Developmental characteristics, influencing factors and prediction of fractures for a tight gas sandstone in a gentle structural area of the Ordos Basin, China

Abstract

The study of fracture development characteristics of tight gas sandstone reservoirs in the gentle structural areas of the Ordos Basin has been a research hot spot in recent years. However, there remains a lack of systematic research in this field. In this paper, we conducted a systematic study of the developmental characteristics, influencing factors and prediction of fractures for the tight gas sandstone in the Lower Permian He 8 Member in the Sulige gas field. The results show that the development degree of the fractures in the He 8 Member is mainly concentrated between 1 and 2 m−1. Meanwhile, the degree of fracture development is positively correlated with the cumulative sand body thickness, porosity and permeability and that it has no obvious correlation with gas saturation. Moreover, the degree of fracture development is positively correlated with the energy storage coefficient (Esc), indicating that the enrichment of natural gas in the tight gas sandstone reservoir of the He 8 Member is obviously affected by the fractures. The fracture index U is constructed by the finite element method and has a positive power exponential correlation with the fracture linear density. Finally, the fracture index was divided into three grades according to its coupling relationship with the gas well productivity.