A kerogen pyrolysis experiment and hydrocarbon generation kinetics

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A kerogen pyrolysis experiment and hydrocarbon generation kinetics in the Dongpu Depression, Bohai Bay Basin, China Kangnan Yan, Yinhui Zuo, Meihua Yang, Yongshui Zhou, Yunxian Zhang, Changcheng Wang, Rongcai Song, Renpeng Feng, and Yanjun Feng Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.9b02159 • Publication Date (Web): 25 Aug 2019 Downloaded from pubs.acs.org on August 29, 2019

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A kerogen pyrolysis experiment and hydrocarbon generation kinetics in the Dongpu Depression, Bohai Bay Basin, China Kangnan Yan†,‡, Yinhui Zuo*,†,‡,§, Meihua Yang†, Yongshui Zhou‖, Yunxian Zhang‖, Changcheng Wang†, Rongcai Song†, Renpeng Feng†, Yuanjun Feng⁋ †

State Key Laboratory of Oil and Gas Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China



Shandong Provincial Key Laboratory of Depositional Mineralization & Sedimentary Minerals,Shandong University of Science

and Technology, Qingdao 266590, China §



State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China

Research Institute of Exploration and Development, Zhongyuan Oilfield, SINOPEC, Puyang 457001, China Coal Mining Research branch, China Coal Research Institute, Beijing, 100013, China



ABSTACT: Recently, petroleum exploration of the Dongpu Depression has become increasingly difficult, primarily due to the unclear potential and distribution of deep strata resources (specifically, the Shahejie 3 Formation). A pyrolysis experiment and hydrocarbon generation kinetics can provide important parameters for hydrocarbon generation history and resource re-evaluation. Therefore, four samples of the Dongpu Depression were selected for a kerogen pyrolysis experiment, and the software KINETICS 2000 was used to calculate the pre-exponential factors (A) of different components and the activation energies (E) of the reactants to further establish the kinetic parameters of different kerogens in the Dongpu Depression. The hydrocarbon generation history of the sample was determined using the software BasinMod 1D based on thermal and burial histories, and the hydrocarbon generation characteristics of different sags and different types of kerogen were studied. The results show that the hydrocarbon generation potential in the northern Dongpu Depression is stronger than that in the south. Moreover, the activation energies (E) distribution of type Ⅰ kerogen (Well W146) is widest, 1

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followed by type Ⅱ1 (Well C9) and type Ⅱ2 kerogens (Well H88); and type Ⅲ kerogen (Well X8) is the most concentrated. Moreover, the potential for hydrocarbon generation in the Qianliyuan the Haitongji-Liutun areas is high. Keywords: Hydrocarbon generation history; Dongpu Depression; Shahejie 3 Formation; Pyrolysis experiment; Kerogen type.

1. INTRODUCTION In petroliferous basins, the hydrocarbon generation history of source rocks involves a long and complex geological and geochemical process, and its hydrocarbon generation involves a geological process and hydrocarbon-generating material properties.1-12 The kerogen pyrolysis experiment is an effective means for scientifically evaluating source rocks and reappearing hydrocarbon generation process.13-16 In its early stages of development, based on the kerogen pyrolysis experiment, a direct study on the hydrocarbon generation process of the source rocks was carried out. Many petroleum exploration studies have proved that there are still some obvious differences between the kerogen hydrocarbon generation characteristics obtained in a short time and at high temperatures in the laboratory and the kerogen hydrocarbon generation under low temperatures and extremely slow geological conditions.17-20 The extrapolation of the kinetic method of kerogen hydrocarbon generation was established to study the relationship between laboratory data and geological processes.17-21 This method is often used in petroleum resource evaluation, oil source comparison and other research work.22-26 The Dongpu Depression is situated in the southwestern margin of the Bohai Bay Basin, China (Figure 1a). The depression is a typical Cenozoic oil- and gas-rich rift depression.27-29 In 1955, a geological survey of the 2

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Dongpu Depression was initiated, and the first exploration of Well PC1 was drilled. In 1975, the Zhongyuan Oilfields were established and large-scale exploration and development of petroleum began.30 At present, shallow petroleum exploration is more difficult in the Dongpu Depression, and thus exploration has moved to deep strata, mainly for the Shahejie 3 Formation. However, the exploration success rate in the deep strata is very low as the hydrocarbon generation potential and distribution is largely uncertain. Therefore, 4 samples with different kerogen types from 4 wells of the Dongpu Depression were selected to conduct a pyrolysis experiment in a closed system, and hydrocarbon generation kinetic parameters of different kerogen types were established. Then, based on the thermal and burial histories, the hydrocarbon generation histories of different sags were restored, and their hydrocarbon generation potentials were defined. This work may provide important parameters for resource re-evaluation in the Dongpu Depression of the Bohai Bay Basin.

