Completion technologies for horizontal and subsea deep-water wells have been developed to make feasible and increase oil production.

Horizontal and subsea wells in Petrobras are usually located at long distances from production facilities and in deepwater. Scale control can be implemented on these wells via bullhead treatment along a service line or down production lines.

The scale potential for deepwater fields from Campos Basin, Brazil, was assessed. Thermodynamic model predicted a moderate barium and strontium sulfate precipitation in production wells (down hole). More severe precipitation was predicted for the lower temperature of the risers (10 to 20°C). Despite of the predictions based on thermodynamic calculation, experimental work performed considering conditions of temperature, residence time and chemistry of produced water showed that precipitation is expected in reservoir rather than in the risers. Laboratory results agree with field data observation. Data from gamma ray log obtained in recent intervention caused by productivity loss in one well of these fields, showed that scale was formed in the production well (screen, gravel and reservoir) rather than in the flow lines. Chemical dissolution treatment was designed and applied in the wells from this field restoring their productivity.

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