江汉盆地潜江凹陷陆相页岩油地质特征

Geologic Characteristics of Continental Shale Oil in the Qianjiang Depression,Jianghan Salt Lake Basin

潜江凹陷是江汉陆相盐湖盆地最好的富烃凹陷。潜江组沉积时期受北部单向物源、古气候频繁交替、高盐度、强蒸发环境影响，沉积了一套最厚达6000m的盐韵律夹砂泥岩的盐系地层，平面上表现为“半盆砂、满盆泥、满盆盐”的特征，形成了具有独特沉积充填特征的陆相盐湖盆地。潜江凹陷发育了两种类型页岩油藏：一是油浸泥岩夹白云岩的页岩油藏，二是盐间油浸泥质白云岩的页岩油藏。两种类型的主力泥页岩层的单层厚度在2～20ro之间，累计厚度在200～3000m之间，泥页岩层分布广，有机碳含量高，测井曲线上具有“三高一低”的特征。泥页岩层脆性矿物含量普遍大于40％。泥页岩储集空间为微裂缝、溶蚀孔、晶间孔，有相对较好储集性能较好。截止目前，在该两类页岩油地层中见到了丰富的油气显示，且有多口井获工业油流，预示着良好的页岩油勘探开发前景。

Qianjiang depression is a best petroliferous depression of Jianghan continental salt lake basin. Influ- enced by northern simplex monodirectional provenance, frequently reciprocating palaeoclimate, highly salinity and evaporation environments, a set of saliferous rhythmic sedimentation successions with sandstone and mudstone, the thickness of 6 000 m, during period of Qianjiang formation sedimentation. The basin characterized by a unique filling character of ＂semi-basin sandstone sedimentation, full-basin mudstone and halite deposition＂. According to lithology and sedimentary facies configuration, two types of shale oil accumulations are developed ： shale oil accu- mulations in the dolomitic oil-soaked mudstones and intersah oil-soaked argillaceous dolomites. The main argillu- tite layers are about 2 - 20 m thick for single layer, adding up to 200 - 3000 m thick. They are rich in organic carbon and widely distributed with sharp characteristics on well log. The content of fragile minerals is more than 40%. Reservoir pore space includes microfractures, emposieus and intercrystalline pores, reservoir quality of these successions is good. The abundant hydrocarbon shows are observed in two types of shale oil deposits and the commercial shale oil flow has been obtained from tens of wells, showing favorable shale oil exploration and devel- opment potential in the depression.