Study On Water Locking Technology Of PW Low Permeability Gas Reservoir

Low permeability tight sandstone gas resource is rich, widely distributed,which is the key to the development of unconventional energy in China. Low permeability tight sandstone gas reservoir, however, because of its characteristics of low permeability reservoirs, are more vulnerable to water locking damage, damage degree is more serious.Based on PW low permeability tight gas reservoir as the research object, the characteristics of gas reservoir with low porosity, low permeability, reservoir density and clay content is higher, the fluid from the well of the absorbing water locking damage is serious, gas reservoir pressure attenuation too quickly to many wells, which lead the pressure too low to production, the production was severely affected. This paper combines the characteristics of the gas reservoir geology, reservoir water lock harm carried out by a detailed experimental study, theoretical analysis and simulation.(1)The core experiment is adopted to analyze the main influencing factor of the water lock and the water locking damage degree. Water locking damage degree intelligent prediction model is established base on the experiment, and the accuracy of the prediction is verified by the experiments.(2)Based on the gas reservoir damage characteristics, scope of water locking damage model is established to predict water invasion depth, and analyzes the water phase countercurrent imbibition law.(3)Combine the water locking damage range model, the water locking damage prediction model and the unstable capacity model together to create a complete water damage prediction system. Combined with gas reservoir single well geological data, comprehensive prediction the wells of the water lock range, the water saturation distribution, water locking damage degree and the pressure field distribution in the process of production, analysis the influence of water locking damage on gas well productivity.(4)In order to efficiently remove water lock damage, reduce the secondary water lock and restore the gas reservoir production capacity, the water lock system and acid system slug injection methods was proposed based on the feature of the gas reservoir damage. Performance evaluation on existing agents, and select the appropriate lift water lock system and acid system. Experiments prove that this method can remove water lock and reduce the secondary water lock effect, has a good application prospect.