Characteristics of the early miocene globigerinid-rich siliciclastic-carbonate reservoirs in ultra-deep water areas of the Baiyun sag, pearl river mouth basin, South China sea

Exploring new types of high-quality reservoirs in terrigenous clastic-starved (ultra-)deep-water areas is a crucial component in ensuring future energy supply. Recent drilling (water depth >1,500 m) in the Pearl River Mouth Basin revealed globigerinid-rich mixed siliciclastic-carbonate rocks with high porosity and low permeability physical properties, providing promising exploration opportunities. Based on core, logging and seismic data across critical wells in ultra-deep water areas (>1,500 m deep) aside the Yunli Low Uplift, this study presents the reservoir properties of the Early Miocene globigerinid-rich siliciclastic-carbonate rocks. These rocks contain 10%–80% terrigenous components and 5%–45% biogenic carbonate grains dominated by Globigerina shells (>90%). Shell chambers exhibit as those are hollow and those filled with carbonates (e.g., micrite, sparite, dolomite) or quartz, glauconite, analcime, and pyrite. Well-preserved visceral foramen pores contribute to reservoir spaces, exhibiting with high porosity (up to 37.7%, average 17.43%). However, interstitial micrite and clay, along with authigenic ferroan calcite and ferroan dolomite, severely reduce permeability (average 0.148 × 10^-3μm²). Accompanied with the Globigerina enrichment within seabed sediments, appropriate amounts of terrigenous components/moderate bottom current dynamics help constrain the chamber fillings from carbonate cementation/micrite and clay matrix. These findings provide theoretical insights for exploring new types of deep-sea high-quality reservoirs.

1 Introduction

Recent ultra-deep water drilling in ultra-deep water areas aside the Yunli Low Uplift, Pearl River Mouth Basin, northern South China Sea (Figure 1), has revealed Early Miocene Globigerina-rich mixed carbonate-siliciclastic reservoirs characterized by high porosity (reaching 30%) and very low permeability. Those biogenic calcareous components provide primary pore space, offering excellent exploration potential. Similar examples over worldwide include Pliocene Globigerina limestone reservoirs in Indonesia’s East Java Basin (porosity up to 52%) (Guo et al., 2020), Cretaceous coccolith-rich reservoirs in Syria’s Tishrine field (porosity up to 35%) (Wu et al., 2013), and North Sea Ekofisk field reservoirs (porosity 30%–50% under deep burial) (Fabricius, 2007). These global cases demonstrate that, despite differences in sedimentary backgrounds and diagenetic histories, biogenic calcareous components can form and preserve high-quality reservoir spaces under specific conditions.

Figure 1

Figure 1. (a) Paleo-oceanic circulation pattern across the South China Sea at 23 Ma; (b) Well site and seismic profile location in this study; (c) Seismic profile connecting wells of 4A, 4B, 9A and 9B.

Comprehensive research has addressed high-porosity, low-permeability characteristics linked to overpressure environments and Mg-rich pore fluids, as well as calcareous microfossil accumulation mechanisms controlled by upwelling, paleo-marine productivity, and bottom current winnowing (Babonneau et al., 2023; Fabricius, 2007; Spaulding, 1991; Thierstein and Young, 2004). Bottom and turbidity current depositional processes play pivotal roles in developing high-quality calcareous reservoirs (Yu et al., 2020). However, compositional variations among global calcareous reservoirs remain complex and diverse, requiring systematic comparative research.

The newly discovered Early Miocene mixed siliciclastic-carbonate reservoirs in the Baiyun Sag of the northern South China Sea share similar biogenic components with those in the East Java Basin, face deep-burial diagenetic challenges analogous to the North Sea reservoirs, and are also influenced by terrigenous clastic input. This coupling of multiple factors makes the reservoir formation mechanisms more complex. This complexity severely constrains reservoir prediction and evaluation in this area and in regions with similar geological settings, creating an urgent need for​ research on their petrological characteristics, pore structure genesis, and the key sedimentary and diagenetic mechanisms controlling high porosity development. This study integrates multi-disciplinary analyses of cores and thin sections from representative wells to systematically (1) characterize the petrology, pore structure, and diagenesis of Early Miocene Globigerina-rich mixed carbonate-siliciclastic rocks and (2) integrate factors responsible for developing porosity and permeability properties. The findings provide critical insights for global exploration and evaluation of siliciclastic-carbonate reservoirs in ultra-deep water settings.