2. GEOLOGICAL SETTINGS The Dongpu Depression is surrounded by the Lankao uplift to the south, the Neihuang uplift to the west and the Luxi uplift to the east.29 The depression, with an area of approximately 5300 km2, is divided into the western slope zone, Lanliao fault zone, eastern and western sub-depressions and central uplift zone (Figure 1b). Its tectonic framework is controlled by three NNE trending large basement faults.30 This Cenozoic rifted basin was developed on a Paleozoic and Mesozoic basement.30-32 The syn-rift stage during the Paleogene includes the initial syn-rift substage that occurred 50.5 to 45 Ma (i.e. the Shahejie 4 Formation depositional period), a tectonic movement that determined the 3

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general shape of the depression and the Shahejie 4 Formation; the intense syn-rift substage that occurred 45 to 38 Ma (i.e. the Shahejie 3 Formation depositional period), when the central uplift zone was formed, and in which the Shahejie 3 Formation is dominated by siltstone and grey mudstone from deep lacustrine to semi-deep lacustrine environments; and the late syn-rift substage from 38 to 17 Ma (i.e. from the Shahejie 2 Formation to the Dongying Formations depositional periods),30-32 in which the Shahejie 2 Formation consists of oil-bearing sandstone, gypsum-bearing mudstone and purplish-red mudstone in the delta and fluvial environments. The Dongpu Depression entered a post-rift stage from the Neogene, along with lithospheric equilibrium and mantle down sinking, and the faults have not exhibited any movement since the Neogene except the Lanliao and Huanghe faults.28,29,33 The strata from the top to the bottom in this area contain the Pingyuan, Minghuazhen, Guantao, Dongying and Shahejie Formations (Figure 2).12,28,29 The dark mudstone of the Shahejie 3 Formation is predominantly distributed in the Gegangji and Qianliyuan areas of the eastern sub-depression, with the maximum thickness of dark mudstone of 2200 and 2000 m, respectively, and the Haitongji-Liutun area of the western sub-depression, with the maximum thickness of dark mudstone of 2400 m (Table 1).12,29 The medium to good source rocks of the Shahejie 3 Formation are distributed in the Haitongji-Liutun and Qianliyuan areas, and the poor-non source rocks of the Shahejie 3 Formation are distributed in the Menggangji and Gegangji areas (Table 2).12,29

3. SAMPLES AND EXPERIMENTAL METHODS 3.1. Samples. To identify the kerogen hydrocarbon generation characteristics of different sags 4

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and different kerogen types in the Dongpu Depression, and to establish corresponding hydrocarbon generation kinetics models, we selected samples based on the principles as follows: (1) samples with low maturity; (2) samples of four kerogen types; and (3) samples from different sags. In this article, four kerogen samples (Table 3, Figure 3) were selected to conduct a pyrolysis experiment (well locations indicated in Figure 1b). 3.2. Experimental methods. The kerogen pyrolysis experimental methods include open36-39, semi-open40,41 and closed systems41-43. In this article, the kerogen pyrolysis experiment was performed using a high-temperature and high-pressure pyrolysis experiment in a closed gold tube-autoclave system. This experimental system is the most widely used closed kerogen pyrolysis experimental system at present.44,45 Compared with a traditional pyrolysis experimental system, its primary advantages include the following four aspects: (1) it automatically controls the heating rate and constantly adjusts to meet different experimental conditions; (2) it features high accuracy temperature control, and its temperature error can be controlled within 1 °C; (3) multiple groups of experimental samples may be simultaneously placed into the autoclave, and the experimental results can be corrected to improve the reliability of the results, and multiple analysis projects can be simultaneously completed; and (4) due to its low hardness, the gold tube deforms under water pressure, thus exerting certain pressure on a sample, simulating the hydrocarbon generation process under geological conditions better than other system types. In this experiment, the samples were first processed and kerogens were prepared using chemical and physical methods. Then, the kerogen pyrolysis experiment was performed. The pressure was set to 50 MPa for each autoclave, and its fluctuation was less than 1 MPa. The 5

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initial experimental temperature was set to 300 ℃. The samples were heated at different heating rates, including 2 and 20 ℃/h, respectively. When the temperature reached 600 ℃, the experiment ended. The temperature fluctuation was less than 1 ℃ during the heating process. There are 12 temperature points in each heating curve, and the yields of C1, C2-5, C6-14, C14+ and the non-hydrocarbon components at each temperature point were measured. This article focused on the characteristics of gaseous hydrocarbon (C1-5) and liquid hydrocarbon (C6+) components changing with increasing temperature.

