SEISMIC METHOD FOR SHALE OIL SWEET SPOT PREDICTION IN QINGSHANKOU FORMATION OF SANZHAO SAG, SONGLIAO BASIN

The oil and gas resources are abundant in the shale of the first member of Qingshankou Formation in Sanzhao Sag, Songliao Basin. To identify the distribution of shale oil sweet spots in the area and guide the deployment of parameter well, the paper studies the sweet spot prediction method based on the logging evaluation of key parameters of single well sweet spot, 3D seismic data and well-seismic combination. First, the cross plot analysis of logging data and core experimental analysis data is used to establish logging evaluation model of lithology, physical properties (porosity and permeability), oil-bearing property(saturation), organic geochemical parameters(TOC and S₁), formation pore pressure and compressibility; Then the broadband constrained inversion technology is applied to predict lithology, the prestack elastic parameter inversion to predict physical properties, oil-bearing property and compressibility, and combination of constrained Dix formula inversion and model constrained wave impedance inversion technology to predict formation pressure; Finally, a set of seismic sweet spot identification technology process suitable for the shale oil of Qingshankou Formation in Songliao Basin is established to realize the double sweet spots prediction of geological and engineering sweet spots. The practice shows that the 3D seismic data can effectively predict shale sweet spots, and the actual drilling results are basically consistent with pre-drilling prediction, which proves the effectiveness of technical process.