ORIGINAL RESEARCH article
Front. Earth Sci.
Sec. Sedimentology, Stratigraphy and Diagenesis
Reservoir Heterogeneity between Intra-Platform and Platform-Margin Settings in an Isolated Carbonate Platform: A Case Study from the Carboniferous, Pre-Caspian Basin
Provisionally accepted
- 1Research Institute of Petroleum Exploration and Development (RIPED), Beijing, China
- 2MangistauMunayGas B.V., Atyrau, Kazakhstan, Atyrau, Kazakhstan
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The Carboniferous isolated platform carbonate reservoirs in the Pre-Caspian Basin exhibit pronounced heterogeneity, which significantly constrains the effective prioritization and optimization of oilfield exploration targets. Importantly, the processes governing the differentiation in reservoir characteristics between intra-platform and platform-margin zones remain poorly understood. This study systematically examines the contrasting features and formation mechanisms of reservoirs in these two settings, drawing upon core and thin-section observations from 28 wells in the Unit 1 reservoir group of the isolated platform, integrated with comprehensive reservoir property assessments and production data. Results demonstrate that intra-platform and platform-margin reservoir rocks are lithologically comparable, predominantly comprising grainstones and packstones, yet exhibit pronounced disparities in pore structure. Intra-platform reservoirs are dominated by matrix-realated porosity, mainly intragranular dissolution and moldic pores, whereas platform-margin zones commonly develop fracture-cavity systems with enhanced petrophysical performance. The differentiation of reservoir spaces is chiefly governed by spatially variable karstification processes: facies-controlled penecontemporaneous exposure dissolution predominantly accounts for the development of matrix-dissolution pores within intra-platform grain banks, while platform-margin zones experience compounded alteration through both penecontemporaneous exposure dissolution and subsequent coastal karstification, thereby producing fracture-cavity reservoir networks. Based on comprehensive analyses of sedimentary, diagenetic, and petrophysical attributes, a differential pore-evolution model is proposed for Carboniferous intra-platform and platform-margin carbonate reservoirs in the Pre-Caspian Basin. These findings offer a robust theoretical foundation for the prediction and assessment of high-quality carbonate reservoirs within the study area and comparable geological provinces.
Keywords: Isolated carbonate platform, pore differential evolution model, Pore structure, Pre-Caspian Basin, Reservoir genesis
Received: 12 Nov 2025; Accepted: 17 Dec 2025.
Copyright: © 2025 Zheng, Wen, Zhao, Zeng, Wang, Chen and Hou. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Lun Zhao
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