LS油田CO₂驱地面集输系统腐蚀与控制方案研究

【作者】 张勇；

【导师】 刘武； 薛建兴；

【作者基本信息】 西南石油大学 ， 石油与天然气工程（专业学位）， 2018， 硕士

【摘要】 LS油田在LB区块开展CO₂驱先导试验,依据LB C02驱试验部署方案,存在对地面集输管线腐蚀规律研究不到位、腐蚀控制技术待提高等问题。本文针对LS油田C02驱地面集输系统,进行集输工艺及腐蚀规律研究,从缓蚀剂、管线材质、管道内涂层优选等方面,提出相应的控制策略,主要研究工作如下:（1）调查、分析国内外CO₂驱地面集输管线腐蚀控制技术及腐蚀控制情况,包括CO₂驱油集输系统工艺现状、CO₂腐蚀控制技术研究、国内外油田地面集输系统防腐控制情况等。（2）针对CO₂驱受效井采出液和伴生气,对脱水后纯原油和伴生气样品的一般性质和原油黏温特性进行了分析评价,针对涵盖CO₂驱地面集油系统压力至采出井正常生产时压力范围内的CO₂和CH4混合物的水合物生成界限开展了室内试验研究,得到不同CO₂含量条件下的水合物生成曲线;通过对比CO₂干法和湿法回收方法,并与相关技术商开展技术交流,选用MEDA溶剂回收CO₂,设计了一整套CO₂回收工艺流程和设备选用。（3）分析集输管线典型腐蚀失效案例,通过实验研究含水率、CO₂和流速对集输管线的影响,得到集输管线腐蚀规律:低含水率条件下,原油在试样形成一层保护膜,能一定程度上减缓试样的腐蚀,随含水率的升高,原油在试样表面无法形成完整的保护膜,局部腐蚀会加剧;LS油田产出液含水率非常高、流速慢,介质易形成三相的层流状态,管线底部腐蚀会加剧;在LS油田地面系统工况条件下,管材的腐蚀速率随CO₂的含量增大而增大。（4）研究LS油田CO₂驱地面集输系统腐蚀控制技术,形成适用于LS油田的腐蚀控制方案,评价在用缓蚀剂效果,研制缓蚀剂配方,研制的CI-6A缓蚀剂的缓蚀效果在随着浓度加大逐渐升高,在针对LS CO₂驱的腐蚀环境下,当浓度达到200mg/L,缓蚀效果接近最佳,CI-6A缓蚀剂对现场在用破乳剂效果无不良影响,投加缓蚀剂防护时遵循以点带面的原则,均匀连续投加足量的缓蚀剂,并形成了在G43-23转油站加药机制:将缓蚀剂加在掺水泵前,加药浓度为200mg/L,每天需投加缓蚀剂50公斤左右,全年共需缓蚀剂约18吨。（5）提出新建的地面集输管线材质建议:掺水管线使用胺固化玻璃钢管、集油管道为玻璃钢管、进站阀组及油气分离器进出口采用不锈钢材质等;对于已建的地面集输管线建议:在管道碳钢材质的基础上,添加适宜于LS油田地面集输系统的缓蚀剂,评价了在用内涂层适用性,优选了 CO₂驱地面集输管线内涂层。更多还原

【Abstract】 The LS oilfield carried out the CO₂ driving test in the LB block.According to the LB CO₂ driving test plan,there are problems such as the incomplete research on the corrosion law of the ground gathering pipeline and the poor technology of corrosion control.Based on the CO₂ driving ground gathering system of LS oilfield,this paper studies the gathering process and corrosion law.The control strategies are proposed from the aspects of corrosion inhibitor,pipeline material and pipeline inner coating.The main research work is as follows:（1）Investigate and analyze the corrosion control technology and corrosion control of CO₂ driving ground gathering pipelines domesitc and abroad,including the current status of CO₂ driving and gathering systems,C02 corrosion control technology research,and anti-corrosion control of oilfield ground gathering systems domestic and abroad.（2）For the C02 drving well production fluid and associated gas,the general properties of the dewatering crude oil and associated gas samples and the viscosity and temperature characteristics of the crude oil were analyzed and evaluated.From the CO₂ driving ground oil collection system pressure to the production well normal pressure,the hydrate formation limit of the mixture of CO₂ and CH4 was carried out in an indoor experimental study.And obtained the hydrate formation curve under different CO₂ content conditions.By comparing the CO₂ dry method and the wet recovery method with the technology of related manufacturers Exchange,decided to use MEDA solvent to recover CO₂.And designing a complete set of CO₂ recycling process and equipment selection.（3）By Analysing the typical corrosion failure case of the gathering pipeline and studing the influence of water content,CO₂ and flow rate on the gathering pipeline through experiments,and obtained the corrosion law of the gathering pipeline:under the condition of low water content,the crude oil forms a protective film on the sample.So It can slow down the corrosion of the sample to some extent.With the increase of water content,the crude oil can not form a complete protective film on the surface of the sample,and local corrosion will be intensified.The water content of the produced liquid in LS oil field is very high,the flow rate is slow.And the medium is easy to form a laminar flow state of three phases.So the corrosion at the bottom of the pipeline will be intensified.Under the conditions of the ground system of the LS oilfield,the corrosion rate of the pipe increases with the increase of the CO₂ content.（4）By studing the corrosion control technology of CO₂ driving ground gathering and transportation system in LS oilfield,forming a corrosion control scheme suitable for LS oilfield.Evaluating the effect of corrosion inhibitor,developing corrosion inhibitor formula.The effect of the CI-6A corrosion inhibitor increases gradually with increasing concentration.Under the corrosive environment for LS CO₂ driving,when the concentration reaches 200mg/L,the corrosion inhibition effect is close to the best.And the CI-6A corrosion inhibitor has no effect on the demulsifier.Following the principle of point-to-face when adding corrosion inhibitor protection,uniformly and continuously adding a sufficient amount of corrosion inhibitor.And forming a dosing mechanism at G43-23 oil station:adding the corrosion inhibitor before the water pump.The concentration of the drug is 200mg/L.About 50kg of corrosion inhibitor is needed every day.And about 18 tons of corrosion inhibitor is needed for the whole year.（5）Proposing materials for new ground gathering pipelines:using ammonia-cured glass pipes for water-mixing pipelines,glass-steel pipes for oil-filled pipelines.Using stainless steel for inlet valve blocks and import and export of oil and gas separators,etc.Suggestions for the pipeline:on the basis of the carbon steel material of the pipeline,a corrosion inhibitor suitable for the ground gathering system of the LS oilfield is added.And the applicability of the inner coating is evaluated and the inner coating of the CO₂ driving ground gathering pipeline is optimized.更多还原