Metho for evaluating dynamic stability of foam in rock core oil-displacing process

Abstract

The invention relates to a method for evaluating the dynamic stability of foam in a rock core oil-displacing process, and belongs to the technical field of improvement of oil recovery through foam flooding. In the prior art, foam flooding can significantly improve crude oil recovery, and the stability of foam is a key factor affecting the wide use of the foam flooding technology; the current method for evaluating the stability of foam is mainly a static evaluation method; and in the actual oil displacing process, the foam is subjected to the dynamic process comprising continuous defoaming andcontinuous foam generating, such that the stability of the foam during the oil displacing cannot be truly reflected by using the static evaluation method. According to the present invention, based onthe nuclear magnetic resonance technology and the mass conservation principle, the gas-liquid mass ratio relationship between the inlet end and the outlet end of the rock core is established, and thedynamic instability factor of the foam is defined, wherein the dynamic instability factor of the foam can evaluate the dynamic stability of the foam during the oil displacing of the rock core, and theproblem that the dynamic stability of the foam cannot be evaluated during the oil displacing of the rock core for a long time can be solved.

Description

technical field [0001] The invention relates to a method for evaluating the dynamic stability of foam in the process of core flooding, and belongs to the technical field of foam flooding enhanced oil recovery. Background technique [0002] Foam flooding can significantly improve oil recovery, and the stability of foam is a key factor affecting the wide application of foam flooding technology. At present, the evaluation methods of foam stability mainly include: [0003] (1) Improved Ross-Miles method: The improved Ross-Miles method is a national standard method (GB / T7462-94) for foam performance testing. This method is to configure a certain concentration of sample solution at a certain temperature, and 200mL of Flow down from a pore with a height of 900mm and an inner diameter of 2.9mm, and pour it into a 50mL sample solution with the same temperature and concentration, and record the foam height when the 200mL solution has been flowed out as the foaming force evaluation in...

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Problems solved by technology

[0007] Aiming at the defects existing in the prior art, the present invention provides a method for evaluating the dynamic stability of the foam in the core during oil displacement based on the nuclear magnetic resonance technology and the principle of mass conservation, and solves the problem that the dynamic stability of the foam in the core cannot be evaluated for a long time The problem

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