摘要
鄂尔多斯盆地下古生界天然气勘探长期以来以奥陶系顶部的古风化壳地层圈闭气藏为目标,近期通过对白云岩成藏机制的深化研究,在古隆起东侧发现了奥陶系中组合新型岩性气藏,其储层主要发育于马家沟组五段5亚段(简称马五5)白云岩中,储层特征明显不同于奥陶系顶部的风化壳储层。受沉积环境控制,中组合马五5白云岩呈SN向带状展布,其中靖边西白云岩带由于临近古隆起,水动力条件强,滩相沉积发育,后期经白云石化后形成的白云岩具有"分布面积广、厚度大、岩性纯,南北向连片展布"的特点,且晶间孔发育,为有利的储层。加里东末期,由于盆地整体抬升造成古隆起东侧中组合地层遭受剥蚀,从而与上古生界煤系烃源岩接触,构成良好的源-储配置关系。受岩性相变控制,中组合马五5滩相白云岩在空间上形成岩性圈闭,有利于油气聚集成藏。
The gas exploration of Lower Paleozoic in Ordos Basin has long been focusing on the stratigraphic trap gas reservoirs of pa leo-weathering crust at the top of Ordovician. Recently, a further study on the accumulation mechanism of dolomite reservoirs has found new lithologic gas reservoirs in the middle assemblages of Ordovician in the east of the palaeouplift. These reservoirs were mainly developed in the dolomites of the 5th sub member of 5th member of Majiagou Formation （Ma5 5 ）, with significantly different characteristics from those of the weathering crust reservoirs at the top of Ordovician. As controlled by sedimentary environment, the Mar 5 dolomites in the middle Ordovician assemblages were distributed in a belt of north south direction. , The dolomite belt in west ern Jingbian County was close to the palaeouplift with strong hydrodynamic conditions and developed shoal facies, and thus the dolo mite products after dolomitization are characterized by vast distribution area, large thickness, pure lithology, and south-north contin uous distribution. These dolomites have developed intercrystalline pores and serve as the favorable reservoirs. In the late Caledonian, the uplift of the entire basin led to the denudation of strata in the middle assemblages in the east of the palaeouplift. This allowed the middle assemblages to be in contact with hydrocarbon source rocks in the Upper Paleozoic, thus forming a good source reservoir rela tionship. Due to lithofacies variations, the dolomites of shoal facies in the Ma5 5 of middle assemblages formed lithological traps, thus favoring the gas accumulation.
出处
《石油学报》
EI
CAS
CSCD
北大核心
2012年第A02期118-124,共7页
Acta Petrolei Sinica
基金
国家重大科技专项"大型油气田及煤层气开发"(2011ZX05004-006)
中国石油天然气股份有限公司重大科技专项(2008E-0706)资助
关键词
鄂尔多斯盆地
奥陶系
中组合
白云岩
岩性圈闭
成藏特征
Ordos Basin
Ordovician
middle assemblages
dolomite
lithologic trap
accumulation characteristic
作者简介
第一作者及通讯作者：黄正良，男，1979年7月生，2006年获长江大学硕士学位，现为中国石油长庆油田公司勘探开发研究院工程师，主要从事天然气地质研究工作。Email：hzl0915_cq@petrochina．com．cn
