Reaction kinetics on supercritical water conversion of shale for hydrocarbon gas production

doi:10.11949/0438-1157.20250403

Abstract

Abstract:

To study the kinetics mechanism on supercritical water conversion of shale for gas production, the experiment was carried out in a batch reactor with high temperature and pressure, which the reaction temperature and reaction time were 450—550℃ and 0—480 min, respectively. The results show that the intermediate products have complex compositions, but are mainly dibutyl phthalate and naphthalene derivatives. The gases produced are mainly CH₄, C₂H₆, C₃H₈, H₂ and CO₂. The total gas production increases with temperature and reaction time. A simple iterative method based on Peng-Robinson (PR) equation is used to calculate the amount of substance in the gas mixture. Based on the experiment results and lumped parameter method, the reaction kinetics model of shale-intermediate-gas was established. This model can explain the oil and gas changes caused by chemical reaction of shale in supercritical water atmosphere, and can quantitatively describe the mutual conversion of gases. The determination coefficient of the calculated and experimental values of the model is greater than 0.98, which indicates that gas concentrations for different reaction times can be fitted within acceptable deviations over the experimental temperature range. In this study, the mechanism of shale transformation and gas production in supercritical water has been more deeply understood. This provides a deeper understanding for gas production mechanism of shale by supercritical water conversion.

Key words: supercritical water, shale, reaction kinetics, gas, hydrocarbon

摘要：

为研究超临界水转化页岩的产气动力学机理，在间歇式高温高压反应器内进行了实验，反应温度450~550℃，反应时间为0~480 min。实验结果表明，中间体产物成分复杂，以邻苯二甲酸二丁酯和萘的衍生物为主。产生的气体主要是CH₄、C₂H₆、C₃H₈、H₂和CO₂。总气体生成量随着温度的升高和反应时间的延长而增加。采用基于Peng-Robinson（PR）方程的简单迭代法计算混合气体的物质的量。基于实验结果与集总参数法，建立了页岩-中间体-气体的反应动力学模型。该模型可以较好地解释超临界水氛围中页岩因化学反应而产生的油气变化，并可以定量描述气体之间的相互转化。该模型的计算值和实验值的决定系数大于0.98，表明在实验温度范围内，能在可接受的偏差内拟合不同反应时间的气体浓度。本研究对超临界水转化页岩的产气机理有了更深入的认识。

关键词: 超临界水, 页岩, 反应动力学, 气体, 碳氢化合物

CLC Number:

TQ 519

Yanlong ZHANG, Qiuyang ZHAO, Zhangjian LI, Yin CHEN, Hui JIN, Liejin GUO. Reaction kinetics on supercritical water conversion of shale for hydrocarbon gas production[J]. CIESC Journal, 2025, 76(11): 5594-5603.

张延龙, 赵秋阳, 李章剑, 陈引, 金辉, 郭烈锦. 超临界水转化页岩生烃气反应动力学研究[J]. 化工学报, 2025, 76(11): 5594-5603.

Figures/Tables 12

Fig.1 Schematic diagram of the experimental device for supercritical water conversion of shale

Table 1 The Ultimate analysis and proximate analysis of shale sample

元素分析/%（质量）						工业分析/%（质量）
C	H	O	N	S		Ash	Moisture	Volatile	FC
13.56	2.26	1.01	1.53	4.75		75.21	1.68	16.62	4.34

