鄂尔多斯盆地长73亚段页岩油可动烃资源量评价方法

鄂尔多斯盆地长7₃亚段发育一套富有机质泥页岩夹薄层粉—细砂岩的细粒沉积，具有整体生烃、普遍含油的特征。明确不同类型细粒沉积的含烃量、赋存状态、烃类组分等，对于该类型页岩油资源潜力分析和甜点优选具有重要意义。基于CY1井长7₃亚段岩心系统测试分析，运用多粒级多极性分步抽提方法，对黑色页岩、暗色泥岩、粉砂岩、细砂岩等4种细粒沉积岩石类型开展可动烃研究，评估了盆地长7₃亚段页岩油的可动烃资源量。结果表明，多粒级多极性分步抽提分析不同类型细粒沉积在不同粉碎条件下（1 cm³、0.5 cm³、150目）的含烃量及其组分，单位抽提量大小顺序为细砂岩>黑色页岩>粉砂岩>暗色泥岩，步骤1、步骤2抽提可溶有机质以轻质—中质组分为主，属于可动烃；步骤3和步骤4抽提可溶有机质为不可动烃。实验结果表明长7₃亚段黑色页岩、暗色泥岩、粉砂岩和细砂岩的可动烃量分别为3.35 mg/g、1.45 mg/g、3.28 mg/g和4.48 mg/g。对城80井区220 km²长7₃亚段页岩油可动烃资源量进行评价，初步评价结果为（0.37~0.51）×10⁸ t。鄂尔多斯盆地长7₃亚段页岩油有利分布面积约为1.5×10⁴ km²。通过类比分析，评价其可动烃资源量为（25~35）×10⁸ t，该类型页岩油有望成为盆地石油勘探新的接替领域。

Research on evaluation method of movable hydrocarbon resources of shale oil in the Chang 73 sub-member in the Ordos Basin

A set of fine-grained sediments of organic-rich shale interbedded with thin layer silt and fine grained sandstones developed in the Chang 7₃ sub-member of the Ordos Basin. It has the characteristics of overall hydrocarbon generation and general oil-bearing. It is of great significance to clarify the hydrocarbon content， occurrence state and hydrocarbon components of different types of fine-grained sediments for the potential analysis and sweet spot selection of this type of shale oil resources. This study is based on the systemical core testing and analysis of the Chang 7₃ sub-member of Well CY1， movable hydrocarbon research on four fine-grained sedimentary rock types is carried out， including black shale， dark mudstone， siltstone and fine-grained sandstone， by using multi-granular multi-polar sequential extraction methods， and the movable hydrocarbon resources of shale oil in the Chang 7₃ sub-member is evaluated in the Ordos Basin. The research results show that the hydrocarbon content and its components of different types of fine-grained sediments under different particle size crushing conditions（1 cm³，0.5 cm³，150 mesh） are analyzed by multi-particle multi-polar sequential extraction. The unit extraction amount of hydrocarbon is fine-grained sandstone>black shale>siltstone>dark mudstone. The soluble organic matter extracted by step 1 and step 2 is mainly light-medium components and belongs to movable hydrocarbons. Soluble organic matter extracted by steps 3 and 4 is immobile hydrocarbon. Based on the above test methods， the movable hydrocarbon of black shale， dark mudstone， siltstone and fine sandstone in the Chang 7₃ sub-member are 3.35 mg/g， 1.45 mg/g， 3.28 mg/g and 4.48 mg/g， respectively. The movable hydrocarbon resources of 220 km² shale oil in Cheng 80 well block in the Chang 7₃ sub-member were evaluated. The preliminary evaluation results were （0.37-0.51）×10⁸ t. The distribution area of shale oil in the Chang 7₃ sub-member in the Ordos Basin is about 1.5×10⁴ km². Through analogy analysis， it is estimated that its movable hydrocarbon resources are （25-35）×10⁸ t. This type of shale oil is expected to become a new replacement area for oil exploration in the basin.