Method and device for realizing carbon dioxide miscible-phase displacement laboratory experiment

Abstract

The invention provides a method and a device for realizing a carbon dioxide miscible-phase displacement laboratory experiment, and mainly aims at solving the problem of technical bottleneck of the existing carbon dioxide miscible-phase displacement laboratory experiment. The method is characterized by comprising the following steps of: firstly preparing two visual fine pipes capable of completely simulating an actual rock core according to the actual rock core pore throat features; screening reagents through a high-temperature high-pressure visual device, determining a reagent capable of achieving a miscible-phase effect with carbon dioxide, and determining a miscible-phase pressure-volume curve of the carbon dioxide and an added reagent at different proportions; in the miscible-phase reaching range by a system, injecting the system into the visual fine pipes, and ensuring the carbon dioxide and the added reagent to perform the miscible-phase operation in pores; injecting the system achieving the miscible-phase goal into oil saturation visual fine pipes, regulating the injection proportion of the carbon dioxide and the added reagent in the miscible-phase range until the miscible phase of the system and crude oil is formed, and determining the injection proportion of the carbon dioxide and the added reagent and a pressure-volume curve of the system; and using the minimum miscible-phase pressure determined by a fine pipe experiment as the return pressure to inject the carbon dioxide and added reagent system at the proportion into the actual rock core so that the crude oil and the carbon dioxide realize the miscible phase.

Description

technical field [0001] The invention relates to a method and a device for an indoor experiment of miscible flooding in the technical field of improving oil well recovery by carbon dioxide flooding. Background technique [0002] Carbon dioxide flooding is currently a very promising method for enhancing oil recovery in tertiary oil recovery. Carbon dioxide flooding is divided into miscible flooding and immiscible flooding, and the oil displacement effect of miscible flooding is better than that of immiscible flooding. In order to evaluate the effect of miscible flooding and how to better realize miscible flooding in the mine, it is necessary to conduct laboratory experiments in advance. At present, the indoor experimental research of carbon dioxide flooding mainly includes carbon dioxide miscible flooding experiments and thin tube test minimum miscible pressure experiments, but the current laboratory memory Technical deficiencies in two aspects limit the development of corres...

AI Technical Summary

Problems solved by technology

In order to evaluate the effect of miscible flooding and how to better realize miscible flooding in the mine, it is necessary to conduct laboratory experiments in advance. At present, the indoor experimental research of carbon dioxide flooding mainly includes carbon dioxide miscible flooding experiments and thin tube test minimum miscible pressure experiments, but the current laboratory memory Technical deficiencies in two aspects limit the development of corresponding carbon dioxide miscible flooding experiments

The corresponding technical defects are as follows: Technical defect 1, the short core used in laboratory experiments cannot realize the miscibility of carbon dioxide and crude oil in a short time, resulting in the inability to accurately evaluate the effect of complete miscible flooding

Technical defect 2, the pore throat size of the sand packing pipe in the thin tube test minimum miscible pressure experiment is not of the same order of magnitude as the actual core pore throat size, which makes the minimum miscible pressure tested by the device inaccurate

The reason is that the sand-packed tube is used to test the minimum miscible pressure in the laboratory at present. The sand-packed tube is filled with quartz sand. The porosity is too large compared with the actual reservoir. The pore-throat size is not in the same order of magnitude as the actual core pore-throat size, which makes the minimum miscible pressure tested by the device inaccurate. The results obtained are far from the actual situation. Under the condition of large pore throats, the contact area between carbon dioxide and crude oil is larger, the opportunities are more, and the miscibility may be greatly increased. The difficulty of miscibility increases greatly under the pressure, so the minimum miscible pressure tested by the device is not accurate enough

In many oilfields in my country, the measured minimum miscible pressure is too high due to factors such as the heavy component of crude oil, even exceeding the rupture pressure, making it difficult to realize miscible flooding. At present, a relatively promising way is to inject and add reagents to change the properties of crude oil or carbon dioxide to achieve a reduction. The purpose of its minimum miscibility pressure

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