From Lost Fluids to Lost Production: Integrated Scale Diagnostics Linking Reservoir Contamination to Electric Submersible Pump Plugging in a Gulf of Mexico/America Carbonate Well

Summary

Recurring electric submersible pump (ESP) failures due to a combination of inorganic scale and asphaltene deposition pose a severe and costly challenge to production assurance in carbonate reservoirs. In this paper, we present a comprehensive, integrated study of Well X, which experienced a 60% decline in productivity index (PI), and multiple ESP pulls within several years. The root cause was diagnosed as a complex interplay of massive historical seawater and oil-based mud (OBM) losses, creating a persistent in-situ contamination that led to severe barium sulfate (BaSO4) and calcium sulfate (CaSO4) scaling upon production. A novel multidisciplinary workflow was used, combining (1) advanced reservoir simulation with tracer modeling to quantify contaminant volumes and forecast breakthrough, (2) statistical multivariable water-sample screening for representative formation water selection, (3) high-fidelity thermodynamic scale and asphaltene modeling using proprietary software, (4) dynamic wellbore modeling for pressure-temperature (P-T) profiling, and (5) theoretical inhibitor performance screening via induction time kinetics.

Key findings quantitatively demonstrate that OBM contamination increases total scaling mass by 55%, elevating BaSO4 contribution to 22% of the total scale. The critical seawater mixing ratio was confirmed at 20%. The study innovatively overlays dynamic wellbore P-T profiles onto scale contour maps to identify the pump intake as the highest-risk deposition zone. While asphaltene content was low (<1% mass), we conclude the paper with a ranked mitigation strategy, prioritizing optimal configurations of chemical treatments for solid dilution, reformulated sulfate-scale-targeted inhibitor squeezes, and operational changes to startup procedures. This workflow provides a robust, replicable template for diagnosing and managing multimechanism flow assurance failures in contaminated wells worldwide.