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Cao H.,Engineering Research Institute of North China Oilfield | Wang Y.,Engineering Research Institute of North China Oilfield | Tian H.,Engineering Research Institute of North China Oilfield | Liu J.,Engineering Research Institute of North China Oilfield | And 2 more authors.
Drilling Fluid and Completion Fluid | Year: 2014

The overall formation conditions of the Suqiao underground gas storage (UGS) group are suitable for building new UGS, but the old wells drilled nearby destroy the closed boundary of the formation, thus requiring plugging treatment to the old wells to restore the original storage sealing condition and to ensure the safety of UGS. Three cementing slurry formulas and the corresponding plugging technology are developed based on the understanding of the formation characteristics of the Suqiao UGS. The first cementing slurry has fine particle sizes and can penetrate into the micro space of the cement sheathes, making up for the deficiency the conventional cement slurries have in plugging. The second cementing slurry has a characteristic of static gel which minimizes the arbitrary free flowing of cement slurry, forcing the cement slurry to stay and set in the thief zones. The third cement slurry is a conventional one and has a temperature stability of 170°C, enabling itself to stay stable, to be in good suspension status, to have no free water and to have no shrinking of the set cement at high temperatures. A five-stage plugging technology is developed to effectively and efficiently plugging the old wells. Two wells have been successfully plugged with the developed cement slurries and technology, demonstrating the feasibility of this technology. Source

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