Case Studies

Putting theory into practice

The Challenge

An oil and gas exploration, development and Production Company required assistance verifying field anomalies on its 24" above ground pipeline.

The customer was in the process of a multi-year thermal development program as this project is a thermal in situ operation that produces > 50,000 barrels per day. As the line transports hot fluid it experiences large temperature changes. It is well isolated and includes a high number of bends to allow expansion. Deposits appear in the form of bitumen, which in its natural state is too viscous to flow. When bitumen is too deep (> 80 m) to economically mine, steam is injected to warm it. This reduces the viscosity and allows it to be pumped through surface wells.

Field investigations of this line identified cracking features. The presence of such features determined a possibility that some features located within bends had exhibited axial/circumferential cracking with complex angles. Because of this, time was now a main concern for all consecutive actions. A streamlined repair schedule was required to bring this line back into service as soon as possible.

This would be the first completed inspection for the line, which has been operational for six years and would form a starting point for ongoing integrity management. Although no previous projects were completed for this customer, NDT Global was chosen based on a Reputation for customer service, accuracy and quality data analysis.

The Solution

An NDT Global field verification expert worked closely with the field crew and conducted phased array UT (PAUT). PAUT was used to enhance the understanding of the crack geometries and provided crack depths prior to non-destructive testing.

This enabled the prioritization of structured maintenance according to the identified features. As a replacement pipe was not readily available, custom-built replacement solutions would be required and their fabrication would take a number of weeks. This meant that maintenance prioritization was crucial for this project.

Working alongside third-party NDE groups, NDT Global’s field verification expert performed additional measurements using phased array, time-of-flight diffraction (TOFD) and traditional shear wave technologies. NDT Global utilized 24" ultrasonic crack and circumferential crack detection tools, as anomalies were identified outside of tool resolutions. As complex angle cracking was outlined as a threat, both crack detection tools were custom built and configured to record data at a 1.5 mm (0.05 in) axial resolution to ensure the data was provided with the best resolution to accurately detect and size features to a minimum length of 20 mm.

The Results

Streamlined repair program: A streamlined repair program was introduced based on reliable ILI reports. This enabled the customer to prioritize maintenance, repairs and resources, while having a starting point for ongoing integrity management of this asset.

Tight schedules: The entire project from inquiry to delivery of final reports occurred within 80 days. The reporting timelines were extremely tight with the first preliminary report delivered within 7 days of receipt of the tool, and the final reports were delivered within 30 days.

Detailed results: NDT Global provided 53 circumferentially-oriented and 52 axially-oriented features from the final analysis phase. Additionally, through customized analysis targeting features outside of tool reporting tolerances, specifically in areas of the bends, another 348 potential sloping crack like indications were identified. Of the combined axial, circumferential and potentially sloping indications, 119 were investigated to determine the accuracy and reliability of the inspection data as well as to complete the integrity management program on this system and bring it back into operation.

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