Quartz types, genesis and their geological significance within the Wufeng-Longmaxi Formation in north-western Hunan, China

Abstract

Quartz is an important mineral component in the Late Ordovician – Early Silurian Wufeng-Longmaxi Formation with various forms and sources and has a significant impact on the properties of shale gas reservoirs. In this study, geochemical analysis, scanning electron microscopy (SEM) observation, and rock mechanics testing were performed on shale samples from the Wufeng-Longmaxi Formation in north-western Hunan, South China. Quartz is classified into four types based on morphological features and cathodoluminescence (CL) images under SEM – terrigenous detrital quartz, quartz overgrowths, biogenic skeletal quartz and microquartz. The quartz in Upper Longmaxi Formation is predominantly of terrigenous origin and contains a small amount of quartz formed by clay transformation. The quartz in the Wufeng-Lower Longmaxi Formation is predominantly biogenic. The biogenic quartz has a direct effect on organic matter (OM) abundance, pore structure and brittleness. It is indicated by the positive correlation with TOC content and biogenic Ba content that biogenic quartz-rich strata have high paleoproductivity. The rigid frameworks formed by biogenic quartz during the early diagenesis stage facilitated the preservation of the primary pores. The interparticle pores of biogenic quartz are the space for OM preservation and migration, creating conditions for the development of OM pores. Additionally, the calculated brittleness index (BI) shows a positive correlation with biogenic quartz content, indicating that layers rich in biogenic quartz are more conducive to fracture. Therefore, the Wufeng-Lower Longmaxi Formation has higher OM content, porosity and represents a more favorable exploration and development target.

Graphical abstract

Keywords

quartz / silica source / porosity / organic matter / rock mechanics

References

[1] Adachi M, Yamamoto K, Sugisaki R (1986). Hydrothermal chert and associated siliceous rocks from the northern pacific — their geological significance as indication of ocean ridge activity. Sediment Geol, 47(1–2): 125–148

[2] Barghoorn E S, Tyler S A (1965). Microorganisms from the Gunflint Chert: these structurally preserved Precambrian fossils from Ontario are the most ancient organisms known.Science, 147(3658): 563–575

[3] Bernard S, Horsfield B, Schulz H M, Wirth R, Schreiber A, Sherwood N (2012). Geochemical evolution of organic-rich shales with increasing maturity: a STXM and TEM study of the Posidonia Shale (Lower Toarcian, northern Germany).Mar Pet Geol, 31(1): 70–89

[4] Boles J R, Franks S G (1979). Clay diagenesis in Wilcox sandstones of Southwest Texas: implications of smectite diagenesis on sandstone cementation.J Sediment Res, 49(1): 55–70

[5] Chalmers G R, Bustin R M, Power I M (2012). Characterization of gas shale pore systems by porosimetry, pycnometry, surface area, and field emission scanning electron microscopy/transmission electron microscopy image analyses: examples from the Barnett, Woodford, Haynesville, Marcellus, and Doig units.AAPG Bull, 96(6): 1099–1119

[6] Chung F H (1974). Quantitative interpretation of X-ray diffraction patterns of mixtures. I. Matrix-flushing method for quantitative multicomponent analysis.J App Crystallography, 7(6): 519–525

[7] Curtis M E, Sondergeld C H, Ambrose R J, Rai C S (2012). Microstructural investigation of gas shales in two and three dimensions using nanometer-scale resolution imaging.AAPG Bull, 96(4): 665–677

[8] Dong T, He S, Chen M F, Hou Y G, Guo X W, Wei C, Han Y J, Yang R (2019). Quartz types and origins in the paleozoic Wufeng-Longmaxi Formations, eastern Sichuan Basin, China: implications for porosity preservation in shale reservoirs.Mar Pet Geol, 106: 62–73

[9] Francois R, Honjo S, Manganini S J, Ravizza G E (1995). Biogenic barium fluxes to the deep-sea – implications for paleoproductivity reconstruction.Global Biogeochem Cycles, 9(2): 289–303

[10] Gambacorta G, Trincianti E, Torricelli S (2016). Anoxia controlled by relative sea-level changes: an example from the Mississippian Barnett Shale Formation.Palaeogeogr Palaeoclimatol Palaeoecol, 459: 306–320

[11] Guan Q Z, Dong D Z, Zhang H L, Sun S S, Zhang S R, Guo W (2021). Types of biogenic quartz and its coupling storage mechanism in organic-rich shales: a case study of the Upper Ordovician Wufeng Formation to Lower Silurian Longmaxi Formation in the Sichuan Basin, SW China.Pet Explor Dev, 48(4): 813–823

[12] Guo Z Q, Li X Y, Liu C, Feng X, Shen Y (2013). A shale rock physics model for analysis of brittleness index, mineralogy and porosity in the Barnett Shale.J Geophys Eng, 10(2): 025006

