Impact of pyrite on shale gas enrichment—a case study of the Lower Silurian Longmaxi Formation in southeast Sichuan Basin

doi:10.1007/s11707-021-0907-8

Front. Earth Sci.

2021, Vol. 15

Issue (2) : 332-342 https://doi.org/10.1007/s11707-021-0907-8

RESEARCH ARTICLE

Impact of pyrite on shale gas enrichment—a case study of the Lower Silurian Longmaxi Formation in southeast Sichuan Basin

Xin CHEN^1,², Lei CHEN^1,²(

), Xiucheng TAN^1,², Shu JIANG³, Chao WANG⁴

¹. Sichuan Key Laboratory of Natural Gas Geology, Southwest Petroleum University, Chengdu 610500, China
². School of Geoscience and Technology, Southwest Petroleum University, Chengdu 610500, China
³. Energy & Geoscience Institute (EGI), University of Utah, UT 84108, USA
⁴. Exploration and Development Research Institute, SINOPEC Jianghan Oiled Field Company, Wuhan 430223, China

Download: PDF(4028 KB) HTML
Export: BibTeX | EndNote | Reference Manager | ProCite | RefWorks

Abstract

Pyrite is one of the important components of shale and plays a crucial role in shale gas enrichment. However, currently there are just a few studies on this subject matter. Therefore, the characteristics of pyrite in organic-rich shale section of the Longmaxi Formation and its impact on shale gas enrichment was studied in this paper by using outcrops, drilling cores, thin sections and test data. Result shows that pyrite occurred in different forms (macro-micro scale) in the Longmaxi Formation in the southeast Sichuan Basin. The formation and content of pyrite has a close relation with TOC content. Pyrite may catalyze the hydrocarbon generation of organic matter. Interparticle pores within the pyrite framboids and organic matter pores in the pyrite-organic matter complex are well-developed in the Longmaxi Shale, which serves as a major reservoir space for shale gas. Pyrite can promote shale gas enrichment by absorbing shale gas on its surface and preserving free gas in the interparticle pores and organic matter pores. In addition, as a kind of brittle mineral, pyrite can improve the brittleness of shale reservoir and increase the micro-nano pore system in shale reservoir, thereby improving the transmission performance of shale reservoir and boosting shale gas recovery.

Keywords shale reservoir pyrite Longmaxi Formation southeast Sichuan Basin

Corresponding Author(s): Lei CHEN

Online First Date: 19 July 2021 Issue Date: 26 October 2021

Cite this article:

Xin CHEN,Lei CHEN,Xiucheng TAN, et al. Impact of pyrite on shale gas enrichment—a case study of the Lower Silurian Longmaxi Formation in southeast Sichuan Basin[J]. Front. Earth Sci., 2021, 15(2): 332-342.

URL:

https://academic.hep.com.cn/fesci/EN/10.1007/s11707-021-0907-8
https://academic.hep.com.cn/fesci/EN/Y2021/V15/I2/332

Fig.1 (a) Location of the study area and (b) stratigraphic column of the Longmaxi Formation, and the gamma-ray log of the X1 Well (After Wang et al., 2002).

Well	Pyrite content (mean)/%	TOC content (mean)/%	Adsorbed gas content (mean)/(m³·t⁻¹)	Rock pyrolysis parameters
Well	Pyrite content (mean)/%	TOC content (mean)/%	Adsorbed gas content (mean)/(m³·t⁻¹)	S1 (mean)/(0.01 mg·g⁻¹)	S2 (mean)/(0.01 mg·g⁻¹)
X1	1.3–6.6 (3.33)	0.83–5.62 (2.60)	1.0–3.01 (1.84)	0.66–2.3 (1.32)	2.63–7.59 (4.21)
X2	1.4–7.5 (2.81)	0.75–4.97 (2.46)	1.42–3.35 (2.21)	1.0–3.0 (1.89)	/
X3	2.0–7.0 (4.06)	0.86–6.67 (3.17)	/	/	/
Total	$1.3 − 7.5 ? (3.21) n = 177$	$0.83 − 6.67 ? (2.60) n = 177$	$1 − 3.35 ? (1.97) n = 21$	$0.66 − 3.0 ? (1.45) n = 93$	$2.63 − 7.59 ? (4.21) n = 62$

