塔河-轮南油区奥陶系潜山油气藏特征

Characteristics of the Ordovician buried hill reservoirs in Tahe-Lunnan oil area

庞雯 江同文 郑浚茂 史鸿祥

Pang Wen Jiang Tongwen Zheng Junmao Shi Hongxiang

塔河-轮南油区奥陶系为潜山型油气藏,潜山形成于古生代、定型于中生代,经过多期构造抬升、剥蚀作用,潜山构造作用、岩溶作用比较发育,由构造、岩溶作用形成的缝洞系统构成奥陶系储层。中部、西部以风化壳岩溶作用为主,东部以深部岩溶作用为主。区内奥陶系潜山整体含油,局部富集成藏,油气分布受储层发育的控制。由于奥陶系油气藏具有多期生油、多次运移、成藏、调整的特点,造成区内不同构造带油气藏特征不同。西部为重质油或稠油油藏,中部斜坡区西部为正常密度的原油油藏,桑塔木断垒、桑南斜坡、轮南断垒的东部为带油环的凝析气藏,东部为凝析气藏。在潜山顶部"天窗"作用下,形成油水界面倾斜的悬挂式油气藏。

The Ordovician in Tahe-Lunnan oil area contains buried hill type reservoirs developed during the Paleozoie and finalized in the Mesozoic.Multi-stage tectonic uplift and denudation resulted in well-developed buried hill and karst,forming fracture-vug systems that constitute the Ordovician reservoirs.Weathering crust karstification mainly happened in the west and central areas of Tahe-Lunnan oil area,while deep karstification mainly occurred in the east in the whole Ordovician.Oil occurs in buried hill but only enriches locally to form oil pool, and the distribution of oil and gas is controlled by the development of reservoirs.Multiple stages of oil generation,migration,accumulation,and tectonic adjustment in this oil area caused the Ordovician reservoir characteristics varying with different structural zones:the west part of the area contains heavy oil reservoirs,the west of the central slop hold oil of normal density,Sang-ta-mu fault horst,the south slop of Sang-ta-mu,and the east of Lunnan fault horst,harbor condensate gas reservoirs with oil rim,and the east slope has condensate gas reservoirs.Hanging hydrocarbon reservoir with an inclined oil-water contact was also formed due to the skylight effect at the buried hill top.

10.11743/ogg20070609