天然气轻烃指标的地质意义——以鄂尔多斯盆地神木气田与塔西南坳陷山前带天然气藏为例  

Geological significance of light hydrocarbon index of natural gas:Taking Shenmu gas field and piedmont zone of the southwest Tarim Basin as examples

作　　者：韩文学[1] 麻伟娇[1,2] 侯连华 陶士振[1] 胡国艺[1] 彭威龙[1] 

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]北京大学地球与空间科学学院,北京100871

出　　处：《石油与天然气地质》2017年第5期869-877,共9页Oil & Gas Geology

基　　金：国家科技重大专项(2016ZX05046-001)

摘　　要：轻烃中蕴含有丰富的地球化学信息,具有重要的地质意义。依据一系列轻烃参数指标,对神木气田及塔西南坳陷山前带的天然气进行了系统分析。结果显示:神木气田及阿克莫木气田以煤成气为主,前者个别井可能有少量油型气的混入,而柯克亚-柯东气田则为混合成因气。首次提出链烷烃指数标准,当其大于2时,为油型气或混合气,小于2时,为煤成气。根据Mango参数K_1和K_2值,神木气田的天然气来自同一套烃源岩,而塔西南坳陷山前带天然气则来自不同的烃源岩。根据Mango参数交会图版综合判断,神木气田及阿克莫木气田的天然气主要来源于陆相高等植物,而柯克亚-柯东气田的天然气主要为混合成因。根据异庚烷及庚烷辨识标准,神木气田处于低成熟-成熟阶段,阿克莫木气田处于成熟阶段,而柯克亚-柯东气田则属于高成熟阶段。Light hydrocarbon has abundant geochemical information and great geological significance.Using a series of light hydrocarbon parameters,the natural gas from Shenmu gas field in the Ordos Basin and piedmont zone of the southwest Tarim Basin were analyzed.The results show that the Shenmu and Akemomu gas field are mainly coal-derived gas.However,the former is mixed by partial oil-type gas.The natural gas from Kekeya-Kedong gas field is mainly mixed gas.For the first time,the alkane index parameter is put forward.When the index is above 2,it means the gas is oil-derived gas or mixed gas.When it is below 2,it means the gas is oil-derived gas.The natural gas from Shenmu gas field originated from the same source rocks according to K_1 and K_2 parameter.However,the gas from piedmont zone of the southwest Tarim Basin originated from different source rocks.According to Mango parameter intersection chart,the source rocks of Shenmu and Akemomu gas field were mainly from terrestrial higher plant origins.However,the source rocks of KekeyaKedong gas field are mixed.Based on isoheptane and n-heptane parameter,the maturity of Shenmu,Akemomu and Kekeya-Kedong gas field is low-normal stage,mature gas and high maturity gas stage,respectively.

关 键 词：成熟度 轻烃指标 气源对比 成因类型 天然气 神木气田 塔西南坳陷 

分 类 号：TE122.1[石油与天然气工程—油气勘探]