FY oilfield belongs to an ultra-low permeability oilfield, with complex geological structures, poor reservoir properties, incomplete injection and production, prominent planar contradictions, and failure to form effective displacement, which easily leads to the formation of residual oil enrichment areas. In order to further enrich the efficient transformation technology sequence of difficult to recover reserves in FY oilfield, two on-site tests of segmented fracturing of sidetracking horizontal well were carried out. During the experiment, by optimizing the wellbore trajectory, drilling fluid formula, segmented fracturing technology and tools, and innovating the use of self expanding packers, the problems of wellbore necking collapse and inability to insert segmented fracturing columns were solved, achieving two-stage fracturing in the open hole. At the initial stage of the test well, the daily oil increase was 4.0 tons, and it is predicted that the final cumulative oil increase will be 1588 tons. Good production increase and economic benefits have been achieved, achieving directional tapping of remaining oil in ultra-low permeability reservoirs.