Numerical simulation of plastic compaction packing outside casing in horizontal wells in unconsolidated sandstone reservoirs

Key words:  horizontal wells  unconsolidated sandstone reservoir  outside casing gravel packing  plastic compaction packing  numerical simulation

Abstract:

For the gravel packing outside-casing in horizontal wells, the region near the wellbore can be divided into three sections, in terms of rock mechanics, namely elastic deformation, plastic compaction and gravel pack. A systematic model for high pressure plastic compaction packing was developed to predict packing area size around horizontal wells in unconsolidated sandstone reservoirs, which was based on Mohr-Coulomb rock failure law and axial symmetry plane strain theory. The numerical simulation results show that, due to the formation heterogeneity and variations of rock properties, the size and profile of the plastic compaction packing area changes greatly along the wellbore trajectory. The radius of compacting failure area increases with the rock strength decreasing. High bottomhole injection pressure can induce more serious rock failure than that of low injection pressure. As the injection pressure increases, the effect of the Poisson ratio on extension ratio of the packing can be ignored, but the influence of other factors, such as internal fraction angel,cohesive strength and elastic modulus, needs to be considered.