Method for leakage pre-plugging of well cemented through lining pipe

Abstract

The invention relates to the technical field of oilfield lining pipe reinforcing operation, in particular to a method for leakage pre-plugging of a well cemented through a lining pipe. The method comprises the following steps that 1, a drill rod is tripped to 30-50 m of the upper portion of a perforation interval or a sleeve leakage point, and a packer is arranged on the position with 80-120 m distance from the upper portion of the perforation interval or the sleeve leakage point; 2, well flushing fluid is positively injected for one week, and then the packer is set; and 3, a plugging agent Ais injected to plug the perforation interval or the sleeve leakage point in advance, and the plugging agent A is composed of a water-based drive-adjusting reagent, a lignin particle plugging agent andwater. According to the method, before well cementing construction, chemical agents are injected to pre-plug the well sections, with cement slurry prone to loss, of the perforation interval, a leakage loss point, the sleeve leakage point and the like, the chemical agents in use are high in plugging rate and high in compression strength, a leakage loss layer can be efficiently plugged, leakage loss of cement slurry in well cementing construction through lining pipe reinforcing is avoided, meanwhile, the plugging agent does not damage the oil layer, the oil well production capacity is not affected, and smooth conducting of well cementing construction is ensured.

Description

Technical field: [0001] The invention relates to the technical field of oilfield liner reinforcement operations, in particular to a pre-plugging method for liner reinforcement wells. Background technique: [0002] Heavy oil thermal recovery wells have been developed for many years. Due to factors such as production parameters, high-temperature steam injection, formation stress, and downhole falling objects, the casing damage and deformation of the casing in the oil layer have occurred to varying degrees, resulting in shutdown of the oil well. Conventional casing repair technology cannot Effective restoration of wellbore conditions. To solve this problem, the liner reinforcement technology is often used, that is, a small-sized casing is run in on the basis of the original casing to replace the original production wellbore, and a small-sized production string is run in for normal production after being put into production. [0003] However, in daily construction, in low-press...

AI Technical Summary

Problems solved by technology

It overcomes the shortcomings of the existing leaking well plugging methods that the plugging strength is not high and the crude oil layer is damaged