The effects of basaltic lava flows on the petrophysical properties and diagenesis of interbedded aeolian sandstones: an example from the Cretaceous Paraná Basin, Brazil

IF 1.9 4区地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Petroleum Geoscience Pub Date : 2020-12-23 DOI:10.1144/petgeo2020-036

G. Bertolini, A. Hartley, J. Marques, D. Healy, J. Frantz

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引用次数: 2

Abstract

An analysis of the petrophysical and diagenetic effects of the emplacement of Cretaceous basaltic lava flows (Serra Geral Formation) on aeolian sandstones (Botucatu Formation) has been undertaken on core samples from the Paraná Basin, Brazil. Between 0.1 and 1 m from the contact zone, acoustic wave velocities and porosities in sandstones show a significantly wider scatter than those located >1 m away from the lava contact. Higher P-wave values (average 3759.3 m s−1) occur between 0.1 and 1 m from the lava contact in contrast to those areas >1 m away (average 3376.8 m s−1), whilst the average porosity is 6.5% near the contact (0.1–1 m) and 10.7% away from the contact (>1 m). Petrographical evaluation reveals two diagenetic pathways responsible for modification of the petrophysical properties: early hydrothermal Mg-rich authigenesis (Type 1) and early chemical dissolution (Type 2). Type 3 diagenesis occurs away from the lava–sediment contact (>1 m), with the appearance of poikilitic calcite and smectite. The sandstone samples associated with Type 1 and Type 2 diagenesis display a decrease in porosity and increased acoustic velocities in relation to Type 3, while Type 3 samples show little or no variation in reservoir properties. The lava-induced diagenetic effects at the sandstone–lava contacts (0.1–1 m) may form a baffle or seal to fluids around the margins of the sandstone bodies. Therefore, whilst diagenesis associated with lava emplacement may hinder reservoir quality around the margins, the original reservoir properties are preserved within these large sandstone bodies. Supplementary material: Petrophysical and petrographical data are available at https://doi.org/10.6084/m9.figshare.c.5244473

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玄武岩熔岩流对互层风成砂岩岩石物理性质和成岩作用的影响——以巴西白垩纪巴拉那盆地为例

对巴西巴拉那盆地的岩芯样本进行了白垩纪玄武岩熔岩流（Serra Geral组）在风成砂岩（Botucau组）上侵位的岩石物理和成岩作用分析。介于0.1和1之间距离接触带m处，砂岩中的声波速度和孔隙率显示出比位于>1处的砂岩明显更宽的散射 m距离熔岩接触处。较高的P波值（平均3759.3 m s−1）出现在0.1和1之间与那些>1的区域相比，距离熔岩接触面m m（平均3376.8 m s−1），而接触附近的平均孔隙率为6.5%（0.1–1 m）距离接触10.7%（>1 m）。岩石学评价揭示了导致岩石物理性质改变的两种成岩途径：早期热液富镁自生（类型1）和早期化学溶解（类型2）。第3类成岩作用发生在远离熔岩-沉积物接触的地方（>1 m），外观为方晶方解石和蒙脱石。与类型3相比，与类型1和类型2成岩作用相关的砂岩样品显示出孔隙度降低和声速增加，而类型3样品显示出储层性质几乎没有变化。熔岩在砂岩-熔岩接触处引起的成岩作用（0.1–1 m）可以对砂岩体边缘周围的流体形成挡板或密封。因此，虽然与熔岩侵位相关的成岩作用可能会阻碍边缘的储层质量，但这些大型砂岩体内保留了原始的储层性质。补充材料：岩石物理和岩石学数据可在https://doi.org/10.6084/m9.figshare.c.5244473

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来源期刊

Petroleum Geoscience 地学-地球科学综合

CiteScore

4.80

自引率

11.80%

发文量

审稿时长

>12 weeks

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.