摘要
天然气水合物是一种清洁高效的潜在替代能源,提高开采效率对促进其产业化发展具有重要意义。本文借助开源程序HydrateResSim,针对具有强封闭性边界的第三类水合物藏薄层进行了直井和径向井降压开采天然气水合物产能模拟,对比了直井和径向井降压开采过程中温度场、压力场、水合物饱和度及产能变化规律,分析了径向井降压开采增产机理。模拟发现径向井降压开采能够显著降低近井区域的渗流阻力,增加储层中的有效泄流面积。通过促进压降向储层内部传播,径向井不仅扩大了水合物的分解范围,也减缓了开采过程中水合物的二次生成。由于水合物的分解是一个吸热过程,径向井开采水合物时所产生的低温区域不仅范围更大,且温度更低。相同压降条件下,径向井开采1000 d时累计产气量超过25万m^(3),是直井的3倍以上,累计产气产水比超过60,约为直井的2倍,表现出较好的增产潜力。研究表明径向井能显著提高水合物产能,有助于促进我国南海水合物早日实现商业化开发。
Natural gas hydrate is a potential alternative source of energy for the future,and improving the extraction efficiency is of great significance to promote its industrial development.In this study,productivity simulation of natural gas hydrate by radial well depressurization and vertical well depressurization is studied with the use of Hydrate Res Sim.This numerical model was developed for thin layers of Class 3 hydrate reservoirs with closed boundaries.By comparing the changes of temperature,pressure and hydrate saturation during gas production by a vertical well and a four-branch radial well,the reservoir stimulation mechanism of radial wells is investigated.We find that depressurization through radial wells can significantly reduce the seepage resistance in the near-well area and increase the effective drainage area.Besides,radial wells can promote the propagation of pressure drop to the inside of the reservoir,which expands the region of hydrate dissociation and slows down the secondary formation of hydrate.The decomposition of hydrate is an endothermic process.Therefore,the low temperature area generated in the hydrate extraction process by a radial well has a larger range and has a more significant temperature drop.Under the same pressure drop,radial wells’cumulative gas production exceeds 250 thousand cubic meters during 1,000 days’production,which is more than three times that of the vertical well.The cumulative gas-to-water ratio of the radial well exceeds 60,which is about twice that of the vertical well.Results show that radial wells can significantly improve hydrate recovery efficiency,which helps to promote the commercial exploitation of hydrates in the South China Sea.
作者
张潘潘
田守嶒
张逸群
李根生
武晓亚
王宇豪
ZHANG Panpan;TIAN Shouceng;ZHANG Yiqun;LI Gensheng;WU Xiaoya;WANG Yuhao(State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum-Beijing,Beijing 102249,China;China University of Petroleum-Beijing at Karamay,Karamay 834000,China;Jiangzuan Company of Petroleum Machinery Company Limited of Sinopec,Wuhan 430000,China)
出处
《石油科学通报》
2021年第3期417-428,共12页
Petroleum Science Bulletin
基金
国家自然科学基金国际(地区)合作与交流项目(41961144026)
国家自然科学基金重大项目课题(51991362)
国家自然科学基金重大科研仪器研制项目(51827804)联合资助国家自然科学基金青年基金(51804320)。
关键词
天然气水合物
径向井
降压法
产能模拟
中国南海
natural gas hydrate
radial well
depressurization method
production simulation
South China Sea
