Oriented thick section preparation of sandstone samples from outcrop for fluid inclusion analysis in hydrocarbon-bearing basin and its significance

Key words:  oriented fluid inclusion thick section  preparation method  sandstone samples of outcrop  fluid inclusion planes  structural diagenesis  structural fractures in reservoirs

Abstract:

The preparation of high-quality oriented fluid inclusion thick sections is the key and precondition to do in-depth study of attributes of structural fractures in sandstone reservoirs in hydrocarbon-bearing basins from the perspective of structural diagenesis. As such, this paper proposes a preparation method on oriented thick sections of fluid inclusions in sandstone samples from outcrop in hydrocarbon-bearing basin. In order to make sure the oriented fluid inclusion thick sections keep orientation information of sandstones correctly, preserving original orientation information of sandstone samples from outcrop effectively is the main theme throughout the whole processes of thick section preparation, which is concretely embodied in the following steps, including:collecting oriented sandstones from outcrop, reconstructing original orientation of sandstone sample, marking cutting lines on sample, first-cutting, mounting, marking orientation of sample on slide, and so on.The thick sections prepared by the method proposed in this paper, possess dual functions of oriented thin section and fluid inclusion thick section, which can guarantee petrographic observation of fluid inclusions trapped in sandstones, and can also lay the foundations for the accurate reconstructions of original orientations of veins and fluid inclusion planes in samples and for the follow-up analyses on fluid geochemistry. Therefore, the oriented thick sections of fluid inclusions in sandstones from outcrop prepared by this method are helpful to better understand the structural fracture attributes in terms of structural diagenesis, and to improve the quantitative researches of hydrocarbon accumulation processes related to fractures in sandstone reservoirs.