4. EXPERIMENTAL RESULTS According to the variation of gaseous hydrocarbon (C1-5) and liquid hydrocarbon (C6+) components with changing temperature under two heating rates for the four samples in the Shahehie 3 Formation of the Dongpu Depression (Figures 4, 5), the gas and oil production rates have the following characteristics: (1) The hydrocarbon cumulative production rates varied with the different total organic carbon (TOC) content of source rocks. The hydrocarbon cumulative production is closely related to TOC content. The higher the TOC content, the greater the hydrocarbon cumulative production rates (Figures 4, 5). (2) The gas and oil production rates of the samples are connected with the heating rate and pyrolysis temperature. As the pyrolysis temperature increased, the hydrocarbon accumulative production rate increased. Moreover, the maximum production rate was reached at a slow heating rate faster than at a quick heating rate. In addition, liquid hydrocarbon reached its maximum production rate earlier than gaseous hydrocarbon (Figures 4, 5). 6

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To compare the hydrocarbon generation potential of different kerogen types, different pyrolysis production rates were converted into unit TOC production rates (Figures 6, 7). When the maturity was less than 0.6%, the liquid hydrocarbon production rate increased with the increase in maturity (Figure 6). When the maturity was between 0.6% and 1.0%, it reached a maximum (Figure 6). As the maturity continued to increase, oil was cracked and the cumulative production rate gradually decreased to zero (Figure 6). When the RO was less than 2%, the gaseous hydrocarbon production rate increased with the increase in maturity (Figure 7). When 2%≤ maturity ≤2.5%, it reached a maximum value (Figure 7). Subsequently, the gas was cracked (Figure 7), and because the mass of non-hydrocarbon gas is not included in the gaseous hydrocarbon production rate, the cumulative production rate decreased slightly. Based on the relationship between kerogen types and production rates, the maximum gas and oil production rates of the type Ⅰ kerogen (Well W146) are 281.47 and 693.56 mg/gTOC, respectively; the type Ⅱ1 kerogen rates (Well C9) are 210.00 and 369.57 mg/gTOC, respectively; the type Ⅱ2 kerogen rates (Well H88) are 173.02 and 235.46 mg/gTOC, respectively; and the type Ⅲ kerogen rates (Well X8) are 83.63 and 263.56 mg/gTOC, respectively (Figures 6, 7). Thus, the oil and gas production rates from low to high are the type Ⅲ kerogen, the type Ⅱ2 kerogen, the type Ⅱ1 kerogen and the type Ⅰ kerogen, respectively. The indicates that the better the kerogen type, the higher the hydrocarbon generation potential. 5. ANALYSIS OF HYDROCARBON GENERATION KINETICS 5.1. Calculation method of hydrocarbon generation kinetic parameters. With increasing temperature and pressure, some specific components can generate partial liquid and/or gaseous 7

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hydrocarbons. Each kinetic reaction has its owner frequency factor (A) and activation energy (E).46 The hydrocarbon generation process includes a series of parallel first-order chemical reactions, generally.18,47,48 To quantitatively characterize hydrocarbon generation characteristics, experimental data processing and kinetic analogue computation were performed using the software KINETICS 2000, compiled by the Lawrence Livermore National Laboratory at Stanford University.49,50 The software applies several parallel first-order hydrocarbon generation kinetic models, and all models have the same frequency factor. Then, the kinetic characteristics of hydrocarbon generation in the Dongpu Depression are analysed using the kinetic parameters. 5.2. Hydrocarbon generation kinetic parameters of the Dongpu Depression. The E and A of the hydrocarbon generation for each sample were obtained via kinetic analogue computation. The E distribution characteristics of the gaseous and liquid hydrocarbons of the 4 samples were further clarified (Figures 8, 9). The E distribution of the gaseous hydrocarbon of type Ⅰ kerogen (Well W146) is the widest, ranging from 50 to 74 kcal/mol; the distribution of type Ⅱ1 (Well C9) and Ⅱ2 kerogen (Well H88) ranges from 39 to 58 kcal/mol and 41 to 50 kcal/mol, respectively; and that of type Ⅲ kerogen (Well X8) is the most concentrated, ranging from 38 to 53 kcal/mol. This is because alkyl chains of the different types of kerogen break with increasing pyrolysis temperature, forming free radicals (Table 4). The alkyl fragments are unstable, and hydrogen ions can be quickly obtained in the surrounding media to form alkanes. Pyrolysis temperature, however, is positively correlated with E. In regard to type Ⅰ kerogen, the temperature range in which free radicals exist is larger than that of other kerogen types; therefore, its range of E for hydrocarbon generation is also larger than the other kerogen types (Table 4).51 8

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Comparing the E distributions of the liquid and gaseous hydrocarbons of the four samples, the E frequency peak of the liquid hydrocarbons was approximately that of the gaseous hydrocarbons; however, the E peak of the liquid hydrocarbons was slightly lower than that of the gaseous hydrocarbons (Figures 8, 9). Furthermore, the E distribution of the liquid hydrocarbons was more concentrated than that of the gaseous hydrocarbons, which indicated that the liquid hydrocarbons can achieve a higher conversion rate in a narrow temperature range once they begin to form (Figures 8, 9).