Tab.1 The number of samples and data of the test results

Fig.2 Photos of drilling cores showing macroscopic characteristics of pyrite in the Longmaxi shale in the southeast Sichuan Basin. (a) Pyrite laminations, X2 well, 2412.5 m; (b) pyrite nodules developed within the pyrite laminations, X2 well, 2396.85 m; (c) pyrite nodules, X2 well, 2358.62 m; (d) dispersed granular pyrites with particle size less than 0.5 mm, X2 well, 2370.46 m.

Fig.3 Microscopic photos showing pyrite characteristics in the Longmaxi Formation shale in the southeast Sichuan Basin. (a) Normal spherical pyrite framboid; (b) pyrite framboids shadows without intragranular nanopore; (c) pyrite framboid aggregation; (d) irregular allotriomorphic-subhedral pyrite clump; (e) allotriomorphic-subhedral pyrite grains; (f) subhedral-euhedral pyrite particles.

Fig.4 Relationship between pyrite content and TOC content of the Longmaxi Formation shale in the southeast Sichuan Basin.

Fig.5 Relationship between pyrite content and S1 content in the Longmaxi Formation shale in the southeast Sichuan Basin.

Fig.6 Relationship between pyrite content and S2 content in the Longmaxi Formation shale in the southeast Sichuan Basin.

Fig.7 Energy dispersive spectrum (EDS) analysis of pyrite in the Longmaxi Formation shale in the southeast Sichuan Basin. (a) Energy dispersive spectrum for pyrite framboid, X1 Well. 1998.21 m; (b) Energy dispersive spectrum for euhedral pyrite, X1 Well, 1997.34 m; (c) Energy dispersive spectrum for pyrite framboids, X1 Well, 2044.17 m; (d) Energy dispersive spectrum for irregular pyrite, X1 Well, 2049.11 m.

Fig.8 Relationship between pyrite content and adsorption gas content in the Longmaxi Formation shale in the southeast Sichuan Basin.

Fig.9 Common pore types associated with pyrite in the Longmaxi Formation shale in the southeast Sichuan Basin. (a) Intergranular pore of pyrite, X2 well, 2330.46 m; (b) Intergranular pore of pyrite, X2 well, 2346.50 m; (c) Organic pore in pyrite framboid, X2 well, 2366.74 m; (d) Organic pore in pyrite, X2 well, 2402.65 m.

