Steel pipeline is the optimum choice for transporting oil and gas due to its excellent strength,
material properties and cost. Some pipeline services require special attention to avoid
corrosion or erosion, e.g., corrosive water injection systems. To address this, internal liners
have been introduced, including cement-lined to protect the pipelines from such conditions.
Even though cement-liners enhance the reliability of the pipelines, there are still challenges
related to inspection. The inspection of cement-lined pipelines is difficult with in-line
inspection tools (ILI) due to surface roughness of the cement, which impacts the movement.
Also, the cement lining is too thick for the sensors of the ILI tool to measure the steel
thickness through the liner.
Cement-lined pipelines are frequently used for water injection system facilities where
common inspection techniques cannot be used due to inherent limitations. As safety,
reliability and continuity are important at Saudi Aramco operations, the team spare no effort
to ensure the integrity of these pipelines utilizing different inspection techniques. In 2017,
electromagnetic acoustic transmission (EMAT) inspection technology was utilized for the first
time on cement-lined pipelines at the water injection facilities. This paper describes the
capability and successful deployment of EMAT inspection technology.
Large standoff magnetometry (LSM), a novel screening technology, has shown strong industry relevance in several pipeline integrity investigations. LSM is used to detect changes in the magnetic field of a pipeline due to changes in the magnetic susceptibility of steel. These changes are known as inverse magnetostriction (a.k.a. the Villari effect) and occur when a ferromagnetic material (steel) is subjected to mechanical stress, such as the presence of stress on the wall of a pipeline. Geometric anomalies (ovalities, dents, wrinkles), hoop stress, ground and slope movement, bend strain, thermal expansion, cracks, and material defects are examples of potential sources of stress that LSM can detect from aboveground.
This paper summarizes the use of LSM as a complimentary tool in several pipeline integrity assessments conducted on oil and gas pipelines, in this case, to pinpoint a lost inline inspection pig and to identify dents, cracks, buckles, slope movement, casing ends, unknown valve locations and other pipeline integrity and direct assessment applications. Ongoing development programs and lessons learnt from practical, real-life projects and validations of the technology are presented to demonstrate the effectiveness of LSM for pipeline integrity investigations.