2 Regional setting

The study area locates in the Baiyun Sag (Figure 1) within the Pearl River Basin, northern South China Sea. The Cenozoic stratigraphic filling sequence in the Pearl River Mouth Basin includes, from bottom to top, the Eocene Wenchang Formation–Enping Formation, the Oligocene Zhuhai Formation, the Miocene Zhujiang Formation–Hanjiang Formation–Yuehai Formation, the Pliocene Wanshan Formation, and Quaternary strata, with a total thickness locally exceeding 13 km (Liu B. et al., 2024) (Figure 2). Of particular relevance, the Late Oligocene Zhuhai Formation (below the T60 unconformity at ∼23 Ma) is characterized by deltaic-shallow marine sand-mudstone interbeds, reflecting transitional marine-continental environments (Xie et al., 2013; Xie et al., 2024; Zeng et al., 2020). The overlying Early Miocene Zhujiang Formation (∼23 Ma to 21 Ma) developed large-scale sandstone reservoirs of deep-sea turbidity fans (Li et al., 2013; Yu et al., 2021). From the perspective of tectonic evolution, the Baiyun Sag is primarily controlled by NE-trending faults during the Cenozoic, forming a pattern of “zoning in the north-south direction and blocking in the east-west direction” (Shi et al., 2010). The Baiyun Movement at 23 Ma caused the shelf-slope break zone to migrate rapidly from the vicinity of the Yunli Low Uplift in the southern part of the Baiyun Sag to the Panyu Low Uplift area in the northern part of the sag, triggering intense regional subsidence and a significant rise in paleo-sea level, which established the deep-water environment in the Baiyun Sag that has persisted to the present day (Liu et al., 2011) (Figure 2). This environmental shift, driven by rapid relative sea-level rise, favored the proliferation of planktonic foraminifera productivity and the enrichment of their shell accumulations (Liu et al., 2022). Meanwhile, during the period of 27–18 Ma, the CaCO₃ content in sediments from the South China Sea seabed significantly increased, the calcareous nannofossil assemblage shifted to being dominated by warm-water species with increased abundance, and the Sc/Sr ratio markedly decreased. These phenomena likely correspond to the background of tectonic extension in the South China Sea, where the rapid deepening of the sea basin, weakening of upwelling of bottom water, rising seawater temperature, and decreasing calcium carbonate solubility led to an increase in seawater carbonate saturation, thereby driving a significant deepening of the CCD (Carbonate Compensation Depth), creating extremely favorable conditions for the extensive deposition and preservation of calcareous shells such as those of Globigerina (Wang et al., 2024).

Figure 2

Figure 2. Comprehensive stratigraphic column and tectonic activity, subsidence/spreading rates, and sea-level change diagram of the South China Sea.

The Early Miocene paleogeographic sedimentary pattern in the Pearl River Mouth Basin was shaped jointly by the position of the shelf-slope break zone, source supply systems, and deep-sea circulation. Dual sources from the paleo-Pearl River Delta and the carbonate platform of the Dongsha Uplift created a mixed-source depositional environment (Liu B. et al., 2024). The topographic background of the shelf-slope break zone, being higher in the north and lower in the south, promoted the development of deep-water canyon systems. Relative sea-level changes influenced sediment supply: during forced regression–lowstand periods, sand-rich clastic rocks predominated, while during transgression–highstand periods, carbonate rocks became dominant.

The South China Sea paleo-oceanic circulation controlled by global climate and tectonics during the Early Miocene (Ao et al., 2021; Rasmussen, 2004; Steinthorsdottir et al., 2021; Sun et al., 2016). With the opening of the South China Sea from the late Oligocene to Early Miocene (approximately 23–16 Ma) (Hall, 2002), deep-water circulation primarily connected with the Indian Ocean through the Indonesian Gateway, while Circumpolar Deep Water flowed into the South China Sea from the eastern Indian Ocean, forming an anti-cyclonic deep circulation pattern that influenced the northern continental slope region of the South China Sea (Liu S. et al., 2024) (Figure 1a). This circulation was intensified by the expansion of the Antarctic ice sheet and the restriction event of the Drake Passage during the Early Miocene, leading to increased activity of bottom currents. This enhanced the erosion and sedimentation by bottom currents on the seabed, promoting the development of bottom current depositional systems within the South China Sea basin (Liu S. et al., 2024).

3 Methods

To clarify the sedimentary background and sedimentary distribution, a combined sedimentological analysis was conducted, involving with precise horizon calibration and the establishment of a structural-stratigraphic framework for the 3D seismic data volume, as well as lithological data from drilling (Figure 3).

