Occurrence and controls of shale absorbed gas in Liupanshan Basin

The Liupanshan Basin has potentially favorable conditions for oil and gas exploration. An absorbed gas model and other methods were used to study the mud shale in the Cretaceous Madongshan Formation in the well GY 1 in the Liupanshan Basin in order to discuss the occurrence and controls of the shale absorbed gas. The Cretaceous shale in the basin has a relatively low content of organic matter, but the maximum methane adsorption capacity ranges from 1.73 to 2.35 m³/t with a mean value of 2.03 m³/t indicating a relatively high gas storage capacity. The adsorption capacity of the shale increases first and then decreases with increasing depth. There is a deep inflection point. Pressure plays a major role in shallow formations, while temperature plays a major role at depth. The occurrence conditions of shale absorbed gas were mainly affected by six factors, among which the influence of organic matter abundance, maturity and moisture content were not significant, while mineral content, microscopic properties, temperature and pressure were the main influencing factors. When the external geological conditions are suitable, the gas enrichment degree of the shale reservoir in the Liupanshan Basin could be relatively high and very favorable for exploration.