湖相页岩油系统中液态烃赋存特征及其对有效物性参数的影响

The liquid hydrocarbons occurrence is complicated in shale oil systems, and the mobility is quite different with different type of liquid hydrocarbons occurrence. Besides, different from the shale gas system, the liquid hydrocarbon occurrence must affect the effective physical parameters of the rock because it is still stored in the rock. Therefore, detail study of the liquid hydrocarbon occurrence and their influences on effective petrophysical parameters is the foundational and basic for understanding the mechanism of hydrocarbon-rich shale oil and mobility research, and lacustrine shale oil exploration. This project will focus on key scientific questions in the context of "Characteristics of liquid hydrocarbon occurrence and their influences on the effective petrophysical parameters in lacustrine shale oil system", and take the Jiyang Depression in Bohai Bay Basin as the main object, and will follow four approaches. Firstly, based on the petrology analysis, the liqid hydrocarbon occurrence will be quantitatively analyzed through a combination of micro-ultramicro-morphology organic petrology methods (e.g. Microscope, FIB-SEM, AFM etc.), and geochemistry method (Rock-Eval and Chloroform bitumen"A"). Secondly, through comparation petrophysical parameter (including porosity, permeability and pore throat) studies of samples with different liquid hydrocarbon occurrence before and after chloroform extracted, and building a method to analysis the solvent flow test of the shale oil samples, the project try to figure out the liquid hydrocarbon occurrence influences on petrophysical parameters in the shale oil system. Investigation of these scientific issues will promote foundation theoretical researches for storage and mobilities mechanisms of shale oil system, and will provide theoretical guidance and reference for shale oil exploration specific to China, especially for lacustrine shale oil exploration in eastern China.

页岩油系统中液态烃类赋存特征（游离、岩石与干酪根吸附等）复杂，不同赋存形式烃类流动性差异较大；同时，由于液态烃还滞留在岩石中，页岩油样品的有效物性参数表征（孔隙度与渗透率等）不能简单按照页岩气样品（气态烃在分析时已逸散）的分析方法进行。本项目以“湖相页岩油系统中液态烃赋存特征及其对有效物性参数的影响”为核心问题，以济阳坳陷为主要解剖对象，（1）在对页岩油样品的岩石学、岩相学分析基础上，通过显微镜、聚焦离子束扫描电镜和原子力显微镜等显微－超显微分析技术，结合热解、抽提物分析等地球化学分析，综合解剖不同岩相下页岩油系统中液态烃类赋存特征，赋存类型及赋存规律；（2）挑选不同液态烃类赋存特征的样品进行岩石溶剂抽提前后物性参数对比分析，建立岩石原位溶剂渗流实验，揭示不同赋存状态液态烃类及含量对其有效物性参数影响，为页岩油系统中烃类富集机理及可动性研究提供理论依据和新的指标。

页岩油系统包括已生成油气的富有机质泥页岩层及紧邻的非烃源岩薄夹层，本项目针对济阳坳陷沙河街组页岩油层系，进行岩石学、地球化学与岩石物理学特征分析，揭示页岩油中烃类赋存特征其对有效物性参数的影响。 . 首先，岩石学与地球化学特征分析，提出了适合页岩油勘探最优的沉积微相类型。以樊页1井为例，识别出了A-H类沉积微相及四种烃类赋存特征，其中以碳酸盐岩为主的D类与E类微相较高的含油饱和指数OSI值（371.3和 199.9），为优质目标层系。. 其次，通过岩石物理参数与地球化学特征，建立了有效孔隙度与烃类占据孔隙度的计算评价方法。实验氦气孔隙度(ΦHe)为1.3% ~6.4%之间，氦气渗透率在63 ~ 2300 nDarcy之间。烃类占据孔隙度(ΦS1)根据S1含量与压裂产出油的密度进行计算，恢复到原始地下的S10含量，可获得地下原始的烃类占据孔隙度特征(ΦS10)及含油饱和度参数。该方法获得结果与现场测井解释的结果一致，成熟度是影响烃类孔隙度和总孔隙度的关键因素。页岩中赋存的液态烃的不可压缩性，导致含油页岩的压力敏感性较气页岩的高。. 第三、建立了围压下溶剂渗流实验技术，近似地下条件下揭示页岩中烃类的可动性及溶剂渗流特征。三个小圆柱样品代表了三种溶剂渗流模式：1号穿层渗流，2号平行渗流，3号为裂缝型平行渗流。实验收集的萃取物进行色谱质谱GC分析，揭示不同时间萃取物的地球化学特征；溶剂渗流实验后的样品进行CT分析揭示溶剂渗流路径特征；实验前后的Rock-Eval热解分析解释前后萃取的可动烃与重烃特征分析。结果表明， 3号样品层间裂缝极其发育，萃取速率最快，可动烃萃取率最高，同时17%重烃被萃取。层间裂缝是页岩油烃类运移的主要通道，层间微裂缝发育的岩层是页岩油勘探的优质层段。. 该项目成果目前已应用在了胜利油田页岩油勘探生产中，并获得了中石化研究院的基础性前瞻性项目研究科学奖一等奖。