东濮断陷含油气系统分析与勘探发现

Analysis of Petroleum System and Discovery of Oil and Gas in Dongpu Depression

运用含油气系统理论研究了东濮断陷含油气系统,提出了"纵向分层、横向分洼、洼中分层"的新思路,将东濮断陷含油气系统精细划分为4个级别:东濮断陷含油气系统为一级,是以古近系沙河街组(Es)为烃源岩,以三叠系(T)和Es为储层,即Es—T、Es的含油气系统。指出二级系统Es3—T、Es4、Es3、Es2为主力含油气系统,前梨园、濮城等主力生油洼陷中Es3—T、Es4、Es3、Es2三级含油气系统是油气勘探的靶区。油气勘探实践在一度认为没有油的地方取得了突破,发现了新层系、新类型和高产稳产区块。在濮城洼陷以Es43亚段为烃源岩的Es43-T、Es4、Es3、Es2四级含油气系统中,位于北部中央隆起带的文明寨、卫城地垒上新探明了三叠系致密砂岩裂缝油气田,其裂缝含油,基质不含油,裂缝的规模具有一定的尺度,既为油气渗流通道,也能作为油气的储集空间,探明规模储量数百万吨,突破了渤海湾盆地的找油模式,丰富了油气藏类型,该勘探和研究对东部老油区的挖潜勘探将会有所借鉴。

This paper studies petroleum system characteristics of Dongpu Depression based on petroleum system theory. This system can be divided into four sub-petroleum systems： the mudstone of deep lacustrine facies from interval Es3 of Paleogene Shahejie Formation as an excellent source rock, the thick sandstone of fluvial facies from interval Es2 as an excellent reservoir bed , the interval Es1 as the source rock, and delta from interval Es1 as reservoir bed separately. It is pointed out that the interval Es3 as source rock, interval Es3 and Es2 as reservoir beds should be the target area for oil exploration and development among the principal hydrocarbon generating sub depressions of Qianliyuan, Pueheng, Haitongji and Liutun, and the 4 third class petroleum systems. It is revealed that reservoir distribution is controlled by central uplift developed chronically and successively. While the reverse faulted blocks, faulted nose and faulted anticline are the main types for prolific reservoir spreading near the major rupture. Sandbody on both flanks of central uplift is found to pinch out or form a structural-lithologic reservoir sheltered from salt dome, thus becoming the target area for recent exploration. All this suggests that the key to discovering prolific reservoirs should be the location of the minor faults and the micro structures as well as the distribution of the sandbody.