Fig.2 Effect of temperature and reaction time on gas production

Table 2 Produced oil components at 450 and 550℃ at 240 min

No.	组分	450℃	550℃
1	2,4-二甲基苯乙烯	0.79	—
2	萘	3.21	1.44
4	2-甲基十一烷	3.08	1.00
5	1H-茚，1-亚乙基	2.42	4.41
6	萘，1-甲基	3.34	1.35
7	萘，1,2,3,4-四氢-1,8-二甲基	0.55	0.49
8	庚烷，2,3-二甲基	1.36	1.75
9	萘，2,7-二甲基	7.41	2.43
10	戊-1-炔-3-烯，4-甲基-3-苯基	0.45	0.32
11	非腺苷	3.12	3.25
12	1,6,7-三甲基萘	7.16	2.62
13	2,5-双（1,1-二甲基乙基）苯酚	1.28	0.64
14	芴	0.41	—
15	萘，1-（2-丙烯基）	1.49	1.39
16	1,6-二甲基-3-乙基萘	1.77	—
17	2-异丙基-7-甲基萘	0.98	3.22
18	5,8,11,14-二十碳四烯酸	1.79	0.54
19	2-[2-苯乙烯基]苯酚	0.78	0.36
20	十五烷，5-甲基	0.77	0.29
21	菲	5.81	3.84
22	乙醇，2-（十八烷氧基）	0.94	—
23	3,5,3'，5'-四甲基联苯	2.60	—
24	4-甲基菲	1.92	3.08
25	庚烷，9-己基	3.28	—
26	邻苯二甲酸二丁酯	17.39	11.82
27	1,2-苯二甲酸	4.16	3.13
28	蒽，9-乙基-9,10-二氢-10-羟基	0.74	—
29	2,7-二甲基菲	1.50	0.72
30	芘，4,5,9,10-四氢	1.11	—
31	芘	1.47	1.56
32	2,2'-二乙烯基二苯甲酮	1.33	0.53
33	乙酸，α-（1-萘基）苄酯	1.02	1.55
34	1,2,3,4-四氢三苯撑	1.58	2.26
35	8,9-苯并二异丙基[2.2.2.4]癸烷，7-（3-甲氧基- 2-氧杂-1-氧代环戊-5-基）-10-苯基	1.09	—
36	2,6,10,15-四甲基庚烷	2.20	1.14
37	苯酚，2,2'-亚甲基双[6-（1,1-二甲基乙基）-4-甲基	3.07	1.61
38	苯并蒽，6,12-二甲基-1,2,3,4-四氢	2.28	—

Fig.3 Reaction network for supercritical water conversion of shale

Table 3 The equation for the reaction path

First column	Second column
$O M → k 1 M e d 1$	$M e d 2 + 8 H 2 → k 6 M e d 3 + 8 C H 4$
$O M → k 2 M e d 2$	$C O 2 + 4 H 2 ⇌ k 7 k 8 C H 4 + 2 H 2 O$
$M e d 1 + 20 H 2 O → k 3 10 C O 2 + 24 H 2$	$C 3 H 8 + 2 H 2 → k 9 3 C H 4$
$M e d 2 + 83 H 2 → k 4 M e d 3 + 83 C 3 H 8$	$C 2 H 6 + H 2 → k 10 2 C H 4$
$M e d 2 + 4 H 2 → k 5 M e d 3 + 4 C 2 H 6$

Table 3 The equation for the reaction path

First column	Second column
$O M → k 1 M e d 1$	$M e d 2 + 8 H 2 → k 6 M e d 3 + 8 C H 4$
$O M → k 2 M e d 2$	$C O 2 + 4 H 2 ⇌ k 7 k 8 C H 4 + 2 H 2 O$
$M e d 1 + 20 H 2 O → k 3 10 C O 2 + 24 H 2$	$C 3 H 8 + 2 H 2 → k 9 3 C H 4$
$M e d 2 + 83 H 2 → k 4 M e d 3 + 83 C 3 H 8$	$C 2 H 6 + H 2 → k 10 2 C H 4$
$M e d 2 + 4 H 2 → k 5 M e d 3 + 4 C 2 H 6$

Table 4 The sequence number of reactant

物质	x_i	物质	x_i
页岩(OM)	x₁	H₂	x₆
萘(Med1)	x₂	CO₂	x₇
邻苯二甲酸二丁酯(Med2)	x₃	CH₄	x₈
1,2-苯二甲酸(Med3)	x₄	C₂H₆	x₉
H₂O	x₅	C₃H₈	x₁₀

