Dropping-fishing type shaft bottom sampling tool

Abstract

The invention discloses a dropping-fishing type shaft bottom sampling tool, comprising an outer cylinder, a transition joint and a sealed sampling mechanism, which are in threaded connection from top to bottom, as well as an inner cylinder, a sliding bush and a protecting jacket of which the inner side is provided with a sealing piston, wherein the inner cylinder is fixed on the inner side of the outer cylinder; the sliding bush and the protecting jacket are sequentially sheathed on the outer side of the sealed sampling mechanism from top to bottom and are fixed on the sealed sampling mechanism by virtue of shear pins; and the sliding bush and the protecting jacket are respectively used for plugging a liquid inlet hole and protecting the shear pins from being broken when the tool enters water for the first time. The dropping-fishing type shaft bottom sampling tool is simple in structure and convenient in operation, and is dropped from the ground surface and falls to a shaft bottom by depending on the weight, and after the bottom of the sampling tool dashes against the tools including an ignition rod, an ignition head, a ball socket and the like in an oil pipe, the sliding bush is cut off automatically, the shear pins leak out of a sampling channel, and shaft bottom fluid enters the sampling tool under the action of a pressure to complete a liquid taking process.

Description

technical field [0001] The invention relates to the technical field of downhole tools used in the development and application of oil and gas fields, in particular to a fishing-type bottom-hole sampling tool. Background technique [0002] After the oil test well is perforated, the formation water needs to be sampled and analyzed. The conventional method is to lower the wellbore liquid level before perforating, measure the liquid level height before and after perforation, and then obtain samples from the outlet of the tubing through backwashing the well; this method The method requires that the ground measurement must be accurate, and the water produced by the formation must be sufficient. Generally, the real sample can only be obtained when the water produced is more than 2 square meters. In addition, when using this method to obtain samples, due to the mixing zone between well flushing water and formation water, the samples are often mixed with well flushing water, which has...

AI Technical Summary

Problems solved by technology

In addition, when using this method to obtain samples, due to the mixing zone between the well flushing water and the formation water, the samples are often mixed with the well flushing water, which has a large error with the real water sample

Especially when the formation permeability is low and the water yield is small, it is more difficult to obtain bottom hole fluid samples by this method

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