6. DISCUSSIONS The kinetic parameters (E and A) reveal to some extent the differences in the hydrocarbon generation process among different types of organic matters. The hydrocarbon generation kinetic parameters of different kerogens were established according to the above parameters. Based on the thermal and burial histories,28,29 the hydrocarbon generation histories of different sags were restored using software BasinMod 1D in the Dongpu Depression, such that the hydrocarbon generation characteristics of different kerogens and different sags could be accurately identified. These can provide important parameters for evaluating petroleum resources in a petroliferous basin and the accurate inference of oil and gas production and composition at different periods. 6.1. Hydrocarbon generation potential of different kerogens. To compare the hydrocarbon generation history and potential of different kerogens, it is necessary to ensure that all the parameters of different kerogen types except the kinetic parameters are consistent during geological extrapolation. Combined with the thermal and burial histories of Well C9, the kerogen kinetic parameters (Tables 5, 6) are replaced by other different kerogen types to obtain the 9

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differences in hydrocarbon generation history and hydrocarbon generation potential of different kerogen types (Figure 10). The results revealed that liquid and gaseous hydrocarbon generation potentials for type Ⅰ kerogen (Well W146) are the highest, with maximum values of 680 and 230 mg/gTOC, respectively; followed by type Ⅱ1 (Well C9) and type Ⅱ2 kerogens (Well H88); and type Ⅲ kerogen (Well X8) was the poorest, with maximum values of 188 and 70 mg/gTOC, respectively (Figure 10). 6.2. Hydrocarbon generation histories of primary sags. All of the four areas have reached an overmature stage in the Dongpu Depression (Figure 11). The present maturity of the bottom source rocks of the Shahejie 3 Formation is 1.65%, 1.63%, 1.71% and 2.65% in the Gegangji, Menggangji, Haitongji-Liutun and Qianliyuan areas, respectively (Figure 11). The source rocks of the Shahejie 3 Formation in the four areas are predominantly classified as first-stage hydrocarbon generation from the Shahejie 3 Formation dopositional period to the end of the Dongying Formation depositional period. Only the Menggangji area has weak second-stage hydrocarbon generation (Figure 12). For the source rocks of the Shahejie 3 Formation, the hydrocarbon generation potential was the greatest in the Hongtongji-Liutun area, with maximum liquid and gaseous hydrocarbon generated masses of 375 and 235 mg/gTOC, respectively, followed by the Qianliyuan and Gegangji areas. Whereas the potential of the Menggangji area was the poorest, with maximum values of 141 and 13 mg/gTOC, respectively (Table 7, Figure 12).

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Overall, based on the organic matter abundances, maturities, hydrocarbon generation histories and dark mudstone thicknesses of the four areas, it is concluded that the hydrocarbon generation potentials of the Haitongji-Liutun area in the western sub-depression and Qianliyuan area in the eastern sub-depression are relatively good, and the Gegangji area in the eastern sub-depression and Menggangji area in the western sub-depression are relatively poor. Therefore, petroleum exploration for the deep strata in the Dongpu Depression should be carried out around the source rocks of the Shahejie 3 Formation in the Haitongji-Liutun and Qianliyuan areas.

7. CONCLUSIONS (1) The cumulative hydrocarbon production rate of kerogen has a positive correlation with the TOC content and pyrolysis temperature. (2) The hydrocarbon generation potential of type Ⅰ kerogen (Well W146) is relatively good, and its activation energy distribution is wide; while the hydrocarbon generation potential of type Ⅲ kerogen (Well X8) is relatively poor, and its activation energy distribution is narrow; and the hydrocarbon generation potential and the activation energy distributions of type Ⅱ1 (Well C9) and type Ⅱ2 kerogens (Well H88) are relatively centered. (3) The hydrocarbon generation potentials of the Haitongji-Liutun and Qianliyuan areas are relatively better than ones of the Gegangji and Menggangji areas. 

AUTHOR INFORMATION

Corresponding Author *E-mail: [email protected]. Phone: +86-18280398276 ORCID 11

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Yinhui Zuo: 0000-0003-1272-0219 Notes The authors declare no competing financial interest. 

ABBREVIATIONS TOC = total organic carbon; Tmax = peak temperature of pyrolysis; E = activation energy; A = frequency factor; D = degradation rate; HI = hydrogen index.



ACKNOWLEDGMENTS

This study was jointly funded by the Sichuan Science and Technology Foundation (Grant No. 2016JQ0043);

the

National

Science

and

Technology

Major

Project

(Grant

No.

2016ZX05006-004); the Geoscience Young Science Foundation of Liu Baojun (Grant No. DMSMX2019009); the State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing (Grant No. PRP/open-1705); and the Scientific and technology innovation fund supported by Coal Mining Research Branch (Grant No. KJ-2019-TDKCMS-03). Our sincerest gratitude also goes to Prof. Jinzhong Liu for his guidance and helpful suggestions during the research. We are also grateful to Prof. Minghou Xu and the anonymous reviewers for their constructive and helpful comments.

