Multistage fracturing horizontal well inter-crack interval CO2 flooding oil extraction method

Abstract

The invention relates to a multistage fracturing horizontal well inter-crack interval CO2 flooding oil extraction method. The method includes following steps: performing sectional fracturing on a horizontal well shaft to form multiple fracturing cracks perpendicular to the horizontal well shaft; mounting an oil pipe I and an oil pipe II in a casing in the horizontal well shaft, mounting flow controllers I at positions, corresponding to even-level cracks, of the oil pipe I, mounting flow controllers II at positions, corresponding to odd-level cracks, of the oil pipe II, and arranging a packer at a position, between the odd-level cracks and the even-level cracks, in an annular space of an oil jacket; at an initial production stage, utilizing natural energy for extraction until bottom hole pressure is lowered to bubble point pressure, and utilizing crack intervals for extraction, injecting CO2 into the oil pipe I, wherein CO2 enters the even-level cracks, and crude oil is output from the odd-level cracks and enters the oil pipe II at the same time; when oil yield is lower than economic limit yield, stopping injecting CO2. By the method, crude oil recovery rate can be increased substantially, and gas channeling can be inhibited effectively.

Description

technical field [0001] The invention belongs to the technical field of oil and gas reservoir development, and in particular relates to a CO 2 Oil flooding method. Background technique [0002] With the rapid growth of global oil demand, the objects of oil and gas exploration and development are becoming more and more complex, and the grade of reserves is getting worse and worse. Low-permeability and ultra-low-permeability reservoirs will become the main targets of oilfield development in the future. Among the new proven reserves of crude oil in my country's onshore oilfields, the proportion of low-permeability reservoirs has increased sharply. Therefore, low-permeability and tight reservoirs are gradually becoming the focus of my country's future oil and gas development. [0003] Multi-stage fractured horizontal wells are usually used to develop low-permeability oil fields, which can provide channels for oil and gas flow, thereby increasing production. However, on the one ...

AI Technical Summary

Problems solved by technology

This technical solution is relatively complicated. In a horizontal well, only three fractures can be injected with water and oil produced at a time. After the three fractures have completed water injection and oil production, the other three adjacent fractures can be injected with water and produced oil. It can be seen that there are many production processes. The production efficiency is low. In addition, this technical solution cannot quantitatively evaluate the total oil production and the oil production of each fracture.

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