Influences of pore fluid on gas production from hydrate-bearing reservoir by depressurization  

作　　者：Yi-Fei Sun Bo-Jian Cao Hong-Nan Chen Yin-Long Liu Jin-Rong Zhong Liang-Liang Ren Guang-Jin Chen Chang-Yu Sun Dao-Yi Chen 

机构地区：[1]State Key Laboratory of Heavy Oil Processing,China University of Petroleum,Beijing 102249,China [2]Division of Ocean Science and Technology,Tsinghua Shenzhen International Graduate School,Tsinghua University,Shenzhen,Guangdong 518055,China [3]School of Chemistry and Food Engineering,Changsha University of Science&Technology,Changsha,Hunan 410114,China [4]Oilfield Chemicals R&D Institute,COSL,Hebei 065201,China

出　　处：《Petroleum Science》2023年第2期1238-1246,共9页石油科学（英文版）

基　　金：financially supported by the National Natural Science Foundation of China,China(Nos.52004136,22127812,U20B6005);China Postdoctoral Science Foundation,China(Nos.2020M670347,2021T140382);Guangdong MEPP Fund(No.GDNRC[2021]055).

摘　　要：In addition to the temperature and pressure conditions,the pore fluid composition and migration behavior are also crucial to control hydrate decomposition in the exploitation process.In this work,to investigate the effects of these factors,a series of depressurization experiments were carried out in a visible one-dimensional reactor,using hydrate reservoir samples with water saturations ranging from 20%to 65%.The results showed a linear relationship between gas production rates and gas saturations of the reservoir,suggesting that a larger gas-phase space was conducive to hydrate decomposition and gas outflow.Therefore,the rapid water production in the early stage of hydrate exploitation could release more gas-phase space in the water-rich reservoir,which in turn improved the gas production efficiency.Meanwhile,the spatiotemporal evolution of pore fluids could lead to partial accelerated decomposition or secondary formation of hydrates.In the unsealed reservoir,the peripheral water infiltration kept reservoir at a high water saturation,which hindered the overall production process and caused higher water production.Importantly,depressurization assisted with the N2 sweep could displace the pore water rapidly.According to the results,it is recommended that using the short-term N2 sweep as an auxiliary means in the early stage of depressurization to expand the gas-phase space in order to achieve the highest production efficiency.

关 键 词：CH4 hydrate Water saturation DEPRESSURIZATION Gas-phase space N2 sweep 

分 类 号：TE37[石油与天然气工程—油气田开发工程]