Experimental investigation on permeability evolution law during sand production process of weak sandstone

Sand production is a crucial engineering problem in the process of reservoir development. In this work, a self-developed experimental platform was established as a reliable technique to study the permeability evolution law during sand production process. The core used in experiment was from Kingfisher (KF) oilfield, which is a typical weak sandstone reservoir. The pressure differences across the core were recorded continuously to further detail analysis. In the water injection process weak sandstone reservoirs, the permeability of weak sandstones is no longer constant, but belongs to nonlinear seepage due to the transport of rock particles. However, the traditional Darcy's law can not describe the nonlinear seepage, so a new concept of 'transient permeability' was presented to describe the nonlinear seepage of sand production process at first. Meanwhile, based on the new concept of 'transient permeability', we further proposed two new concepts of 'relative prevailing index' and 'stability index' for quantitative characterization the dynamic evolution process of sand production. A lot of data was got during the experiments, six typical stages have been screen out by careful data analysis, which can be well described the whole dynamic evolution process of sand production.