美国Eagle Ford页岩油气产量递减规律新认识  

New Cognition on Shale Oil and Gas Output Successive Decline Pattern in Eagle Ford,US

作　　者：徐兵祥 白玉湖 陈岭 李彦尊 董志强 Xu Bingxiang;Bai Yuhu;Chen Ling;Li Yanzun;Dong Zhiqiang(CNOOC Research Institute Co.Ltd.,Beijing 100028)

机构地区：[1]中海油研究总院有限责任公司,北京100028

出　　处：《中国煤炭地质》2021年第12期15-19,共5页Coal Geology of China

基　　金：国家重点研发计划项目“页岩气资源勘查、地质评价与开发过程关键技术标准研究”(2018YFF0213802)。

摘　　要：页岩油气井生产通常表现出初期递减速度快、递减指数大于1的“非常规”递减特征,递减规律的认识也从最初的Arp’s双曲递减、到之后的Arp’s修改双曲递减、幂律指数递减、SEDM、Duong递减等,至今没有统一观点,尤其是中后期产量递减,目前认识尚不清楚。以美国Eagle Ford某页岩挥发油区块为例,研究了页岩油气中长期产量递减规律,分析了油气递减率和递减指数变化特征,结果表明:20a生产周期内该区页岩油气生产满足双曲递减规律;研究区产油量首年递减率为65%,产气量为42%,生产气油比逐年升高;早期生产历史递减指数大于1,但随时间推移,递减指数有减小趋势,目前全区分析的油气递减指数分别为0.59和0.55。敏感研究表明:递减指数变化规律受储层物性影响较大,受流体性质影响较小。建议对于生产历史较短的页岩油气井,运用递减分析方法时应考虑后期递减指数的变化,拟合时不应拘泥于递减指数大于1,应根据实际情况在合理范围内调整变化,以提高后期产量预测精度。Shale oil and gas production usually shows preliminary stage output quick successive decline with decline exponent greater than 1“unconventional”feature.Cognition on decline pattern is also from inchoative Arps hyperbolic decline to afterwards Arps modified hyperbolic decline,power law index decline,SEDM decline,and Duong decline etc,there is no uniform understanding so far,especially for middle and later stage output decline,current cognition still not clear.Taking a shale volatile oil block in Eagle Ford,US as an example,studied shale oil and gas medium and long term output decline pattern,analyzed oil and gas decline rate and decline exponent variation features.The result has shown that within a 20 years production cycle,the area’s shale oil and gas production accord with hyperbolic decline pattern.Study area first year oil output decline rate is 65%,gas output decline rate 42%,production gas-oil ratio increase year after year.Preliminary production history decline exponent is greater than 1,but with passage of time,decline exponent has decrease trend.At present,all area analyzed oil and gas decline exponent is 0.59 and 0.55 respectively.The sensitivity discussion has shown that decline exponent variation pattern has largely impacted by reservoir physical property,less from fluid properties.It is proposed that to production history shorter shale oil and gas wells,using decline analysis method should consider later stage decline exponent variation,fitting should not be stuck on decline exponent larger than 1,adjusted and changed within reasonable scope to promote later stage output prediction accuracy.

关 键 词：Eagle Ford 页岩油气 产量 递减规律 递减率 递减指数 

分 类 号：TE33[石油与天然气工程—油气田开发工程]