Evolution and controls of high reservoir quality in Oligocene sandstones from moderate to deep burial, Nanpu Sag, Bohai Bay Basin, China

Wu, Hui; Ji, Youliang; Du, Zhiwei; Zhou, Yong; Zou, Juan; Zhang, Yunzhao; Du, Wei; Liu, Haiqing

doi:10.1016/j.sedgeo.2022.106275

Cited by 6 publications

(16 citation statements)

References 54 publications

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“…The effective porosity can separate the effective reservoir from the ineffective reservoir, and can be determined using the specific method proposed by Wang et al (2009). The log-interpreted porosities of different oil-bearing layers and dry layers were used to determine the lower limit of effective porosity at depth interval of 300 m in the range of 2000-4500 m by using the cumulative distribution function (Wang et al, 2009;Wu et al, 2022). There existed very significant power correlation between the lower boundary of effective porosity and depth with a coefficient of determination of 0.98.…”

Section: Ahpz Determinationmentioning

confidence: 99%

“…The complex and variable interplay of factors, such as the detrital composition, grain texture and prolonged diagenetic alteration after sediment deposition, yields a wide range of potential outcomes with respect to the pore structure and reservoir quality (Ajdukiewicz and Lander, 2010;Taylor, et al, 2010;Lai et al, 2018;Griffiths et al, 2019;Quandt et al, 2022;Wu et al, 2022;Marghani et al, 2023). There is no significant difference in the grain size and composition among the AHP, NHP, and NLP reservoirs in the AHPZ (Figures 6A, B).…”

Section: Diagenetic Controls On the Formation Of Ahpmentioning

confidence: 99%

“…With the declines in production of conventional hydrocarbon resources and the quickly growing energy needs, the tight sandstone reservoirs have become one of the important exploration targets for petroleum industry (Law and Curtis, 2002;Desbois et al, 2011;Zou et al, 2012;Li et al, 2020). The tight sandstone reservoirs generally have poor physical property, which are characterized by highly variable reservoir quality in spatial distribution (Wu et al, 2022). Nevertheless, anomalously high porosity zone (AHPZ) is still developed in some tight sandstone reservoirs.…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, anomalously high porosity zone (AHPZ) is still developed in some tight sandstone reservoirs. The AHPZs are defined as the reservoirs having higher porosity relative to expected background values for their burial depth (Bloch et al, 2002;Nielsen et al, 2019), and can be widely developed across different geological periods, sedimentary facies and buried depth intervals in the various petroliferous basins (Sun et al, 2013;Cao et al, 2014;Yuan et al, 2015a;Wu et al, 2022). The determination of AHPZ is the central work of the genetic analysis and prediction of high-quality sandstone reservoirs, which are the sweet spots for hydrocarbon exploration, especially for deeply buried sandstone reservoirs.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the formation of AHPZs in the mid-deep layers in some areas cannot be explained by secondary dissolution. The primary porosity-preserving mechanisms, such as hydrocarbon emplacement (Emery et al, 1993;Xia et al, 2020;Wu et al, 2022), high fluid pressure (Jin et al, 2011;Nguyen et al, 2013), microcrystalline quartz coatings (Aase et al, 1996;Worden et al, 2012), and clay coatings (Heald and Larese, 1974;Taylor et al, 2010;Zhou et al, 2016), have suggested to dominate the AHPZ formation. The deeply buried sandstone reservoirs of the lower member of the Middle Jurassic Xishanyao Formation (J 2 x 1+2 ) in the Taibei Sag of Turpan-Hami Basin show anomalous high porosities than expected background values for the burial depth, and more primary intergranular pores dominate these high-porosity sandstones, indicating that high porosity may be related to the primary porosity-preserving capacity.…”

Section: Introductionmentioning

confidence: 99%

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Controls on anomalously high porosity/permeability of Middle Jurassic deeply buried tight sandstones in the Taibei Sag, Turpan-Hami Basin, northwestern China: Implications for reservoir quality prediction

Ban²,

Du³

et al. 2023

Front. Earth Sci.

