Main controlling factors and enrichment model of a multi-layer tight sandstone gas reservoir: case study from the Linxing Gas Field, eastern Ordos Basin, Northern China

Determining the main controlling factors and the enrichment model of a tight sandstone gas (TSG) accumulation remains a key challenge in natural gas exploration. The characteristics and main controlling factors of a TSG reservoir were determined, and multi-part enrichment models were observed in the Linxing gas field. The main lithology of the gas-producing layers is medium- to coarse-grained lithic arkose sandstone with an average porosity of 10.11% and median permeability of 0.81 × 10 −3 μm 2 . The TSG reservoir comprises two sub-types: a lenticular lithological reservoir and a lithological-fault reservoir; these show vertically superimposed and laterally continuous quasi-continuous distribution. This enrichment of the multi-layer TSG is controlled by the reservoir, gas source, fault, and structural high point that respectively possesses distribution laws of “high-quality reservoir enrichment,” “sufficient gas source supply,” “moderate fault efficiency,” and “favorable local high point.” As the enrichment factors of natural gas are markedly different at various layers and areas, the enrichment models can be categorized into three groups that represent different areas: (1) X area: Excellent reservoir, highly efficient fault system, near-source gas-rich model; (2) Y area: Excellent reservoir, favorable high point, in- and adjacent-source gas-rich model; (3) Z area: Moderately good reservoir, over-developed fault system, gas-poor model, distributed around the Zijinshan Structural Belt. The findings of this study are expected to provide a theoretical basis for expanding the enrichment model theory of TSG and aid in locating TSG reservoirs in multi-layer exploration target settings.