Biomechanical influence of organic matter enrichment and sedimentary environment in the Ordos Basin

Abstract

To study the correlation between organic matter enrichment and sedimentary environment in the Ordos Basin, hydrocarbon source rocks in the region of the eastern edge of the central plain of the basin are selected for analysis. With reference to the related theories of sedimentary rocks and organic geochemistry, the means including pyrolyzed rocks, organic carbon determination, and detection of main trace elements are adopted. The relationship between the regional sedimentary environment and organic matter enrichment is examined after the features of the paleo-sedimentary environment in the study area are examined. At the same time, from the perspective of biomechanics, the concepts of fluid mechanics and material transport are introduced to analyze the influence of hydrodynamic conditions in sedimentary environments on the migration and enrichment of organic matter. The following results were obtained through the study of organic matter enrichment and sedimentary environment in the Ordos Basin: (1) In the analysis of microscopic features, the study area is mainly composed of matrix vitrinite (accounting for more than 68%) and sericite, and also found woody fibers, microbial debris, and pyrite. (2) In organic matter analysis, it was found that the hydrocarbon generation potential (S1 + S2) of the B-S group was divided into multiple levels. According to the relationship, coal can be classified as a good source rock, while the carbonaceous mudstone in the S group belongs to a poor source rock. Group B-T is mainly composed of type III kerogen (humic type). (3) In the analysis of geochemical indicators, the concentrations of Si, Al, and Fe are very high. Further analysis shows that Si and Ti are the main enriched elements, while Re and Mo are abnormally enriched elements. (4) In the analysis of sample physical properties, sample characterization indicates that the source rock is mainly microporous, with few micropores in sandstone, mainly consisting of fractures and medium to large pores. Research has found that there is a correlation between the pore conditions of the sample and organic matter, and the pore volume increases relatively with the increase of organic matter. (5) Organic matter, abdominal muscles, and sediment environment analysis, according to the examination of geochemical indicators, the research area’s environment changed significantly from humid to arid and semi-arid conditions at various points during the early, middle, and end of the study period. The salinity of the water body in different regions differed significantly, which was related to the regional climate. The study of the carbon content of organic matter and the characteristics of the sedimentary environment displayed that the redox reaction in the early stages of the region and the local climate had a major influence on the enrichment of organic matter. These two factors became the primary controlling factors affecting the region’s organic matter enrichment. The investigation of geological structures and the extraction of local rock gas and minerals can both benefit from the technological assistance this study can offer. At the same time, by introducing the principles of fluid mechanics and material transport in biomechanics, a new perspective is provided for understanding the migration and enrichment mechanism of organic matter in sedimentary environments.