The multi-component thermal fluid huff and puff pilot for offshore heavy oil has been conducted in Bohai Oilfield since 2008. Currently, part of the wells has entered the second cycle of the huff and puff. With the increase of the stimulation cycles, the steam breakthrough becomes serious due to the steam fingering and overlapping.

In order to further improve the oilfield development performance, technology that could impede the steam breakthrough is developed. Experiments are designed and carried out for selection of suitable foam systems and the optimization of injection parameters in laboratory. And the temperature-sensitive gel is also developed for the steam breakthrough treatment which presents as liquid at normal conditions, begins to solidify at about 70°C and could become liquid again when the temperature decreases below 70°C. Then technology based on these two plugging agent are applied in the actual wells.

The experimental results indicate that the selected foam system could meet the requirement of high temperature resistance and plugging strength. The injection mode of the foam system are all studied and optimized. Based on the experimental results and reservoir simulation, a project for steam breakthrough treatment in Bohai Oilfield has been designed by using both the selected foam system and the temperature-sensitive gel. The simulation prediction shows that this technology could achieve high oil increment for single cycle which indicates that this technology is efficient for impeding the steam breakthrough and improving the oil production rate. The actual field implementation has been conducted.

This is the first time that this technology is applied for steam breakthrough treatment in Bohai Oilfield. This technology could provide useful guidance for treatment of steam breakthrough in offshore heavy oil reservoirs.

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