Oil extraction method for injecting water among well fissures of multistage fractured horizontal well at intervals

Abstract

The invention relates to an oil extraction method for injecting water among well fissures of multistage fractured horizontal well at intervals. The oil extraction method sequentially comprises the following steps: carrying out staged fracturing on a shaft of a horizontal well, so as to form multiple fractured fissures vertical to the shaft of the horizontal well; arranging a one-way valve at each odd-level fissure, respectively, and arranging an injection allocation valve at each even-level fissure, respectively; carrying out exploiting for a period of time by virtue of natural energy at the initial production stage until the bottom hole pressure drops to a bubble point pressure; automatically switching off the one-way valves and automatically switching on the injection allocation valves by virtue of interval fissure water injection exploiting, and simultaneously injecting water into an oil sleeve annular space formed between an oil pipe and a sleeve for displacement; and after injected water flows into the even-level fissures for a period of time, stopping the injection of water, automatically switching off the injection allocation valves, and simultaneously automatically switching on the one-way valves, so that crude oil is produced through the odd-level fissures and enters the oil pipe. The method has the beneficial effects that the process is simple, the operation is convenient, the cost can be lowered, the uniform displacement can be realized, the yield is increased, and the practical application value is relatively high.

Description

Technical field [0001] The invention belongs to the technical field of oil and gas reservoir development, and specifically relates to a method for interfracture interval water injection and oil production in a multi-stage fracturing horizontal well. Background technique [0002] Multi-stage fractured horizontal wells are an effective technology to increase the production of low-permeability and tight reservoirs. Since the formation pressure of low-permeability and ultra-low-permeability oil reservoirs generally declines rapidly after a period of time after using natural energy to develop, it is necessary to supplement energy to improve the development effect of such reservoirs. The conventional well pattern form for supplementing energy is vertical well water injection and multi-stage fracturing horizontal well oil production. This method requires vertical wells to be arranged around the horizontal well, and also needs to consider factors such as the length of the horizontal sect...

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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