摘要
中国海相页岩沉积时代老、热演化程度高、保存条件复杂,原有的页岩气资源潜力评价方法未考虑页岩成烃演化的动态过程,不能有效地反映页岩气的真实生成能力。为此,基于四川盆地JY2井上奥陶统五峰组—下志留统龙马溪组海相高演化页岩沉积埋藏史和热演化史,提出了一种针对海相高演化页岩气生成与保存能力动态评价的方法,并通过热模拟实验研究排油效率控制下的页岩生气能力,再采用正反演相结合的方法从生排滞的角度对页岩气生成与保存的全过程开展(半)定量评价,并在此基础上探讨了页岩气有利区的总有机碳含量(TOC)下限。研究结果表明:①正演热模拟实验可以明确干酪根和滞留油对页岩气的生成贡献,可建立不同排油效率下页岩的生气潜力图版;②热模拟实验五峰组—龙马溪组页岩生油阶段最大排油效率为68.79%,与固体沥青反演计算得到JY2井的平均排油效率66.52%相近;③四川盆地JY2井海相高演化页岩气保存比例为10%~40%,总体上散失了60%~90%;④TOC对页岩气的保存有一定控制作用,残余TOC大于1.50%的页岩散失了60%~80%的天然气,残余TOC小于1.50%的页岩散失了70%~90%的天然气;⑤当页岩气散失效率为70%、排油效率为50%~80%时,有机质成熟度为2.00%的有利区页岩TOC下限为1.77%~3.00%,有机质成熟度为3.00%的有利区页岩TOC下限为0.95%~1.70%。结论认为,海相高热演化阶段的页岩气评价既要重视后期改造页岩气的散失,也要关注早期油的排出,从动态演化角度来确定页岩气有利区的页岩TOC评价指标。
Marine shale in China is characterized by old sedimentary age,high degree of thermal evolution and complex preservation conditions.The original method of evaluating resource potential of shale gas neglets the dynamic process of shale gas generation and evolution,so it fails to reflect the real shale gas generation capacity effectively.Based on the sedimentation,burial and thermal evolution histories of the Upper Ordovician Wufeng Formation–Lower Silurian Longmaxi Formation highly evolved marine shale in Well JY2 of the Sichuan Basin,this paper proposes a dynamic evaluation method of the generation and preservation capacity of highly evolved marine shale gas.In addition,the shale gas generation capacity controlled by oil expulsion efficiency is studied by means of thermal simulation experiments.And from the perspective of shale gas generation,expulsion and retention,the whole process of shale gas generation and preservation is(semi-)quantitatively evaluated by combining forward and inverse modeling methods.On this basis,the TOC lower limit in favorable zones of shale gas is discussed.The following results are obtained.First,the forward thermal simulation experiments can show the contribution of kerogen and retained oil to the generation of shale gas,and can be used to establish the shale gas generation potential chart at different oil expulsion efficiencies.Second,the thermal stimulation experiments show that the largest oil expulsion efficiency of Wufeng–Longmaxi Formation in the oil generation stage is 68.79%,which is close to the average oil expulsion efficiency(66.52%)of Well JY2 inverted from solid bitumen.Third,the preservation ratio of highly evolved marine shale gas in Well JY2 of the Sichuan Basin is 10%–40%,which means 60%–90%of shale gas is lost in general.Fourth,TOC content has a certain controlling effect on the preservation of shale gas.The natural gas lost from the shale with residual TOC greater than 1.5%accounts for 60%to 80%,and that from the shale with residual TOC less than 1.5%accounts for 70%to 90%.Fifth,when the shale gas loss rate is 70%and the oil expulsion efficiency ranges between 50%and 80%,the TOC lower limit of shale in favorable zones is 1.77%–3.00%(Ro=2.0%)and 0.95%–1.70%(Ro=3.0%),respectively.In conclusion,the evaluation of highly evolved marine shale gas should not only focus on the loss of shale gas in the late reworking stage,but also on the oil expulsion in the early stage.The TOC evaluation index of favorable zones of shale gas should be determined from the perspective of its dynamic evolution.
作者
马中良
崔海骕
宋振响
王远
何川
MA Zhongliang;CUI Haisu;SONG Zhenxiang;WANG Yuan;HE Chuan(State Key Laboratory of Shale Oil&Gas Enrichment and Effective Development,Wuxi,Jiangsu 214126,China;State Energy KeyLaboratory of Carbonate Oil and Gas,Wuxi,Jiangsu 214126,China;Sinopec Key Laboratory of Petroleum Accumulation Mechanisms,Wuxi,Jiangsu 214126,China;Wuxi Research Institute of Petroleum Geology,Sinopec Exploration and Production Research Institute,Wuxi,Jiangsu 214126,China)
出处
《天然气工业》
北大核心
2025年第5期57-68,共12页
Natural Gas Industry
基金
国家自然科学基金项目“三大盆地深层—超深层海相油气高效勘探开发基础研究”(编号:U24B6001)
中国石化科技攻关重大项目“中国石化‘十四五’资评评价方法与数据库建设”(编号:P23229)
中国石化基础前瞻性研究项目“深层古老烃源岩生排滞油气机制与有效性评价”(编号:P24206)。
关键词
四川盆地
上奥陶统五峰组—下志留统龙马溪组
海相高演化页岩气
模拟实验
排油效率
TOC下限
Sichuan Basin
Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation
Highly evolved marine shale gas
Simulation experiment
Oil expulsion efficiency
TOC lower limit
