Method for plugging old underground gas storage well

Abstract

The invention discloses a method for plugging an old underground gas storage well. The method comprises the steps of utilizing a cement bearing device and adopting padding mixed with superfine cement to plug a jetted air reservoir target layer in an extruding mode and reserving a cement plug; utilizing the cement bearing device and adopting padding mixed with superfine cement to plug perforated well sections under the jetted air reservoir target layer in the extruding mode and reserving a cement plug; utilizing the cement bearing device and adopting padding mixed with superfine cement to plug perforated well sections above the jetted air reservoir target layer in the extruding mode and reserving a superfine cement plug; selecting superfine sections with high superfine permeability to solve the problem that the well cementation quality of well sections above the target layer is disqualified, and arranging cement partition plates after perforation so as to prevent gas channeling outside tubes; plugging the target layer and other perforated well sections and waiting on cement setting under pressure by utilizing the cement bearing device; and arranging a whole cement plug and reserving cement faces to be 300m higher than the perforated well sections. The method for plugging the old underground gas storage well can effectively save plugging materials and improve the plugging effect.

Description

technical field [0001] The invention relates to oil and gas workover technology, in particular to a permanent well sealing method for an underground gas storage. Background technique [0002] Natural gas is flammable, explosive, and easy to leak. In the construction of gas storage, the most important thing is to consider the sealing of the gas storage, that is, to ensure that the natural gas stored underground cannot move uncontrollably to the wellhead, nor can it move to the wellhead. Non-reservoir migration. In recent years, my country has combined the geology and production characteristics of oil reservoirs in the construction of gas storages in China. After many demonstrations and years of practice by experts, it has formed a process route for treating old wells using sandstone oil and gas reservoirs in my country. This process route is comparable to that of foreign countries. The main difference is that the focus of treatment is on the treatment of old well gas reservoi...

AI Technical Summary

Problems solved by technology

At present, in the gas storage that has been built, there has been a phenomenon of gas leakage outside the casing due to the improper selection of the plugging process, which has caused a great safety and environmental protection hazard.

[0003] At present, ordinary or ultra-fine cement is generally used in the oil field to seal the reservoir and the well section outside the pipe, and the pressure test method is basically used to check whether the plugging is successful. The cement particle size is not selected according to the size of the formation pore throat, and sometimes the plugging effect will appear. The phenomenon that the pressure test is qualified, but the cementing quality is not up to the quality requirement; or the plugging effect is not up to the requirement when the amount of plugging material is large

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