Abstract: A large amount of oil, gas and water resources are stored in the argillaceous siltstone, but its exploitation is always limited due to its low permeability condition and sand control difficulty. In this work, the sand control and gas production laws are analyzed by setting N2 displacement experiment under cut condition. After comparing the vertical grain grading curve of the displacement reservoir before and after the test, it is found that the grain grading curve before and after the test does not coincide, which indicates that after the test, the particles of the reservoir have migrated and rearranged, forming the structure of “mud skin + sand arch” which combines the fine particles and sand arch. It takes the stable sand arch as the support and its fine particle structure as the sand blocking structure to block the fine particles together with transport of granular materials. Through the scanning electron microscope, it is found that there are pinhole like pores in the fine-grained layer, which ensures the gas production without blocking. This work provides a reference for similar projects.

Key words: high water conten, displacement experiments, argillaceous siltstone, vertical stratification