液态二氧化碳注入井环空带压规律研究  

Performance study on sustained annular pressure in liquid CO_(2)injector

作　　者：王发清[1] 秦德友[1] 王鹏[1] 王方智 余福春[2] WANG Faqing;QIN Deyou;WANG Peng;WANG Fangzhi;YU Fuchun(PetroChina Tarim Oilfield Company,Korla Xinjiang 841000,China;SINOPEC Shengli Petroleum Engineering Tarim Company,Korla Xinjiang 841000,China)

机构地区：[1]中国石油塔里木油田分公司,新疆库尔勒841000 [2]中国石化胜利石油工程有限公司塔里木分公司,新疆库尔勒841000

出　　处：《石油化工应用》2022年第7期29-33,53,共6页Petrochemical Industry Application

基　　金：塔里木油田目的层溢流、漏喷转换在用处置方法评估与提升,项目编号:201019111038。

摘　　要：二氧化碳注入是CCUS(碳捕集、利用与封存)技术的重要组成环节,而将其以液态注入地下则是一种常用的消减温室气体、提高原油采收率工艺。在注入过程中,由于液态二氧化碳造成的井下恶劣环境导致的井筒失效问题日益突出,严重危及生产安全。在总结某油田液态二氧化碳注入实践的基础上,针对油管柱泄漏与否,用商业软件OLGA反演出三条规律。当油管柱未发生漏失,由于注入二氧化碳的低温效应,使得整个井筒温度剖面均低于地温,故环空压力会因其内的保护液冷却收缩而降低。当油管柱存在一处漏失点时,漏点越浅,井口套压值越高,直至接近于注入油压。当先后出现两处泄漏时,液态二氧化碳总是从浅的漏点由油管漏入环空,与此同时,环空保护液从深的漏点流入油管;到泄漏终止时,各漏失点处环空与油管压力达到平衡,漏点以上的环空全部为液态二氧化碳所充填,井口套压与注入油压持平,且与两漏点的位置无关。本研究成果便于快速评价环空安全风险等级,为二氧化碳注入井的完整性评价、修井作业安全提供技术支撑。Carbon dioxide injection is an integral part of CCUS(Carbon Capture,Utilization and Storage).It is commonplace to inject CO_(2) in liquid state both to mitigate greenhouse gas and enhance oil recovery.During carbon dioxide injection,the problem of wellbore failure due to the harsh enivonment caused by liquid carbon dioxide becomes increasing ly prominent,which seriously endangers production safety.After reviewing CO_(2) injection practices in an oilfield,three conclusions are arrived at,utilizing a commercial software OLGA.For a non-leaky tubing string,low temperature CO_(2) injection leads to wellbore flowing temperatures being less than ambient ones.Therefore packer fluids contract in annulus because of low temperatures,resulting a fall in casing pressures.For a single leak on tubing pipe,the nearer to wellhead it is,the higher wellhead casing pressure develops,with the minimum being following injection tubing pressure.For double leaks occurred sequentially,liquid CO_(2) ingresses into annulus through the upper leak,packer fluid seeps into tubing strings concurrently.At the end of leakage,pressure is balanced on either side of the flow path for both leaky locations,filling the annulus with clean pure CO_(2).Upon its stable condition,wellhead casing pressure is equal to flowing tubing pressure,regardless of where any of these two leaks are located.This study is vital to quick annular pressure safety ranking,integrity appraisal of liquid CO_(2) injectors,well control during stimulation operations.

关 键 词：CCUS 管柱泄漏 二氧化碳注入井 完整性 

分 类 号：TE357.45[石油与天然气工程—油气田开发工程]