摘要
松辽盆地断陷层系大、中型油气田主要分布于贯穿松辽盆地中央区域的北北东向孙吴-双辽岩石圈断裂两侧的深断陷之中。这些深断陷具有良好的成油气地质条件:1)断陷持续快速沉降,且周边断陷阻隔了盆缘大型物源,使之发育继承性大型深水、半深水湖泊,形成巨厚烃源岩系;2)在早-中燕山期的强烈走滑拉张时期,发生强烈走滑拉分作用,引发盆地火山活动及快速深陷,发育深水、半深水湖相泥岩夹火山岩、碎屑岩建造,由此形成火山岩、砂岩两类储集体;3)在断陷形成后,仍继承性快速沉降,披覆坳陷层系多套具有异常压力的巨厚湖相泥、页岩系,使断陷烃源岩持续热演化生烃,并使断陷具有良好的天然气封盖条件;4)后期稳定沉降,未发生强烈抬升,区域盖层保存良好,从而具有良好的气藏保存条件;5)基底深断裂在晚白垩世活动性明显减弱,对天然气藏的破坏明显减小。主要深断陷油气聚集规律研究表明,大、中型油气田分布在箕状深断陷生烃中心周缘发育的缓坡坡折带、坡垒带及陡坡坡折带上的一批近东西向继承性鼻状隆起构造与地层超覆尖灭、岩性复合圈闭之中,其中两个深断陷之间的隆起带是大油气田最有利的分布区域。
Middle and large oil/gas fields are largely distributed in the deep fault depressions along the two sides of NNE Sunwu-shuangliao lithosphere fault crossing the central part of Songliao basin. These fault depressions has favorable geological conditions for hydrocarbon reservoiring. First, very thick source rocks were deposited in the inherited large abyssal-hypabyssal lakes caused by constant and quick subsidence of the fault depression and the surrounding depressions＇ blockade of the large proveniences on basin edge. Secondly, two types of reservoir roeks-voleanies and sandstone-were formed when a severe strike slip extensional movement happened in early- middle Yanshan period and caused the development of lacustrine facies mudstone with volcanic rocks and detrital rocks interbedded. Thirdly, after the formation of fault depression, the continuous quick subsidence, together with the lacustrine facies mudstone and shale sequences with abnormal pressure in drape depression, forced the source rocks go through thermal evolution and hydrocarbon generation and shaped the cap rocks into favorable sealing material for natural gas in the depressions. Fourthly, as the depressions experienced stable subsidence with no severe lifting in the later period, well-preserved regional cap rocks provide favorable preservation condition for gas reservoirs. Finally, much less activities of basal deep faults in the Late Cretaceous in duced less destruction to the gas reservoirs.A study on the accumulation pattern in deep fault depressions shows that middle and large oil/gas fields are mainly distributed in the inherited latitudinally trending nose-like structure,stratigraphic overlapping pinch out traps,and complex lithological traps,among them the uplift zone between two deep fauly depressions is where the largest oil/gas fields are distributed.
出处
《石油与天然气地质》
EI
CAS
CSCD
北大核心
2006年第6期820-826,840,共8页
Oil & Gas Geology
关键词
断陷层系
油气富集带
大、中型油气田
勘探方向
松辽盆地
fault depressions,hydrocarbon enriehment zone
middle-and large-seale oil/gas fields
exploration target
Songliao basin
