湖相页岩排烃性能的实验研究与应用

Concerning oil and gas geochemistry, hydrocarbon expulsion, which plays a dominant role in the conventional and unconventional shale oil and gas exploration, remains an enigmatic issue. At present, the whole-rock-based pyrolysis experiment is mainly devoted to study the hydrocarbon expulsion of source rocks. Taking the Yanchang lacustrine shale (T3y) from Ordos basin as an example, we will investigate the effects of different particle size, abundance of organic matter, and the openness of system on hydrocarbon expulsion in this project. The intrinsic correlation of particle size, abundance of organic matter with the hydrocarbon expulsion threshold, hydrocarbon expulsion efficiency and hydrocarbon expulsion yields will be established through the Rockeval pyrolysis kinetics experiment. The thermal simulation experiments with either semi-closed or closed systems, using the same source rocks, will be conducted, and then a detailed comparison of its effects on hydrocarbon expulsion will be performed. Meanwhile, the changes of mineral composition and pore structure will be measured, and the interaction between organic and inorganic processes in the process of hydrocarbon expulsion will also be studied. The results based on the PetroMod simulation software will be applied to specific drilling well and natural areas, to investigate the hydrocarbon expulsion characteristics and the relevant factors of lacustrine shale under natural conditions. The results of this project will provide important significant implications for the lacustrine shale-related unconventional shale oil and gas exploration and development.

烃源岩排烃一直以来是油气地球化学研究的薄弱环节，但排烃是显著影响常规与非常规页岩油气勘探的关键问题。目前基于全岩的热模拟实验是研究烃源岩排烃的一种重要手段。本次研究拟以鄂尔多斯盆地延长组湖相页岩为研究对象，探讨烃源岩粒径、有机质丰度、实验体系开放度对烃源岩排烃的影响。采用全岩Rockeval热解动力学实验对不同粒径和有机质丰度的烃源岩进行模拟，探讨粒径和有机质丰度对烃源岩排烃门限、排烃效率及排烃量的影响。对相同烃源岩开展半封闭和封闭体系热模拟实验，对比不同体系对源岩排烃的影响。同时对烃源岩生排烃过程中矿物组分、孔隙结构的变化特征以及排烃过程中有机与无机相互作用进行研究，并通过盆地模拟软件将模拟实验结果推至具体的钻井和实际地区，探讨自然条件下延长组湖相页岩排烃特征及影响因素。研究结果对湖相页岩常规非常规页岩油气勘探开发具有重要意义。

烃源岩的排烃是决定能否形成工业油气藏的关键因素。近年来, 非常规页岩油气表现出了巨大的勘探潜力, 而非常规油气的的勘探主要取决于烃源岩中残留烃的含量。因此, 如何有效评价烃类的生成和排出对于认识烃源岩中残留烃的组成与演化特征十分关键。从某种程度上讲, 烃源岩的排烃同时决定了常规(排出烃)与非常规(残留烃)两类油气藏的形成。烃源岩的排烃受多种因素的影响, 主要为成熟度、有机质丰度及有机质类型等。传统的热解实验方法常采用干酪根或者粉末进行热模拟实验研究。干酪根的实验结果可以相对准确的表征有机质的生烃行为和生烃过程, 但没有考虑排烃因素, 而粉末由于破坏了无机矿物格架, 反映的是有机质与矿物均匀混合的状态。因此, 它们都不能准确反映实际地质条件下烃源岩的排烃过程。本人博士期间主要从事基于全岩不同类型烃源岩生-留-排烃的实验模拟研究工作, 研究发现粒径、TOC含量及有机质类型都会影响烃源岩的生排烃过程。本次研究以鄂尔多斯盆地平凉组海相页岩和延长组湖相页岩为研究对象, 开展页岩排烃影响因素的实验研究。对不同粒径、不同TOC含量及不同有机质类型进行Rockeval热解动力学实验来研究烃源岩排烃过程。结果表明, 粒径、有机质丰度以及有机质类型都会影响烃源岩的排烃, 并且粒径越大、TOC含量越高和有机质类型越好, 影响越明显。