MODELING PARTICLE MOBILIZATION IN UNCONSOLIDATED FORMATIONS DUE TO FLUID INJECTION

High injection rate in water injectors leads to mobilization of particles in unconsolidated formations and creates preferential flow paths within the porous medium. Channelization in porous medium occurs when fluid-induced stresses becomelocally larger than a critical threshold (rock stress); grains are then dislodged and carried away, hence porosity and permeability ofthe medium will be altered along the induced flow paths. Additionally, rapid shut-ins result in pressure imbalance between thewellbore and formation. Flowback of the particles results in sand accumulation, and consequently loss of injectivity, which is acommon problem in unconsolidated formations like the ones in deep water Gulf of Mexico. However, experimental studies haveconfirmed the presence of dependent and independent flow patterns, there is no integrated model to describe flow patterns andpredict probable issues for water injection at the reservoir scale. Objective of this study is to provide a model forinitiation/propagation channel during injection and flowback in injection wells. A finite volume model is developed based onmultiphase fraction volume concept that decomposes porosity into mobile and immobile phases where these phases changespatially and evolve over time that leads to development of erosional channels in radial patterns depending on injection rates,viscosity, magnitude of in situ stresses and rock properties. The model accounts for both particle releasing and the suspensiondeposition. The developed model explains injectivity change with injection rates observed in unconsolidated reservoirs