Oil production method of nitrogen and carbon dioxide composite huff and puff

Abstract

The invention discloses an oil production method of nitrogen and carbon dioxide composite huff and puff. The oil production method comprises the following steps that an injection-production integrated pipe column is put downward to a target oil layer in an oil well; the top of the injection-production integrated pipe column is connected with gas injection devices and thin oil injection device on the ground, wherein the gas injection devices comprises the nitrogen injection device and the carbon dioxide injection device; the gas injection devices inject gas into the oil well through the injection-production integrated pipe column; after nitrogen, carbon dioxide and thin oil are injected, shut in well is conducted; when the pressure of an wellhead after shut in well is stable, blow-off is controlled through an oil nozzle; and after the wellhead pressure and the blow-off well liquid amount both are smaller than predetermined values, extracting starts to be conducted through the injection-production integrated pipe column. The nitrogen and the carbon dioxide jointly serve as one-time injection media, the nitrogen replaces attic oil in the high positions of the periphery of the well, the carbon dioxide achieves the functions of dissolution, viscosity reducing and expansion energy increasing on stratum thick oil, and by utilizing the double composite functions of gas cap energy increasing of the nitrogen and stratum viscosity reducing of the carbon dioxide, the recovery efficiency of an ultra-deep fracture-cavity type thick oil reservoir is increased.

Description

technical field [0001] The invention relates to an oil recovery method, in particular to a nitrogen and carbon dioxide composite huff and puff oil recovery method. Background technique [0002] At present, with the gradual deepening of the development process of various oilfields at home and abroad, more and more reservoirs have entered the development stage of medium and high water cut, and the trend of water flooding effect is getting worse. More and more oilfields choose gas injection as the recovery of water injection. rate technology. Generally, there are three kinds of gas injection media after water flooding: carbon dioxide, natural gas and nitrogen. The test oilfields have carried out targeted research and field tests according to the objective and actual characteristics of the reservoirs, and have achieved certain test results. 3-5%. However, the research and application are mainly for sandstone reservoirs. There are few reports on the research and application of g...

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Problems solved by technology

Conventional formation viscosity reduction technology with steam injection thermal recovery is affected by ultra-deep and high formation pressure, resulting in large wellbore heat loss, and it is difficult to form large-scale thermal effect displacement under reservoir conditions

The formation viscosity reduction technology of fire flooding is affected by the high temperature and high pressure of fractured-cavity reservoirs and the serious heterogeneity of reservoir bodies, and the complex flow rules. It is difficult to select supporting technologies such as ignition, and it is difficult to control safety risks. Viscosity enhanced oil recovery technology is difficult to adapt to the efficient development of ultra-deep fracture-vuggy heavy oil reservoirs

[0004] 2) Conventional gas injection huff and puff technology is prone to extraction under reservoir conditions, resulting in gradual deterioration of oil properties. It is required that the injection method can effectively slow down the impact of extraction

[0006] In view of the fact that the recovery rate of ultra-deep fractured-vuggy heavy oil reservoirs is still low after water flooding, and a large amount of remaining oil is buried underground and cannot be produced efficiently, it is hoped that through technological innovation, we can develop and design "attic oil" that can produce high positions, It can also realize the enhanced oil recovery technology of reducing the viscosity of deep heavy oil formations, provide technical support for the continuous innovation of tertiary oil recovery technology in the petroleum industry, and provide good technical reference for the efficient development of oil reservoirs with similar properties at home and abroad

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