**3. Materials and Methods**

The logging data used in this study were collected from five wells in the Xihu Sag, East China Sea basin, including three water-based mud wells and two oil-based mud wells (Table 3). The oil-based mud wells and water-based mud wells in the study area are measured by *T*<sup>2</sup> spectrum with the MREx nuclear magnetic resonance logging tool developed by Baker Hughes company, and the echo space is 0.6 ms. The maximum radial detection radius of the instrument is approximately 11.43 cm, which primarily detects the hydrogen signal of the fluid in the formation invasion zone. In addition, rock cast thin section image data and 29 rocks used for NMR experiments were obtained from these wells, and the data were provided by CNOOC Shanghai Branch.


**Table 3.** Summary of the wells logging information.

<sup>1</sup> 3 combo includes gamma-ray, density-neutron, resistivity.
