秘鲁Ucayali盆地油气地质特征及勘探潜力分析

Petroleum geology and exploration potential of Ucayali Basin,Peru

秘鲁Ucayali盆地是位于安第斯山山前的前陆盆地之一,盆地内发育多套储盖组合。盆地内主力烃源岩包括上三叠统—下侏罗统Pucara组和二叠系Ene组的泥岩;发育多套储层,包括白垩系Chonta,Vivian,Cushabatay,Agua Caliente和Raya组储层,以及下二叠统的Ene组砂岩层等;盖层条件良好。北部主要发育基底相关的逆冲断层,而在盆地的南部发育薄皮式的逆冲断层,盆地内已发现的油气田的圈闭类型主要是与逆冲断层相关的断背斜圈闭。北Ucayali次盆Pucara组生成的油气运移至该组地层的剥蚀面,充注至白垩系,但遭到后期造山运动的破坏,通过再次运移聚集成藏。南Ucayali次盆中处于高—过成熟阶段的二叠系Ene组泥岩生成的天然气运移至上覆的二叠系和白垩系储层中。北Ucayali次盆西部的逆冲—前渊带圈闭、Pucara组碳酸盐岩圈闭、二叠系圈闭,以及盆地东部白垩系中的地层岩性圈闭是该盆地4个重要的潜力勘探领域。

The Ucayali Basin is one of the sub-Andean foreland basins with several types of pays.There are two sets of main source rocks including the Pucara Formation（T-J） and the Ene Formation（P）.Multiple sets of reservoirs generated,such as the Chonta,Vivian,Cushabatay,Agua Caliente and Raya Formations of Cretaceous and the Ene Formation of Permian.And the seal factors for the reservoirs are excellent.There are two types of thrust deformations in the Ucayali Basin.Basement-involved structures mainly occur in the north,while thin-skinned thrusting structures exist in the south.Traps of the discovered fields in the basin are mainly anticlines related to thrust faults.In the Northern Ucayali sub-Basin,hydrocarbons from the Pucara Formation move through unconformities and faults towards Cretaceous formations,and re-accumulate after the Quechua tectonic movement.However,in the Southern Ucayali sub-Basin,natural gas generate from the over mature shales of the Ene Formation,and migrate into the Permian and Cretaceous reservoirs.Four types of exploration leads exist in the basin： traps in thrustfold-foredeep belt,Carbonate reservoir in the Pucara Formation,gas prospects of Permian in the northern basin,and Cretaceous stratigraphic traps in the east of the basin.