Sensitivity Analysis of Rock Electrical Influencing Factors of Natural Gas Hydrate Reservoir in Permafrost Region of Qilian Mountain, China

It has been found that the relatively low abundance of gas hydrate in the Muli area of the Qilian Mountain causes gas hydrate reservoirs to have low-resistivity characteristics similar to those of low-resistivity oil and gas reservoirs. Therefore, it has great significance to research the main controlling factors affecting the electrical properties, and then come up a new logging identification and evaluation model for low-resistivity gas hydrate reservoirs. In this investigation, the rock samples of sandstone from gas hydrate reservoirs were scanned by CT and combined with gas hydrate distribution characteristics. The three-dimensional digital rocks with different hydrate saturation were constructed using the diffusion limited aggregation (DLA) model, and the resistivity was simulated via the finite element method. After sorting out the influencing factors of electrical characteristics, the sensitivity of the factors affecting electrical properties was evaluated using orthogonal analysis, using variance analysis and trend analysis to quantitatively evaluate the influencing factors of rock electrical sensitivity, so as to distinguish the main and secondary factors affecting rock electrical sensitivity. The results show that the sensitivity of rock electrical properties to the six influencing factors from strong to weak are: formation water salinity, water film thickness, shale content, conductive mineral content, micropores, and average coordination number.