source and storage pressure difference is high, and the filling degree is high; shale oil itself is the oil-bearing layer system, which is the oil and gas that has been generated, has not been discharged, and is retained in the shale pores or cracks. Lastly, brittleness differences are revealed in the study, tight oil reservoir has good brittleness, shale brittleness is different due to the different composition, which is the key factor for the evaluation of shale oil dessert. Exploration constituency, tight oil dominant reservoir facies belt, high-quality source rock and the matching relationship between them are favorable for dense oil enrichment area, "sandwich" interlayer is the most favorable type; shale oil is controlled by the rock mature and rich in organic matter, and rock of brittle facies, which emphasizes the search for shale oil with higher brittleness in the enriched hydrocarbons.