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Problem statement: Scale deposition is one of the most serious oil field problems that inflict water injection systems primarily when two incompatible waters are involved. Approach: This study was conducted to investigate the permeability reduction caused by deposition of calcium, strontium and barium sulphates in sandstone cores from mixing of injected Malaysian sea waters (Angsi and Barton) and formation water that contained high concentration of calcium, barium and strontium ions at various temperatures (60-90°C) and differential pressures (125-175 psig). The solubility of common oil field scales formed and how their solubilities were affected by changes in salinity and temperatures (40-90°C) were also studied. The morphology and particle size of scaling crystals formed as shown by Scanning Electron Microscopy (SEM) were also presented. Results: The results showed that a large extent of permeability damage caused by calcium, strontium and barium sulphates that deposited on the rock pore surface. The rock permeability decline indicates the influence of the concentration of calcium, barium and strontium ions. Conclusion: At higher temperatures, the deposition of CaSO₄ and SrSO₄ scales increases and the deposition of BaSO₄ scale decreases since the solubilities of CaSO₄ and SrSO₄ scales decreases and the solubility of BaSO₄ increases with increasing temperature. The deposition of CaSO₄, SrSO₄ and BaSO₄ scales during flow of injection waters into porous media was shown by Scanning Electron Microscopy (SEM) micrographs

Kerak pemendapan merupakan satu daripada masalah paling penting dan serius dalam sistem suntikan air. Kerak kadangkala mengehadkan atau menghalang penghasilan gas dan minyak melalui penyumbatan matrik atau perpecahan pembentukan minyak dan jeda yang berlubang. Makalah ini mengetengahkan kesimpulan pengukuran makmal bagi kerak terbentuk di dalam keterlarutan medan minyak biasa dalam sintetik air masin (pembentukan air dan air laut) bagi pembentukan air yang mengandungi barium dan kandungan garam yang tinggi pada suhu 40 hingga 90°C pada tekanan atmosfera. Keputusan uji kaji mengesahkan pola kebergantungan keterlarutan bagi kerak medan minyak biasa pada keadaan ini. Pada suhu yang lebih tinggi, kerak bagi CaCO3, CaSO4, dan SrSO4 meningkat manakala kerak BaSO4 menurun disebabkan oleh keterlarutan CaCO3, CaSO4, dan SrSO4 menurun dan keterlarutan BaSO4 meningkat dengan kenaikan suhu. Kata kunci: Masalah pengskalaan; skala keterlarutan; paras kandungan garam tinggi; logam barium tinggi Scale deposition is one of the most important and serious problems which water injection systems are generally engaged in. Scale sometimes limits or blocks oil and gas production by plugging the oil–producing formation matrix or fractures and the perforated intervals. This paper presents a summary of the laboratory measurements of the solubility of common oil field scales in synthetic brines (formation water and sea water) of high–barium and high–salinity formation waters at 40 to 90°C and atmospheric pressure. The experimental results confirm the general trend in solubility dependencies for common oil field scales at these conditions. At higher temperatures the deposition of CaCO3, CaSO4 and SrSO4 scale increases and the deposition of BaSO4 scale decreases since the solubilities of CaCO3, CaSO4 and SrSO4 scales decreases and the solubility of BaSO4 increases with increasing temperature. Key words: Scaling problems; solubility of scale; high salinity; high barium