Figure 3

Figure 3. Well-to-seismic correlation for Well 4A, calibrating the GR log across the target interval of the Fifth Member of the Zhujiang Formation.

3.1 Thin-section observations and descriptions

Rock samples were vacuum-impregnated with blue epoxy resin, cut into standard thin sections (∼30 μm), and stained with Alizarin Red-S. Petrographic analysis using a Leica DM2700P polarizing microscope determined volume percentages of quartz, feldspar, mica, lithic fragments, clay minerals, calcite varieties, glauconite, pyrite, and bioclasts. These components were grouped into three endmembers—terrigenous clastics, chemical calcite, and biogenic calcite (dominated by globigerinids)—and normalized percentages were plotted on a ternary diagram for rock classification (Xie et al., 2018).

3.2 Acquisition of physical properties and pore structure

Total porosity and absolute permeability were measured on core samples via helium porosimetry and pulse-decay permeametry (nitrogen), respectively. The latter method is particularly suitable for ultra-low permeability samples (<1 mD). High-pressure mercury injection experiments characterized pore-throat size distribution, displacement pressure, and median pressure. The complete dataset from these analyses is provided in Supplementary Table S1.

SEM(Scanning Electron Microscope) examination of samples with fresh fracture faces (Hitachi S-2400, 20 kV) revealed microscopic pore structure and authigenic minerals. High-resolution micro-CT scanning (Zeiss Xradia 520 Versa, 100 kV, 3 μm/voxel) was performed to quantitatively characterize 3D pore network structure and connectivity through image reconstruction (Avizo/Dragonfly) and threshold segmentation.

4 Results

4.1 Petrological composition and lithofacies

The lithological components of the Early Miocene globigerinid-rich siliciclastic-carbonate rocks in the study area are primarily composed of planktonic foraminiferal (globigerinid) shells (5%–45%), terrigenous clastics (quartz, clay) (10%–80%), and micritic/crystalline carbonates (5%–75%). Based on the relative proportions of these components and guided by the lithology-based triangular classification scheme for mixed siliciclastic-carbonate sediments (Ye et al., 2018), this study further incorporate physical property criteria to develop a classification more applicable to reservoir evaluation. Accordingly, three distinct compositional assemblages are defined in this study (Table 1).

Table 1

Table 1. Three compositional assemblages of the Early Miocene globigerinid-rich siliciclastic-carbonate rocks.

The first compositional assemblage (I) has been identified as the Globigerinid-bearing (<25%) micritic/non-micritic carbonate grain-siliciclastic rocks and (micritic/non-micritic) carbonate grain-bearing siliciclastic rocks. The second compositional assemblage (II) refers to the Globigerinid-rich (>30%) (Bioclast-bearing) (carbonate-bearing/carbonate-rich) (micritic) siliciclastic rocks. The third compositional assemblage (III) refers to the Globigerinid-bearing, siliciclastic-poor (<10%)​ micritic limestones (dolomites), (non-/carbonate grain-bearing/carbonate grain-rich) (non-bioclastic or bioclastic) (micritic) siliciclastic-poor​ limestones (dolomites), and siliciclastic-bearing (micritic) carbonate grain limestones (dolomites).

4.2 Physical properties, pore structures and diagenetic features

Core petrophysical analysis results from three representative wells in the study area show that the porosity of this suite of siliciclastic-carbonate rocks ranges from 4.98% to 37.7%, with a high average value of 17.43%. The permeability is extremely low, ranging from (0.001–3.38) × 10⁻³μm², with an average value of only 0.148 × 10^-3μm², and the vast majority of samples are below 1mD. Microscopic observations of SEM scanning and digital core 3D pore visualization images present that the reservoir space is almost entirely composed of primary pores, out of the relatively isolated chamber pores of globigerinids (Figures 4a,b).

Figure 4

Figure 4. (a) SEM images of a single foraminifera test; (b) 3D visualization of digital core pores (from Well 4A, 2,926 m below sea level), showing well-preserved intra-skeletal pores as the primary reservoir space; (c) Relationship between porosity and permeability of the Early Miocene globigerinid-rich siliciclastic-carbonate rocks.