 REFERENCES 12

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(25) Tang Y.; Perry J.; Jenden P. D.; Schoell, M. Mathematical modeling of stable carbon isotope ratios in natural gases. Geochimica et Cosmochimica Acta. 2000, 64(15): 2673–2687. (26) Braun, R. L.; Brurnham, A. K.; Reynolds, J. G. Methamatical model of oil generation, degradation and expulsion. Energy & Fuels 1990, 4, 132–146. (27) Zuo, Y. H.; Qiu, N. S.; Hao, Q. Q.; Zhang, Y. X.; Pang, X. Q.; Li, Z. C.; Gao, X. Present geothermal fields of the Dongpu sag in the Bohai Bay Basin. Acta Geologica Sinica (English Edition) 2014, 88 (3), 915–930. (28) Zuo, Y. H.; Tang, S. L.; Zhang, W.;. Zhang, Y. X.; Xin, Y. P.; Zhou, Y. S. Cenozoic thermal history of the Dongpu Depression, Bohai Bay Basin. Earth Science Frontiers 2017, 24(3), 149–156 (in Chinese with English abstract). (29) Zuo, Y. H.; Ye, B.; Wu, W. T.; Zhang, Y. X.; Ma, W. X.; Tang, S. L.; Zhou, Y. S. Present temperature field and Cenozoic thermal history in the Dongpu Depression, Bohai Bay Basin, North China. Marine and Petroleum Geology 2017, 88, 696–711. (30) Su, H.; Qu, L. P.; Zhang, J. C.; Wang, P. X.; He, F.; Wang, M.; Wang, Q.; Hu, Y. J. Tectonic evolution and extensional pattern of rifted basin: a case study of Dongpu depression. Oil & Gas Geology 2006, 27(1), 70–71 (in Chinese with English abstract). (31) Su, H.; Qu, L. P.; Li, G. X.; Wang, J. Y.; Song, J. Balanced section and tectonic evolution in the Dongpu Depression. OGP. 2000, 35(4), 469–478. (32) Lu, X. S.; Jiang, Y. L.; Chang, Z. H.; Wu, X. L. Calculation of the erosion thickness of Dongying Formation in Dongpu Depression and its significance. Geological Science and Technology Information 2007, 26(2), 8–12 (in Chinese with English abstract). 16

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(33) Huang, C. Y.; Zhang, J. C.; Wang, H.; Shu, J. Lacustrine shale deposition and variable tectonic accommodation in the rift basins of the Bohai Bay Basin in Eastern China. Journal of Earth Science 2015, 26(5), 700–711. (34) Lang, D. S.; Jin, C. Z.; Guo, X. Y. Pyrogenation and gas chromatogram evaluation technology of reservoir fluid. Beijing: Petroleum Industry Press 1999 (in Chinese). (35) Espitalié, J.; Deroo, G.; Marquis, F. La pyrolyse Rock-Eval et ses applications, première partie. Rev. Inst. Fr. Pétrole 1985, 40(5), 563-579. (36) Cramer, B.; Faber, E.; Gerling, P.; Krooss, B. M. Reaction kinetics of stable carbon isotopes in natural gas insights from dry, open system pyrolysis experiments. Energy & Fuels 2001, 15(3), 517–532. (37) Peters, K. E.; Burnham, A. K.; Walters, C. C.; Schenk, O. Guidelines for kinetic input to petroleum system models from open-system pyrolysis. Marine and Petroleum Geology 2018, 92, 979–986. (38) Makeen, Y. M.; Abdullah, W. H.; Hakimi, M. H.; Mustapha, K. A. Source rock characteristics of the Lower Cretaceous Abu Gabra formation in the Muglad Basin, Sudan, and its relevance to oil generation studies. Marine and Petroleum Geology 2015, 59, 505−516. (39) Makeen, Y. M.; Abdullah, W. H.; Abdul Ghofur, M.N.; Ayinla, H.A.; Hakimi, M.H.; Shan, X.; Mustapha, K.A.; Shuib, M.K.; Liang, Y.; Zainal Abidin, N.S. Hydrocarbon generation potential of Oligocene oil shale Deposit at Onshore Penyu Basin, Chenor, Pahang, Malaysia. Energy & Fuels 2019, 33(1), 89–105. (40) Michels, R.; Enjelvin–Raoult, N.; Elie, M.; Mansuy, L.; Faure, P.; Oudin, J. L. Understanding of reservoir gas compositions in a natural case using stepwise semi-open artificial maturation. Marine and Petroleum Geology 2002, 19(5), 589–599. (41) Takahashi, K. U.; Suzuki, N. Semi–open and closed system pyrolysis of Paleogene coal for evaluating 17

