Coiled tubing is a fast growing technology and is becoming an alternative to jointed pipe in a wide range of oil and gas well operations. The technology is pushed by the use of coiled tubing for complex operations that are safety, cost and environmentally sensitive. During operations the coiled tubing must retain its integrity under increasing conditions of pressure, load and depth. Since the tubing integrity is mainly determined by its physical properties, real-time inspection during operations is an excellent method to ensure safety and enhance reliability.

Abstract

Since the combination of measuring fatigue and corrosion in one system would be ideal but not possible for now, the best way to ‘guard’ the coiled tubing's integrity before or during operation, is to detect corrosion or other anomalies in a very early stage. Calculations on form and depth of CT anomalies to predict its growth and behavior still turn out to be very difficult.

This means online detecting on a very small scale would give you a better and immediate view on the growing speed of anomalies and thus your total decay of the CT string. ROSEN does this by means of her well-known knowledge in the Magnetic Flux Leakage principle and her 20+ years experience in pipeline inspections.

For Hibernia Canada we introduced a new feature in our software concentrating on corrosion finding and wall thickness.

We have divided the wall thickness into 9 different wall thickness part sections around the circumference. This means a more precise indication (and therefore better resolution) of the wall thickness part (40° coverage each), which could contain a wall thinning including its clock position.

Mechanical damage, corrosion parts or pits as small as approx 0.3mm (0.01") in depth can now be detected!

Introduction

The use of coiled tubing for well intervention and drilling operations is subject to undesirable safety, environmental and cost/risk factors due to possible failure of the tubing while in service. Safety is the foremost concern of operators, and further development of CT management has to focus on maximizing the safety of operations while maximizing the use of CT.

The working life of CT is affected by various factors such as fatigue, changes in tube geometry, corrosion, manufacturing failures and mechanical damages caused by operational constrains or improper handling of the CT. The most common cause of failure is due to local surface defects created while running the tubing in and out of the well while passing through various wellhead and completion equipment. The repeated plastic deformation of the tubing during these operations eventually leads to local failure that is accelerated by the stress concentration at the defects.

To determine the optimum safe and cost effective working life of CT, operators must establish acceptance criteria for CT quality control and lifetime prediction. It is desirable, if not essential, to be able to continuously monitor the CT during operation in order to be able to automatically provide an assessment of the tube integrity for estimation of life expectancy.

A system for automatic coiled tubing inspection and integrity monitoring is a basic item of a coiled tubing management system for quality control and lifetime prediction. Looking at the needs of the industry, which are safer, more reliable and economical coiled tubing (CT) on- and offshore operations, ROSEN has developed an inspection device called ACIM, Automatic Coiled Tubing Inspection and Monitoring, a sophisticated real time inspection system that can assist operators in improving coiled tubing integrity. The ACIM was designed for and with the coiled tubing manufacturers. It is aimed to make coiled tubing operations more safe, mechanically reliable and cost effective.

The ACIM allows operators to monitor the condition and performance of the coiled tube as well as their own practices from one moment to the next. Besides gathering all necessary raw data, real time visualization of the evaluated data is an important part of the automatic CT integrity monitoring system.

The monitoring results must be presented clearly and understandably. The ACIM offers a wide range of interfaces to provide the operator with all the information needed in a convenient format.

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