Influence factors | Impact mechanism | |
Macro factors | Rock type | The adsorption capacity of shale and silty mudstone is relatively high, while that of fine siltstone and limestone is relatively low; Siliceous shale and carbonaceous shale are conducive to the occurrence of shale gas. |
Temperature and pressure | With the increase of formation temperature, the gas content decreases; As the formation pressure increases, the gas content increases. When the pressure increases to a certain extent, the gas content increases slowly. | |
Construction conditions | Positive structure and overpressure are conducive to shale gas enrichment. | |
Micro factors | Total organic carbon content | The higher the organic carbon content, the greater the hydrocarbon generation potential and the higher the shale gas content. |
Kerogen type | Type I kerogen contributes less to shale gas content, while type II and type III kerogen are favorable gas sources and contribute more to gas content. | |
Maturity of organic matter | At the initial stage of gas generation, the higher the maturity of organic matter is, the more conducive to the increase of gas content; In the later stage, the gas content has a downward trend with the increase of maturity. | |
Clay mineral | The high content of clay minerals is conducive to shale gas adsorption, but not conducive to fracture development. | |
Porosity | The larger the pore specific surface area and total pore volume, the greater the content of adsorbed gas; The size of effective pore determines the content of free gas; The influence of fractures on gas content has two sides. | |
Water content | The higher the water content, the lower the gas storage capacity and storage space, and the smaller the gas content. |