摘要
海域天然气水合物藏往往伴随着大量游离气的存在,而储层的低渗透性限制了不同层系的气水流动,利用储层中的水合物分解气和游离气是提升水合物藏产气效率的关键。基于中国南海神狐海域的实际地质数据,使用TOUGH+HYDRATE模拟器,建立3种不同水合物储层垂直井联合开采的数值模型,分析了产气、产水、温度、压力场和水合物饱和度的空间变化,进而提出天然气水合物的优化降压开采策略。结果表明:降压开采过程中,气和水不断向开采井汇集,井周围的温度压力迅速下降;持续降压开采10 a,随着产气速率的减小,产水速率不断增大,三层联合开采方式的累计产气量最高可达4.59×106 m^(3),其累计产水量为8.31×10^(5)m^(3);水合物的分解由降压的压力梯度控制,井周围的水合物优先分解,下伏层水的流动会加快储层水合物的分解。
Offshore natural gas hydrate reservoirs are often accompanied by a large amount of free gas.However,the low permeability of the reservoir limits the flow of gas and water in different layers.Therefore,the fully exploitation of the hydratedissociation gas and free gas in the reservoir is the key to improve gas production efficiency.Based on the actual geological data in the Shenhu area of the South China Sea,the TOUGH+HYDRATE code is used to establish the numerical model of the combined exploitation of three different hydrate reservoirs with vertical wells.The spatial changes of gas production,water production,temperature,pressure field and hydrate saturation are analyzed,and then the optimized depressurization production strategy of natural gas hydrate is put forward.The results show that during the depressurization production,gas and water are continuously collected to the production well,and the temperature and pressure around the well drop rapidly.After continuous production for ten years,the water production rate continues to increase with the decrease of gas production rate.The cumulative gas production of three-layer combined mining method is up to 4.59×106 m^(3),and the cumulative water production is 8.31×10^(5)m^(3).Hydrate dissociation is controlled by the depressurized gradient,hydrates around the well are preferentially dissociated,and the flow of underlying water will accelerate the dissociation of reservoir hydrates.
作者
杨作亚
武晓敏
YANG Zuoya;WU Xiaomin(Chongqing City Management College,School of Smart finance and Economics,Chongqing 401331,China;Chongqing City Management College,School of Civil Affairs and Social Governance,Chongqing 401331,China)
出处
《油气藏评价与开发》
CSCD
2023年第3期393-402,共10页
Petroleum Reservoir Evaluation and Development
基金
重庆市教委科学技术研究项目“煤层水力压裂渐进损伤增透机理及优化可抽采范围研究”(KJQN202003302)
重庆城市管理职业学院第三批创新团队项目“矸石资源化利用与力学分析”(KYTD202003)。
关键词
天然气水合物
产气效率
联合开采
数值模型
神狐海域
natural gas hydrate
gas production efficiency
combined exploitation
numerical model
Shenhu area