Porosity and permeability exhibit a good positive correlation (Figure 4c). The linear relationship is expressed as log10 (Permeability) = 0.056799 × Porosity - 2.132195, with a coefficient of determination r² = 0.3858.​ It should be noted that the reservoir is heterogeneous, and this positive correlation is a phenomenon that only indicates the overall trend; regardless of lithological homogeneity, higher overall porosity tends to correspond to higher permeability.​ Compositional assemblage I (porosity of 17.16%–23.40%, 20.62% in average), II (porosity of 20.45%–37.71%, 25.86% in average) and III (porosity of 6.39%–11.32%, 8.04% in average) have been distributed in the upper right, middle, and lower left areas of Figure 4c, respectively. For samples from intervals with higher terrigenous clastic content (Figure 5), a small amount of primary (siliciclastic) intergranular pores can be observed, although the connectivity of these pores is also extremely poor. Both between globigerinid chambers and between clastic particles, there are dense fillings of clay, silt and (or) later diagenetic cements.

Figure 5

Figure 5. Thin-section photographs of three compositional assemblages of the Early Miocene globigerinid-rich siliciclastic-carbonate rocks.

4.3 Vertical cyclic sequences of lithofacies and petrophysical properties

Three cycles ①, ②, and ③ can be identified in the vertical sequence of Well 4A at a depth of 2,924–2,933 m below sea level. Cycle ① spans the interval from 2,924 to 2,926.9 m, Cycle ② from 2,926.9 to 2,929.1 m, and Cycle ③ from 2,929.1 to 2,932.5 m. The three compositional assemblage are identified within each of the three cycles (Figure 6a). Within each cycle, from bottom to top, Class I, II, III, II, and I reservoirs are observed in vertical succession (Figure 6b).

Figure 6

Figure 6. (a) Vertical cyclic sequences ①, ② and ③ of lithofacies and petrophysical properties out of well 4A; (b) The bidirectional grading sequence (lower part of ① and full ②) from core and thin-section features (Well 4A, 2,925.7–2,929.1 m below sea level).

Class I exhibits the highest GR value of 102.74 API and the highest RHOB(Bulk Density) value of 2.349 g/cm³, a relatively lower porosity of 20.62%, alongside moderate permeability of 0.2431 mD and an NPOR2(Neutron Porosity Version 2) value of 16.06%. Class II is characterized by a moderate GR value of 76.11 API and a moderate RHOB value of 2.266 g/cm³, a slightly higher NPOR2 value of 17.13%, and the highest porosity and permeability values of 25.86% and 0.3113 mD respectively. Class III shows a relatively low GR value of 59.19 API, a high RHOB value of 2.408 g/cm³ and the lowest NPOR2 value of 10.29%, and the lowest porosity and permeability values of 8.042% and 0.04164 mD respectively.

5 Discussion

5.1 Factors responsible for developing high porosity

Planktonic foraminiferal enrichment provides the material foundation, with well-preserved shell integrity at high proportions (14.47%) and significant contribution of intraskeletal pores to total porosity (69.71%) (Figures 4a,b). The target interval in the study area is buried at a considerable depth of up to 2.8 km. The shells of Globigerina mostly remain intact, with fewer instances of breakage caused by mechanical compaction, ensuring that the intraskeletal pores of Globigerina contribute up to 68.07% to the total porosity. Multiple global case studies of deep-water carbonate reservoirs exhibit similar genetic characteristics: their high-porosity material foundation primarily stems from abundant and well-preserved microfossil shells, such as planktonic foraminifera and coccolithophores, which provide intraskeletal and intergranular pores. Specifically, the reservoir space in the East Java and Ekofisk cases is dominated by intraskeletal pores and intergranular pores of planktonic foraminifera (Owen, 1972); whereas the Cretaceous reservoir of the Tishrine oil field in Syria primarily features intraskeletal micropores and intergranular micropores of coccolithophores (a type of calcareous nannofossil). SEM images show intact coccolithophore individuals with shield diameters less than 6μm, forming extensive intergranular micropore systems (Zhang et al., 2012). These cases collectively reveal that primary pores provided by microfossil frameworks are the common material foundation for such high-porosity reservoirs. The Baiyun Movement at 23 Ma caused the northward leap of the shelf-slope break zone, accompanied by rapid sea-level rise. The study area, located at the margin of a carbonate platform distal from terrigenous supply, experienced rapid water deepening which induced upwelling, providing a high-productivity background for the proliferation of Globigerina. Concurrently, the rapid transgression significantly reduced regional sedimentation rates, creating favorable conditions for the enrichment of Globigerina shells and the preservation of primary pores. The aforementioned cases (East Java, Ekofisk, Tishrine, and this study area) are all controlled by the macroscopic process of tectonic subsidence leading to transgression, forming deep-water enrichment environments distal from terrigenous sources.

