Research and Application of Complex Old Well Blocking Technologies in Liaohe Gas Storage

Blocking old wells connected the reservoir layers was a prerequisite for converting depleted oil and gas reservoirs into gas storage facilities. Since most complex old wells had experienced serious downhole accidents, it was difficult to achieve effective blocking, affecting the construction and operational safety of the gas storage facilities. Therefore, this paper proposed blocking methods to solve the problems of unknown positions of fish, stuck drill pipes, and caving of empty wellbores. Moreover, the technologies such as passive magnetic guidance and pressure-resistant plugging were applied to three different types of blocking wells, namely Well X, Well Y, and Well Z, and achieved good practical results. The results showed that the holes were found and the fish were contacted for two sets of the fish without a trace, and ultrafine cement was squeezed into the annulus of fish and the wellbore respectively in Well X. The drill string of the fish at a depth of 2823 m was used as the squeezing channel, to complete the perforation and cement squeezing operations in Well Y. Besides, the original open hole of 2570 m was restored in Well Z, and the blocking was achieved through casing running and cementing, with cementing qualified rate of 97.84% and cap-rock continuous high-quality section of 93.6 m. The achievements of this paper not only enriched the technical reserve for blocking complex old wells in the Liaohe Gas Storage, reducing cost and improving efficiency, but also provided technical support for the subsequent construction of similar gas storage facilities in China.