Oil extraction method with polymer-surfactant binary oil displacement system assisting in carbon dioxide huff and puff

Abstract

The invention discloses an oil extraction method with a polymer-surfactant binary oil displacement system assisting in carbon dioxide huff and puff and belongs to the technical field of increasing the crude oil recovery rate. The method includes the steps that a polymer-surfactant binary oil displacement system front plug, a carbon dioxide main plug, a polymer-surfactant binary oil displacement system rear plug, a blocking agent plug and water are sequentially injected into an oil reservoir; well opening is carried out after well shutting-in is carried out for a preset time, and crude oil extraction is carried out. The polymer-surfactant binary oil displacement system front plug and the polymer-surfactant binary oil displacement system rear plug are prepared from, by mass, 0.10%-0.40% of polyacrylamide, 0.05%-0.20% of surfactant compounded by N-dodecyl-N,N-dimethylglycine and hexadecyl trimethyl ammonium bromide and the balance water. The blocking agent plug is prepared from, by mass, 0.25%-0.50% of partially hydrolyzed polyacrylamide, 0.20%-0.50% of cross-linking agent, 0.01%-0.03% of stabilizer, 0.01%-0.02% of pH modifier and the balance water. By means of the method, the mobility ratio can be reasonably controlled, the displacement efficiency is improved, the carbon dioxide utilization rate is increased, and the recovery rate is increased.

Description

technical field [0001] The invention relates to the technical field of enhanced crude oil recovery, in particular to an oil recovery method with the assistance of a carbon dioxide huff and puff by a poly-surface binary flooding system. Background technique [0002] Carbon dioxide huff and puff oil recovery technology is an important enhanced oil recovery technology, which has been widely used in oil fields such as Daqing Oilfield, Jilin Oilfield and Jidong Oilfield. Carbon dioxide huff and puff oil recovery technology refers to injecting a certain amount of carbon dioxide into the oil layer under a certain pressure, soaking the well for a period of time to make the carbon dioxide diffuse in the formation and dissolve in the crude oil, and then open the well for production. [0003] The mechanism of CO2 huff and puff oil recovery technology to enhance oil recovery is: after injecting carbon dioxide into the oil layer, the carbon dioxide will dissolve in the crude oil and form...

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Problems solved by technology

[0004] In the process of realizing the present invention, the inventors have found that there are at least the following problems in the prior art: due to the heterogeneity of the reservoir, after multiple rounds of carbon dioxide stimulation, carbon dioxide will flow along the high permeability zone in the reservoir Or the channeling of large pores, the affected area is greatly reduced; when the well is opened for production, the carbon dioxide will return along the original path of the injected pores, which causes the ineffective circulation of carbon dioxide; The stripping effect of crude oil is small, so that even after passing through the area affected by carbon dioxide, there is still a large amount of remaining crude oil that cannot be recovered

In summary, the existing CO2 huff and puff oil recovery technology cannot play a good role in enhancing oil recovery

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