Asynchronous co2 injection recovery method in grouped different wells with symmetrical fractures

Abstract

The invention relates to a grouping different-well asynchronous CO2-injecting oil extracting method adopting symmetric-type crack distributing. The grouping different-well asynchronous CO2-injecting oil extracting method adopting symmetric-type crack distributing comprises the following steps that in a horizontal well I, an injection control unit I corresponding to an even stage crack is started, and CO2 is injected into an injection oil pipe I and enters the even stage crack; in a horizontal well II, an injection control unit II corresponding to an odd stage crack is started, and CO2 is injected into an injection oil pipe II and enters the odd stage crack; in the horizontal well I, an oil-extracting control unit I corresponding to the odd stage crack is started, and crude oil is extracted from the odd stage crack and enters an oil-extracting pipe I; and in the horizontal well II, an oil-extracting control unit II corresponding to the even stage crack is started, and crude oil is extracted from the even stage crack and enters an oil-extracting pipe II; and at the area between the two horizontal wells, part of the crude oil enters the natural cracks and extracted through the odd stage crack of the horizontal well I and the even stage crack of the horizontal well II. According to the injecting and extracting method, the high seepage capacity of the natural cracks is adopted, and the problems such as water channeling and water logging are prevented.

Description

technical field [0001] The invention belongs to the technical field of oil and gas reservoir development, and in particular relates to asynchronous injection of CO in grouped different wells with symmetrical fracture layout 2 Oil recovery method. Background technique [0002] In recent years, due to the drastic reduction in the recoverable resources of conventional oil and gas, the exploration and development of unconventional oil and gas has become a new focus, and tight oil is one of them. Tight oil reservoirs are usually developed by depletion at the initial stage of development, but the natural energy of tight oil reservoirs in my country is generally insufficient, and the depletion recovery method alone will cause a rapid drop in reservoir pressure and a rapid decline in production, so energy supplementation is required after a period of development , such as water injection development, CO injection 2 development etc. [0003] Due to the low porosity and permeability...

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Problems solved by technology

[0003] Due to the low porosity and permeability of tight reservoirs, poor formation connectivity, large seepage resistance, and high heterogeneity, a series of problems may occur when using conventional water injection methods and injection-production well patterns: the injection pressure of water injection wells Usually large, injection is difficult; water channeling is easy to form; and because the seepage resistance of the formation is relatively large, and the flow capacity of the injected water in the formation is poor, resulting in a relatively small swept volume and a relatively limited increase in production of a single well, etc.

Although this invention patent can increase the oil recovery rate, due to the single-well injection and production, for oil and gas reservoirs with a large oil layer area, the swept volume, sweep efficiency and recovery degree will be limited, thereby reducing the oil recovery. Realize the displacement of the dead oil zone in the formation

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