1	O H Ardakani, H Sanei, A Ghanizadeh, M McMechan, F Ferri, C R Clarkson (2017). Hydrocarbon potential and reservoir characteristics of Lower Cretaceous Garbutt Formation, Liard Basin Canada. Fuel, 209: 274–289 https://doi.org/10.1016/j.fuel.2017.07.106
2	R A Berner, J W De Leeuw, B Spiro, D G Murchison, G Eglinton (1985). Sulphate reduction, organic matter decomposition and pyrite formation. Philos Trans R Soc Lond, 315(1531): 25–38 https://doi.org/10.1098/rsta.1985.0027
3	T T Cao, M Deng, Z G Song, G X Liu, Y R Huang (2018). Study on the effect of pyrite on the accumulation of shale oil and gas. Nat Gas Geosci, 29(03): 404–414 (in Chinese)
4	T T Cao, Z G Song, S B Wang, J Xia (2015). A comparative study of the specific surface area and pore structure of different shales and their kerogens. Sci China Earth Sci, 58(4): 510–522 https://doi.org/10.1007/s11430-014-5021-2
5	K Chen, J C Zhang, X Tang, J D Yu, Y Liu, C Yang (2016b). Main controlling factors on shale adsorption capacity of the Lower Silurian Longmaxi Formation in western Hunan-Hubei area. Oil & Gas Geol, 37(1): 23–29 (in Chinese)
6	L Chen, Y C Lu, S Jiang, J Q Li, T L Guo, C Luo (2015). Heterogeneity of the Lower Silurian Longmaxi marine shale in the southeast Sichuan Basin of China. Mar Pet Geol, 65: 232–246 https://doi.org/10.1016/j.marpetgeo.2015.04.003
7	Q Chen, J C Zhang, X Tang, W J Li, Z M Li (2016a). Relationship between pore type and pore size of marine shale: an example from the Sinian-Cambrian Formation, Upper Yangtze region, south China. Int J Coal Geol, 158(3): 13–28 https://doi.org/10.1016/j.coal.2016.03.001
8	L Chen, G Wang, Y Yang, C Jing, M Chen, X Tan (2019). Geochemical characteristics of bentonite and its influence on shale reservoir quality in Wufeng–Longmaxi Formation, south Sichuan Basin, China. Energy Fuels, 33(12): 12366–12373 https://doi.org/10.1021/acs.energyfuels.9b03510
9	J W Cui, R K Zhu, S T Wu, B Bai (2013). The role of pyrite on organic matter enrichment, hydrocarbon generation and expulsion and shale oil accumulation. Geol Rev, 59: 783–784 (in Chinese)
10	J W Cui, C N Zou, R K Zhu, B Bai, S T Wu, T Wang (2012). New advances in shale porosity research. Adv Earth Sci, 27(12): 1319–1325 (in Chinese)
11	J B Curtis (2002). Fractured shale-gas system. AAPG Bull, 86(11): 1921–1938
12	S T Grimes, K L Davies, I B Butler, F Brock, D Edwards, D Rickard, D E G Briggs, R J Parkes (2002). Fossil plants from the Eocene London Clay: the use of pyrite textures to determine the mechanism of pyritization. J Geol Soc London, 159(5): 493–501 https://doi.org/10.1144/0016-764901-176
13	T L Guo (2015). The Fuling shale gas field — a highly productive Silurian gas shale with high thermal maturity and complex evolution history, southeastern Sichuan Basin, China. Interpretation (Tulsa), 3(2): SJ25–SJ34 https://doi.org/10.1190/INT-2014-0148.1
14	F Hao, H Y Zou, Y C Lu (2013). Mechanisms of shale gas storage: implications for shale gas exploration in China. AAPG Bull, 97(8): 1325–1346 https://doi.org/10.1306/02141312091
15	A L Harrison, A D Jew, M K Dustin, D L Thomas, C M Joe-Wong, J R Bargar, N Johnson, G E Brown Jr, K Maher (2017). Element release and reaction-induced porosity alteration during shale-hydraulic fracturing fluid interaction. Appl Geochem, 82: 47–62 https://doi.org/10.1016/j.apgeochem.2017.05.001
