A kind of high-temperature high-salt oil reservoir anti-CO2 gas channeling plugging agent and preparation method thereof

Abstract

The invention discloses a CO2 gas channeling prevention plugging agent for high-temperature high-salinity oil reservoirs and a preparation method of the CO2 gas channeling prevention plugging agent. By taking carboxymethyl (carboxyethyl) chitosan, acrylamide, heat-resistant and salt-tolerant monomers and acrylic acid as reaction monomers, taking phenol and formaldehyde as crosslinking agents and taking azobis(isobutylamidine hydrochloride), azodiisobutyronitrile or (NH4)2S2O8-NaHSO3 system as an initiator, polymerization and crosslinking of monomer molecules are realized synchronously under stratigraphic conditions to form gel in situ. The plugging agent is capable of selectively entering (micro) cracks with slight matrix damages and effectively moving deep to a stratum to realize effective plugging of a predominant pathway and is applicable to moderate or strong acid environment with the oil reservoir temperature being 80-140 DEG C and the maximum mineralization being 10*104mg / L, the problem of low supercritical CO2 plugging performance of existing plugging agents in high-temperature high-salinity low-permeability oil reservoirs is effectively solved, and the plugging agent has a promising market application prospect.

Description

technical field [0001] The present invention relates to a kind of oil tank suitable for oil reservoir temperature 80℃~130℃, maximum salinity 10×10 4 mg / L, medium or strong acidic environment, can effectively block CO 2 A gel plugging agent for gas channeling and a preparation method thereof belong to the field of oil field chemistry. Background technique [0002] In the initial stage of oilfield exploitation, the reservoir is rich in energy, and through the release of elastic energy of the formation and fluid, the crude oil is displaced to the wellbore, which is called primary oil recovery. With the shortage of elastic energy in oil reservoirs, the recovery rate of crude oil decreases, water injection and gas injection technology to supplement formation energy are inevitable measures to improve the recovery of crude oil [Ye Zhongbin, Pu Wanfen et al. Enhanced Oil Recovery (Second Edition), Petroleum Industry Press, 2007]. CO 2 Flooding not only effectively solves major p...

AI Technical Summary

Problems solved by technology

[0005] The object of the present invention is to provide a high-temperature high-salt oil reservoir 2 Gas channeling plugging agent, the plugging agent has a certain molecular size before gelling, can effectively selectively enter (micro) cracks, has little damage to the matrix, and the viscosity of the plugging agent base fluid is much smaller than that of the cross-linked polymer base fluid It can effectively migrate to the deep part of the formation and effectively block the dominant channel. It is suitable for reservoirs with a temperature of 80°C to 140°C and a maximum salinity of 10×10 4 mg / L, medium or strong acidic environment, which effectively solves the problem of supercritical CO in high temperature, high salt and low permeability reservoirs 2 Insufficient sealing performance and other problems

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