Screw type local reverse circulation casing milling fishing tool

Abstract

The screw type local reverse circulation casing milling fishing tool. The tool comprises a screw drilling tool assembly, a flow guide connector, an outer working barrel and a casing milling barrel which are sequentially connected from top to bottom, a screw pump assembly arranged in the flow guide connector, a grinding machine and a magnetic center pipe which are arranged in the outer working barrel, and a female cone arranged in the casing milling barrel. According to the tool, positive circulation liquid flow is changed into local reverse circulation through the built-in pore channel structures, through mutual cooperation of a screw drill and a screw pump, a negative pressure suction effect can be generated in the barrel relative to well bottom liquid without extra power, so that small fallen objects are selectively adsorbed or crushed to flow back, the female cone can be used for making buckles, reversing buckles and salvaging at the same time of milling, the probability of drill jamming accidents caused by ferromagnetic fragments entering an annulus can be reduced under conventional pump pressure and displacement, casing milling is completed at a time, the construction period of casing milling salvaging is shortened, the construction cost is effectively saved, the working efficiency of casing milling salvaging is improved, and the probability of the drill jamming accidentsis reduced.

Description

technical field [0001] The invention relates to the technical field of downhole operation of oil and gas wells, in particular to a screw type partial reverse circulation casing milling fishing tool. Background technique [0002] After overhauling the workover, it is invalid to remove the sticking through activities, and it is necessary to use the method of casing milling to clean the annular space between the falling objects and the casing before salvage; because the bottom of the well is not suitable for direct fishing, the top of the fish needs to be casing After milling and repairing, salvage treatment is carried out; or there are small pieces of falling objects and iron filings at the bottom of the well, which need to be salvaged with salvage tools. This process is called casing milling and salvage construction in underground operations. [0003] At present, in the field construction process of major workover wells, for conventional casing milling construction, double ra...

AI Technical Summary

Problems solved by technology

This casing milling fishing construction method is relatively simple and has a high success rate in relatively conventional shallow wells and vertical wells, but in deep wells, deviated wells, lost wells, especially when dealing with corroded oil pipes in water injection wells, due to the large number of metal fragments in the wells, The quality of the metal fragments is large and difficult to return, so it is very easy to cause drill stuck accidents during the construction process

[0004] In order to avoid sticking accidents caused by the difficulty of returning metal debris, the site often adopts the method of increasing the pump injection displacement, the overall reverse circulation work mode, frequently moving the pipe string to check whether there is jamming in the pipe string, and carrying out long-term drilling after a section of casing milling. Although these methods have certain effects, they also bring about the problems of long construction period and high construction cost. Therefore, the efficiency of casing milling is not always high, and the occurrence of stuck pipe accidents cannot be completely avoided.

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