FRACTURING LAYER SELECTION FOR VERTICAL WELL IN LACUSTRINE SHALE MATRIX RESERVOIR: A Case Study of SYY3 Well in Sanzhao Sag of Songliao Basin

The lacustrine shale matrix reservoir is the main carrier for shale oil in China, but it is more difficult for fracturing reformation and industrial development compared with interlayered and fractured reservoirs. Therefore, the selection of fracturing layers is of vital importance. Taking the SYY3 well in Sanzhao sag of Songliao Basin as an example, the paper establishes a set of fracturing layer selection method for vertical wells in lacustrine shale matrix reservoir. First, the Type Ⅰ shale oil reservoir in the 1st member of Qingshankou Formation in SYY3 well is optimized by well logging and interpretation data. Then 6 indicators including electrical property, physical property, oil-gas possibility, source rock lithology, brittleness and fracability of Type Ⅰ shale oil reservoir are comprehensively analyzed. Finally, the comprehensive ranking of Type Ⅰ shale oil reservoir is conducted by analytic hierarchy process based on the above 6 indicators, and Nos. 27, 25 and 23 layers are determined as the most favorable shale oil reservoirs. Fracturing and oil testing of the above shale oil reservoirs are performed in SYY3 well, which has achieved a breakthrough in the industrial oil flow of shale oil in Sanzhao sag. It is proved that the method is feasible and effective, and can be applied to the optimization of sweet spot layer and horizontal well deployment of lacustrine matrix shale oil.