内蒙古二连盆地岩性油藏形成与分布的优势性特征

近几年在内蒙古二连盆地岩性油藏勘探方面的突破表明,岩性油气藏的形成和分布比构造油气藏更具优势性特征。岩性油气藏形成的优势性表现在:(1)岩性圈闭多期形成有利于多期捕集油气;(2)近源短距离运移有利于成藏;(3)低部位岩性圈闭比高部位构造圈闭成藏期要早;(4)相对有利的盖层条件。保存条件也比构造油气藏要更具优势:(1)抬升剥蚀对岩性油藏的破坏程度小于对构造油藏的;(2)断层破坏对岩性油藏的破坏程度小于对构造油藏的。岩性油气藏的空间展布范围也更广阔:(1)同构造油藏相比,其分布范围更宽,陡坡带、缓坡带和洼槽带均可分布;(2)岩性油藏分布的体系域更宽,低水位体系域和高水位体系域都有富集;(3)岩性油藏分布的压力场更宽,在各种压力场环境中都有发现。因此,提出二连盆地岩性油气藏形成和分布具有“优势性特征”的观点。

Predominant Characteristics of Formation and Distribution for Lithologic Petroleum Reservoir in Erlian Basin, Inner Mongolia

The exploration in Erlian Basin in recent years shows that the lithologic reservoir has more predominant conditions in formation and distribution.The predominance in formation includes 4 aspects: ① lithologic traps have more forming periods and times,and it is helpful to entrap oil;② lithologic reservoirs can be formed with only primary migration and short distance secondary migration;③ lithologic reservoirs can be charged with oil earlier than structure reservoirs;④ lithologic reservoirs have more advantaged sealing conditions.Lithologic reservoirs experience little destruction in the later structural activities: uplift and fault activities can destroy(lithologic) reservoirs little than structure reservoirs.The scope of distribution of lithologic reservoirs is more(abroad:) ① lithologic reservoirs can distribute not only in steep slope structure belt,but also in gentle slope structure belt and sag belt;② lithologic reservoirs can enrich not only in low system tracts(LST),but also in high system tracts(HST);③ lithologic reservoirs can distribute in all types of geopressures.So it is concluded that the lithologic reservoirs in Erlian Basin have predominant conditions in their formation and distribution.