Method for evaluating gas wettability effect by using core flooding experiment

Abstract

The invention discloses a method for evaluating a gas wettability effect by using a core flooding experiment. The method comprising the steps that an untreated saturated air core sample is selected; the basic data of the core rock sample are measured; salt water is injected into the core sample; a steady state condition is achieved, and data are recorded the first time; humidified nitrogen and pure methanol are used to displace and remove salt water in the core sample, and data are recorded the second time; the core sample is put in an oven and is dried; a gas wet reversal agent is injected into the core sample, so that the core sample is completely saturated; finally the core sample is aged in the oven; salt water is re-injected into the core rock sample to a steady state; humidified nitrogen is used to displace the salt water of the core rock sample, and data are recorded the third time; and according to the data recorded the first time, the second time and the third time, and the effect of the changed wettability is comprehensively judged. The method provided by the invention is simple and easy to implement, is suitable for the evaluation of different lithologies such as sandstone and carbonate rock, and can acquire a simple and visual test result.

Description

technical field [0001] The invention relates to a method for evaluating the wettability effect of gas by using a core displacement experiment, and belongs to the technical field of oil and gas field development. Background technique [0002] "Liquid lock" damage is one of the most important and serious damage types in condensate oil and gas reservoirs. According to research, the high water / oil saturation in the reservoir is mainly caused by the strong liquid wettability of rocks, while the high water / oil saturation Saturation is one of the main causes of "liquid lock" damage in reservoirs. Wetting phenomenon refers to the phenomenon that one fluid is replaced by another fluid on the solid interface. The wettability of reservoir rocks generally includes water wet, oil wet and neutral wet. Neutral wetting is gas-phase wetting, that is, treating solids with fluorine-containing surfactants to make their surfaces hydrophobic and oleophobic, with amphobia, to achieve the purpose ...

AI Technical Summary

Problems solved by technology

The evaluation method of gas wettability is different from oil wettability and water wettability. The conventional wettability evaluation is carried out in the oil (water)-rock system, while the measurement of gas wetness requires the gas-oil (water)-rock system The two are not in the same system, so the conventional wettability measurement method has certain limitations in the measurement of gas wetness; at the same time, the existing evaluation technology cannot truly reflect the effect of the improvement of gas wetness inside the core, and cannot truly simulate the formation in the formation. gas-liquid two-phase seepage

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