注烟道气辅助采油过程中的井筒腐蚀规律研究

发布时间：2018-09-14 17:00

【摘要】：随着人们对环境治理力度的加大以及原油价格的上涨,烟道气驱油技术有着很大的发展空间,烟道气主要含有N2和CO_2,驱油机理兼具二氧化碳驱和氮气驱机理,但是烟道气具有很强的腐蚀性,会对油气井内的油管、套管等造成腐蚀。因此深入开展注烟道气的腐蚀机理及其影响因素和腐蚀规律的研究,对于保证油气井的生产寿命具有重要意义。本文模拟烟道气腐蚀的腐蚀环境,采用挂片实验方法,对烟道气腐蚀进行了实验研究,通过烟道气腐蚀产物成分分析和腐蚀产物膜分析,阐述了烟道气腐蚀机理。同时还研究了温度、压力、流速、O_2含量、SO_2含量、SO3含量、HCO3-含量、CO32-含量和Cl-含量对烟道气腐蚀规律的影响,利用关联度分析方法,得到各因素对腐蚀速率的影响,影响从大到小为:温度T、O_2含量、压力P、SO_2含量、Cl-含量、流速V和HCO3-含量。结合烟道气在井筒内的流动与传热,基于相平衡理论和逸度方程,建立井筒内烟道气酸凝结的计算模型,研究烟道气注入井筒的酸凝结规律。通过计算模型,得到了烟道气状态参数和酸凝结规律与烟道气成分(水蒸气含量、SO_2含量)和注入参数(压力、温度、流量)的关系。依据模型计算结果,利用烟道气腐蚀特性测试装置进行烟道气对井筒腐蚀的室内动态实验模拟,研究结果表明,烟道气的状态逐渐从烟道气中水蒸气过热变为烟道气出现酸凝结,最后烟道气干度开始下降,井筒腐蚀速率依次变大,因此要提高酸凝结温度和干度。设计N80钢分别在两种水型(NaCl和NaHCO_3)下的烟道气腐蚀正交实验,以正交实验得到的实验数据为基础,根据遗传算法和BP神经网络原理,建立N80钢分别在两种腐蚀介质(NaCl和NaHCO3)下的烟道气腐蚀速率的BP神经网络预测数学模型,实现了以实验数据为基础的烟道气对N80钢腐蚀速率的预测。
[Abstract]:With the increase of environmental control and the rise of crude oil prices, flue gas flooding technology has a great space for development. Flue gas mainly contains N2 and CO_2, oil displacement mechanism, both carbon dioxide and nitrogen drive mechanism. But the flue gas is very corrosive, it will corrode the tubing and casing in oil and gas well. Therefore, it is of great significance to study the corrosion mechanism, influencing factors and corrosion law of flue gas injection in order to ensure the production life of oil and gas wells. In this paper, the corrosion environment of flue gas corrosion is simulated and the corrosion mechanism of flue gas is described by means of composition analysis of flue gas corrosion product and analysis of corrosion product film. At the same time, the effects of temperature, pressure, flow rate and so _ 2 content, so _ 3 content, CO _ 3- content and Cl- content on the corrosion law of flue gas were studied. By using the method of correlation analysis, the influence of various factors on the corrosion rate was obtained. The effects from big to small are as follows: temperature tio _ 2 content, pressure PSO _ 2 content and Cl-content, flow rate V and HCO3- content. Combined with the flow and heat transfer of flue gas in wellbore, based on the theory of phase equilibrium and fugacity equation, the calculation model of acid condensation of flue gas in wellbore is established, and the law of acid condensation of flue gas injected into wellbore is studied. The relationship between the state parameters of flue gas and the law of acid condensation and the composition of flue gas (water vapor content so _ 2 content) and injection parameters (pressure, temperature, flow rate) is obtained by the calculation model. According to the results of model calculation, the indoor dynamic experiment simulation of flue gas corrosion to wellbore is carried out by using the test device of flue gas corrosion characteristics. The results show that, The state of flue gas gradually changed from steam overheating in flue gas to acid condensation in flue gas. Finally the dry degree of flue gas began to decrease and the corrosion rate of wellbore increased in turn. Therefore the acid condensation temperature and dryness should be increased. The orthogonal experiments of flue gas corrosion of N80 steel under two kinds of water types (NaCl and NaHCO_3) were designed. Based on the experimental data obtained from the orthogonal experiment, according to the principle of genetic algorithm and BP neural network, A mathematical model for predicting the corrosion rate of flue gas of N80 steel under two corrosive media (NaCl and NaHCO3) was established by using BP neural network. The prediction of corrosion rate of N80 steel by flue gas based on experimental data was realized.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE983

【参考文献】