Status Quo and Recommendations on the Technology of Gas Hydrate Production in technology in South China Sea

Introduction. Marine gas hydrates are an unconventional resource of natural gas that is stored in deep-sea sediments in a solid state. It has a wide distribution and large reserves, and is also considered as an important alternative energy source for oil and natural gas in the future. The United States, Japan, China and other countries have introduced relevant laws and regulations regarding this energy source and have conducted a sufficient number of scientific studies. Currently, gas hydrate extraction technologies on the Chinese shelf mainly include the pressure reduction method and the solidphase fluidization method. These methods have their advantages and disadvantages, but they are difficult to meet the needs of commercial mining.

Materials and methods of research. Gas hydrates, commonly known as «combustible ice», are mainly found in the sediments of the seabed and permafrost on land. After decomposition, they can form gases such as methane, which is a clean energy source with rich resources and various countries consider it as an important alternative energy source in the future. However, traditional natural gas resources in China are struggling to meet the demand for clean energy as a result of economic development, and the extraction of gas hydrates promises to be an effective way to solve this problem. Thus, the study of gas hydrates can not only contribute to the early commercial exploitation of gas hydrate resources in the South China Sea, but also allows us to hope for a reduction in the cost of deep-sea traditional natural gas resources.

The results of the study and their discussion. The article provides a detailed description of each method of gas hydrate extraction technology in China with a comparative analysis of their advantages and disadvantages of application in practice. Tests of gas hydrates in the South China Sea with an assessment of their results are also given as an example.

Conclusions. The article provides recommendations on the issue of gas hydrate production in the South China Sea. Recommendations are given on the need for simultaneous research of traditional technologies and breakthrough production technologies, as well as improving the technology of interpretation and evaluation of gas hydrates in the sea area, with subsequent cost reduction in terms of the entire life cycle and, as a result, the study of key equipment and technologies for deep-sea operations.

1. Duan Y., Shnip O.A. Gas hydrates in the South China Sea. Theoretical foundations and technologies of oil and gas prospecting and exploration. M.: Publishing house: Scientific Research Design Institute of Oil and Gas, 2013. No. 4, p. 41–43. (In Russ.)

2. Shits E.Yu., Koryakina V.V. Gas hydrates: a brief information review of modern foreign studies // Gas Industry, No. 12, 2020, p.1–13. (In Russ.)

3. Shnyukov E.F., Gozhik P.F., Krayushkin V.A., Klochko V.P. Three steps from the submarine production of gas hydrates // Geology and minerals of the world ocean, 2020, No. 2, volume 16, p. 32–51. (In Russ.)

4. Hou L., Sun N.D., Zhang H. Z. World’s major oil companies’ basic predictions on the industry development prospects in the post-COVID-19 epidemic era // World Petroleum Industry, 2020. Vol. 27. No. 5. P. 36–41.

5. Lee J. Y., Ryu B. J., Yun T. S. et al. Review on the gas hydrate development and production as a new energy resource // KSCE Journal of Civil Engineering, 2011. Vol. 15. No. 4. P. 689–696. https://doi.org/10.1007/s12205-011-0009-3.

6. Wu X. S., Huang W. B., Liu W. C., et al. World-wide progress of resource potential assessment, exploration and production test of natural gas hydrate. Marine Geology Frontiers, 2017. Vol. 33 No. 7. P. 63–78.

7. President Biden orders U.S. to rejoin Paris Agreement on climate change. URL: http://www.xinhuanet.com/english/2021-01/21/c_139685346.htm. (Accessed 22.06.2022).

8. From «deep sea entry» to «deep sea exploration anddevelopment ». URL: https://www.sohu.com/a/199422623_120702 (Accessed 22.06.2022).

9. Yu T., Guan G. Q., Abdula A. Production performance and numerical investigation of the 2017 offshore methane hydrate production test in the Nankai Trough of Japan // Applied Energy, 2019. No. 251. P. 113338. https://doi.org/10.1016/j.apenergy.2019.113338.

10. Liang Y. P., Tan Y. T., Luo Y. J. et al. Progress and challenges on gas production from natural gas hydratebearing sediment // Journal of Cleaner Production, 2020. No. 261. P. 121061. https://doi.org/10.1016/j.jclepro.2020.121061.

11. Li S. D., Li X., Wang S. J. et al. A novel method for natural gas hydrate production: depressurization and backfilling with in-situ supplemental heat // Journal of Engineering Geology, 2020. Vol. 28. No. 2. P. 282–293. https://doi.org/10.1021/acsomega.1c01143.

