Method for improving CO2 injection capacity through nano-particle composite low-salinity water

Abstract

The invention discloses a method for improving CO2 injection capacity by compounding nano-particles with low-salinity water, and belongs to the technical field of geological storage and utilization of CO2. The method comprises the following steps: injecting a silane coupling agent modified SiO2 nanofluid into a stratum; after injection of the modified SiO2 nanofluid slug is finished, injection is stopped, and well soaking is conducted for a period of time; after soaking is finished, low-salinity water is injected into the stratum, and high-salinity stratum water around the well is displaced and diluted; and after injection of the low-salinity water is finished, supercritical CO2 is immediately transferred and injected, and CO2 is sealed, stored and utilized. According to the method, the formation particles around the well can be fixed, the hydrophobicity of rocks can be enhanced, and the hypersalinity formation water can be subjected to displacement dilution, so that the comprehensive prevention and control of the salting-out precipitation and particle migration damage around the well can be realized, and the injection capacity of CO2 can be greatly improved.

Description

technical field [0001] The present invention belongs to CO 2 The technical field of geological storage and utilization, in particular to a nanoparticle composite low-salinity water to improve CO 2 A method of injecting capabilities. Background technique [0002] With the acceleration of the modernization process of human society, CO 2 Excessive emissions of gases lead to a rise in global temperature, which seriously threatens the earth's ecological environment. In response to global warming, countries have adopted corresponding carbon emission reduction measures and decisions, among which CO 2 Geological storage and utilization is considered to be the most economical and effective way to reduce carbon emissions, mainly including CO 2 Storage, CO 2 Enhanced oil extraction and CO 2 Displace coalbed methane. However, CO 2 The sequestered geological bodies mostly contain formation water with high salinity. 2 continuous injection, the formation water near the injection w...

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Problems solved by technology

[0004] (1) Low-salinity water can only prevent and control the salting-out effect in a short period of time. 2 With continuous injection, the saturation of water (wetting phase) around the well decreases continuously, and the formation water with high salinity will flow back under the action of capillary force, and salt precipitation will be induced again;

[0005] (2) Low-salinity water will increase the repulsion of the electric double layer between the formation particles and the pore wall, and the particles will change from favorable adhesion conditions to unfavorable conditions, which will intensify the shedding of formation particles, induce large-scale particle migration, and block pores Throat space;

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