苏丹M盆地储集层流体地球化学特征与油藏注入史

Geochemistry characteristics of fluid and the filling history of heavy oil reservoir in the M Basin,Sudan

苏丹M盆地萨加隆起带Dar群稠油油藏的原油为典型的陆相盆地生成原油。m／z 191萜烷系列中，三环、四环萜烷含量较低，C29新藿烷、C30-重排藿烷含量较高，伽马蜡烷含量较低；m／z 217甾烷系列中，C27、C29重排甾烷含量高，C27、C28、C29甾烷呈“V”型分布，C29甾烷4个异构体中αββ构型含量低。这些地化特征反映原油母质发育于淡水沉积的水介质，以陆源有机质与水生生物混合输入为主，原油为生油高峰之前正常成熟的原油。包裹体中油的成熟度比孔隙中油的低，母质以陆源有机质占绝对优势，包裹体中的油是陆源有机质早期低温生成的原油。A．G．组油藏充注较早，在Dar群沉积末期（距今90Ma）就有油气充注储集层，主要充注时期应该是Amal组沉积时期（距今55～80Ma），Amal组沉积期末（距今50～55Ma）的剥蚀期是Dar群稠油油藏形成的主要时期，轻组分散失是Dar群稠油油藏形成的主要原因。

The crude oil in the heavy oil reservoir of the Sajia uplift zone in M Basin,Sudan, is typically generated in a continental basin. The crude oil is of lower maturity and with lower concentration of C29 Ts and C30-diahopane in m/z 191 . The distribution of C27 ,C28 ,C29 sterane is in the letter ＂V＂ form. The circumstance of source rock is fresh water sedimentation,and the organic matter of source rock is composed of terrestrial organic matter and aquatic organism. The oil maturity degree of inclusion is lower than that of pore-oil of sandstone and the source rock is dominated by terrestrial organic matters. The crude oil begins infilling into the sandstone of A.G. in late Dar episode and the primary period of forming oil reservoir is in the Areal period （55-80Ma）. The end of Amal （50-55 Ma） is the primary period of forming the heavy oil pool of Dar, and the major reason is that the light parts of crude oil were dissipated.