泥质粉砂型天然气水合物被认为是储量最大开采难度亦最大的水合物储层，2017年南海天然气水合物试采，初步验证了此类水合物储层具备可开采性。在总结前次试采认识的基础上，对试采矿体进行优选、精细评价、数值与试验模拟和陆地试验，中国地质调查局于2019年10月—2020年4月在南海水深1225 m神狐海域进行了第二次天然气水合物试采。本次试采攻克了钻井井口稳定性、水平井定向钻进、储层增产改造与防砂、精准降压等一系列深水浅软地层水平井技术难题，实现连续产气30 d，总产气量86.14×104 m3，日均产气2.87×104 m3，是首次试采日产气量的5.57倍，大大提高了日产气量和产气总量。试采监测结果表明，整个试采过程海底、海水及大气甲烷含量无异常。本次成功试采进一步表明，泥质粉砂储层天然气水合物具备可安全高效开采的可行性。
The natural gas hydrates-bearing shaly silt reservoirs are considered to be the most difficult target in exploitation. The first trial production test of the gas hydrate in the South China Sea conducted in 2017 proved that the reservoir is exploitable. On the basis of the understanding of the previous trial production, optimization and fine description of hydrate deposits, numerical simulation and onshore tests, the second gas hydrate trial production test were carried out by the China Geological Survey in the Shenhu sea area of the South China Sea from October 2019 to April 2020. This trial production overcame a series of technical problems, such as well head stability, horizontal well drilling, reservoir stimulating and sand controlling and accurate depressurizing, and achieved continuous gas production for 30 days, with a total gas output of 861400 cubic meters and a daily average gas production of 28700 cubic meters, which is 5.57 times the first trial production, thus greatly increasing the daily gas production and total gas production. The results show that there existed no abnormal methane content in sea floor, sea water and atmosphere during the whole process. The success of this test shows that it is possible to efficiently and safely develop the gas hydrate in shaly silt reservoirs.
叶建良,秦绪文,谢文卫,卢海龙,马宝金,邱海峻,梁金强,陆敬安,匡增桂,陆程,梁前勇,魏士鹏,于彦江,刘春生,李彬,申凯翔,史浩贤,卢秋平,李晶,寇贝贝,宋刚,李博,张贺恩,陆红锋,马超,董一飞,边航. 中国南海天然气水合物第二次试采主要进展[J]. 中国地质, 2020, 47(3): 557-568.
YE Jianliang, QIN Xuwen, XIE Wenwei, LU Hailong, MA Baojin, QIU Haijun, LIANG Jinqiang, LU Jing'an, KUANG Zenggui, LU Cheng, LIANG Qianyong, WEI Shipeng, YU Yanjiang, LIU Chunsheng, LI Bin, SHEN Kaixiang, SHI Haoxian, LU Qiuping, LI Jing, KOU Beibei, SONG Gang, LI Bo, ZHANG He'en, LU Hongfeng, MA Chao, DONG Yifei, BIAN Hang. Main progress of the second gas hydrate trial production in the South China Sea[J]. Geology in China, 2020, 47(3): 557-568(in Chinese with English abstract).