New method for determining first contact miscibility pressure of CO2/oil phase system by using interface phenomena

Abstract

Based on the importance of first contact miscibility pressure parameters of a co2 / oil phase system and the lack of current measurement methods, the present invention provides an intuitive and flexiblemeasurement method that satisfies the requirements for efficient and accurate testing of the first contact miscibility pressure parameters. In the measurement method, CO2 is injected into a pressurevessel to form a surrounding phase during experiments, after stabilization, an oil phase is injected into the pressure vessel at a constant flow rate, the injection process is taken by a CCD camera, and a computer is used for screenshot. A 10% rule is adopted, namely, a region where a local image gray value differs from an average image gray value by more than 10% does not exceed 10% of the totalarea in a frame, a tendency to be unified of physical parameters in the region is determined, the influence of an interphase mass transfer process on a two-phase dynamic miscibility process is negligible, and reach of a first miscibility point of CO2 / oil phase can be determined. Attached figures show changes of different interface phenomena under different pressures, and the rightmost figure is the first miscibility state. The pressure of a pressure gauge at the time of the first miscibility state is record, and the pressure is the first miscibility pressure of the oil phase.

Description

technical field [0001] The patent of the present invention relates to the determination of CO under the geological conditions of the reservoir by using the interface phenomenon 2 / The primary miscible pressure of the oil phase system is a method that can efficiently and accurately measure CO under different temperature conditions. 2 The invention discloses a new method for the primary miscibility pressure of an oil phase system, which belongs to the field of measurement of two-phase dynamic miscibility characteristics. Background technique [0002] In the study of CO2 flooding process, how to obtain CO 2 The pressure parameter of the miscibility point between fluid and formation oil phase is a very important technical issue. The prior art is to determine the minimum miscibility pressure (Minimum Miscibility Pressure-MMP) of the system by testing the change of the interfacial tension between phases through the sudden disappearance interfacial tension technique (Vanishing I...

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Problems solved by technology

while for CO 2 / The determination of the primary miscible pressure of the oil phase system currently lacks an efficient and accurate method

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