Internal corrosion has caused ADNOC to suffer containment loss in the pipeline of a huge onshore oil field.The desire to eliminate this problem and the need to define a specification and an accurate future streamline integrity management plan has led to the field trial application of grooved and flangeless high-density polyethylene (HDPE) lining technology in carbon steel pipes.This paper describes a successful 5-year field test program and confirms that the application of HDPE linings in carbon steel pipes is a cost-effective method to mitigate internal corrosion in oil pipelines by isolating metal pipes from corrosive fluids.The technology is cost-effective in managing corrosion inside oil pipelines.
In ADNOC, Flowlines are designed to last more than 20 years.This is important for business continuity and reducing operating costs.However, maintaining these lines made of carbon steel becomes challenging because they are subject to internal corrosion from corrosive fluids, bacteria, and stagnant conditions caused by low flow rates.The risk of integrity failure increases with age and changes in reservoir fluid properties.
ADNOC operates pipelines at pressures of 30 to 50 bar, temperatures up to 69°C and water cuts in excess of 70%, and has suffered many cases of containment loss due to internal corrosion in pipelines in large onshore fields.Records show that the selected assets alone have more than 91 natural oil pipelines (302 kilometers) and more than 45 gas lift pipelines (100 kilometers) with severe internal corrosion.The operating conditions that dictated the implementation of internal corrosion mitigation included low pH (4.8–5.2), presence of CO2 (>3%) and H2S (>3%), gas/oil ratio greater than 481 scf/bbl, line temperature greater than 55°C, flow Line pressure above 525 psi.High water content (>46%), low flow velocity (less than 1 m/sec), stagnant fluid, and the presence of sulfate-reducing bacteria also affected mitigation strategies.Streamline leak statistics show that many of these lines were faulty, with as many as 14 leaks over a 5-year period.This poses a serious problem as it leads to leaks and interruptions that adversely affect production.
The loss of tightness and the need for sizing and an accurate future flowline integrity management plan resulted in a field trial application of slotted and flangeless HDPE lining technology in 3.0 km of Schedule 80 API 5L Gr.B 6 inches.Streamlines to eliminate this problem.Field trials were first applied to 3.527 km of carbon steel pipelines at selected assets, followed by intensive testing in 4.0 km of pipelines.
The Gulf Cooperation Council (GCC) oil major in the Arabian Peninsula had installed HDPE liners as early as 2012 for crude oil pipelines and water applications.A GCC oil major operating in conjunction with Shell has been using HDPE linings for water and oil applications for over 20 years, and the technology is sufficiently mature to address internal corrosion in oil pipelines.
The ADNOC project was launched in the second quarter of 2011 and installed in the second quarter of 2012.Monitoring began in April 2012 and was completed in the third quarter of 2017.The test spools are then sent to the Borouge Innovation Center (BIC) for evaluation and analysis.The success and failure criteria set for the HDPE liner pilot were zero leakage after liner installation, low gas permeability through the HDPE liner, and no liner collapse.
Paper SPE-192862 describes strategies that contribute to the success of field trials.The focus is on planning, laying pipelines, and evaluating the performance of HDPE liners to gain the knowledge needed to locate integrity management strategies for field-wide implementation of HDPE pipelines in oil pipelines.This technology is used in oil pipelines and transmission lines.In addition to existing oil pipelines, non-metallic HDPE liners can be used for new oil pipelines.Highlights best practices for eliminating pipeline integrity failures due to damage from internal corrosion.
The full paper describes the implementation criteria for HDPE gaskets; gasket material selection, preparation, and installation sequence; air leakage and hydrostatic testing; annular gas venting and monitoring; line commissioning; and detailed post-test test results.The Streamline Life Cycle Cost Analysis table illustrates the estimated cost-effectiveness of carbon steel versus HDPE linings for other corrosion mitigation methods, including chemical injection and pigging, non-metallic piping, and bare carbon steel.The decision to conduct a second enhanced field test after the initial test is also explained.In the first test, flanged connections were used to connect the various sections of the flowline.It is well known that flanges are prone to failure due to external stress.Manual venting at flange locations not only requires periodic monitoring, which increases operating expenses, but also results in permeable gas emissions to the atmosphere.In the second trial, the flanges were replaced with welded, flangeless connectors with an automatic refill system, and a slotted liner with a vent at the end of the remote degassing station that would Terminate in a closed drain.
A 5-year trial confirms that the use of HDPE linings in carbon steel pipes can mitigate internal corrosion in oil pipelines by isolating metal pipes from corrosive fluids.
Add value by providing uninterrupted line service, eliminating internal pigging to remove deposits and bacteria, saving costs by eliminating the need for anti-scaling chemicals and biocides, and reducing workload
The purpose of the test was to mitigate internal corrosion of the pipeline and prevent the loss of the primary containment.
Slotted HDPE liners with welded flangeless joints are used in conjunction with the re-injection system as an improvement based on lessons learned from the initial deployment of plain HDPE liners with clips on flanged terminals.
According to the success and failure criteria set for the pilot, no leaks have been reported in the pipeline since installation.Further testing and analysis by BIC has shown a 3-5% weight reduction in the used liner, which does not cause chemical degradation after 5 years of use.Some scratches were found that did not extend into the cracks.Therefore, it is recommended to consider the difference in density loss in future designs.Implementation of internal corrosion barriers should be the main focus, where HDPE lining options (including already identified improvements such as replacing flanges with connectors and continuing the lining and applying a check valve in the lining to overcome the gas permeability of the lining) are A reliable solution.
This technology eliminates the threat of internal corrosion and provides significant savings in operating expenses during chemical treatment procedures, as no chemical treatment is required.
Field validation of the technology has had a positive impact on operators’ flowline integrity management, providing more options for proactive flowline internal corrosion management, reducing overall costs and improving HSE performance.Flangeless grooved HDPE liners are recommended as an innovative approach to managing corrosion in oilfield streamlines.
HDPE lining technology is recommended for existing oil and gas fields where pipeline leaks and water injection line interruptions are common.
This application will reduce the number of flowline failures caused by internal leaks, extend flowline life, and increase productivity.
New full site developments can use this technology for in-line corrosion management and cost savings on monitoring programs.
This article was written by JPT Technical Editor Judy Feder and contains highlights from the SPE 192862 paper, “Innovative Field Trial Trial Results of Flangeless Grooved HDPE Liner Application in a Super Gigantic Field for Oil Flowline Internal Corrosion Management” by Abby Kalio Amabipi, SPE, Marwan Hamad Salem, Siva Prasada Grandhe and Tijender Kumar Gupta of ADNOC; Mohamed Ali Awadh, Borouge PTE; Nicholas Herbig, Jeff Schell and Ted Compton of United Special Technical Services for the 2018 2018 in Abu Dhabi, November 12-15 Prepare for the Abu Dhabi International Petroleum Exhibition and Conference.This paper has not been peer-reviewed.
The Journal of Petroleum Technology is the flagship journal of the Society of Petroleum Engineers, providing authoritative briefs and features on advances in exploration and production technology, oil and gas industry issues, and news about SPE and its members.