塔里木盆地寒武系海相烃源岩有机成熟度及演化史

Maturity and its history of Cambrian marine source rocks in the Tarim Basin

原生有机组分(镜状体和动物有机组分)反射率是评价塔里木盆地寒武系海相烃源岩有机成熟度的有效方法。从分析的探井和露头区110多个寒武系样品有机组分反射率数据来看,塔里木盆地寒武系烃源岩均处于高过成熟阶段,尚未发现目前仍处于生油窗阶段的寒武系中等成熟的烃源岩。利用BasinMod-1D软件计算了250口探井,26条地震测线中约340个人工井点有机成熟度随时间的变化,据此编制不同地质时期塔里木盆地台盆区寒武系有机成熟度平面变化图。目前满加尔凹陷中下寒武统烃源岩镜质体反射率在3%以上,中下寒武统烃源岩成熟度相对较低区分布在塔中隆起主垒带、塔北隆起的凸起区(英买力凸起)和巴楚断隆一部分地区,其等效镜质体反射率Ro在1.6%～2.0%之间。

The reflectance of primary organic macerals(vitrinite-like maceral and zooclast)are effective index for assessing the maturity of Cambrian m arine source rocks in the Tarim Basin,According to the primary organic macerals reflectance data of more th an 110samples from Cambrian marine s ource rocks in wells and outcrops,th e middle and lower Cambrian source roc ks of the Tarim Basin are in the high ma ture and overmature phase,no Cambrian source rocks still exist in the maturity phase of oil windows pre sently.Maturity distribution and e volution of Cambrian source rocks are delinea ted using software BasinMod-1D on 250wells and 340pseudowells from the 26seismic profiles.Presently,the vitrinite reflectance equivalents(VRE)of Cambrian source rocks are higher t han3%in the Manjaer Depression,and hig her than 4%in the central area of the Manjee Depression.The relative lower maturity area of the middle and lower Cambrian source rocks are loca ted in the high areas of the Tazhong Uplift and the Tabei Uplift,and limi ted area of the Bachu Uplift,with VRE ranging from 1.6%to 2.0%.