A method for intensifying shale gas recovery by freezing and thawing cycles with large temperature difference

A technology for shale gas exploitation and freeze-thaw cycle, which is applied in the fields of exploitation fluid, earthwork drilling, wellbore/well components, etc. limited and other problems, to achieve the effect of increasing the cracking effect, the cracking effect is good, and the cracking effect is improved

CN109577939BActive Publication Date: 2020-09-01XUZHOU UNIV OF TECH
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2020-09-01

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Abstract

The invention discloses a method for enhancing shale gas exploitation through a large-temperature-difference freeze-thaw cycle. The method comprises the following steps of firstly, injecting magnetized water into a shale gas exploitation pipe of a shale gas well through pulsation; secondly, driving the magnetized water to move into shale as much as possible through high-pressure nitrogen, and thenconducting liquid-nitrogen freezing and high-temperature nitrogen melting on the magnetized water several times to fully utilize the permeability of the magnetized water, the driving property of thehigh-pressure nitrogen, the expansion force of the frozen magnetized water and an ultra-large-temperature-difference freeze-thaw cycle formed by the liquid nitrogen and the high-temperature nitrogen in order to cause complete cracking of the shale. Moreover, the high-temperature nitrogen can also provide energy for the shale gas to be separated from the shale, correspondingly the cracking effect of the shale can be effectively improved, the crack expansion range of the shale can be effectively expanded, and the shale permeability is increased, so that large-flow, high-concentration and long-time exploitation of the shale gas is improved.
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Description

technical field

[0001] The invention relates to a method for intensifying the exploitation of shale gas, in particular to a method for intensifying the exploitation of shale gas with a large temperature difference freeze-thaw cycle. Background technique

[0002] Shale gas is natural gas extracted from shale formations, and its composition is mainly methane. It is an important unconventional natural gas resource. my country's shale gas resource reserves are abundant. The geological resource potential of shale gas in land areas is 134.42 trillion cubic meters, and the recoverable resource potential is 25.08 trillion cubic meters. The mining life and growth cycle are long. Therefore, the commercial exploitation of shale gas is expected to improve the current situation that my country's conventional natural gas resources cannot be self-sufficient.

[0003] The main method of existing shale gas exploitation is to rely on its own desorption. After a period of gas extraction, the ...

Examples

Embodiment Construction

[0022] The present invention will be further described below.

[0023] Concrete steps of the present invention are:

[0024] A. Open the first valve 9 and the second valve 13, start the magnetized water generator 14 and the pulsating pump 11, the pulsating magnetized water is pulsated by the pulsating pump 11 to obtain pulsating magnetized water, and the pulsating magnetized water passes through the third pipeline 12 and the second pipeline The pipeline 10 and the first pipeline 4 enter the shale gas extraction pipe 3, and impact the shale layer 1 to develop and expand shale fractures, control the pulsation frequency of pulsating magnetized water to 0.02Hz-0.15Hz, and the pulsation pressure to 30MPa ~50MPa, pulse time is 2h~5h;

[0025] B. After the injection of the pulsating magnetized water is completed, close the magnetized water generator 14, the pulsating pump 11, the first valve 9 and the second valve 13 in sequence;

[0026] C. Open the fifth valve 23, the fourth valv...