摘要
南海荔湾区域赋存有大量的天然气水合物资源,储层具有薄层和厚层水合物互层分布特征,极具开发潜力。因此,基于该区域多层水合物地质资料,利用TOUGH+HYDRATE建立了该区域水平井降压开采数值模型,井底开采压力取值为0.2倍的第三层水合物底部初始压力,主要研究了储层渗透率对水合物开采的影响规律。结果表明:降压法能够有效促进井周水合物分解,但受到地层低渗透率的制约,水合物有效分解范围主要局限于井周有限的圆形区域内,且在分解前缘面附近易形成少量的二次水合物;增大地层渗透率对水合物增产效果影响最为显著,当地层渗透率增大至20 mD时,水平井布设在最下部水合物层中间时,可以同时开采三层水合物,从而极大提高了开采效率,但同时也会导致地层流体涌入井眼,产水量急剧增大。
There are a lot of natural gas hydrates buried in Liwan Area of South China Sea,and the reservoir has the characteristics of interbedded distribution of thin and thick hydrate layers,which shows a promising production potential.Therefore,based on the available geological data of hydrate reservoirs in this region,a production model using horizontal well by depressurization was established in TOUGH+HYDRATE.The bottom hole pressure was assigned to be 0.2 times the initial bottom pressure of the third hydrate layer.The effect of reservoir permeability on gas recovery behaviors was investigated in detail.The results show that depressurization can effectively trigger hydrate dissociation around the well,but the dissociation range is primarily distributed in a limited circular area,which is mainly caused by the low formation permeability.In addition,a small amount of secondary hydrate forming near the dissociation front can be observed.Increasing the formation permeability presents the most significant enhancement effect on gas recovery.When the formation permeability is increased to 20 mD,the horizontal well deployed in the middle position of the lower hydrate layer is able to extract all hydrates in three layers together,which sharply improves the production efficiency.However,the formation fluid may also invade into the wellbore,resulting in the dramatic increase in water production.
作者
孙嘉鑫
赵洪宝
曹鑫鑫
毛佩筱
SUN Jia-xin;ZHAO Hong-bao;CAO Xin-xin;MAO Pei-xiao(Faculty of Engineering,China University of Geosciences(Wuhan), Wuhan 430074, China;China Construction Eighth Engineering Division Co.,Ltd, Nanjing 210033, China)
出处
《科学技术与工程》
北大核心
2021年第24期10246-10256,共11页
Science Technology and Engineering
基金
国家重点研发计划(2018YFE0126400)
国家自然科学基金(51904280)
广东省自然资源厅项目([2020]047)
中央高校基本科研业务费(CUG190620)。
关键词
天然气水合物
数值模拟
开采
储层响应
natural gas hydrate
numerical simulation
production
reservoir response
