Abstract

The success of chemical treatments to prevent or remove formation damage, depend on the placement efficiency. In down-hole scale control treatments, diversion techniques are applied for improved placement of scale dissolvers or scale inhibitors in the potentially productive intervals. Foamed scale treatment is a new diversion technology developed by the operator and two oil service companies. The new approach is to foam the scale inhibitor and scale dissolver solutions for improved placement of down-hole scale inhibitor squeezes and scale dissolver treatments. An additional benefit is that the gas used to create foam is perfectly suited for wells with low reservoir pressure and with no gas lift system in place. In theory the foamed fluid will enter the highly injective zones at a higher rate than the others so that the resistance to flow increases in the zones which have accepted the foamed fluid.

The technical qualification of the foamed scale chemicals was divided into advanced bottle tests and dynamic flooding tests. The first ever field application was performed in a Norne subsea well, under challenging weather conditions from an intervention vessel. Two subsequent pumping operations; one foamed scale dissolver and one foamed scale inhibitor operation were done. The post job evaluation concluded that the foamed scale treatments were successful and the technology is qualified for future use at the Norne field. The well became protected against scaling as seen from the scale inhibitor return curve, and the well came easily on stream following each treatment. The operational challenges were mostly in connection with wave height and vessel movement affecting the Nitrogen pumping stability.

The benefits seen with this technology are: it is a solid free system, it can be deployed by bullheading, the foaming agent is environmentally friendly and the system helps a quick post treatment production.

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