Method applicable to repeatedly transforming stratum nearby shaft of low-pressure gas field old well to complete permanent blocking

Abstract

The invention provides a method applicable to repeatedly transforming a stratum nearby a shaft of a low-pressure gas field old well to complete permanent blocking. The method is characterized by mixing micro-grade resin with cement before repeated transformation, pumping a mixture of the micro-grade resin and the cement into the stratum nearby the shaft, and permanently blocking holes and cracks in a low-pressure voidage zone around the old well. According to the method applicable to repeatedly transforming the stratum nearby the shaft of the low-pressure gas field old well to complete the permanent blocking, provided by the invention, the micro-grade resin and the cement are mixed, and the mixture of the micro-grade resin, and the cement is pumped into the stratum around the shaft before refracturing; since the particle diameter of ultrafine plugging agent particles is smaller and the ultrafine plugging agent particles have good fluidity and good penetrability, the ultrafine plugging agent particles can permeate into the holes of a reservoir stratum so as to permanently block the holes and the cracks in the low-pressure voidage zone around the old well, leakage of fracturing liquid to the stratum is slowed down, and the fracture making efficiency of the fracturing liquid is increased.

Description

technical field [0001] The invention belongs to the technical field of reservoir reformation in low-pressure and low-permeability gas fields, and in particular relates to a method for permanent sealing of formations near wellbores suitable for repeated reformation of old wells in low-pressure gas fields. Background technique [0002] With the deepening of gas field development, the proportion of low-production and low-efficiency wells is increasing year by year, and the situation of stable production is becoming increasingly severe. In order to increase single well production and tap the production potential of oil and gas wells, some old wells with well-developed sand bodies in the main layer, good reservoir physical properties and excellent accumulation conditions, but poorer production performance than adjacent wells were selected for refracturing. Different from the reconstruction of new wells, due to the long-term production of old wells, the formation energy in the nea...

AI Technical Summary

Problems solved by technology

Different from the reconstruction of new wells, due to the long-term production of old wells, the formation energy in the near-wellbore area is insufficient, resulting in a large amount of well killing fluid and fracturing fluid leakage during construction, which not only causes secondary damage to the reservoir, but also has low fluid fracture efficiency. The extension distance of cracks is limited, the drainage period is long after renovation, the drainage effect is poor, and the expected renovation goal cannot be achieved

[0003] At present, Changqing Oilfield only uses low-damage temporary plugging and killing fluid to prevent leakage of the killing fluid for repeated reconstruction of low-pressure gas wells and old wells, but the application effect is not obvious and cannot effectively solve practical problems

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