Application of nuclear magnetic resonance logging in Shengli shale oil reservoir

The mineral composition of shale oil reservoirs in Jiyang Depression of Bohai Bay Basin, East China, is complex, the storage space is fine and tiny, and conventional logging  methods have poor applicability. Therefore, nuclear magnetic resonance logging, which can directly obtain pore information, has been widely applied in the Shengli Jiyang shale oil reservoirs. By systematically analyzing the one-dimensional and two-dimensional nuclear magnetic resonance logging data of shale oil wells in Shengli Oilfield, combined with asymmetric Gaussian function fitting technology and clustering analysis methods, the corresponding T2 cut-off values and T1/T2 value range limits for different fluid types were respectively determined. The results indicate that the pore fluid classification results of two-dimensional nuclear magnetic resonance logging are more detailed, and the movable fluid is located in the upper right corner of the spectrum, corresponding to T1/T2 values of 3 to 20. Using this model to calculate effective porosity and movable oil porosity. By comparing the tracer results, it indicates that the effective porosity of the high-yield well sections of the actual production wells was 6% to 13%, and the movable oil porosity was 2% to 6%. In other well sections, the effective porosity was less than 6%, and the movable oil porosity was less than 2%. Based on this as the main basis, the evaluation criteria for sweet spots in Shengli shale oil were established, and the shale sweet spot level was divided.