Table 5 Rate equations for each reaction

物质	反应速率	物质	反应速率
x₁	$r 1 = k 1 c 1$	x₆	$r 6 = k 6 c 3 c 6$
x₂	$r 2 = k 2 c 1$	x₇	$r 7 = k 7 c 7 c 6$
x₃	$r 3 = k 3 c 3 c 5$	x₈	$r 8 = k 8 c 8 c 5$
x₄	$r 4 = k 4 c 3 c 6$	x₉	$r 9 = k 9 c 10 c 6$
x₅	$r 5 = k 5 c 3 c 6$	x₁₀	$r 10 = k 10 c 9 c 6$

Table 5 Rate equations for each reaction

物质	反应速率	物质	反应速率
x₁	$r 1 = k 1 c 1$	x₆	$r 6 = k 6 c 3 c 6$
x₂	$r 2 = k 2 c 1$	x₇	$r 7 = k 7 c 7 c 6$
x₃	$r 3 = k 3 c 3 c 5$	x₈	$r 8 = k 8 c 8 c 5$
x₄	$r 4 = k 4 c 3 c 6$	x₉	$r 9 = k 9 c 10 c 6$
x₅	$r 5 = k 5 c 3 c 6$	x₁₀	$r 10 = k 10 c 9 c 6$

Table 6 First order differential equation of reactant concentration

物质	表达式	物质	表达式
x₁	$d c 1 d t = - r 1 - r 2$	x₆	$d c 6 d t = 24 r 3 + 4 r 8 - 83 r 4 - 4 r 5 - 4 r 6 - 4 r 7 - 2 r 9 - r 10$
x₂	$d c 2 d t = r 1 - r 3$	x₇	$d c 7 d t = 10 r 3 + r 8 - r 7$
x₃	$d c 3 d t = r 2 - r 4 - r 5 - r 6$	x₈	$d c 8 d t = 8 r 6 + r 7 + 3 r 9 + 2 r 10 - r 8$
x₄	$d c 4 d t = r 4 + r 5 + r 6$	x₉	$d c 9 d t = 4 r 5 - r 10$
x₅	$d c 5 d t = 2 r 7 - 2 r 8 - 20 r 3$	x₁₀	$d c 10 d t = 83 r 4 - r 9$

Table 6 First order differential equation of reactant concentration

物质	表达式	物质	表达式
x₁	$d c 1 d t = - r 1 - r 2$	x₆	$d c 6 d t = 24 r 3 + 4 r 8 - 83 r 4 - 4 r 5 - 4 r 6 - 4 r 7 - 2 r 9 - r 10$
x₂	$d c 2 d t = r 1 - r 3$	x₇	$d c 7 d t = 10 r 3 + r 8 - r 7$
x₃	$d c 3 d t = r 2 - r 4 - r 5 - r 6$	x₈	$d c 8 d t = 8 r 6 + r 7 + 3 r 9 + 2 r 10 - r 8$
x₄	$d c 4 d t = r 4 + r 5 + r 6$	x₉	$d c 9 d t = 4 r 5 - r 10$
x₅	$d c 5 d t = 2 r 7 - 2 r 8 - 20 r 3$	x₁₀	$d c 10 d t = 83 r 4 - r 9$

Fig.4 Concentration variation of gas production based on modeling reaction network

Table 7 The reaction rate constants change with temperature and the corresponding activation energy and pre-exponential factor

k_i	450℃	500℃	550℃	E/(kJ/mol)	A/min^-1
k₁	1.40	1.83	2.28	24.14	77.92
k₂	2.15	2.42	2.69	11.08	13.58
k₃	2.07×10^-2	3.63×10^-2	5.18×10^-2	45.53	41.28
k₄	1.49	1.79	1.95	13.39	14.01
k₅	5.23×10^-1	6.65×10^-1	7.77×10^-1	19.65	13.87
k₆	1.56	1.93	2.15	15.96	22.48
k₇	3.67	4.34	4.77	13.03	32.34
k₈	2.43×10^-3	3.96×10^-3	7.53×10^-3	55.71	24.84
k₉	1.53×10^-1	1.94×10^-1	3.22×10^-1	36.47	62.87
k₁₀	9.67×10^-3	1.22×10^-2	1.45×10^-2	47.02	15.37

Fig.5 Comparison of experimental values and calculated values

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