Novel method for improving shale pore permeability condition

Abstract

The invention provides a novel method for improving a shale pore permeability condition, and relates to the technical field of oil well recovery efficiency improvement. The method comprises the following steps that a, liquid carbon dioxide, waste triethylene glycol liquid and clear water are sequentially injected into a horizontal section of a shale well; b, the carbon dioxide injected into a stratum enters pores and cracks with small pore throat radiuses at the far end of the stratum; c, after the injection amount is completed, the pressure of a wellhead is rapidly reduced, so that a large pressure difference is formed between the wellhead and the stratum, under the action of the large pressure difference, formed fine particle bridge plugs can be broken through and broken into single particles or small particle clusters, and the single particles or the small particle clusters are carried to a shaft by a large amount of flowback supercritical carbon dioxide; and d, a large amount of calcium and magnesium in shale react with the injected carbon dioxide and the waste triethylene glycol liquid around the near well to generate a triethylene glycol, diethylene glycol and carbon dioxide complex, a product destroys an oil film adsorbed on rock of a near wellbore area, the oil film is transformed into oil drops, and the oil drops are carried out in the rapid flowback process, so that the pore permeability condition around the near well is improved.

Description

technical field [0001] The invention belongs to the technical field of oil well recovery enhancement, and in particular relates to a new method for improving shale porosity and permeability conditions. Background technique [0002] The Daqing Gulong shale has a high clay content, but because it is located in a structural depression, the reservoir is buried deep and the temperature is high, a large amount of clay minerals are transformed into illite, forming secondary quartz, and the brittleness increases. Advantageous conditions are provided. Due to the brittle nature of the Gulong shale and the well-developed lamination, after large-scale dense cutting and fracturing, the rock is severely broken and a large number of fine particles are produced. With the continuous production in the later stage, these fine particles will gradually migrate to the bottom of the well, and become larger particle clusters in the form of bridging, blocking the effective pores and fractures aroun...

AI Technical Summary

Problems solved by technology

[0003] In order to solve the clogging problem formed in the two situations in the background technology, the present invention provides a new method for improving the shale porosity and permeability conditions. The present invention starts from the two problems of clogging and effectively improves the porosity and permeability of the reservoir conditions, and achieved a significant oil-increasing effect