A method for repairing damaged casing by combined settlement and floating plugging

Abstract

The invention discloses a plugging and repairing method for damaged or corroded perforated casings, which proposes for the first time a combined subsidence and floating plugging technology, without considering the relative position of the leaky layer of the formation and the damaged point of the casing, and can fully fill the leaky point of the formation With the annulus, effective filling is formed above and below the casing damage point, which solves the plugging defect that the traditional method only satisfies the relative position of the leakage layer at the bottom, effectively improves the plugging effect of the damaged casing; and enables the plugging agent to effectively stay Retention and plugging of casing corrosion and damage caused by long-term mining; after repair, it can meet the pressure bearing requirements and meet the requirements of subsequent mining construction; and has low requirements for the repair environment such as temperature and formation fluid salinity, which is environmentally friendly and suitable for wide range.

Description

technical field [0001] The invention belongs to the technical field of oil and gas exploitation, and relates to a damage repairing technology for casing pipes in oil and gas fields, in particular to a method for repairing damaged casings combined with settlement and floating. Background technique [0002] The transportation of oil and gas from the bottom of the well to the surface is realized through the wellbore and auxiliary equipment. In addition to the necessary oil production equipment, it also includes tubing, casing, cement sheath and other tubing arranged in the wellbore during the drilling and completion process. The cement sheath and formation are the structures of the wellbore from the inside to the outside. In the long-term production process of oil and gas fields, since the cement slurry does not return to the ground during the cementing process, the formation fluid will contact the casing. During the long-term contact process, the formation fluid will corrode t...

AI Technical Summary

Problems solved by technology

[0006] 1) The plugging material generally has a relatively high density. Due to its own gravity, it will squeeze into the annular space and move to the lower part of the leak point. This method may be more effective for sealing the formation leak point below the casing damage point. However, it may also cause insufficient filling of the upper part of the annulus at the damaged point of the casing, which will affect the repair and plugging effect; 2) For the situation where the formation leakage point is above the casing damage point, this type of material cannot realize the filling and sealing of the formation leakage layer. The source of casing corrosion and damage cannot be solved fundamentally; 3) Due to the influence of formation water, the plugging agent cannot form a good residence at the casing damage point, thereby affecting the plugging effect; 4) It cannot meet the requirements of high mineralization Oil and gas well plugging effect of formation water