The impact of diagenesis on reservoir properties is significant. This is​ to some extent analogous to the planktonic foraminiferal limestone facies developed in deep-water environments of the early Miocene in northwestern East Java (Guo et al., 2020), where bottom current activity of moderate intensity effectively winnows away clayey matrix and mud, preserving more primary pore spaces (Figure 7). Similarly, the Pliocene Globigerina limestone in the Ekofisk field, Norwegian North Sea, also primarily uses intraskeletal pores and intergranular pores of planktonic foraminifera as its main reservoir space (Owen, 1972). The key commonality between the East Java and Ekofisk cases lies in their relatively shallow burial depth (typically <1500 m), relatively weak diagenetic cementation, and the effective cleansing action of moderate-intensity bottom currents which purifies the sediment, improves reservoir properties, and allows for the preservation of high-quality pores, typically exhibiting high porosity and medium-high permeability characteristics.

Figure 7

Figure 7. Appropriately intense bottom current activity winnowed fine-grained matrix clay/lime mud while moderate terrigenous clastics inhibited carbonate cementation.

In contrast, both this study area and the Tishrine oil field in Syria face a deep burial background. Their pore types are also dominated by well-developed intergranular pores and intraskeletal pores. Within this context, intense compaction and strong cementation (e.g., by calcite, ankerite) caused by calcium-rich fluids in deep settings become the main controlling factors for reservoir properties, resulting in reservoirs generally characterized by high porosity and low permeability. Research on the Tishrine field indicates that pressure dissolution and cementation by calcite under deep burial are extremely intense, leading to very low permeability (mostly <1 × 10⁻³ μm²). In this study area, due to greater water depth and deeper burial, the modifying effect of bottom currents on porosity is more complex: excessively strong bottom current winnowing forms pure carbonate facies, which can conversely induce intense cementation; whereas overly weak bottom currents fail to effectively winnow away terrigenous mud, leading to matrix clogging the pores (Figure 7). Over the study area, the 23 Ma Baiyun Movement induced northward migration of the shelf-slope break and rapid sea-level rise (Xie et al., 2022). Wells 4A, 4B, 9A and 9B located at the margin of a carbonate platform (Figure 1), experienced productivity explosion of planktonic foraminifera (with the dominant species Paragloborotalia nana comprising 35.3%–87.8%). Possible upwelling backgrounds promoted planktonic foraminiferal proliferation and rapid transgression reduced sedimentation rates (Górny et al., 2022), creating favorable conditions for shell enrichment.

5.2 Factors responsible for developing low permeability genesis

Excessive bottom current winnowing generates pure carbonate facies that, under conditions of abundant deep-derived fluids and dissolved calcium (Zhang et al., 2021; Xu et al., 2024) readily undergoes intense calcite or iron dolomite cementation, filling pores and occluding narrow throat channels (Figures 5–7). However, the difference lies in that although the Globigerina limestone in the East Java Basin has experienced bottom current winnowing, its burial depth is mostly less than 1500m, resulting in relatively weak cementation and permeability reaching (1–600) × 10⁻³μm², classifying it as a high-porosity, medium-high permeability reservoir. In stark contrast, the target interval in the study area reaches a burial depth of up to 2.8 km. The deep burial background combined with calcium-rich diagenetic fluids makes intense cementation the main controlling factor for the low permeability in this study area, which is fundamentally different from the formation mechanisms observed in the East Java and Ekofisk cases. This point is extremely similar to the situation in the Tishrine oil field, where its Cretaceous reservoir also suffers from very low permeability (mostly <1 × 10^-3μm²) due to intense pressure dissolution and cementation by calcite under a deep burial background, confirming that intense compaction and cementation in deep burial environments are the common key factors leading to the low permeability of such biogenic micropore reservoirs. This phenomenon contrasts sharply with the property-improving effects of bottom currents observed in the East Java case, reflecting the influence of the study area’s distinctive diagenetic setting.

