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Special Section of Evaluation of Natural Gas Hydrate Resource Potential in the South China Sea
Petroleum Science >2022, lssue 1: - DOI: https://doi.org/10.1016/j.petsci.2021.12.008
Evaluation of natural gas hydrate resources in the South China Sea by combining volumetric and trend-analysis methods Open Access
文章信息
作者：Xing-Wen Zhang, Tao Hu, Xiong-Qi Pang, Yao Hu, Tong Wang, En-Ze Wang, Zhi Xu, Xiao-Han Liu, Zhuo-Ya Wu,
作者单位：
投稿时间：
引用方式：Xing-Wen Zhang, Tao Hu, Xiong-Qi Pang, Yao Hu, Tong Wang, En-Ze Wang, Zhi Xu, Xiao-Han Liu, Zhuo-Ya Wu, Evaluation of natural gas hydrate resources in the South China Sea by combining volumetric and trend-analysis methods, Petroleum Science, Volume 19, Issue 1, 2022, Pages 37-47,
文章摘要
Abstract
Natural gas hydrate (NGH), considered as a type of premium energy alternative to conventional hydrocarbons, has been broadly studied. The estimate of the total NGH resources in the world has decreased by more than 90% since the first evaluation in 1973. Geographic and geophysical conditions of the South China Sea (SCS) are favorable for the formation of NGH, which has been proved by drilling results up to date. The recoverability of the NGH in the SCS has been confirmed by the production tests using both vertical and horizontal wells. Since 2001, 35 estimates of NGH resources in the SCS have been made, with relatively stable results varying between 600 and 900 × 109 ton oil equivalent. In these estimations, the volumetric method was commonly adopted, but the geological conditions, the migration-accumulation mechanisms of NGH, and the practical recoverability were not considered. These estimates cannot be regarded as evaluated resources according to the international resource evaluation standards, but are at most about prospective gas content of NGH, thus inefficient for guiding explorations and developments. To solve these problems, this study divides the past NGH surveys in the SCS into seven stages, acquires key geological parameters of every stage based on previous studies and analogy with other areas, evaluates the NGH resources of these seven stages by using the volumetric method, then adopts a new trend-analysis method to simulate the downward trend of these estimates, and finally predicts the NGH resources in the SCS at 2025 and 2030. The downward trend is because of the continuous improvement of NGH understanding over time, which is consistent with the trend of global NGH estimates. At the present stage (from 2019 to 2021), the average technically recoverable resource (ATRR) is 7.0 × 1012 m3, and the estimates of 2025 and 2030 ATRR are 6.46 × 1012 m3 and 4.01 × 1012 m3 respectively, with a difference of less than 40%. Therefore, it can be inferred that the ATRR of NGH in the SCS is between 4.0 and 6.5 × 1012 m3, with an average of 5.25 × 1012 m3.
Natural gas hydrate (NGH), considered as a type of premium energy alternative to conventional hydrocarbons, has been broadly studied. The estimate of the total NGH resources in the world has decreased by more than 90% since the first evaluation in 1973. Geographic and geophysical conditions of the South China Sea (SCS) are favorable for the formation of NGH, which has been proved by drilling results up to date. The recoverability of the NGH in the SCS has been confirmed by the production tests using both vertical and horizontal wells. Since 2001, 35 estimates of NGH resources in the SCS have been made, with relatively stable results varying between 600 and 900 × 109 ton oil equivalent. In these estimations, the volumetric method was commonly adopted, but the geological conditions, the migration-accumulation mechanisms of NGH, and the practical recoverability were not considered. These estimates cannot be regarded as evaluated resources according to the international resource evaluation standards, but are at most about prospective gas content of NGH, thus inefficient for guiding explorations and developments. To solve these problems, this study divides the past NGH surveys in the SCS into seven stages, acquires key geological parameters of every stage based on previous studies and analogy with other areas, evaluates the NGH resources of these seven stages by using the volumetric method, then adopts a new trend-analysis method to simulate the downward trend of these estimates, and finally predicts the NGH resources in the SCS at 2025 and 2030. The downward trend is because of the continuous improvement of NGH understanding over time, which is consistent with the trend of global NGH estimates. At the present stage (from 2019 to 2021), the average technically recoverable resource (ATRR) is 7.0 × 1012 m3, and the estimates of 2025 and 2030 ATRR are 6.46 × 1012 m3 and 4.01 × 1012 m3 respectively, with a difference of less than 40%. Therefore, it can be inferred that the ATRR of NGH in the SCS is between 4.0 and 6.5 × 1012 m3, with an average of 5.25 × 1012 m3.
关键词
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Resource evaluation; Natural gas hydrates; The South China Sea; Volumetric method; Trend-analysis method