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Three-electrode potential difference type detection method for inner coating of tubing and casing in downhole

A detection method, oil casing technology, applied in the direction of measurement, earthwork drilling, wellbore/well components, etc., can solve the problem of qualitative detection and quantitative detection of coating damage rate or damage level, etc., to achieve the optimization of oil casing The effect of coating design, good accuracy and convenient logging operation

Active Publication Date: 2016-01-13
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] The purpose of the present invention is to solve the problem that the existing technology cannot determine the damage rate or damage level of the inner coating of the downhole oil casing through qualitative detection and quantitative detection

Method used

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  • Three-electrode potential difference type detection method for inner coating of tubing and casing in downhole
  • Three-electrode potential difference type detection method for inner coating of tubing and casing in downhole
  • Three-electrode potential difference type detection method for inner coating of tubing and casing in downhole

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Effect test

Embodiment 1

[0038] The invention provides a three-electrode potential difference detection method for the inner coating of downhole oil casing, which comprises the following steps:

[0039] Step 1: Prepare the downhole instrument string. The downhole instrument string includes a well logging cable 112. One end of the well logging cable 112 is electrically connected to the magnetic locator 102, the positive electrode 104, the lower test electrode 105, and the upper test electrode in sequence from bottom to top. 107. Bridle 106, the bottom end of the well logging cable 112 is connected to the centralizer 100, the well logging cable 112 has a weighting rod 101 connected in series between the centralizer 100 and the magnetic locator 102, and the other end of the well logging cable 112 is electrically connected to a constant The current source 113, the constant current source 113 is electrically connected to the dynamic logging system 115, the dynamic logging system 115 is electrically connecte...

Embodiment 2

[0063] On the basis of Embodiment 1, a conductivity electrode 103 for detecting the conductivity of the electrolyte is provided between the positive electrode 104 and the bridle 106 described in step one. The speed of lifting the logging cable 112 upward at a constant speed described in step 2 and step 7 is less than 1000m / hr. The dynamic logging system 115 adopts SKD3000 numerical control logging surface system. The distance between the lower testing electrode 105 and the upper testing electrode 107 is at least 0.5m.

[0064] The three-electrode potential difference detection method of the inner coating of the downhole oil casing provided by the present invention can realize the detection of the downhole oil casing through processing and interpreting the collected data when there are conductive media such as oil and water in the oil-water well. The coating makes accurate qualitative and quantitative judgments, with good accuracy, fast logging, convenient and safe operation, ...

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Abstract

The invention belongs to the field of detection of anticorrosion coatings and provides a three-electrode potential difference type detection method for an inner coating of a tubing and casing in a downhole. The method includes: descending a positive electrode and auxiliary matched instrument strings into the tubing and casing, providing constant voltage for the positive electrode, and acquiring potential difference between a lower test electrode and an upper test electrode in a process of lifting the instrument strings out of the downhole, wherein the potential difference reflects quality of the inner coating of the tubing and casing. The three-electrode potential difference type detection method for the inner coating of the tubing and casing in the downhole has the advantages that under the condition of existence of conductive media such as oil, water and the like in oil-water wells, acquired data can be processed and interpreted to realize accuracy in qualitative judgment and quantitative judgment of the inner coating of the tubing and casing in the downhole, and high precision, quickness in logging, convenience and safety in operation and low detection cost are realized.

Description

technical field [0001] The invention belongs to the technical field of anti-corrosion coating detection, and in particular relates to a three-electrode potential difference detection method for the inner coating of downhole oil and casing pipes. Background technique [0002] For the carbon steel (conforming to API5CT material) oil casing (abbreviation of oil pipe and casing) of highly corrosive oil wells, the internal coating protection technology of organic coating can effectively prolong the life of the casing, and has been adopted by many domestic and foreign oilfields on a large scale. The annual application of inner-coated oil casing is more than 1 million meters. There are many logging technologies for internal corrosion, damage and leakage of oil and casing, and a series of relatively mature logging methods have been formed and widely used in the industry, mainly including downhole electromagnetic thickness measurement, dobby hole diameter and well temperature , opti...

Claims

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Application Information

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IPC IPC(8): E21B47/00
Inventor 程碧海薛建强李琼玮张鑫柱杨会丽姜毅孙雨来刘伟付彩利苑慧莹周佩
Owner PETROCHINA CO LTD