CO2 flooding asphaltene blocking degree quantitative calculation method

The degree of bituminous blockage during CO2 displacement was quantitatively evaluated by online nuclear magnetic resonance (NMR) testing, which solved the problem of reduced reservoir permeability, optimized displacement strategies, improved recovery rate and reduced environmental impact, and promoted the development of related research.

CN121994855APending Publication Date: 2026-05-08PETROCHINA CO LTD
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Patent Information

Application Number
CN202411590986.2
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2024-11-08
Publication Date
2026-05-08

AI Technical Summary

Technical Problem

In existing technologies, CO2 flooding technology has insufficient research on asphaltene deposition in unconventional reservoirs, which leads to reduced reservoir permeability, affects oil and gas flow and recovery rate, and reservoir damage prediction is complex, lacking an effective method for calculating the degree of asphaltene blockage.

Method used

In-situ online NMR testing was conducted using core samples. By measuring the NMR T2 spectra during static and CO2 displacement processes, permeability and porosity damage rates were calculated to obtain the CO2-driven asphaltene blockage index, which quantitatively evaluated the degree of asphaltene blockage.

Benefits of technology

It provides more accurate data support, optimizes displacement strategies, improves recovery rate, reduces environmental impact, enhances research level, and provides scientific guidance for oilfield management.

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Abstract

The invention discloses a CO2 flooding asphaltene blocking degree quantitative calculation method, and relates to the technical field of oil and gas field development. According to the technical scheme, the method comprises the following steps: executing on-line core in-situ condition nuclear magnetic testing: preparing a solution for saturating a core, preparing a saturated rock sample, determining a static pore throat nuclear magnetic T2 spectrum, determining a CO2 displacement process nuclear magnetic T2 spectrum, and determining a CO2 displacement post-nuclear magnetic T2 spectrum; the permeability damage rate and the porosity damage rate of the rock core are calculated by respectively obtaining static pore throat nuclear magnetic T2 spectrums and CO2 displacement process nuclear magnetic T2 spectrums of different rock cores, so that the CO2 displacement asphaltene blockage index is obtained. The method has the beneficial effects that the core in-situ condition on-line nuclear magnetic experiment is adopted, the micro-pore structure characteristics of the reservoir core are classified and researched, the CO2 displacement micro-dynamic process is observed by using the representative real core, the asphaltene and wax blocking degree of each stage can be quantitatively analyzed, the observation and operation are simple, the cost is low, and the method is suitable for large-scale popularization and application. And the support is provided for improving the recovery efficiency and reducing the residual oil distribution in the later-stage work of the oil field.
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