Long-term Well Closure Method for Salt Cavern Reservoir Using Salt Rock Damage Self-healing Property

Abstract

The invention discloses a long-term well closing method for a salt cave storage by using the damage self-healing characteristic of salt rock. The long-term well closing method comprises the steps that(1) casing forging and milling are conducted on the upper portion of a well drilling casing shoe, and a fresh rock stratum is exposed; (2) a lead ball is put into a downhole to form preliminary plugging of the top of the downhole cavern, and then a suspended cement plug is driven on the upper portion of the lead ball to form a manual downhole; (3) a well of the salt rock section above the cementplug is filled with salt rock powder with the water content being 3-12% and compacted, thus compacted type slat is recrystallized, and the compacted type slat and the original salt rock on the well wall are healed into a whole; and (4) an ash plug is built at the bottom of the non-salt-rock layer well section above the salt rock section, then cement rising is conducted, and a wellhead cap is welded to the upper portion of the cement rising section. According to the long-term well closing method, the type slat is recrystallized, and the type slat and the salt rock on the well wall are healed toform the whole, so that a salt cave drilled well is closed, storage medium leakage or other safety accidents can be better avoided, the long-term well closing method can be widely used for long-termclosing of various salt layer driller wells, and the well closing safety is improved.

Description

technical field [0001] The invention relates to the technical field of salt wells, in particular to a method for long-term or permanent sealing of salt caverns. Background technique [0002] As of the middle of 2017, my country's strategic oil reserves are about 33.25 million tons, which can be maintained for 34 days in the case of complete interruption of imports and stable production of domestic oil fields. However, compared with Japan's 140-day strategic oil reserves and the United States' 85-day strategic oil reserves, for China, which is increasingly importing oil, it is an inevitable choice to continue to strengthen long-term strategic oil storage. According to the "National Petroleum Reserve Medium and Long-term Plan", before 2020, the total reserve size equivalent to net imports will be formed, then this requires China's oil reserves to reach 100 million tons, which is about three times the current reserve. [0003] Salt rock has low permeability, low porosity, good...

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Problems solved by technology

[0005] In view of this, the purpose of the present invention is to provide a method for long-term well sealing of salt cavern storage by using the self-healing property of salt rock damage, so as to solve the problem of plugging materials at high temperatures when drilling in and out of salt cavern storage for a long time. The problem of corrosion and failure in the environment is easy to achieve long-term or permanent sealing of underground salt cavern storage.

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