A method for determining the ultimate permeability corresponding to the complete plugging of a reservoir by a polysurfactant

Abstract

The invention provides a method of determining limit permeability corresponding to a poly-surfactant completely-sealing reservoir. The method comprises steps: a prepared poly-surfactant solution witha preset concentration is adopted to perform displacement on each core, the corresponding relationship between displacement pressure and a displacement multiple corresponding to each permeability coreis recorded, the corresponding relationship between displacement pressure and the displacement multiple is linearly fitted, a slope corresponding to each permeability core is obtained, the slope cumulative change rate corresponding to each permeability core is determined according to the slope corresponding to each permeability core, a corresponding relationship curve between each permeability and the slope cumulative change rate is determined, a slope cumulative change rate corresponding to each permeability core is determined according to the slope corresponding to each permeability core, the corresponding relationship curve between each permeability and a slope cumulative change rate is determined, a first inflection point and a second inflection point of the corresponding relationshipcurve between each permeability and a slope cumulative change rate are determined, and thus, the limit permeability range value corresponding to the poly-surfactant solution completely-sealing reservoir is determined.

Description

technical field [0001] The invention relates to the technical field of oil and gas field development and enhanced recovery, in particular to a method for measuring the limit permeability corresponding to the complete plugging of a reservoir by a surface-polymerizing agent. Background technique [0002] Before conventional oil displacement polymers (such as polyacrylamide) are applied to the field, it is first necessary to determine their matching relationship with the target reservoir through seepage characteristics experiments. The most commonly used method is the resistance coefficient method. The core idea of ​​the resistance coefficient method is: if the injection pressure gradually increases with the increase of the injection multiple, and the pressure increase becomes smaller and smaller, and finally there is an obvious pressure flat section, it is considered that the polymer solution flows in the target reservoir. If all goes well, the polymer solution matches the tar...

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Problems solved by technology

[0004] However, the inventors have found that the determination of the limit permeability corresponding to the complete plugging of the reservoir by the polysurface agent through the traditional resistance coefficient method has at least the following technical problems: Since the molecular structure of the polysurface agent is more complicated than that of the polymer, the polysurface agent During the experiment of the seepage characteristics, with the increase of the injection multiple, the input pressure has been increasing at a basically stable rate, even if the low concentration of the polymeric surface agent displaces the high permeability reservoir, even when the polymeric surface agent When the displacement multiplier has reached tens to hundreds of PV, the pressure is difficult to reach a steady state. Compared with the seepage characteristic experiment where the polymer can enter the pressure gentle section with 3 to 8 PV, the efficiency is greatly reduced

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