Distribution characteristics and influencing factors of methane solubility in shale gas fracturing backflow fluid
Shale gas as a significant natural gas resource,relies heavily on technologies such as hydraulic fracturing for its successful commercial extraction.During the hydraulic fracturing process of shale gas,a large amount of backflow fluid is generated.The study of the solubility of methane in the fracturing backflow fluid and its influencing factors is of great significance for reducing costs and in-creasing efficiency,reducing greenhouse gas effects,and promoting green development of shale gas.This research refined the traditional method for measuring methane solubility according to the characteristics of fracturing backflow fluid.The improved volumetric method can continuously measure methane solubility at different pressures and temperatures without disrupting the dissolution equilibrium,and the stability of the experimental results is relatively high.Based on the improved volumetric method,the methane solubility of shale gas fracturing flowback fluid in Changning area of Sichuan Basin was determined.The methane solubility mainly ranged from 1.32 to 1.60 m3/m3,and it was estimated that 13 200 to 32 000 m3 per well of methane can be recovered through fracturing flowback fluid.Factors such as temperature,pressure,and mineralization have a significant impact on the methane solubility of shale gas fracturing flowback flu-id.Research showed that under low temperature conditions,the solubility of methane gradually decreases with increasing temperature,while at high temperatures,the solubility of methane increases with increasing temperature.The solubility of methane in the backflow fluid exhibits a characteristic of increasing with pressure,and shows a"two-stage"pattern of rapid increase in solubility in the low-pres-sure stage and slow increase in the high-pressure stage.The solubility of methane decreases slightly with the increase of mineralization degree in the flowback fluid.
NETL
NSTL
万方数据