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the timing of hydrocarbon gas expulsion. International Journal of Coal Geology 2017, 178, 100–109. (42) Liu, J. Z.; Tang, Y. C. Kinetic study of the hydrocarbon generation by multi cold trap pyrolysis gas chromatography. Chinese Science Bullen 1996, 41, 1021–1024 (in Chinese). (43) Li, X.; Krooss, B. M.; Ostertag–Henning, C.; Weniger, P.; Littke, R. Liberation of hydrogen-containing gases during closed system pyrolysis of immature organic matter-rich shales. International Journal of Coal Geology 2018, 185, 23–32. (44) Guo, X. L.; Xiong, M.; Zhou, Q.; Tian, H.; Xiao, X. M. Petroleum generation and expulsion kinetics: A case study of the Sahejie Formation source rocks from Linnan sag of Huimin Depression. Acta Sedimentologica Sinica 2009, 27(4), 723–731 (in Chinese with English abstract). (45) Liu, J. Z.; Tang, Y. C. Kinetics of early methane generation from Green River shale. Chinese Science Bulletin 1998, 43(22), 1908–1912 (in Chinese). (46) Xing, L. T.; Zhang, X. B.; Zhang R.; Xu, L.; Li, W. Kinetics of hydrocarbon generation for Jurassic source rocks and application in northern Qaidam Basin: Taking saisenteng depression as an example. Natural Gas Geoscience 2012, 23(1), 161–166 (in Chinese with English abstract). (47) Lorant, F.; Behar, F.; Vandenbroucke, M. Methane generation from methyl-aromatics: Kinetic study and carbon isotope modeling. Energy & Fuels 2000, 14(10), 1143–1155. (48) Burnham, A. K.; Braun, R. L.; Samoun, A. M. Further comparison of methods for measuring kerogen pyrolysis rates and fitting kinetic parameters. Organic Geochemistry 1998, 13(4/6), 839–845. (49) Quigley, T. M.; Mackenzie, A. S. The temperature of oil and gas formation in the sub–surface. Nature 1998, 333(9), 549–553.

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(50) Chen, Z. H.; Guo, Q. L.; Jiang, C. Q. Source rock characteristics and Rock-Eval—based hydrocarbon generation kinetic models of the lacustrine Chang-7 Shale of Triassic Yanchang Formation, Ordos Basin, China. International Journal of Coal Geology 2017, 18(2), 52–65. (51) Cheng, Y. C.; Li, K.; Liu, S. B. Organic geochemistry of oil and gas. Beijing: Geological Publishing House, 2015 (in Chinese).

Tables and figures captions Table 1. Parameters of the Shahejie 3 Formation for four main source rock developing areas. Table 2. Organic matter abundance of the Shahejie 3 Formation in the Dongpu Depression. Table3. Source rock samples of the Shahejie 3 Formation in the Dongpu Depression. Table 4. Thermal simulated radical concentration of different kerogen types. Table 5. The primary and secondary crackings of hydrocarbon generation of the Dongpu Depression. Table 6. The hydrocarbon-generating potential of the Dongpu Depression. Table 7. Liquid and gaseous hydrocarbon generated mass of the Shahejie 3 Formation in the Dongpu Depression. Figure 1. (a) Structural unit division of the Baihai Bay Basin and position of the Dongpu Depression. (b) Structural unit diversion and well positions in the Dongpu Depression. Jun Junggar Basin; QD - Qaidam Basin; YE - Yingen-Ejinaqi Basin; EL - Erlian Basin; HL - Hailaer Basin; SL - Songliao Basin; BH - Bohai Bay Basin; SNC - Southern part of North China Basin; SC - Sichuan Basin; HN - Hainan; TW - Taiwan. Figure 2. Stratigraphic column section of Dongpu Depression. Form - Formation; PY - Pingyuan; 19

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MHZ - Minghuazhen; GT - Guantao; DY - Dongying. Figure 3. The kerogen types of the Dongpu Depression. (a) Lang’s diagram;34 (b) Espitalié’s diagram.35 Tmax = Peak temperature of pyrolysis; HI = Hydrogen index; D = Degradation rate. Figure 4. Gaseous hydrocarbon production rate in the Dongpu Depression. (a) Well W146; (b) Well C9; (c) Well H88; (d) Well X8. Figure 5. Liquid hydrocarbon production rate in the Dongpu Depression. (a) Well W146; (b) Well C9; (c) Well H88; (d) Well X8. Figure 6 Liquid hydrocarbon production for different kerogens in the Dongpu Depression. Figure 7. Gaseous hydrocarbon production for different kerogens in the Dongpu Depression. Figure 8. Activation energy distribution of gaseous hydrocarbon in the Dongpu Depression. (a) Well W147 (type Ⅰ); (b) Well C9 (type Ⅱ1); (c) Well H88 (type Ⅱ2); (d) Well X8 (type Ⅲ). Figure 9. Activation energy distribution of liquid hydrocarbon in the Dongpu Depression. (a) Well W147 (type Ⅰ); (b) Well C9 (type Ⅱ1); (c) Well H88 (type Ⅱ2); (d) Well X8 (type Ⅲ). Figure 10. The comparison of hydrocarbon generation history of different kerogen types. (a) Liquid hydrocarbon potential; (b) Gaseous hydrocarbon potential. Figure 11. Comparison of maturity in four major hydrocarbon-generating areas in the Dongpu Depression. (a) Menggangji area (Well PS6); (b) Haitongji-Liutun area (Well PS14); (c) Gegangji area (Well T8); (d) Qianliyuan area (Well PS4). Figure

12.