[13] Ishii E, Sanada H, Iwatsuki T, Sugita Y, Kurikami H (2011). Mechanical strength of the transition zone at the boundary between opal-A and opal-CT zones in siliceous rocks. Eng Geol, 122(3–4): 215–221

[14] Ko L T, Loucks R G, Zhang T W, Ruppel S C, Shao D Y (2016). Pore and pore network evolution of Upper Cretaceous Boquillas (Eagle Ford-equivalent) mudrocks: results from gold tube pyrolysis experiments.AAPG Bull, 100(11): 1693–1722

[15] Li Y, Wang Z S, Gan Q, Niu X L, Xu W K (2019). Paleoenvironmental conditions and organic matter accumulation in Upper Paleozoic organic-rich rocks in the east margin of the Ordos Basin, China.Fuel, 252: 172–187

[16] Li Y, Yang J H, Pan Z J, Tong W S (2020). Nanoscale pore structure and mechanical property analysis of coal: an insight combining AFM and SEM images.Fuel, 260: 116352

[17] Li Y, Chen J Q, Yang J H, Liu J S, Tong W S (2022). Determination of shale macroscale modulus based on microscale measurement: a case study concerning multiscale mechanical characteristics.Petro Sci, 19(3): 1262–1275

[18] Lin D L, Tang S H, Xi Z D, Zhang B, Ye Y P (2021). Geochemical characteristics of Late Ordovician shales in the Upper Yangtze Platform, south China: implications for redox environmental evolution.Minerals (Basel), 11(7): 710

[19] Liu J, Li Y, Zhang Y, Liu S, Cai Y (2017). Evidences of biogenic silica of Wufeng-Longmaxi Formation shale in Jiaoshiba area and its geological significance. J China U Petroleum (Nat Sci), 41(1): 34–41 (in Chinese)

[20] Liu S G, Deng B, Li Z W, Sun W (2012). Architecture of basin-mountain systems and their influences on gas distribution: a case study from the Sichuan basin, South China.J Asian Earth Sci, 47: 204–215

[21] Lynch F L (1997). Frio shale mineralogy and the stoichiometry of the smectite-to-illite reaction: the most important reaction in clastic sedimentary diagenesis.Clays Clay Miner, 45(5): 618–631

[22] Metwally Y M, Chesnokov E M (2012). Clay mineral transformation as a major source for authigenic quartz in thermo-mature gas shale.Appl Clay Sci, 55: 138–150

[23] Milliken K L, Ergene S M, Ozkan A (2016). Quartz types, authigenic and detrital, in the Upper Cretaceous Eagle Ford Formation, South Texas, USA.Sediment Geol, 339: 273–288

[24] Milliken K L, Esch W L, Reed R M, Zhang T W (2012). Grain assemblages and strong diagenetic overprinting in siliceous mudrocks, Barnett Shale (Mississippian), Fort Worth Basin, Texas.AAPG Bull, 96(8): 1553–1578

[25] Milliken K L, Olson T (2017). Silica diagenesis, porosity evolution, and mechanical behavior in siliceous mudstones, Mowry Shale (Cretaceous), Rocky Mountains, USA.J Sediment Res, 87(4): 366–387

[26] Niu X, Yan D T, Zhuang X G, Liu Z X, Li B Q, Wei X S, Xu H W, Li D W (2018). Origin of quartz in the lower Cambrian Niutitang Formation in south Hubei Province, upper Yangtze platform.Mar Pet Geol, 96: 271–287

[27] Peltonen C, Marcussen O, Bjorlykke K, Jahren J (2009). Clay mineral diagenesis and quartz cementation in mudstones: the effects of smectite to illite reaction on rock properties.Mar Pet Geol, 26(6): 887–898

[28] Pommer M, Milliken K (2015). Pore types and pore-size distributions across thermal maturity, Eagle Ford Formation, southern Texas.AAPG Bull, 99(9): 1713–1744

[29] Reynolds J H, Verhoogen J (1953). Natural variations in the isotopic constitution of silicon.Geochim Cosmochim Acta, 3(5): 224–234

[30] Rowe H D, Loucks R G, Ruppel S C, Rimmer S M (2008). Mississippian Barnett Formation, Fort Worth Basin, Texas: bulk geochemical inferences and Mo-TOC constraints on the severity of hydrographic restriction. Chem Geol, 257(1–2): 16–25

[31] Schieber J, Krinsley D, Riciputi L (2000). Diagenetic origin of quartz silt in mudstones and implications for silica cycling.Nature, 406(6799): 981–985

[32] Shan C A, Zhang T, Wei Y, Zhang Z (2017). Shale gas reservoir characteristics of Ordovician-Silurian formations in the central Yangtze area, China.Front Earth Sci, 11(1): 184–201