16	T H He, S F Lu, W H Li, Z Z Tan, X W Zhang (2018). Effect of salinity on source rock formation and its control on the oil content in shales in the Hetaoyuan Formation from the Biyang Depression, Nanxiang Basin, Central China. Energy Fuels, 32(6): 6698–6707 https://doi.org/10.1021/acs.energyfuels.8b01075
17	L He, Y P Wang, D F Chen, Q X Wang, C Wang (2019). Relationship between sedimentary environment and organic matter accumulation in the black shale of Wufeng-Longmaxi Formations in Nanchuan area, Chongqing. Nat Gas Geosci, 30(02): 203–218 (in Chinese)
18	T H He, S F Lu, W H Li, D Q Sun, W Q Pan, B S Zhang, Z Z Tan, J F Ying (2020). Paleoweathering, hydrothermal activity and organic matter enrichment during the formation of earliest Cambrian black strata in the northwest Tarim Basin, China. J Petrol Sci Eng, 189: 106987 https://doi.org/10.1016/j.petrol.2020.106987
19	J Z Huang, S J Chen, J R Song, L S Wang, X M Gou, T D Wang, H M Dai (1997). Hydrocarbon source systems and formation of gas fields in Sichuan Basin. Sci China Ser D Earth Sci, 40(1): 32–42 https://doi.org/10.1007/BF02878579
20	J M Hunt, M D Lewan, J C Hennt (1991). Modelling oil generation with time-temperature index graphs based on the Arrhenius equation. AAPG Bull, 75(4): 795–807
21	I R Kaplan, K J Bird, I L Tailleur (2012). Source of molten elemental sulfur and hydrogen sulphide from the Inigok well, northern Alaska. AAPG Bull, 96(2): 337–354 https://doi.org/10.1306/05021110202
22	D Li, C H Ou, Z G Ma, P P Jin, Y J Ren, Y F Zhao (2018). Pyrite-shale interaction in shale gas enrichment and development. Geophys Prospect, 57(3): 332–343 (in Chinese)
23	Z Y Liu, J C Zhang, Y Liu, W W Yu, W He, B W Li (2016). The particle size characteristics of pyrite in Western Hunan and Hubei areas’ Wufeng-Longmaxi Formation shale. Sci Tech Eng, 16(26): 34–41 (in Chinese)
24	R G Loucks, R M Reed, S C Ruppel, D M Jarvie (2009). Morphology, genesis, and distribution of nanometer-scale pores in siliceous mudstones of the Mississippian Barnett Shale. J Sediment Res, 79(12): 848–861 https://doi.org/10.2110/jsr.2009.092
25	R G Loucks, S G Ruppel (2007). Mississippian Barnet shale: lithofacies and depositional setting of a deep-water shale-gas succession in the Fort Worth Basin, Texas. AAPG Bull, 91(4): 579–601 https://doi.org/10.1306/11020606059
26	L G Love, G C Amstutz (1966). Review of microscopic pyrite from the Devonian Chattanooga shale and Rammelsberg Banderz. Fortschr Mineral, 43: 273–309
27	Y S Ma, X Y Cai, P R Zhao (2018). China’s shale gas exploration and development: understanding and practice. Pet Explor Dev, 45(4): 589–603 https://doi.org/10.1016/S1876-3804(18)30065-X
28	F D Mango (1992). Transition metal catalysis in the generation of petroleum and natural gas. Geochim Cosmochim Acta, 56(1): 553–555 https://doi.org/10.1016/0016-7037(92)90153-A
29	H K Nie, J C Zhang (2012). Shale gas accumulation conditions and gas content calculation: a case study of Sichuan Basin and its periphery in the Lower Paleozoic. Acta Geol Sin, 86(02): 349–361 (in Chinese)
30	H K Nie, Z J Jin, X Ma, Z B Liu, T Lin, Z H Yang (2017). Graptolites zone and sedimentary characteristics of Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in Sichuan Basin and its adjacent areas. Acta Petrol Sin, 38(2): 160–174 (in Chinese)
31	Y Shu, Y C Lu, L Chen, C Wang, B Zhang (2020). Factors influencing shale gas accumulation in the lower Silurian Longmaxi Formation between the north and south Jiaoshiba area, southeast Sichuan Basin, China. Mar Pet Geol, 111: 905–917 https://doi.org/10.1016/j.marpetgeo.2019.06.029