12. Chen Q., Hu G. W., Li Y. L. et al. A prospect review of new technology for development of marine gas hydrate resources // Marine Geology Frontiers, 2020. Vol. 36. No. 9. P. 44–55. https://doi.org/10.16028/j.1009-2722.2020.081.

13. Li N., Wang X. H., Lyu Y. N. et al. Challenges and key technologies in development of natural gas hydrates // Petroleum Science Bulletin, 2016. Vol. 1. No. 1. P. 171–174. https://doi.org/10.3389/fenrg.2022.860591.

14. Lu Q. P. Study on multiphase flow in wellbore of deepwater gas hydrate coiled tubing horizontal well // China Petroleum and Chemical Standard and Quality, 2019. Vol. 39. No. 5. P. 70– 71, 74. https://doi.org/10.1088/1755-1315/632/2/022049.

15. Pan D. B., Chen C., Yang L. et al. Physical simulation experiment system for jet erosion of natural gas hydrate // Drilling Engineering, 2018. Vol. 45. No. 10. P. 27–31. https://doi.org/10.3969/j.issn.1672-7428.2018.10.006.

16. Li J. F., Ye J. L., Qin X. W. et al. The first offshore natural gas hydrate production test in South China Sea // China Geology, 2018. No. 1. P. 5–16. https://doi.org/10.31035/cg2018003.

17. Wang Z. G., Zhang Y. Q., Liang J., et al. Theoretical study on the application of SAGD technology in exploitation of natural gas hydrate in land permafrost region // Exploration Engineering (Rock & Soil Drilling and Tunneling), 2017. Vol. 44. No. 5. P. 14–18. https://doi.org/10.3969/j.issn.1672-7428.2017.05.003.

18. Zhou S. W., Chen W., Li Q. P. et al. Research on the solid fluidization well testing and production for shallow non-diagenetic natural gas hydrate in deep water area // China Offshore Oil and Gas, 2017. Vol. 29. No. 4. P. 1–8. https://doi.org/10.1007/s11708-020-0684-1.

19. Li Y. L., Liu C. L., Liu L. L. et al. Mechanical properties of methane hydrate-bearing unconsolidated sediments //Journal of China University of Petroleum. Edition of Natural Science, 2017. Vol. 41. No. 3. P. 105–113. https://www.sciencedirect.com/science/article/pii/S2096519219300060 (Accessed 22. 06.2022).

20. Zhang X. H., Lu X. B. A new exploitation method for gas hydrate in shallow stratum: mechanical-thermal method // Chinese Journal of Theoretical and Applied Mechanics, 2016. Vol. 48. No. 5. P. 1238–1246.

21. Wei N. Charts of cuttings carrying capacity in different hole enlargement modes for drilling horizontal wells in marine gas hydrate reservoirs // Oil Drilling & Production Technology, 2019. Vol. 41. No. 4. P. 435–440. https://doi.org/10.3390/en13051129.

22. Wu N. Y., Huang L., Hu G. W. et al. Geological controlling factors and scientific challenges for offshore gas hydrate exploitation // Marine Geology & Quaternary Geology, 2017. Vol. 37. No. 5. P. 1–11. https://doi.org/10.16562/j.cnki.0256-1492.2017.05.001.

23. Fu Q., Wang G. R., Zhou S. W. et al. Development of marine natural gas hydrate mining technology and equipment // Strategic Study of CAE, 2020. Vol. 22. No. 6. P. 32–39. https://doi.org/10.15302/J-SSCAE-2020.06.005.

24. Li F. G., Yuan Q., Li T. D. et al. A review: Enhanced recovery of natural gas hydrate reservoirs // Chinese Journal of Chemical Engineering, 2018. Vol. 27. No. 9. P. 2062–2073. https://doi.org/10.1016/j.cjche.2018.11.007.

25. Liang Y. P., Tan Y. T., Luo Y. J. et al. Progress and challenges on gas production from natural gas hydratebearing sediment // Journal of Cleaner Production, 2020. Vol. 261. P. 121061. https://doi.org/10.1016/j.jclepro.2020.121061.

26. The first successful trial production of natural gas hydrate (combustible ice) in China. URL: http://www.gmgs.cgs.gov.cn/tbzl/shwsc/201801/t20180103_448661.html (Accessed 22.06.2022).

27. Chen H. L., Wan X. M., Chen J. et al. Record of the second round of trial production of natural gas hydrate in China. URL: https://www.cgs.gov.cn/gzdt/zsdw/202004/t20200403_629610.html (Accessed 22.06.2022).

28. Yang J. H., Hou L., Guo X. X. et al. Prospect for lowcost development of marine gas hydrate // World Petroleum Industry, 2020. Vol. 27. No. 4. P. 22–26. https://doi.org/10.1051/e3sconf/202020801002.