On the other side, too weak bottom current activity results in excessive terrigenous material transported by distal turbidity currents (Figure 7) (Shanmugam, 2008), diluting planktonic foraminiferal abundance and causing clayey matrix and mud to fill intraskeletal and intergranular pores (Figure 5), severely choking the already-narrow throat passages. In the East Java and Ekofisk cases, due to being distal from terrigenous sources, the impact of argillaceous filling is relatively minor; whereas in this study area during periods of overly weak bottom currents, the input of terrigenous mud increases, similar to the damaging effect of argillaceous content on pores in the Cretaceous reservoir of the Tishrine oil field. Moreover, framboidal pyrite, authigenic kaolinite, glauconite, and other pore-filling minerals further deteriorate pore connectivity (Bello et al., 2022). Thus, The dual-damage mechanism of cementation infilling and matrix occlusion represents a unique low-permeability genesis distinguishing this area from other regions.

5.3 Vertical cyclic sequences and global comparision

The key well section displays a symmetric sequence of energy intensity increasing then decreasing upward (Figure 6a), corresponding to fifth-order cycles within the transgressive systems tract (e.g., glacial-interglacial cycles) (Catuneanu et al., 2009). This cyclical pattern is consistent with global deep-sea sedimentary records showing periodic variations in bottom current intensity (Rodríguez-Tovar et al., 2019; Stow et al., 2023) (Figure 6b). During periods of enhanced deep-water circulation (glacial stages), high bottom current intensity drives strong winnowing but results in severe cementation; during periods of weakened circulation (interglacial stages), terrigenous detritus inhibits cementation but excessive matrix infilling occurs (Rahman et al., 2025). Optimal reservoirs form under moderate bottom current intensities where terrigenous detritus suppresses carbonate cementation (distinguishing it from the pure carbonate facies of East Java) while effectively winnowing fine-grained matrix. This illustrates that the formation of high-quality reservoirs requires moderate bottom current intensity that can both effectively winnow fine-grained matrix (Figure 7) and involve the mixing of terrigenous detritus to suppress intense cementation; simultaneously, an appropriate amount of terrigenous input inhibits cementation without causing severe pore filling. Combined with moderate diagenetic cementation and overpressured adjacent zones providing compaction resistance, high-porosity, low-permeability mixed carbonate-siliciclastic reservoirs are effectively preserved. The study area’s distinctive diagenetic background and bottom current-sediment supply coupling relationship generate unique high-porosity-low-permeability characteristics, providing important reference for reservoir prediction in globally analogous geological settings.

6 Conclusion

This work presents that the Early Miocene globigerinid-rich siliciclastic-carbonate reservoir sediments in ultra-deep water areas of the Baiyun Sag, Pearl River Mouth Basin, South China Sea are primarily composed of planktonic foraminiferal (globigerinid) shells (5%–45%), terrigenous clastics (quartz, clay) (10%–80%), and micritic/crystalline carbonates (5%–75%). The reservoir space is primarily composed of the relatively isolated chamber pores of globigerinids. The assemblage I, II and III exhibit the best (%), moderate (%), and poor (%) reservoir properties, respectively.

The reservoir space is predominantly composed of well-preserved primary foraminiferal chambers. The preservation of high porosity benefits from relatively weak mechanical compaction. The inherent isolation of foraminiferal chambers, combined with the blockage of pore-throat channels by interstitial materials such as clay and micrite, as well as authigenic cements including ferroan calcite and ferroan dolomite, results in extremely low permeability.

Accompanied with the rapid sea-lever rise over carbonate platforms, high productivity and low sedimentation rates are extremely favorable for the enrichment of foraminiferal shells. Moderate terrigenous clastics inhibited carbonate cementation and appropriately intense bottom current activity winnowed fine-grained matrix clay/lime mud, which guaranteed the preservation of more foraminiferal chambers and develop the best reservoir properties.

Data availability statement

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

Author contributions

YM: Writing – review and editing, Writing – original draft. LX: Writing – original draft, Writing – review and editing. HJ: Writing – original draft, Writing – review and editing. SY: Writing – review and editing, Writing – original draft. XW: Writing – original draft, Writing – review and editing. HS: Writing – review and editing, Writing – original draft. BC: Writing – review and editing, Writing – original draft.

Funding

The author(s) declared that financial support was received for this work and/or its publication. This research was supported by the project of Genetic Mechanisms and Predictive Model for High-Quality Planktonic Foraminiferal Reservoirs in Baiyun Deep-Water Basin (No. 202515722422).

Conflict of interest

Authors YM, LX, XW, HS, and BC were employed by CNOOC China Limited.

Authors YM, LX, XW, HS, and BC were employed by CNOOC Deepwater Development Limited.

Generative AI statement

The author(s) declared that generative AI was not used in the creation of this manuscript.

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Supplementary material

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/feart.2025.1746835/full#supplementary-material

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