Comparison

of

hydrocarbon

generation

hydrocarbon-generating areas in the Dongpu Depression. 20

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potentials

in

four

major

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(a) Comparison of liquid hydrocarbon potential; (b) Comparison of gaseous hydrocarbon potential. Table 1. Parameters of the Shahejie 3 Formation for four main source rock developing areas. Source rock developing areas

Well

Lithology

Thickness (m)

TOC (%)

Kerogen type

Qianliyuan area

PS4

Mudstone

2000

0.61

Ⅱ1

Gegangji area

T8

Mudstone

2200

0.40



Haitongji-Liutun area

PS14

Mudstone

2400

0.80

Ⅱ2

Menggangji area

PS6

Mudstone

350

0.40



Table 2. Organic matter abundance of the Shahejie 3 Formation in the Dongpu Depression. Structural Chloroform TOC (%) HC (ppm) S1+S2 (mg/g) Evaluation units asphalt “A”(%) 0.001  16.440 0.04  3.85 0.75  1364.52 Gegangji Poor-non 0.0013  0.7160 0.0409 (157) 56.72 (486) 0.40 (508) 0.683 ( 486) area source rock 0.02  6.51 0.0002  1.4153 1.33  50820.90 0.002  61.230 Qianliyuan Medium-good 0.61 ( 2753) 0.1267 (574) 1941.61 (1487 ) 2.339 (1487 ) area source rock 0.04  1.31 0.0013  0.1681 1.08  1784.50 0.001  2.150 Menggangji Poor-non 0 . 40 ( 170 ) 0 . 0278 ( 24 ) 352.07 ( 92 ) 0 . 424 ( 92 ) area source rock 0.04  8.51 0.0004  1.9308 1.08  56135.00 0.001  68.450 Haitongji Medium-good 0 . 80 ( 978 ) 0 . 1776 ( 284 ) 2272.82 ( 576 ) 2.738 ( 576 ) Liutun area source rock TOC = Total organic carbon; HC - Total hydrocarbon content; S1+S2 = Hydrocarbon generation potential.

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Table3. Source rock samples of the Shahejie 3 Formation in the Dongpu Depression. Structural units

Well H88

North

Lithology Gray mudstone

W14

Gray

6

mudstone

X8 South C9

Dark gray mudstone Gray mudstone

Depth (m) 1456.8

2838.9 3156.8 2500.8

Formation

Shahejie 3 Formation Shahejie 4 Formation Shahejie 3 Formation Shahejie 3 Formation

TOC

RO

Kerogen

(%)

(%)

type

0.83

0.45

Ⅱ2

Low

3.29

0.52



High

0.39

0.85



Low

1.05

0.73

Ⅱ1

High

Abundance

TOC = Total organic carbon; Ro = Vitrinite reflectance.

Table 4. Thermal simulated radical concentration of different kerogen types. Experiment temperature (℃)

Free radical concentration (1018 spin/g) Type Ⅰ

Type Ⅱ1

Type Ⅱ2

Type Ⅲ

300 350 400 450 500 600

5.2 8.3 26 34 60 31

15 40 36 44 34 4.6

28 42 49 44 36 /

37 40 48 60 / /

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Table 5. The primary and secondary crackings of hydrocarbon generation of the Dongpu Depression. Well

W146 (Type Ⅰ)

C9 (Type Ⅱ1)

H88 (Type Ⅱ2)

X8 (Type Ⅲ)

Primary cracking

Secondary cracking

Frequency

E (kcal/mol)

A (s-1)

Frequency

E (kcal/mol)

A (s-1)

0.087 0.058 0.797 0.001 0.057 / / / / / / / / 0.096 0.144 0.139 0.449 0.118 0.055

45 46 52 55 56 / / / / / / / / 50 51 55 58 59 62

2.2×1014 2.2×1014 2.2×1014 2.2×1014 2.2×1014 / / / / / / / / 3.5×1016 3.5×1016 3.5×1016 3.5×1016 3.5×1016 3.5×1016

/ / / / / 0.273 0.0173 0.293 0.159 0.173 0.086 / / / / 0.165 0.032 0.226 0.505 0.047 0.019 0.006 /

