Abstract: Taking Permian and Triassic reservoirs in Junggar Basin as an example, this paper firstly points out the petrologic characteristics of low pressure, low permeability, low saturation and high gas content make the reservoir vulnerable to compaction, yet the porosity tends to get improved below 4000m. Secondly, this paper analyses the factors affecting porosity, and deems that organic acid denudation and oil cut are the main effect factors improving reservoir quality. Reservoir denudation is prevalent under SEM survey. Acidic leaching simulation experiment confirms the existence of denudation minerals, and proves that denudation has great potential for improving the quality of reservoir porosity. It probes into how reservoir porosity is affected by oil-bearing characteristics, and shows that the porosity of oil-bearing sandstone is obviously better than non oil-bearing sandstone on the same condition. Mass data analysis confirms oil cut could effectively control the growth of diagenetic authigenic minerals and reduce the content, and thereby maintain effective pore in deep-buried reservoir.

Key words: Junggar Basin, deep reservoir, organic fluid, denudation, oil cut