32	C L Sun, H Liu, J W Ge, Y N Zhang, B Han, M Qin (2019). Changes of functional groups and gas species during oil shale pyrolysis with addition of pyrite. Energ Sourc Recov Util Environ Effects, 41(10): 1242–1252 https://doi.org/10.1080/15567036.2018.1545001
33	Y S Sun, S B Guo (2017). Characteristics of microscopic pores of shale from Upper Sinian Doushantuo Formation in the western of Hunan and Hubei, China and the main controlling factors. J Earth Sci Env, 39(1): 114–125 (in Chinese)
34	M J Tan, K Y Mao, X D Song, X Yang, J J Xu (2015). NMR petrophysical interpretation method of gas shale based on core NMR experiment. J Petrol Sci Eng, 136(12): 100–111 https://doi.org/10.1016/j.petrol.2015.11.007
35	P Tan, Y Jin, L Han, Q L Shan, Y K Zhang, G Chen, Y C Zhou (2018). Influencing mechanism of acidification pretreatment on hydraulic fracture for deep fractured shale reservoirs. Chinese J Geotechn Eng, 40(2): 384–390 (in Chinese)
36	L Tang, Y Song, Q W Li, X Q Pang, Z X Jiang, Z Li, X L Tang, H L Yu, Y Sun, S C Fan, L Zhu (2019). Quantitative evaluation of shale gas content in different occurrence states of the Longmaxi Formation: a new insight from Well JY-A in the Fuling Shale Gas Field. Acta Geol Sin, 93(02): 400–419 https://doi.org/10.1111/1755-6724.13816
37	E Tannenbaum, I R Kaplan (1985). Role of minerals in the thermal alteration of organic matter--I: generation of gases and condensates under dry condition. Geochim Cosmochim Acta, 49(12): 2589–2604 https://doi.org/10.1016/0016-7037(85)90128-0 pmid: 11539655
38	Q T Wang, H Lu, C C Shen, J Z Liu, P A Peng, C S Hsu (2014b). Impact of inorganically bound sulfur on late shale gas generation. Energy Fuels, 28(2): 785–793 https://doi.org/10.1021/ef401468w
39	Y M Wang, D Z Dong, H Yang, L He, S Q Wang, J L Huang, B L Pu, S F Wang (2014a). Quantitative characterization of reservoir space in the Lower Silurian Longmaxi Shale, southern Sichuan, China. Sci China Earth Sci, 57(2): 313–322 https://doi.org/10.1007/s11430-013-4645-y
40	X J Wang, Z R Yang, B Han (2015). Superposed evolution of Sichuan Basin and its petroleum accumulation. Earth Sci Front, 22(03): 161–173 (in Chinese)
41	Z C Wang, W Z Zhao, L Zhang, S X Wu (2002). Structural Sequence and Natural Gas Exploration in Sichuan Basin. Beijing: Geological Publishing House (in Chinese)
42	R T Wilkin, H L Barnes, S L Brantley (1996). The size distribution of framboidal pyrite in modern sediments: an indicator of redox conditions. Geochim Cosmochim Acta, 60(20): 3897–3912 https://doi.org/10.1016/0016-7037(96)00209-8
43	C J Wu, M F Zhang, W Y Ma, Y Liu, D M Xiong, L N Sun, J C Tuo (2014). Organic matter characteristic and sedimentary environment of the Lower Cambrian Niutitang Shale in southeastern Chongqing. Nat Gas Geosci, 25(8): 1267–1274 (in Chinese)
44	J Wu, Z Q Hu, J Xie, Z B Liu, J H Zhao (2018). Macro–micro occurrence mechanism of organic matters in Wufeng–Longmaxi shale in the Sichuan Basin and its peripheral areas. Nat Gas Indust, 38(08): 23–32 (in Chinese)
45	J Xiong, X Liu, L Liang, Q Zeng (2017). Methane adsorption on carbon models of the organic matter of organic-rich shales. Energy Fuels, 31(2): 1489–1501 https://doi.org/10.1021/acs.energyfuels.6b03144
