Lasers are an evolving technology in the oil field. Much in the same way that oil and gas service companies have found multiple uses for drones in the field—inspection, leak detection, surveillance—lasers are now being employed for emissions detection, data transfer, and, more recently, pipeline descaling.
In the paper SPE 209972presented earlier this month at the SPE Annual Technical Conference and Exhibition (ATCE), Aramco’s Sameeh Batarseh revealed the results from an initial trial using high-powered lasers to remove pipeline buildup. The idea of using lasers for this work has been around since the late 1990s.
Traditionally, pipeline descaling work has been left to mechanical tools, chemicals, or a mix of both. Lasers have unique properties that lend themselves to the job including accuracy, speed, power, control, and reliability.
The first field descaling deployment in the industry and a successful case study utilizing high-power laser technology was done in December 2021, descaling a 30-ft sample of pipe. The technology was able to descale the blocked flowline section without affecting the substrate integrity.
Protecting the Arteries of the Oilpatch
Scales are amorphous solids that form in pipelines, wellbores, and surface equipment because of thermodynamic, kinetic, and chemical interactions within flowing fluids and between these fluids and their environment. They can restrict hydrocarbon flow, constrain production, and lead to the failure of downhole equipment such as electrical submersible pumps, chokes, and valves. They can be categorized in two families: carbonates (or acid soluble) and sulfates (or acid insoluble).
High-power laser technology has been tested and proven to effectively penetrate and remove materials in all types of rocks regardless of the strength and composition. This includes accumulations and deposits of iron sulfide, calcium carbonate, and asphaltene.
The success of more than 2 decades of research has led to the development of the first high-power laser field system. The design of the system is enclosed, providing safe and environmentally friendly operation; it consists of a laser energy-generator, nitrogen tank, vacuum truck, and the tool. The function of the tool is to control the size and the shape of the beam that focuses on the targeted materials.
The descaling process is done by using the power of a laser to melt, break, or vaporize the materials. All the debris and materials removed are captured in a vacuum truck providing a clean operation. The head of the tool is articulated so that it can steer the laser around any imperfections inside the pipe without damaging the pipe itself.
Laser Performance
Early observations found that the laser removal rate varied with the overall thickness of the scale vs. the total length of the scale relative to the flowline sample length. A 20-ft fresh sample (hydrocarbons present) had varying levels of scale thickness over the full length, with the heaviest thickness being only a couple of inches thick near the end of the flowline.
The speed through the first 8 ft of the pipe was 18 in./min at 4 kW until a thicker scale was reached at 12 ft. From this point, the power was set at 12 kW with a horizontal feed rate of 5 in./min.
According to Batarseh, one of the problems to overcome with in situ testing, which kicks off in November, is delivering enough power to the laser via fiber optics.
The second phase of the laser experiment is to test using it on downhole perforations, which is done using the same laser source, just a different tool is employed.
Batarseh told attendees at ATCE that the laser descaling operation does offer cost savings over conventional descaling, but was not ready to get into specifics, saying only that it was beyond expectations. Keep in mind, lasers will allow reuse of the flowline, so no new section of pipe is required.
For More Reading
SPE 209972 First Industrial Flowlines Descaling Field Deployment Utilizing High Power Laser Technology by Sameeh Batarseh, Saad Al Mutairi, Muhammad Alqahtani, Wiam Assiri, Damian SanRoman Alerigi, and Scott Marshal, Saudi Aramco.
