136-5 Diagenetic types, characteristics, and development mechanisms of high-quality reservoirs in deep marine shale from the Sichuan Basin, China

Session: Micro-Nano Scale Pore-Fracture Architecture and Fluid Dynamics in Shale and Coal Reservoirs

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Abstract:

This study focuses on deep marine shale in the eastern Sichuan Basin, aiming to explore the types and characteristics of diagenesis in overmature shale and reveal the development mechanism of high-quality reservoirs. Through a comprehensive analysis of the petrological characteristics, diagenetic evolution process, and reservoir physical properties of shale, it provides a theoretical basis for the evaluation and optimization of high-quality reservoirs for deep shale gas. This research adopts various technical methods such as geological survey, sample collection, experimental testing, and geostatistics. Firstly, the geological background and shale distribution characteristics of the study area are clarified. Representative shale samples are collected for petrological, mineralogical, and geochemical analyses to determine the composition and lithofacies types of shale. By using combined SEM-EDS-CL, XRD, gas adsorption-high pressure mercury injection, the types of shale diagenesis and the characteristics of pore development are deeply studied. The characteristics of different diagenetic types, including compaction, cementation, dissolution, and recrystallization, and their impact on reservoir physical properties are analyzed. On this basis, combined with reservoir physical properties and basin simulation results, the burial-uplift evolution history of shale reservoirs is reconstructed, and the development conditions and mechanism of high-quality reservoirs are discussed. Our results show that the deep marine shale has undergone a complex diagenetic process, forming various types of reservoir spaces. Compaction and cementation are the main factors leading to the deterioration of reservoir physical properties, while the generation and expulsion of organic matter hydrocarbons, dissolution, and recrystallization are conducive to improving reservoir physical properties. The development of high-quality reservoirs is closely related to factors such as the mineral composition, organic matter content, pore structure, and fluid activity of shale. Through the analysis of typical wells and geostatistical analysis, the development pattern of high-quality reservoirs is further revealed. This study not only enriches the theoretical system of deep shale diagenesis but also provides important support for the prediction and evaluation of high-quality reservoirs. The innovation of this study lies in the comprehensive application of multiple technical methods to deeply analyze the diagenetic evolution process and reservoir development mechanism of deep shale, providing an important scientific basis for the exploration and development of shale gas.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-6403

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