46	Z X Xu, S M Han, Q C Wang (2015). Characteristics of pyrite and its hydrocarbon significance of shale reservoir of Doushantuo Formation in middle Yangtze area. Lithologic Reservoirs, 27(02): 31–37 (in Chinese)
47	L J You, Y L Kang, P F Yang (2016). A method of increasing fracture network density in shale gas well fracturing. CN105626028A, 2016–06–01 (in Chinese)
48	L J You, Y L Kang, Q Chen, C H Fang, P F Yang (2017). Prospect of shale gas recovery enhancement by oxidation-induced rock burst. Nat Gas Indust, 4(6): 449–457 (in Chinese) https://doi.org/10.1016/j.ngib.2017.05.014
49	K H Yu, Z K Jin, K Su, X D Dong, W Zhang, H Y Du, Y Chen, W D Zhang (2013). The Cambrian sedimentary characteristics and their implications for oil and gas exploration in north margin of Middle-Upper Yangtze Plate. Sci China Earth Sci, 56(6): 1014–1028 https://doi.org/10.1007/s11430-013-4611-8
50	G R Zhang, H K Nie, X Tang, W Du, C X Sun, S Chen (2020). Pyrite type and its effect on shale gas accumulation: a case study of Wufeng-Longmaxi shale in Sichuan Basin and its periphery. Petrol Geol & Exper, 42(3): 459–466 (in Chinese)
51	C C Zhang, Y M Wang, D Z Dong, X J Li, Q Z Guan (2016). Evaluation of the Wufeng-Longmaxi shale brittleness and prediction of “sweet spot layers” in the Sichuan Basin. Nat Gas Indust, 36(9): 51–60 (in Chinese)
52	L C Zhao, C B Sun, S T Zhang, W Q Xie, X Y Zheng, K Liu (2015). Characteristic of thermal decomposition kinetics of main gold-bearing sulfides pyrite. Chinese J Nonferrous Metals, 25(08): 2212–2217 (in Chinese)
53	Y L Zheng, C L Mou, X P Wang (2019). Sedimentary geochemistry and patterns of organic matter enrichment of Wufeng-Longmaxi Formations in the southern margin of Sichuan Basin, China—a case study of Tianlin Profile in Xuyong Area. J Earth Sci Env, 41(05): 541–560 (in Chinese)
54	C N Zou, D Z Dong, S J Wang, J Z Li, X J Li, Y M Wang, D H Li, K M Cheng (2010). Geological characteristics and resource potential of shale gas in China. Pet Explor Dev, 37(6): 641–653 https://doi.org/10.1016/S1876-3804(11)60001-3
55	C N Zou, D Z Dong, Y M Wang, X J Li, J L Huang, S F Wang, Q Z Guan, C C Zhang, H Y Wang, H L Liu, W Bai, F Liang, W Lin, Q Zhao, D Liu, Z Yang, P Liang, S Sun, Z Qiu (2016). Shale gas in China: characteristics, challenges and prospects (II). Pet Explor Dev, 43(2): 182–196 https://doi.org/10.1016/S1876-3804(16)30022-2
56	C N Zou, J H Du, C C Xu, Z C Wang, B M Zhang, G Q Wei, T S Wang, G S Yao, S H Deng, J L Liu, H Zhou, A Xu, Z Yang, H Jiang, Z Gu (2014). Formation, distribution, resource potential, and discovery of Sinian-Cambrian giant gas field, Sichuan Basin, SW China. Pet Explor Dev, 41(3): 306–325 https://doi.org/10.1016/S1876-3804(14)60036-7

[1]	Xin NIE, Yu WAN, Da GAO, Chaomo ZHANG, Zhansong ZHANG. Evaluation of the in-place adsorbed gas content of organic-rich shales using wireline logging data: a new method and its application[J]. Front. Earth Sci., 2021, 15(2): 301-309.
[2]	Yuehua ZHAO, Shouyu CHEN, Jianli CHEN, Shuaiji WU. Trace elements of pyrite and S, H, O isotopes from the Laowan gold deposit in Tongbai, Henan Province, China: implications for ore genesis[J]. Front. Earth Sci., 2020, 14(3): 578-600.
[3]	GONG Yiming, XU Ran, FENG Qi, ZHANG Lijun, MA Huizhen, ZENG Jianwei. Hypersaline and anoxia in the Devonian Frasnian–Famennian transition: Molecular fossil and mineralogical evidence from Guangxi, South China[J]. Front. Earth Sci., 2007, 1(4): 458-469.

Viewed

Full text

Abstract

Cited

Shared

Discussed