A New Thermodynamic-Hydrodynamic Model for Prediction of Downhole Corrosion in Oil Wells Based on Multiphase Flow Simulation

Abstract

Abstract The findings of one downhole corrosion study for one oil field, to envisage reasons of downhole corrosion failures, and to recommend corrosion control procedures standing on an economical feasibility study are presented. The prevalent corrosion mechanisms are erosion corrosion due to excessive multiphase flow velocity of the produced fluids, under slug / transitional to annular flow regime, impingement corrosion in tubings at locations where flow changes direction, carbon dioxide sweet localized pitting corrosion (mesa), and ringworm corrosion at the upset of the tubings. Results of assessment models reflected a moderate corrosivity, that would not alone cause such severe corrosion failures, unless augmented by other influential factors as the hydrodynamics of production, and the geometry of the well. This study has developed one new realistic downhole corrosion predictive model to assess risks of downhole corrosion based on the correlation of the thermodynamic production conditions, and the chemical properties of the produced fluids to both of the well geometry, and the hydrodynamic production conditions as obtained by multiphase flow simulation of the wells. The model was verified through comparison to the results of the corrosion caliper surveys in same wells. The study recommended both of the long and short term corrosion mitigation methods and procedures to control downhole corrosion in this field based on the production optimization, sand control, and the establishment of effective corrosion monitoring, inspection and visual inspection programs.