Inter-crack space synchronous water injection-oil extraction method of multistage fracturing horizontal well

Abstract

The invention relates to an inter-crack space synchronous water injection-oil extraction method of a multistage fracturing horizontal well. The method comprises the following steps: forming multiple cracks of the staged fracturing horizontal well; extracting with natural energy in the initial production stage until bottom hole pressure is reduced to bubble point pressure; taking out an oil pipe; mounting an injection-extraction separation device on each odd-level crack, mounting an injection allocation valve on each even-level crack, forming jet holes, corresponding to the odd-level cracks, in the oil pipe, and putting the oil pipe to the home position; closing a well mouth oil extraction valve, starting the injection allocation valves, and injecting water into the annular space of an oil jacket, wherein the injected water flows through a guide pipe and enters the even-level cracks; and opening the well mouth oil extraction valve, wherein crude oil is produced from the odd-level cracks and enters an annular space formed by the guide pipe and a sleeve and the oil pipe and then is extracted through the oil pipe while water injection into the even-level cracks is continuously kept. Each injection-extraction separation device comprises a guide pipe and a packer. The method is simple in technology, can realize uniform displacement and has relatively high practical application value.

Description

technical field [0001] The invention belongs to the technical field of oil and gas reservoir development, and in particular relates to a method for simultaneous water injection and oil production at intervals between multistage fracturing horizontal wells and fractures. Background technique [0002] Multi-stage fracturing of horizontal wells is an effective technology to improve the production of low-permeability and tight oil reservoirs. Since the formation pressure of low-permeability and ultra-low-permeability reservoirs generally drops rapidly after being exploited with natural energy for a period of time, energy needs to be supplemented to improve the development effect of such reservoirs. The conventional well pattern for supplementing energy is vertical well water injection and multi-stage fracturing horizontal well production. This method requires vertical wells to be arranged around the horizontal wells, and factors such as the length of the horizontal section, the ...

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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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