Plugging method for abandoned well of gas storage

Abstract

The invention provides a plugging method for an abandoned well of a gas storage, and belongs to the technical field of gas storage production. The plugging method comprises the steps that superfine cement paste is injected into the position, corresponding to a reservoir stratum, in the to-be-plugged abandoned well, and a reservoir stratum cement plug is formed in the to-be-plugged abandoned well to plug the reservoir stratum; conventional cement paste is injected into the position, corresponding to a cover layer, in the to-be-plugged abandoned well, a cover layer cement plug is formed in the to-be-plugged abandoned well to plug the cover layer, and the cover layer is an original layer located above the reservoir stratum and used for sealing the reservoir stratum; the conventional cement paste is injected into the position above the cover layer cement plug in the to-be-plugged abandoned well, and a continuous cement plug is formed above the cover layer to plug the cover layer cement plug; and barite paste is injected into the position above the continuous cement plug in the to-be-plugged abandoned well, and a heavy cement plug is formed above the continuous cement plug to compact and seal the continuous cement plug. According to the plugging method for the abandoned well of the gas storage, the plugging effect can be remarkably improved.

Description

technical field [0001] The disclosure belongs to the technical field of gas storage production, in particular to a plugging method for an abandoned well of a gas storage. Background technique [0002] Gas storage is a kind of artificial gas field or gas reservoir formed by reinjecting commercial natural gas transported by long-distance pipelines into underground space. Then set up gas storage wells in the gas storage for gas production. The production characteristics of gas storage wells are high-pressure gas injection in spring, summer and autumn, and large-volume gas production in winter to ensure normal gas supply. During the gas injection process, the abandoned wells to be plugged in the gas storage are also subjected to the same high pressure, and the formation pressure is relatively high in the later stage of gas injection. Blocking processing operations. [0003] In related technologies, the plugging of abandoned wells to be plugged in the gas storage generally ado...

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Problems solved by technology

[0004] However, because the operation of the gas storage has the characteristics of periodic strong production and strong injection, even after it is plugged, it still bears high and low pressure alternating loads. Therefore, the above method directly plugs the abandoned well to be plugged, which will make There is a certain micro gap between the cement plug and the casing, which is likely to cause the unsealing of the abandoned well to be plugged, and once the abandoned well to be plugged is unsealed, the natural gas will migrate up and down along the cement plug, or to the non-gas storage layer. and wellhead migration, which will cause huge safety hazards and directly affect the safe production of a well

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