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The lower member of the Middle Jurassic Xishanyao Formation (J2x1+2) sandstones are significant exploratory targets for hydrocarbon resources in the Taibei Sag of the Turpan-Hami Basin, northwestern China. Formation of anomalously high porosity/permeability in deeply buried J2x1+2 sandstones and reservoir quality prediction were investigated using a variety of petrographic analyses. These results show that the J2x1+2 sandstones are mostly feldspathic litharenites and litharenites, which are characterized by moderate-to good sorting, silty to medium granularity, and point- to long grain contacts. The J2x1+2 sandstone has low porosity (avg 6.0%) and permeability (avg 1.12 mD), but shows anomalously high porosity/permeability at depth interval of 3850–4050 m. There is a noticeable variation in pore types and sizes from intergranular-intragranular dissolution pores with a size mode of 2.0 μm in anomalously high porosity (AHP) sandstones, to major intragranular dissolution pores with a size mode of 0.5 μm in normally high porosity (NHP) sandstones, to most micropores with a size mode of 0.25 μm occurred in the normally low porosity (NLP) sandstones. The compaction is the main cause of porosity destruction, resulting in an average porosity loss of 89.6%. However, the authigenic minerals have relatively little influence on reservoir quality. The combination of nappe tectonics and well-sorted particles alleviated the compaction and thus preserved more intergranular pores in the AHP sandstones. Dissolution further increases the porosity and eventually forms the AHP sandstones. The strong carbonate-cemented facies (SCC), tightly compacted facies (TC), moderately compacted with moderate dissolution facies (MCMD), and weakly compacted with strong dissolution facies (WCSD) are determined in the J2x1+2 sandstones. The sandstones with SCC and TC are recognized as the NLP reservoirs. The MCMD and WCSD correspond to the NHP and AHP reservoirs, respectively. The reservoir quality predicted using the constructed diagenetic facies charts is in good agreement with the photomicrograph observations and physical property tests. Additionally, the AHP reservoirs are still developed in the deeply buried sandstones with depths larger than 4000 m.

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Section: Ahpz Determinationmentioning

confidence: 99%

Section: Diagenetic Controls On the Formation Of Ahpmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Controls on anomalously high porosity/permeability of Middle Jurassic deeply buried tight sandstones in the Taibei Sag, Turpan-Hami Basin, northwestern China: Implications for reservoir quality prediction

Ban²,

Du³

et al. 2023

Front. Earth Sci.

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Diagenetic controls on pore structure variations in fan deltaic sandstones of the Eocene Shahejie Formation, Bohai Bay Basin, China: Implications for reservoir quality and oiliness heterogeneities

et al. 2023

Geological Journal

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The fan deltaic sandstones in the third section of the third member of the Eocene Shahejie Formation (Es33) are important hydrocarbon exploration targets in the northern Nanpu sag, Bohai Bay Basin, China. The Es33 sandstones are characterized by highly variable pore structures. A total of 364 Es33 sandstone samples were measured by a series of petrological and petrophysical analyzes to investigate these variations and their controls on reservoir quality and oiliness heterogeneities. The heterogeneity of Es33 sandstone can be manifested by type I, type II and type III pore structures. Primary intergranular pores and dissolution pores were the main storage spaces for type I sandstones, while dissolution pores and intercrystalline pores were the main storage spaces for type II and type III sandstones, respectively. These results indicate that compaction is the main factor in the loss of primary intergranular porosity, with an average loss of 78%. The grain size controlled the preservation of primary pores in Es33 sandstones with a carbonate cement content of less than 6%. The different types of clay minerals have various effects on the pore structure. Chlorite plays an active role in the preservation of intergranular pores and the improvement of reservoir quality, while mixed layers of illite and smectite greatly reduced the pore size and connectivity and lowered the reservoir quality. The Es33 sandstones have undergone a more open diagenetic system. Dissolution significantly increased the porosity of type I and type II sandstones with more primary intergranular pores, but exerted a minor role in contributing to the permeability. Furthermore, a pore‐throat radius of approximately 0.4 μm is considered to be the threshold for oil accumulation in Es33 fan deltaic sandstones.

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Research on geological characteristics and development potential of Es31 oil and gas reservoir in Nanpu M Block

Zhang,

Liu,

et al. 2024

Heat Mass Transfer

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Evolution and controls of high reservoir quality in Oligocene sandstones from moderate to deep burial, Nanpu Sag, Bohai Bay Basin, China

Cited by 6 publications

References 54 publications

Controls on anomalously high porosity/permeability of Middle Jurassic deeply buried tight sandstones in the Taibei Sag, Turpan-Hami Basin, northwestern China: Implications for reservoir quality prediction

Controls on anomalously high porosity/permeability of Middle Jurassic deeply buried tight sandstones in the Taibei Sag, Turpan-Hami Basin, northwestern China: Implications for reservoir quality prediction

Diagenetic controls on pore structure variations in fan deltaic sandstones of the Eocene Shahejie Formation, Bohai Bay Basin, China: Implications for reservoir quality and oiliness heterogeneities

Research on geological characteristics and development potential of Es31 oil and gas reservoir in Nanpu M Block

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