Mechanism of Wax Deposition on Wall of Waxy Condensates under the Synergistic Effect of Complex Components

doi:10.12422/j.issn.1672-6952.2023.06.001

Abstract

Abstract:

In order to explore the microscopic mechanism of wax deposition on the pipe wall of high temperature and high?pressure condensate gas wells, this paper uses molecular dynamics simulation technology by the Materials Studio to build condensate oil system with methane, pentane, nonane,n?dodecane, cyclobutane, cyclopentane, benzene and toluene,and the wax component model was built with n?octadecane, and simulate with wax content, asphaltene and scale as variables. The results show that with the increase of wax and asphaltene mass fraction, the wall wax deposition behavior can be intensified, but when the asphalt mass fraction reaches 2.0%,the wall wax deposition behavior can be inhibited.The more kinds of heteroatoms in asphaltene,the more obvious the promotion effect.When there is scale on the pipe wall, sulfate scale has a great influence on wax deposition.The understanding of microscopic mechanism provides a scientific basis for the treatment of wax deposition on the pipe wall.

Key words: Condensate oil, Wax deposition in the wall, Scale, Asphaltene, Molecular simulation

摘要：

为探究高温高压凝析气井管壁结蜡的微观机制，利用Materials Studio分子动力学模拟技术，通过甲烷、戊烷、壬烷、正十二烷、环丁烷、环戊烷、苯及甲苯等构建凝析油体系，用正十八烷构建蜡组分模型，以蜡质量分数、沥青质及垢为变量进行了结蜡机制的模拟。结果表明，随着蜡和沥青质质量分数的增加，壁面结蜡加剧；当沥青质质量分数达到2.0%时，沥青质对壁面结蜡起抑制作用；沥青质中杂原子种类越多，其促进结蜡愈发明显；当管壁存在各种垢物时，硫酸盐类垢对壁面结蜡的影响最为显著。这种微观作用机制为管壁结蜡的治理提供了科学依据。

关键词: 凝析油, 管壁结蜡, 垢, 沥青质, 分子模拟

CLC Number:

TE866

Wenbo LIU, Bowen SHI, Yaming QI, Xiaoyu LIU, Zhihua WANG. Mechanism of Wax Deposition on Wall of Waxy Condensates under the Synergistic Effect of Complex Components[J]. Journal of Liaoning Petrochemical University, 2023, 43(6): 1-10.

刘文波, 史博文, 戚亚明, 刘晓宇, 王志华. 复杂组分协同作用下的含蜡凝析油管壁结蜡机制[J]. 辽宁石油化工大学学报, 2023, 43(6): 1-10.

Figures/Tables 22

组分	质量分数/%	组分	质量分数/%	组分	质量分数/%	组分	质量分数/%
N₂	3.614	C₈	1.421	C₁₉	0.610	C₃₀	0.131
CO₂	0.665	C₉	1.116	C₂₀	0.522	C₃₁	0.121
C₁	61.845	C₁₀	1.015	C₂₁	0.460	C₃₂	0.074
C₂	9.172	C₁₁	0.755	C₂₂	0.395	C₃₃	0.111
C₃	3.571	C₁₂	0.929	C₂₃	0.342	C₃₄	0.093
i⁃C₄	0.998	C₁₃	0.978	C₂₄	0.328	C₃₅	0.052
n⁃C₄	1.299	C₁₄	0.921	C₂₅	0.272	C₃₆	0.012
i⁃C₅	0.817	C₁₅	0.969	C₂₆	0.249	C₃₇	0.007
n⁃C₅	0.627	C₁₆	0.814	C₂₇	0.216	C₃₈	0.005
C₆	1.419	C₁₇	0.831	C₂₈	0.177	C₃₉	0.003
C₇	1.191	C₁₈	0.692	C₂₉	0.162	C₄₀₊	0

组分	质量分数/%	分子个数
甲烷	74.2	1 700
戊烷	6.5	33
壬烷	3.5	10
正十二烷	2.8	6
环丁烷	3.8	25
环戊烷	4.4	23
苯	1.1	5
甲苯	3.8	15

w（蜡）/%	扩散系数/(cm^-5 $⋅$ s^-1)
5.0	1.240
7.0	1.120
9.0	0.773

w（蜡）/%	扩散系数/(cm^-5 $⋅$ s^-1)
5.0	1.240
7.0	1.120
9.0	0.773

w（沥青质）/%	蜡分子扩散系数/(cm^-5∙s^-1)	沥青质分子扩散系数/(cm^-5∙s^-1)
1.0	0.987	0.140
2.0	0.770	0.317
3.0	0.835	0.290

垢物	蜡分子扩散系数/(cm^-5∙s^-1)	垢扩散系数/ (cm^-7∙s^-1)
CaSO₄垢	1.182	6.480
NaCl垢	1.105	4.890
CaCO₃垢	1.142	1.700
MgSO₄垢	1.115	0.200

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