The overarching objectives of this project are to develop, investigate, and validate (for field and commercial deployment) robust pipeline coatings to prevent/minimize gas hydrate deposition in subsea oil flowlines. A robust pipeline coating that is capable of preventing gas hydrate adhesion/deposition will be a major fundamental breakthrough in gas hydrate science and engineering, and to critical Deepwater field operations. The proposed project will address the current major outstanding issue of mitigating gas hydrate deposition in different pipeline conditions, a major outstanding issue that has not been solved to-date, despite previous attempts/studies.
Colorado School of Mines (CSM), Golden, CO 80401
Oceanit Laboratories, Inc., Honolulu, HI 96813
Gas hydrates are considered the major flow assurance problem during Deepwater offshore production and transportation of oil and natural gas, which if not addressed adequately, can present severe production, environmental, and safety issues during operation (Sloan and Koh, 2007). The high-pressure (depths of seawater) and low-temperature (on the seafloor) conditions in Deepwater environments are ideal for providing thermodynamic stability of gas hydrates, thereby enabling gas hydrates to form and potentially plug Deepwater flowlines during oil and gas production and transportation. The formation of flowline blockages due to gas hydrates may result in rupture of the flowline, gas and oil spill and leakage, and hence catastrophic safety, economic, and environmental consequences. Costs for gas hydrate mitigation can exceed $1M/mile of pipeline, plus $100M/year in chemical costs for complete gas hydrate avoidance.
The conventional method of gas hydrate avoidance using thermodynamic inhibition, THI (e.g. using methanol or glycol) is becoming increasingly unfeasible from both an economic and environmental standpoint, particularly with Deepwater developments which present higher pressure conditions and hence more favorable conditions for gas hydrate stability, as well as maturing facilities in which the water content can increase significantly during the lifetime of the field. Thus, there is an imminent need for a new approach that allows operators to produce from wells where traditional gas hydrate mitigation is unfeasible. Low surface energy coating materials—which can be applied in situ to operational pipelines—represent a critical industry solution to gas hydrate mitigation, as these advanced coatings can repel gas hydrate adhesion to the wall, as well as repel the water layer that allows gas hydrates to form directly on the steel surface. Initial testing indicated that gas hydrate adhesion could be decreased by over an order of magnitude, but larger-scale experiments to evaluate and advance coating performance and survivability need to be performed.
As oil and gas production wells mature, the water content can increase and the risk of gas hydrate blockages in flowlines can become unmanageable, with the cost of complete gas hydrate inhibition becoming prohibitive. The ability to mitigate gas hydrate risk in maturing flowlines can extend the life of the field, as well as significantly reduce operational costs from inhibitor injection, and prevent potential safety hazards to personnel and equipment. The proposed research allows for a novel, cost-effective method of mitigating gas hydrate deposition/blockages in flowlines and extending the life of the field, while being minimally disruptive to normal flowline operation. The coating developed in this work can significantly improve the economics of energy transport by providing flow assurance, limiting catastrophic blowouts, and minimizing product loss from small but sustained leaks.
CSM is extending their deposition loop system to allow for larger-scale and more detailed hydrate-phobic coating testing under a variety of flow conditions. The deposition loop extension with structure construction is nearing completion and baseline testing will commence after instrument calibration, high-pressure validation, and leak testing have been completed. Oceanit is creating coupons demonstrating its omniphobic coating for use in CSM’s high-pressure rocking-cell apparatus . In addition, new coating material development is underway to test different material properties and curing procedures. Different coatings will be evaluated in order to determine which material properties will be the most effective in gas hydrate repellency and long term survivability. Internal and external kickoff meetings have been held, including discussions with industry members and NETL to determine areas of interest and align the work with commercial goals during the project.