Reactions of petroleum compounds with hematite grain-coatings and their effects on diagenesis and pore structure of clastic reservoir rocks

该项目的目的是研究石油化合物与储集岩矿物表面赤铁矿涂层的相互作用及其对孔隙度(和渗透率)的影响。大量的岩石学研究记录了红层中典型的成岩事件序列，导致了孔隙结构的实质性变化，从而改变了储集岩的渗透率性质。作为最显著的特征，这些反应序列包括某些区域的还原漂白，导致Fe2+的动员、石油浸渍和在邻近岩石体积中形成更高的孔隙度(水泥和碎屑的溶解)。这种方法的概念是，石油化合物在储集层内与赤铁矿反应而氧化提供酸性物种(如羧酸)，从而引起进一步的成岩反应，从而增加以前被石油污染的储集层附近的孔隙度。拟议的研究允许将广泛的实地证据、无机和有机地球化学实验室数据以及实验工作结合起来。这个涉及有机和矿物质的反应序列的细节将在高温和压力条件下的实验室测试中进行研究。将开发具体的采样技术，以分析在这一过程中产生的羧酸和其他预期有机物种。矿物反应将通过对实验期间采样的孔隙水中离子物种的分析以及实验前后样品砂岩的岩石学-矿物学特征的比较来监测。

The aim of this project is the investigation of the interaction of petroleum compounds with hematite coatings on mineral surfaces in reservoir rocks and their effects on porosity (and permeability). Numerous petrological studies have documented typical sequences of diagenetic events in red beds leading to substantial alterations of the pore structure and, in consequence, changes in the poro-perm properties of reservoir rocks. These reaction sequences comprise, as the most conspicuous features, reductive bleaching of certain domains resulting in Fe2+ mobilisation, oil impregnation and formation of enhanced porosity (dissolution of cements and clasts) in neighbouring rock volumes. The concept of the present approach is that oxidation of petroleum compounds by reaction with hematite within reservoirs provides acidic species (e.g. carboxylic acids) which cause further diagenetic reactions resulting in the enhancement of porespace in the vicinity of formerly oil-stained reservoir intervals. The proposed study allows the integration of extensive field evidence, inorganic and organic geochemical laboratory data, and experimental work. Details of this reaction sequence involving organic and mineral matter will be investigated in laboratory tests under elevated temperature and pressure conditions. Specific sampling techniques will be developed to analyse carboxylic acids and other expected organic species generated in this process. Mineral reactions will be monitored by analysis of ionic species in the pore water sampled during the experiment and by comparison of petrographic-mineralogic features of the sample sandstones prior and after experiments.