Turning foamed acid for heterogeneous reservoir acidification

Abstract

The invention relates to a turning foamed acid for heterogeneous reservoir acidification. The turning foamed acid comprises, by volume, a nitrogen gas phase, 10% of hydrochloric acid, 1.5-3% of hydrofluoric acid, 2WT-60A, 2% of a corrosion inhibitor and 0.5% of citric acid. The 2WT-60A is cocoalkanoylamido propyl betaine or dodecyl dimethyl betaine. After the turning foamed acid is stirred at a stirring rate of 1000r / min for 1min, a foam half-life period is about 91min and form mass is 61.5% of the original mass. The turning foamed acid has the characteristic of self-tackifying, is free of a cross-linking agent and a gel breaker, controls a self-turning function based on a pH value, and has good diffluence performances, good retardance and high flowback performances.

Description

technical field [0001] The invention is a diverting foam acid, which has good retarding performance of the acid solution, and the acid solution has the characteristic of self-increasing viscosity and diverting as the acid-rock reaction proceeds, and is suitable for acidizing operations of heterogeneous reservoirs. Background technique [0002] In the actual acidizing process, due to the heterogeneity between layers and layers, the conventional acid liquid preferentially enters the hyperpermeable layer with the least resistance, and the acid liquid concentrates on the high-permeability layer and cannot improve the low-permeability layer or has pollution. Second, the penetration distance of the acid solution is small, and the pollution in the depth of the reservoir is difficult to remove; low-permeability and low-pressure reservoirs generally have the problem of difficult flowback after acidification. In addition, compared with vertical wells, horizontal wells have a large sca...

AI Technical Summary

Problems solved by technology

[0002] In the actual acidizing process, due to the heterogeneity between layers and layers, the conventional acid liquid preferentially enters the hyperpermeable layer with the least resistance, and the acid liquid concentrates on the high-permeability layer and cannot improve the low-permeability layer or has pollution. Second, the penetration distance of acid liquid is small, and the pollution in the depth of the reservoir is difficult to remove; low-permeability and low-pressure reservoirs generally have the problem of difficult flowback after acidification

In addition, compared with vertical wells, horizontal wells have a large scale of acidizing and a large amount of acid, and it is difficult to properly place the acid in the horizontal section. At the same time, research data show that conventional diverting agents cause serious secondary damage to the formation residues

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