Analisis Potensi Pertumbuhan Scale dan Efektivitas Operasi Acid Washing dalam Scale Cleanout pada Sumur ARN-3

Abstract

Sukowati Field is a mature oil field producing hydrocarbons from the carbonate reservoir of the Tuban Formation, where calcium carbonate (CaCO₃) scale deposition frequently occurs during production. Scale accumulation in the production tubing restricts the flow area and reduces well productivity. In field practice, acid washing has been performed based mainly on production decline and mechanical inspection results without prior evaluation of scale formation potential. Therefore, this study aims to analyze the potential and growth of CaCO₃ scale, evaluate its impact on well production performance, and assess the effectiveness of acid washing in restoring well performance. This study utilized formation water analysis, production data, pressure and temperature profiles, well completion data, and acid washing operational data. Scale formation potential was predicted using OLI ScaleChem, while production performance before scale formation, after scale accumulation, and after acid washing was evaluated through nodal analysis using PROSPER. The results indicate that Well ARN-3 has a high potential for CaCO₃ scale formation throughout the tubing under highly supersaturated conditions. The predicted scale growth reduced the tubing inner diameter, which was consistent with restrictions observed during gauge cutter and coiled tubing inspections. Scale accumulation caused the gross production rate to decline from 3,605 BFPD to 2,554 BFPD, shifted the operating point to a lower production rate, and altered the pressure profile due to increased tubing restriction. Following acid washing, gross production increased to approximately 2,805 BFPD, accompanied by improvements in the operating point and pressure profile, indicating partial restoration of tubing flow capacity. However, the well performance did not return to its pre-scale condition because residual scale deposits were still present along sections of the tubing that were not effectively treated during acid washing.