N. Zeitoum, Dr. Alexandre Campane Vidal, Dr. Eddy Muñoz Ruidiaz, R. V. de Almeida
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引用次数: 0
Abstract
Reservoir quality in carbonates is influenced by various factors, such as depositional environment, burial history, and diagenesis processes. Understanding these geological heterogeneities is essential for successful petroleum exploration. This study characterizes Brazilian pre-salt reservoirs and aims to understand how their heterogeneity impacts reservoir quality. We analyzed carbonate samples from the Barra Velha Formation (Santos Basin) through an integration of petrographic and core plug descriptions, petrographic facies characterization, porosity and permeability measurements, and image analysis to identify the principal controls on porosity and permeability, pore size distribution, and groups with similar petrophysical properties using the Hydraulic Flow Unit (HFU) concept. Five facies groups were recognized: Spherulitestone (F1); Shrubstone (F2); Intraclastic Grainstone (F3); Intraclastic Packstone, Spherulitestone with mud and Shrubstone with mud (F4); Shrub-Spherulite Intercalations and Bioclastic Grainstone (F5). The analysis of porosity and permeability showed that their variations are associated with pore type and cementation rate. Greater contribution of inter-aggregate, interparticle, and vugular porosity, combined with a reduced amount of cement, results in higher porosity and permeability, but the increase of cement tends to reduce the porosity and permeability. Among the facies groups, F2 and F3 exhibited the best porosities and permeabilities, followed by F1, F4, and F5. From image analysis, small pores (1.5 x 10
-5
to 0.01 mm²) are the most frequent in all rocks. However, these small pores contributed significantly to total porosity only in F4 and some samples of F3. For F2 and F3, the large pores (from 0.01 mm² to a maximum of 19.62 mm²) are the main contributors, while F5 has a homogeneous contribution. Lastly, the data were grouped into 5 HFUs. HFU1 and HFU2 represent the zones with the best reservoir quality, primarily composed of F2 and F3.
期刊介绍:
Petroleum Geoscience is the international journal of geoenergy and applied earth science, and is co-owned by the Geological Society of London and the European Association of Geoscientists and Engineers (EAGE).
Petroleum Geoscience transcends disciplinary boundaries and publishes a balanced mix of articles covering exploration, exploitation, appraisal, development and enhancement of sub-surface hydrocarbon resources and carbon repositories. The integration of disciplines in an applied context, whether for fluid production, carbon storage or related geoenergy applications, is a particular strength of the journal. Articles on enhancing exploration efficiency, lowering technological and environmental risk, and improving hydrocarbon recovery communicate the latest developments in sub-surface geoscience to a wide readership.
Petroleum Geoscience provides a multidisciplinary forum for those engaged in the science and technology of the rock-related sub-surface disciplines. The journal reaches some 8000 individual subscribers, and a further 1100 institutional subscriptions provide global access to readers including geologists, geophysicists, petroleum and reservoir engineers, petrophysicists and geochemists in both academia and industry. The journal aims to share knowledge of reservoir geoscience and to reflect the international nature of its development.