/ / / / / 41 42 45 46 48 49 / / / / 47 48 51 52 55 56 58 /

/ / / / / 2.8×1011 2.8×1011 2.8×1011 2.8×1011 2.8×1011 2.8×1011 / / /

0.003 0.007 0.050 0.013 0.148 0.001 0.322 0.054 0.153 0.146 0.016 0.023 0.053 0.001 0.004 0.023 0.011 0.062 0.005 0.120 0.311 0.100 0.330 0.032 0.005 0.045 0.147 0.065 0.094 0.252 0.305 0.079 0.004 0.004 0.003 0.031 0.011 0.494 0.081 0.323 0.031 0.022

50 53 55 56 59 61 62 65 66 68 69 73 74 43 46 49 50 52 53 55 57 58 62 67 39 43 46 47 48 50 53 54 57 58 36 41 42 44 46 47 48 50

1.9×1014 1.9×1014 1.9×1014 1.9×1014 1.9×1014 1.9×1014 1.9×1014 1.9×1014 1.9×1014 1.9×1014 1.9×1014 1.9×1014 1.9×1014 7.5×1012 7.5×1012 7.5×1012 7.5×1012 7.5×1012 7.5×1012 7.5×1012 7.5×1012 7.5×1012 7.5×1012 7.5×1012 6.5×1010 6.5×1010 6.5×1010 6.5×1010 6.5×1010 6.5×1010 6.5×1010 6.5×1010 6.5×1010 6.5×1010 3.1×1010 3.1×1010 3.1×1010 3.1×1010 3.1×1010 3.1×1010 3.1×1010 3.1×1010

5.5×1014 5.5×1014 5.5×1014 5.5×1014 5.5×1014 5.5×1014 5.5×1014

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Table 6. The hydrocarbon-generating potential of the Dongpu Depression. Well

Initial potential of oil (mg/g TOC)

Initial potential of gaseous hydrocarbon (mg/g TOC)

Second potential of gaseous hydrocarbon (mg/g TOC)

W146 C9 H88 X8

693.6 374.44 285.6 184.5

168.4 132.67 61 14.6

113.0 77.0 111.5 45.8

Table 7. Liquid and gaseous hydrocarbon generated masses of the Shahejie 3 Formation in the Dongpu Depression. Source rock developing areas

Well

Liquid hydrocarbon generated mass (mg/gTOC)

Gaseous hydrocarbon generated mass (mg/gTOC)

Qianliyuan area Gegangji area Haitongji-Liutun area Menggangji area

PS4 T8 PS14 PS6

375 180 235 141

229 73 127 13

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Figure 1. (a) Structural unit division of the Baihai Bay Basin and position of the Dongpu Depression. (b) Structural unit diversion and well positions in the Dongpu Depression.12 Jun = Junggar Basin; QD = Qaidam Basin; YE = Yingen-Ejinaqi Basin; EL = Erlian Basin; HL = Hailaer Basin; SL = Songliao Basin; BH = Bohai Bay Basin; SNC = Southern part of North China Basin; SC = Sichuan Basin; HN = Hainan; TW = Taiwan.

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Figure 2. Stratigraphic column section of Dongpu Depression.12 Form = Formation; PY = Pingyuan; MHZ = Minghuazhen; GT = Guantao; DY = Dongying.

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Figure 3. The kerogen types of the Dongpu Depression. (a) Lang’s diagram;34 (b) Espitalié’s diagram.35 Tmax = Peak temperature of pyrolysis; HI = Hydrogen index; D = Degradation rate.

Figure 4. Gaseous hydrocarbon production rate in the Dongpu Depression. (a) Well W146; (b) Well C9; (c) Well H88; (d) Well X8.

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Figure 5. Liquid hydrocarbon production rate in the Dongpu Depression. (a) Well W146; (b) Well C9; (c) Well H88; (d) Well X8.

Figure 6. Liquid hydrocarbon production for different kerogens in the Dongpu Depression. 28

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Figure 7. Gaseous hydrocarbon production for different kerogens in the Dongpu Depression.

Figure 8.

Activation energy distribution of gaseous hydrocarbon in the Dongpu Depression.

(a) Well W147 (type Ⅰ); (b) Well C9 (type Ⅱ1); (c) Well H88 (type Ⅱ2); (d) Well X8 (type Ⅲ). A = Frequency

factor. 29

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Figure 9. Activation energy distribution of liquid hydrocarbon in the Dongpu Depression. (a) Well W147 (type Ⅰ); (b) Well C9 (type Ⅱ1); (c) Well H88 (type Ⅱ2); (d) Well X8 (type Ⅲ). A = Frequency

factor.

Figure 10. The comparison of hydrocarbon generation history of different kerogen types. (a) Liquid hydrocarbon potential; (b) Gaseous hydrocarbon potential. 30

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Figure 11. Comparison of maturity in four major hydrocarbon-generating areas in the Dongpu Depression.

Figure 12. Comparison of hydrocarbon generation potentials in four major hydrocarbon-generating areas in the Dongpu Depression. (a) Comparison of liquid hydrocarbon potential; (b) Comparison of gaseous hydrocarbon potential.

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