[33] Shimizu H, Masuda A (1977). Cerium in chert as an indication of marine environment of its formation.Nature, 266(5600): 346–348

[34] Tatzel M, von Blanckenburg F, Oelze M, Bouchez J, Hippler D (2017). Late Neoproterozoic seawater oxygenation by siliceous sponges.Nat Commun, 8(1): 621

[35] Thyberg B, Jahren J, Winje T, Bjorlykke K, Faleide J I, Marcussen O (2010). Quartz cementation in Late Cretaceous mudstones, northern North Sea: changes in rock properties due to dissolution of smectite and precipitation of micro-quartz crystals.Mar Pet Geol, 27(8): 1752–1764

[36] Tribovillard N, Algeo T J, Lyons T, Riboulleau A (2006). Trace metals as paleoredox and paleoproductivity proxies: an update. Chem Geol, 232(1–2): 12–32

[37] van de Kamp P C (2008). Smectite-illite-muscovite transformations, quartz dissolution, and silica release in shales.Clays Clay Miner, 56(1): 66–81

[38] van den Boorn S H J M, van Bergen M J, Nijman W, Vroon P Z (2007). Dual role of seawater and hydrothermal fluids in Early Archean chert formation: evidence from silicon isotopes.Geology, 35(10): 939–942

[39] Wedepohl K H (1971). Environmental influences on the chemical composition of shales and clays.Phys Chem Earth, 8: 307–333

[40] Williams L A, Parks G A, Crerar D A (1985). Silica diagenesis, I. solubility controls.J Sediment Res, 55(3): 301–311

[41] Wright J (2001). Making loess-sized quartz silt: data from laboratory simulations and implications for sediment transport pathways and the formation of ‘desert’ loess deposits associated with the Sahara. Quat Int, 76–77: 7–19

[42] Xi Z D, Tang S H, Zhang S H, Yi Y X, Dang F, Ye Y P (2019). Characterization of quartz in the Wufeng Formation in northwest Hunan Province, south China and its implications for reservoir quality.J Petrol Sci Eng, 179: 979–996

[43] Xi Z D, Tang S H, Zhang S H, Lash G G, Ye Y P (2022). Controls of marine shale gas accumulation in the eastern periphery of the Sichuan Basin, South China.Int J Coal Geol, 251: 103939

[44] Xie W D, Wang M, Wang H, Ma R Y, Duan H Y (2021). Diagenesis of shale and its control on pore structure, a case study from typical marine, transitional and continental shales.Front Earth Sci, 15(2): 378–394

[45] Xu C, Rong J Y, Yue L, Boucot A J (2004). Facies patterns and geography of the Yangtze region, South China, through the Ordovician and Silurian transition. Palaeogeogr Palaeoclimatol Palaeoecol, 204(3–4): 353–372

[46] Xu H, Zhou W, Hu Q H, Yi T, Ke J, Zhao A K, Lei Z H, Yu Y (2021). Quartz types, silica sources and their implications for porosity evolution and rock mechanics in the Paleozoic Longmaxi Formation shale, Sichuan Basin.Mar Pet Geol, 128: 105036

[47] Yamamoto K (1987). Geochemical characteristics and depositional environments of cherts and associated rocks in the Franciscan and Shimanto Terranes. Sediment Geol, 52(1–2): 65–108

[48] Yang X R, Yan D T, Wei X S, Zhang L W, Zhang B, Xu H W, Gong Y, He J (2018). Different formation mechanism of quartz in siliceous and argillaceous shales: a case study of Longmaxi Formation in South China.Mar Pet Geol, 94: 80–94

[49] Ye Y P, Tang S H, Xi Z D (2020). Brittleness evaluation in shale gas reservoirs and its influence on fracability.Energies, 13(2): 388

[50] Zhao J H, Jin Z K, Jin Z J, Wen X, Geng Y K (2017). Origin of authigenic quartz in organic-rich shales of the Wufeng and Longmaxi Formations in the Sichuan Basin, south China: implications for pore evolution.J Nat Gas Sci Eng, 38: 21–38

[51] Zhou L, Algeo T J, Shen J, Hu Z F, Gong H M, Xie S C, Huang J H, Gao S (2015). Changes in marine productivity and redox conditions during the Late Ordovician Hirnantian glaciation.Palaeogeogr Palaeoclimatol Palaeoecol, 420: 223–234

[52] Zou C N, Yang Z, Sun S S, Zhao Q, Bai W H, Liu H L, Pan S Q, Wu S T, Yuan Y L (2020). “Exploring petroleum inside source kitchen”: shale oil and gas in Sichuan Basin.Sci China Earth Sci, 63(7): 934–953

Acknowledgments

This study was financially supported by the National Science and Technology Major Project of China (No. 2017ZX05035). We thank all of the editors and reviewers for their helpful comments and suggestions.

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